Synthesis of Sulfo-Phenylated Terphenylenes: Molecules, Polymers and Copolymers

by Thomas Joseph Gilbert Skalski

M.Sc. (Chimie), Université de Montréal, Québec, Canada, 2013 M.Sc. (Chimie), Université de Lille 3, Villeneuve d’Ascq, France, 2010 B.Sc (Chimie), Faculté des Sciences Jean Perrin, Lens, France, 2008

Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy

in the Department of Chemistry Faculty of Science

©Thomas Skalski 2019 SIMON FRASER UNIVERSITY Spring 2019

Copyright in this work rests with the author. Please ensure that any reproduction or re-use is done in accordance with the relevant national copyright legislation. Approval

Name: Thomas Joseph Gilbert Skalski Degree: Doctor of Philosophy Title: Synthesis of Sulfo-Phenylated Terphenylenes: Molecules, Polymers and Copolymers Examining Committee: Chair: Robert Brittron Professor Steven Holdcroft Senior Supervisor Professor Hua-Zhong (Hogan) Yu Supervisor Professor Jeff Warren Supervisor Assistant Professor Peter Wilson Internal Examiner Associate Professor Cathleen Crudden External Examiner Professor Chemistry Queen’s University

Date Defended/Approved: April 16th, 2019

ii Abstract

This thesis reports the synthesis and study of a new class of fluorine-free, acid-bearing polymers for potential usage in proton exchange membrane fuel cells. The polymers were prepared via the synthesis of a pre-sulfonated monomer, followed by homo- and copolymerization by [4+2] Diels-Alder cycloaddition. Molecular structures were determined by mass spectrometry, infrared spectroscopy, 1H NMR and 2D COSY spectroscopies, and single crystal X-ray diffraction.

Disulfonated tetracyclone and tetrasulfonated bistetracyclone molecules were used to synthesize two model compounds to determine the potential isomers present. Tetrasulfonated bistetracyclone was polymerized with 1,4-diethynylbenzene co-monomer. + The resultant polymer, sPPP-HNEt3 , was prepared with a high molecular weight and converted into its acid form, prior to casting as a membrane. The membranes possessed a high ion exchange capacity (IEC) of 3.49 meq/g and a proton conductivity of 118 mS/cm at room temperature and at 95% relative humidity (RH), respectively, four and a half time superior as the current benchmark NRE 211®. The polymer film was found to become soluble during exposure to aggressive oxidative solutions no significant chemical changes were observed.

The final part of this work focused on increasing the polymer film stability by judiciously tuning the hydrophilic content of the polymer. A family of random-copolymers was prepared based on the above monomers. The parameters for polymerization were studied and the optimal conditions were found using size exclusion chromatography to determine molecular weight. The measured IEC for these copolymers correlated well with the theoretical IEC, ranging from 1.86 to 3.50 meq/g. The conductivity of these polymers at 80°C and 95% RH was found to reach 338 mS/cm. Fuel cell tests were performed using the membranes and provided a peak power density of 770 mW/cm2.

Keywords: Prefunctionalized monomers; Hydrocarbon polymer; polyphenylenes Diels-Alder Cycloaddition; Electrophilic aromatic substitution; Proton- exchange membranes; Fuel cells; 1H NMR polymer characterization ; ion- exchange membranes

iii Dedication

To my soulmate Benita, my parents Hervé & Véronique, and my grandmother Paulette who have supported and believed in me and allowed me to be where I stand today.

To the great scientist who claimed, “don’t add too many benzene rings, you might decrease the oxidative durability of the polymer backbone”.

For those few who did not believe in me: the Maréchal Cambronne said it all.

iv Acknowledgements

All of this work would not have be possible without the great help and guidance from my senior supervisor Prof. Steven Holdcroft who accepted my application into his group in 2012. He gave me the opportunity to work in a new field, he supported my ideas, and he allowed me to do my research. I am thankful for his patience, his endless help, and the motivation he provided throughout the years, and for the relaxing moments we had after our successes.

I thank and acknowledge the following people:

My supervisory committee members, Prof. Hogan Hu and Prof. Jeffrey Warren for their supervision, advice and motivation to help me to finish these projects.

Dr. Timothy J. Peckham, ex-lab manager of the team who was always there to talk, and to provide advice, motivation and jokes throughout the years.

All my professors and teachers at SFU, especially Prof. Vance William and Daniel Leznoff, who were patient and enhanced my curiosity for research through their classes.

Professor Barbara Frisken and Eric Schlibi from the Department of Physics, SFU, for help in characterizing our materials using the X-ray facility at SFU and Docteur Sandrine Lyonnard for the neutron scattering studies performed in Grenoble, France.

SFU staff members, Nathalie Fournier, Amber Schroeder, Jen Jackson, Shirley Purdon, and Hamel Tailor.

Drs. Julie Lunniss, Uwe Kreis, and Dev Sharma, who were always there and helpful during my teaching duties; and members of the teaching laboratory, Paul Saunders, Pingping Zhang, and Paul Mulyk.

Members of the mass spectrometry and nuclear magnetic resonance group: Drs. Hongwen Chen, Yilin (Colin) Zhang, Andrew Lewis, and Eric Ye.

Members of the “Centre Régionale de Spectrometrie de Masse de l’Université de Montréal”, including Dr Alexandra Furtos-Matei and Marie-Christine Tang for their help characterizing difficult compounds.

v Members of the Catalysis Research for Polymer Electrolyte Fuel Cells (CARPE FC) network: Dr. Kunal Karan of the University of Calgary, and Dr. Gillian Goward of McMaster University.

Some of my best friends whom I met at SFU: Dr. Takashi Mochizuki, for his help in the characterization of polymer membranes. Dr. Hsu-Feng Lee, my true friend. Dr Chi (Ben) Zhang for the great times we had in and outside the lab, and for his advice during my PhD studies. Dr. Thomas Weissbach, who showed me that patience and perseverance are the two masterpieces in graduate school. Dr. David Novitski, a true helping friend, always there for anything and everything. Dr. Jiantao Fan, with whom I did great chemistry for three years and who showed me the side of the AEM-FC. Dr. Benjamin Britton, for the nights and weekends he spent running fuel cell tests on my materials. Owen Thomas who showed me the way in the laboratory when I arrived and gave me precious advice on my projects. Ania Sergeenko for her help and teaching me XRD, which I wanted to learn for years. Patrick Fortin, a true supporting friend and brew master, who gave me the virus of brewing. Mike Adamski, my friend and co-worker, who succeeded in a part of my project I didn’t have the time to do, and who helped me to compile all the data at the end of my studies.

The current members of the Holdcroft group and those who have left, including Lukas Metzler and Elizabeth Kitching for all the fun time we had together.

My current and past family, from France and my second family in Vancouver for their love, support, motivation and proof reading, despite the fact that this thesis was not one of their favourite books on the nightstand.

vi Table of Contents

Approval ...... ii Abstract ...... iii Dedication ...... iv Acknowledgements ...... v Table of Contents ...... vii List of Tables ...... xi List of Figures ...... xii List of Acronyms ...... xviii

Chapter 1. Introduction ...... 1 1.1. History of the Fuel Cell ...... 1 1.2. Polymer Electrolyte Membranes ...... 3 1.2.1. Proton Exchange Membrane for Fuel Cell (PEM-FC) ...... 4 1.2.2. Perfluorosulfonated acid ionomer PEMs ...... 4 1.2.3. Non-Fluorinated PEMs ...... 6 1.2.4. Poly(phenylene) PEMs ...... 7 1.3. Electrochemistry of PEMFCs ...... 9 1.3.1. Proton Transport Mechanism ...... 9 1.4. Degradation: Oxidative Stability ...... 11 1.5. Synthetic routes ...... 13 1.5.1. Organometallic Cross-Couplings: Sonogashira Cross-coupling ...... 13 1.5.2. Oxidation of the Carbon-Carbon Triple Bonds ...... 16 1.5.3. Protiodesilylation of Alkynes ...... 19 1.5.4. Knoevenagel Condensation ...... 22 1.5.5. Electrophilic Aromatic Substitution ...... 25 1.5.6. [4+2] Diels-Alder Cycloaddition ...... 29 1.6. Thesis Scope ...... 38

Chapter 2. Techniques and Methods ...... 40 2.1. Nuclear Magnetic Resonance (NMR) ...... 40 2.1.1. 1D NOE ...... 40 2.1.2. 2D COSY ...... 41 2.2. Size Exclusion Chromatography ...... 43 2.3. Polycondensation of AA and BB Monomers ...... 46 2.4. Properties of Polymer Membrane ...... 47 2.4.1. Polymer Casting ...... 47 2.4.2. Ion Exchange Capacity (IEC) ...... 47 2.4.3. Hydrolytic Stability ...... 49 2.4.4. Water Uptake (WU) and Water Content (WC) ...... 49 2.4.5. Volume Uptake (VU) ...... 49 2.4.6. Water Sorption (λ) ...... 50 2.4.7. Acid Concentration ([SO3H]) ...... 50

vii 2.4.8. Effective Proton Mobility (μeff) ...... 50 2.4.9. Proton Conductivity (σ) ...... 51 2.4.10. Polarization Curve and Fuel Cell Efficiency ...... 53

Chapter 3. Model Compounds ...... 55 3.1. An Introduction to Tetracyclones and Bistetracyclones ...... 55 3.2. Synthesis of the Diene: Sulfonation of the Tetracyclone ...... 59 3.2.1. Materials ...... 60 3.2.2. Equipment ...... 61 3.2.3. Strategy ...... 62 3.2.4. Synthesis of Tetracyclone (TC) ...... 62 3.2.5. Functionalization of TC ...... 63 3.2.6. Synthesis of 4,4’-(2-oxo-4,(-diphenylcyclopenta-3,5-diene-1,3- diyl)dibenzenesulfonic acid (sTC(H+)) ...... 65 3.2.7. Characterization of sTC(H+) ...... 65 3.2.8. Crystal Structure of the sTC(H+) ...... 67 3.2.9. Protection of the Sulfonic Acid: Synthesis of bis triethylammonium + Tetracyclone Disulfonate (sTC(HNEt3 )) ...... 68 3.3. Synthesis of the Bis-diene: Functionalization of Tetrasulfonated Bistetracyclone 71 3.3.1. Synthetic Plan ...... 72 3.3.2. 1,4-Bis(phenylethynyl)benzene ...... 72 3.3.3. Oxidation of the 1,4-Bis-(phenylethynyl)benzene ...... 73 Part A: Oxidation Using Iodine/DMSO ...... 73 Part B: Oxidation Using KMnO4/DCM ...... 74 3.3.4. Bistetracyclone (BTC) ...... 75 3.3.5. Synthesis of Tetrasulfonic Acid Bistetracyclone (sBTC(H+)) ...... 75 3.3.6. Characterization of sBTC(H+) ...... 76 + + 3.3.7. Protection of sBTC(H ): Synthesis of sBTC(HNEt3 ) ...... 81 + 3.3.8. Characterization of sBTC(HNEt3 ) ...... 82 3.4. Synthesis of Dienophiles ...... 84 3.4.1. 1,4-Bis(trimethylsilylethynyl)-benzene ...... 85 3.4.2. 1,4-Diethynylbenzene ...... 86 3.4.3. 4,4’-Bis((trimethylsilyl)ethynyl)-1,1’-biphenyl ...... 86 3.4.4. 4,4’-Diethynyl-1,1’-biphenyl ...... 87 3.4.5. ((4-Bromophenyl)ethynyl)triisopropylsilane ...... 88 3.4.6. Triisopropyl((4-((trimethylsilyl)ethynyl)phenyl)ethynyl)silane ...... 89 3.4.7. ((4-Ethynylphenyl)ethynyl)triisopropylsilane ...... 90 3.4.8. Characterization of the Dienophiles ...... 90 3.5. Application of the [4+2] Diels-Alder Cycloaddition for the Synthesis of Model Compounds ...... 91 3.6. Synthesis of Model Compounds ...... 94 + 3.6.1. 2',3',5'-Triphenyl-[1,1':4',1''-terphenyl]-4,4''-Disulfonic Acid (DAsTC(HNEt3 )- Ph) 94 + 3.6.2. 2DAsTC(HNEt3 )-1.4-bz ...... 95 + 3.6.3. 2DAsBTC(HNEt3 )-Ph ...... 96

viii 3.6.4. DATC-TIPS ...... 97 3.6.5. DATC-CCH ...... 98 3.6.6. 2DABTC-TIPS ...... 99 3.6.7. 2DABTC-CCH ...... 99 + 3.6.8. DA-sTC(HNEt3 )-p-DATC ...... 100 + 3.6.9. 2DATC-sBTC(HNEt3 ) ...... 101 + 3.6.10. 2DAsTC(HNEt3 )-BTC ...... 102 + 3.6.11. 2DAsTC(HNEt3 )-Biph ...... 102 3.6.12. 3',6'-Diphenyl-1,1':2',1''-terphenyl (DATC) ...... 103 3.6.13. 2',3'-Diphenyl-[1,1':4',1''-terphenyl]-4,4''-disulfonic acid, DAsTC(H+) ...... 104 3.7. Characterization and Discussion of the Models Compounds...... 104 3.8. Conclusion ...... 115

Chapter 4. Structurally-Defined, Sulfo-Phenylated, Oligophenylenes and Polyphenylenes ...... 116 4.1. Introduction ...... 116 4.2. Instrumentation and Methods ...... 118 4.3. Materials ...... 118 4.4. Synthesis ...... 119 4.4.1. Tetracyclone 3 ...... 119 4.4.2. 4,4'-(2-Oxo-4,5-diphenylcyclopenta-3,5-diene-1,3-diyl)dibenzenesulfonic acid,4. 120 4.4.3. Bis-triethylammonium cyclone disulfonate, 5: ...... 120 4.4.4. Bistetracyclone, 7 ...... 121 4.4.5. Tetra(para-sulfonated) Bistetracyclone, 8 ...... 122 4.4.6. Tetra Triethylammonium Tetra(para-sulfonated) Bistetracyclone 9 ...... 123 4.4.7. 1,4-Bis(trimethylsilylethynyl)-benzene, 12 ...... 124 4.4.8. 1,4-Bis-ethynylbenzene, 13...... 125 4.4.9. Compound 14 ...... 125 4.4.10. Compound 16...... 126 + 4.4.11. sPPP-HNEt3 ...... 127 4.4.12. sPPP-H+ ...... 128 4.4.13. Membrane Casting ...... 129 4.4.14. Fenton’s Reagent Test Procedure ...... 129 4.4.15. Ex-situ Characterization of Membranes ...... 130 4.4.16. Fuel Cell Tests Analyses ...... 131 4.5. Results and Discussion ...... 133 4.6. Conclusion ...... 144

Chapter 5. Sulfo-phenylated Terphenylene Copolymer Membranes and Ionomers 145 5.1. Introduction ...... 145 5.2. Experimental ...... 149 5.2.1. Methods and Equipment ...... 150 5.2.2. Materials ...... 151

ix 5.2.3. Syntheses ...... 152 5.2.4. General Procedure for the Syntheses of sPPP(m)-H+ ...... 152 Membrane Preparation and Characterization ...... 153 Mechanical Properties ...... 154 Dimensional Stability, Ion Exchange Capacity, and Water Sorption ...... 154 Membrane Stability ...... 154 Proton Conductivity (σ) ...... 155 Fuel Cell Characterization ...... 155 5.3. Results and discussion ...... 156 5.3.1. Synthesis, Casting and Characterizations ...... 156 5.3.2. Membrane Stability ...... 164 5.3.3. Analyses in Fuel Cells ...... 165 5.4. Conclusions ...... 169

Chapter 6. Exploratory Projects and Future Work ...... 170 6.1. Ionic and Covalent Crosslinking ...... 170 6.1.1. Ionic Crosslinker in the Polymeric Backbone ...... 170 6.1.2. Ionic Crosslinker as an Additive...... 172 6.1.3. Covalent Crosslinking ...... 172 6.2. Reviewing the Polymerization of sPPP(m)(y) ...... 173

Chapter 7. Conclusion ...... 176

References ...... 178

Appendix. Supporting Information ...... 201

x List of Tables

Table 1: Different Types of Fuel Cells, Temperature of Operation, Reaction, and the Ion Carrier. Adapted with Permission Spinger Nature, © 2010, PEM Fuel Cells and their Related Electrochemical Fundamentals. In: Electrochemical Impedance Spectroscopy in PEM Fuel Cells. Springer, London.4 ...... 2 Table 2: Different Examples and their Composition of Perfluorinated Polymers Containing Sulfonic Acids on the Side Chain Currently Used in Fuel Cells...... 6 Table 3: Proposed Radical Formation During the Fuel Cell Operation, with and without the Presence of Iron. Reprint with Permission from Lorenz Gubler, Sindy M. Dockheer, and Willem H. Koppenol, Journal of The Electrochemical Society, 158(7), B755-B769, Copyright (2011) The Electrochemical Society.73 ...... 12 Table 4: Mechanism of Decomposition of Hydrogen Peroxide in the Presence of Iron(III). Adapted with Permission from Joseph De Laat, Hervé Gallard, Environmental Science and Technology, 33 (16), 2726-2732, Copyright (1999) American Chemical Society.74 ...... 12 Table 5: Examples of Sulfonating Reagents and some of their Reactivity Properties. Reprinted with Permission of Maier, G.; Meier-Haack, J. Adv. Polym. Sci., 216: 1–62, ©2008 Springer.135 ...... 26 Table 6: Effect of Electronic Substituents on a Benzene Ring and their Strength as Donating or Withdrawing Groups ...... 28

Table 7: Adjustment of the Stoichiometry using TMSO-SO2Cl for EAS of the TC 64 Table 8: Mono and Poly Ionized Ions of the sBTC(H+) Observed by High Resolution Mass Spectrometry...... 79 + Table 9: Chemical Shift of the Proton of sBTC(H ) in DMSO-d6 from 298K to 353K...... 81 Table 10: Investigation of [4+2] Diels-Alder Cycloaddtion using the sTC(X) as the Diene and Different Dienophiles at Different Temperature for Different Lenghts of Time...... 92 + Table 11: Yield and Molecular Weights (in Daltons) of (a) sPPP(m)-HNEt3 , and (b) sPPP(m)-H+, as Determined by SEC in DMF...... 158 Table 12: Mechanical Properties of sPPP(m)-H+ Copolymers under Ambient Conditions Compared to Nafion NR-211...... 160 Table 13: Properties of sPPP(m)-H+ Membranes...... 162

xi List of Figures

Figure 1.1: Components of a PEMFC. Adapted with permission Spinger Nature, © 2010, PEM Fuel Cells and their Related Electrochemical Fundamentals. In: Electrochemical Impedance Spectroscopy in PEM Fuel Cells. Springer, London.4 ...... 3 Figure 1.2: Chemical structure of perfluorosulfonated acid ionomer (PFSA)...... 5 Figure 1.3: Different building blocks used to create poly(arylenes)...... 7 Figure 1.4: Simplified mechanisms of proton transport in an hydrated PEM references nb. Adapted with permission authors Journal of Polymer Science, Part B Polymer Physics (2006), 44(16), 2183, © 2006 John Wiley & Sons, Inc.68 ...... 10 Figure 1.5: 2- and 4-electron pathways for the oxygen reduction reaction. Adapted with permission of Journal of Power Source, Wang, B., 152, 1, © 2005 Elsevier B.V.71 ...... 11 Figure 1.6: Proposed mechanism for the Kumada reaction...... 14 Figure 1.7: Proposed mechanism for Sonogashira cross-coupling...... 15 Figure 1.8: Oxidative product expected from the oxidation of the 1,2-diphenylethyne...... 17

Figure 1.9: Proposed mechanism for the oxidation of the 1,2-diphenylethyne with I2- DMSO...... 17 Figure 1.10: Proposed oxidation mechanism of the 1,2-diphenylethyne using permanganate...... 18 Figure 1.11: Two synthetic routes to protect the propargyl alcohol with trimethylsilane: a): via lithiation and pathway, b): via Grignard reagent...... 19 Figure 1.12: Examples of silane protecting groups used for the protection of alkynes...... 20 Figure 1.13: Protiodesilylation of the TMS, TES, TIPS, and BDIPS protecting groups...... 20 Figure 1.14: Proposed mechanism for the protiodesilylation of the 1-trimethylsilyl-2- phenyl-acetylene...... 21 Figure 1.15: a) Examples of selective deprotection used by Ivachtchenko et al.125, i)MeLi-LiBr, Et2O, RT, 15h; b) impact of the nucleophile used for the selective deprotection of a terminal acetylene, ii) was used by Höger et 127 al. : K2CO3, MeOH/THF, 8h, iii) TBAF, THF, 4h...... 22 Figure 1.16: Knoevenagel condensation...... 22 Figure 1.17: Proposed Knoevenagel reaction mechanism between benzaldehyde and malononitrile under basic conditions, reported by Formentin et al.130 ..... 23 Figure 1.18: Proposed mechanism for the synthesis of the tetracyclone...... 24 Figure 1.19: Proposed mechanism for the nitration of an aromatic ring...... 25 Figure 1.20: Proposed mechanism for the sulfonation of a benzene ring by EAS...... 26 Figure 1.21: Proposed mechanism for the sulfonation of benzene using trimethylsilyl chlorosulfonate...... 27

xii Figure 1.22: Condensation of the buta-1,3-diene with the naphthalene-1,4-dione which lead to the discovery of Diels and Alder.42 ...... 30 Figure 1.23: Elementary structure of a diene and dienophile...... 30 Figure 1.24: Structures of dienes and their configuration, which modify their reactivity for [4+2] Diels-Alder cycloaddition.161 ...... 31 Figure 1.25: Dienophiles with and without heteroatoms...... 32 Figure 1.26: Proposed intermediate state during the cycloadditon of the buta-1,3-diene and the maleic anhydride...... 32 Figure 1.27: Scheme showing that different regio-isomers can be formedduring the [4+2] Diels-Alder cycloaddition...... 33 Figure 1.28: Proposed addition mechanism of the dienophile on the diene, based on suprafacial or antarafacial addition...... 33 Figure 1.29: Four addition mechanisms for [4+2] Diels-Alder cycloaddition for the reaction between the penta-1,3-diene and the propyl-acrylate...... 34 Figure 1.30: Additons mechanisms between the maleic anhydride and the cyclopentadiene...... 35 Figure 1.31: Example of a “domino” reaction between a double diene and a double dienophile...... 36 Figure 1.32: Energy diagrams of a diene and dienophile...... 37 Figure 1.33: Inverse and normal Diels-Alder reactions based on the energy levels engaged in the reaction ...... 37 Figure 1.34: Proposed structure of a new sterically encumbered, pre-sulfonated difunctionalized monomer: sBTC(H+) ...... 38

Figure 2.1: Example of 2D COSY NMR spectrum of nitrobenzene in DCM-d2...... 42 Figure 2.2: Example of a Nyquist plot. Modified with permission Spinger Nature, © 2010, PEM Fuel Cells and their Related Electrochemical Fundamentals. In: Electrochemical Impedance Spectroscopy in PEM Fuel Cells. Springer, London.4 ...... 51 Figure 2.3: Schematic representation of a Randles cell with electronic componants...... 52 Figure 2.4: Set up for measuring the EIS. Modified with permission from Journal of electroanalytical Society, Soboleva, T.; Xie, Z.; Shi, Z.; Tsang, E., Navessin, T.; Holdcroft, S. 622, 145, © 2008, Elsevier B.V.175 ...... 52 Figure 2.5: Representative polarization curve for a PEMFC. Modified with permission of Larminie, J.; Dick, A. Fuel cell systems explained, © 2003 John Wiley & Sons Limited.177 ...... 54 Figure 3.1: Schematic preparation of the tetraphenylcyclopentenolone (upper product) proposed by Henderson et al. in 1901 and the 2,3,4,5- tetraphenylcyclopenta-2,4-dienone (lower product) by Ziegler et al. and Loewenbein et al in 1925...... 56 Figure 3.2: Adducts and intermediates (isomers of position) obtained by the Diels- Alder reaction from the TC and the phenylacetylene before the carbon monoxide extrusion...... 57

xiii Figure 3.3: Synthesis of the poly-para-phenylene (PPP) firstly made by Reid et al. using cis-b-dekalol for 24h and the two further post functionalization made by VanKerckoven et al49 and Fujimoto et al.55 ...... 58 Figure 3.4: General structure of the diene (red) and dienophile (green) used in this work...... 62 Figure 3.5: Synthesis of tetracyclone...... 62 Figure 3.6: Resonance structures of tetracyclone...... 64 Figure 3.7: Synthesis of 4,4’-(2-oxo-4,(-diphenylcyclopenta-3,5-diene-1,3- diyl)dibenzenesulfonic acid (sTC(H+))...... 65 1 + Figure 3.8: H NMR (DMSO-d6) spectrum of sTC(H )...... 67 Figure 3.9: X-ray crystal structure of the sTC(H+) co-crystalized with diethylamine (ellipsoids set at 50% probability)...... 68 Figure 3.10: Synthesis of bis triethylammonium cyclone disulfonate...... 69 1 + Figure 3.11: Stack of H NMR spectra of the TC (DCM-d2), sTC(H ) (DMSO-d6) and + sTC(HNEt3 ) (DMSO-d6)...... 70 + + Figure 3.12: Thermogram of sTC(H ) and sTC(HNEt3 ) under nitrogen between ambient temperature and 600°C using a heating rate of 2°C/min...... 71 + Figure 3.13: Synthetic route to sBTC(HNET3 )...... 72 Figure 3.14: Synthetic route to 1,4-bis(phenylethynyl)benzene...... 72 Figure 3.15: Synthesis of bisbenzil using iodine/dimethylsulfoxide...... 73 Figure 3.16 Synthesis of bisbenzil using potassium permanganate/ dichloromethane...... 74 Figure 3.17: Synthesis of bistetracyclone...... 75 Figure 3.18: Synthesis of tetrasulfonic acid bistetracyclone (sBTC(H+))...... 75 1 + Figure 3.19: H NMR (DMSO-d6) spectrum of sBTC(H )...... 77 + Figure 3.20: COSY (2D) NMR (DMSO-d6) spectrum of sBTC(H )...... 78 Figure 3.21: Possible conformation of sBTC(H+) in solution...... 79 Figure 3.22: Possible intramolecular rotation of sBTC(H+)...... 80 1 + Figure 3.23: H NMR (DMSO-d6) stack spectra of sBTC(H ) from 298 K to 353K...... 80 + Figure 3.24: Synthesis of sBTC(HNEt3 )...... 81 1 Figure 3.25: H NMR stack (DCM-d2 in red, DMSO-d6 in green and blue) of BTC, + + sBTC(H ) and sBTC(HNEt3 )...... 83 + + Figure 3.26: Stacked of thermograms of BTC, sBTC(H ) and sBTC(HNEt3 ) between 30°C and 600°C under a nitrogen atmosphere...... 84 Figure 3.27: Synthesis of 1,4-bis(trimethylsilylethynyl)-benzene...... 85 Figure 3.28: Synthesis of 1,4-diethynylbenzene...... 86 Figure 3.29: Synthesis of 4,4’-bis((trimethylsilyl)ethynyl)-1,1’-biphenyl...... 86 Figure 3.30: Synthesis of 4,4’-diethynyl-1,1’-biphenyl...... 87 Figure 3.31: Synthesis of ((4-bromophenyl)ethynyl)triisopropylsilane...... 88 Figure 3.32: Synthesis of triisopropyl((4-((trimethylsilyl)ethynyl)phenyl)ethynyl)-silane...... 89

xiv Figure 3.33: Synthesis of ((4-ethynylphenyl)ethynyl)triisopropylsilane...... 90 Figure 3.34: Synthesis of model compound, DAsTC(X)Ph, and investigation of the parameters for [4+2] Diels-Alder cycloaddtion using sTC(X)...... 92 Figure 3.35: Structure made by Ried et al in 1966 and the derivative attemped in this thesis work...... 93 Figure 3.36: Synthesis of2',3',5'-triphenyl-[1,1':4',1''-terphenyl]-4,4''-disulfonic acid + (DAsTC(HNEt3 )-Ph ...... 94 + Figure 3.37: Synthesis of 2DAsTC(HNEt3 )-1,4-bz...... 95 + Figure 3.38: Synthesis of 2DAsBTC(HNEt3 )-Ph...... 96 Figure 3.39: Synthesis of DATC-TIPS...... 97 Figure 3.40: Synthesis of DATC-CCH...... 98 Figure 3.41: Synthesis of 2DABTC-TIPS...... 99 Figure 3.42: Synthesis of 2DABTC-CCH...... 99 + Figure 3.43: Synthesis of DA-sTC(HNEt3 )-p-DATC...... 100 + Figure 3.44: Synthesis of 2DATC-sBTC(HNEt3 )...... 101 + Figure 3.45: Synthesis of 2DAsTC(HNEt3 )-BTC...... 102 + Figure 3.46: Synthesis of 2DAsTC(HNEt3 )-Biph...... 102 Figure 3.47: Synthesis of 3',6'-diphenyl-1,1':2',1''-terphenyl (DATC)...... 103 Figure 3.48: Synthesis of 2',3'-diphenyl-[1,1':4',1''-terphenyl]-4,4''-disulfonic acid, DAsTC(H+)...... 104 + Figure 3.49: Two possible conformations of the 2DAsTC(HNEt3 ) in solution. Molecules are represented without their cations. The upper right sulfonic acids, on the A, are voluntary bent to facilitated the view...... 105 Figure 3.50: Two possible additions of the dienophile on the diene on one side of the sBTC. The molecules are represented without their counter ions...... 106 Figure 3.51: Six possible isomers of position who could be obtained after the [4+2] Diels Alder cycloaddition and the carbon monoxide extrusion. The molecules are shown without their counter ions. On the bottom row, the sulfonic acids are drawn to provide a better view...... 107 Figure 3.52: Synthesis of 2DABTC-Ph from Shifrina et al.171 Second row, three different isomers that can be produced: p,p’; m-p’ ; and m,p’...... 108 1 Figure 3.53: H NMR (TCE-d2) spectrum at 130°C of the mixture of isomers of the 2DABTC-Ph, in the box. The m,m’-2DBTC-Ph was identified by Shifrina et al.54 ...... 109 Figure 3.54: Proposed mechanism of the Diels-Alder reaction between TC and norbornadiene followed by two retro the Diels-Alder reaction : elimination of cyclopentadiene and CO extrusion...... 113 Figure 4.1: Synthesis of sulfo-phenylated dienes and polyphenylene homopolymer + sPPP(H ). i) KOH/EtOH, reflux; ii) Me3SiOSO2Cl, 1,2-C2H4Cl2; iii) NEt3, n- BuOH; iv) PhNO2: sand bath (180 °C, 12 h) or microwave reactor (195 °C, 2 h) v) 2 M KOH; vi) 0.5 M H2SO4...... 117 Figure 4.2: Synthesis of tetracyclone, 3...... 119 Figure 4.3: Synthesis of cyclone disulfonic acid, 4...... 120

xv Figure 4.4: Synthesis of bis triethylammonium cyclone disulfonate, 5...... 120 Figure 4.5: Synthesis of bistetracylcone, 7...... 121 Figure 4.6: Synthesis of tetra(para-sulfonated) bistetracyclone, 8...... 122 Figure 4.7: Synthesis of tetra triethylammonium tetra(para-sulfonated) bistetracyclone, 9...... 123 Figure 4.8: Synthesis of 1,4-bis(trimethylsilylethynyl)-benzene, 12...... 124 Figure 4.9: Synthesis of 1,4-bis-ethynylbenzene, 13...... 125 Figure 4.10: Synthesis of compound 14...... 125 Figure 4.11: Synthesis of compound 16. Transition states in brackets shows two possible additions resulting in a mixture of isomers...... 126 + Figure 4.12: Synthesis of polymer sPPP-HNEt3 ...... 127 + + Figure 4.13: Conversion of sPPP-HNEt3 to sPPP-H ...... 128 1 1 1 Figure 4.14: H NMR (DMSO-d6) of compound 8 and D NOE irradiation. Red : H spectrum, olive: 1D NOE: irradiation of the Hm; cyan 1D NOE: irradiation of the Ho; purple: 1D NOE: irradiation of the Hcore...... 134 Figure 4.15: Two possible configurations for the compound 8 the sBTC(H+) ...... 135 Figure 4.16: Chemical structure of compound 14 and 16. The dashed line reports the uncertitude of configuration...... 135 1 1 Figure 4.17: H NMR (DMSO-d6) and 1D NOE of compound 14. Red: H NMR 1 1 spectrum; olive: D NOE irradiation of the HDA; cyan: D NOE: irradiation of the Hb1; purple: 1D NOE: irradiation of the Hb2...... 136

Figure 4.18: COSY (2D) NMR (DMSO-d6) of the compound 16...... 138 + Figure 4.19: Synthesis route of the sPPP-HNEt3 ...... 139 1 + Figure 4.20: H NMR (DMSO-d6) spectrum of sPPP-HNEt3 ...... 140 Figure 4.21: Photograph of sPPP-H+ immersed in deionized water at room temperature...... 142 Figure 4.22: Proton Conductivity of sPPP-H+ and Nafion® 211 at 30 °C as a function of RH (data for Nafion NR 211 taken from Peron et al.) ...... 143 Figure 5.1: Preparation of sPPP(m)-H+ copolymers with tunable IECs through introduction of a hydrophobic monomer...... 148 Figure 5.2: The synthetic pathways for the syntheses of (a) monomers, and (b) the sPPP(m)-y copolymers. (i) Pd(PPh3)2Cl2, CuI, HNEt2, 56°C, 6 h; (ii) I2, DMSO, 150°C, 8 h; (iii) KOH, EtOH, 80 °C, 3 h; (iv) TMSO-SO2-Cl, DCE, RT, 8 h; (v) NEt3, n-BuOH, 4 h; (vi) K2CO3, Et2O/MeOH (3/1), RT, 6 h; (vii) nitrobenzene, 195-220 °C, 120 h; (viii) NaOH, MeOH, 4 h, RT; (ix) 2.00 M H2SO4(aq), 4h, RT...... 149 + Figure 5.3: Copolymer sPPP(0.9)-HNEt3 obtained after workup...... 153 1 + Figure 5.4: H NMR (DMSO-d6) of the six copolymers sPPP(m)-HNEt3 ...... 157 1 + Figure 5.5: H NMR (DMSO-d6) of the six ionic copolymers sPPP(m)-H , and sPPP(0.0)...... 158 Figure 5.6: a) Representative stress-strain curves of sPPP(m)-H+ membranes, compared to that of NR-211; b) zoom on the sPPP(m)-H+...... 160

xvi Figure 5.7: Thermograms of sPPP(m)-H+copolymers at 1.0°C per minute under nitrogen...... 161 Figure 5.8: Theoretical and experimental ion exchange capacity (IEC) values for sPPP(m)-H+ polymers...... 162 Figure 5.9: Proton conductivities of sPPP(m)-H+ and Nafion NRE 211, a) at 30 °C and variable RH and; b) the respective log plot; c) at 80 °C and variable RH and; (b) the respective log plot...... 163 Figure 5.10: Residual masses of sPPP(m)-H+ copolymers following immersion in Fenton’s reagent...... 164 Figure 5.11: Membrane data for sPPP-based systems compared to a PFSA reference for a) membrane conductivity from in situ data (iR drop method) and b) hydrogen fuel crossover data determined by chronoamperometry...... 166 Figure 5.12: PPP(1.0)-H+, sPPP-(0.8)-H+, and sPPP(0.6)-H+ as both membrane and ionomer in the catalyst layer, i.e., hydrocarbon-based fuel cells, compared to a standard Nafion reference, operating at zero backpressure (100 kPaabs) and conditions optimized for the Nafion reference: 95% RH, 80 °C, 0.5/1.0 slpm gas flows of H2/O2 (a) or air (b) at the anode/cathode; all data 5 min·pt-1 at 100-200 mA·cm-2 intervals with 1 min·pt-1 at mA·cm-2 intervals to resolve the kinetic region; 0.4 mg Pt·cm-2 cathode/anode catalyst loadings with composition and conditioning as described above and in the supporting information. with composition and conditioning as described in Fuel cell characterization section...... 167 Figure 5.13: Polarization data (IVs) from in situ fuel cell tests for of sPPP(0.6)-H+, sPPP(0.8)-H+, and sPPP(1.0)-H+ as fully hydrocarbon, homogeneous fuel cells (i.e. same polymer employed as both membrane and ionomer in the catalyst layer) compared to a standard Nafion reference (N212 membrane / ND520 ionomer in catalyst layer); all polarization data at 80 °C, 95% RH (optimized for Nafion), zero backpressure, 0.5/1.0 slpm hydrogen/oxygen or air as anode/cathode gas feeds at zero backpressure, showing polarization data from operation in oxygen: a) Including in situ membrane resistance (iR) as a function of current density (inset); b) Including power density (y2-axis); and c) Polarization data from operation in air including power density (y2-axis)...... 168 Figure 6.1: Proposed synthesis route 1 to obtain the crosslinking linker: i: N- iodosuccinimde, ii: Sonogashira cross-coupling with trimethylsilylacetylene, iii: protiodesilylation, iv: added in a solution of monomer(s)...... 171 Figure 6.2: Proposed structure of the ionic crosslinked sPPP with the diethylamine linker derivative and the charge balance on the polymer backbone. .... 171 Figure 6.3: Example of the possible ionic crosslinking in the film using 1,3- diaminobenzene as a crosslinker...... 172 Figure 6.4: Proposed synthetic route for 1,3,5-triethynylbenzene; i) Sonogashira cross-coupling using trimethylsilylacetylene, ii) protiodesilylation...... 173 Figure 6.5: Proposed alternative route to polymerize sBTC(X): iv) Diels-Alder reaction; v) cation exchange with 1.0 mol/L sodium hydroxide; vi) polymerization; vii) cation exchange to the acid form...... 174

xvii List of Acronyms

ACS American Chemical Society ADS Adsorbed AEM Anionic exchange membrane AFC Alkaline fuel cell AFM Atomic force microscopy b Beta BTC Bistetracyclone BDIPS Biphenyldiisopropylsilane BFBTPB 1,2-bis(difluorobenzoyl)-3,4,5,6-tetraphenylbenzene BHPTPB 1,2-bis(4-hydroxybenzene)-3,4,5,6-tetraphenylbenzene COD 1,5-Cyclooctadiene DA Diels-Alder DCE Dichloroethane DEE Diethyl Ether DCM Dichloromethane DMAc Dimethylacetamide DMF Dimethylformamide DMSO Dimethylsulfoxide DPE Diphenylether 0 E ox Standard oxidation potential 0 E red Standart reduction potential EA Ethyl Acetate EAR Electrophilic Aromatic Substitution EWG Electron withdrawing group GPC Gel permeation chromatography (also known as SEC) H+ Proton ion + H3O Hydronium ion + H5O3 Zundel ion + H9O4 Eigen ion HOR Hydrogen oxidation reaction + HNEt3 Triethylammonium ion HR-MS High resolution mass spectrometry

xviii IEC Ion exchange capacity IR Infra-red

MnO2 Manganese dioxide - MnO4 Permangante ion MS Mass spectrometry NaF Sodium fluoride NMR Nuclear magnetic resonance NOE Nuclear Overhauser Effect Nu- Nucleophile ORR Oxygen reduction reaction PEEK Polyether ether ketone) ppm Parts per million PPP Poly(paraphenylene) PTSA Para-Toluenesulfonic acid sBTC Sulfonated bistetracyclone SDAPP0 Unsulfonated Diels-Alder polyphenylene SEC Size extrusion chromatography (also known as GPC)

SO3 Sulfure trioxide sPPB Sulfonated poly(parabiphenylene) sPPN Sulfonated poly(paranaphtalene) sPPP Sulfonated poly(paraphenylene) sTC Sulfonated tetracyclone TBAF Tetrabutylammonium fluoride TC 2,3,4,5-Tetraphenylcyclopenta-2,4-dienone or tetracyclone TCE Tetrachloroethane TES Triethylsilane

TIPS Triisopropylsilyl group : R-Si-(CH(CH3)2)3 THF Tetrahydrofuran

TMS Trimethylsilyl group : R-Si-(CH3)3

TMSO-SO2Cl Trimethylsilyl Chlorosulfonate

xix Chapter 1.

Introduction

1.1. History of the Fuel Cell

In the 19th century, researchers from Germany and England (Christian Friedrich Schönbein and Sir William Grove) created an electrochemical cell that would later become known as a fuel cell. This fuel cell is based on an electrochemical reaction where upon hydrogen is oxidized to protons at an anode, and oxygen is reduced at the cathode to form water. The half cell and overall reactions are shown in Equation 1-1:

� → 2� + 2� � = 0.00� a)

1⁄2 � + 2� + 2� → �� = 1.23� b)

� + 1⁄2 � → �� = 1.23� c)

Equation 1-1: Redox reactions of a H2/O2 fuel cell : a) anode, b) cathode, c) overall reaction.

The anodic oxidation has a standard electrochemical potential, E°, of 0.00V (vs. SHE) and the oxygen reduction reaction or ORR has a standard electrochemical potential 1.23V. The overall reaction, which produces water, has an E° of 1.23V.1,2 Today, almost one hundred and fifty years after its discovery, fuel cell technology is ubiquitous and the basis of many commercial companies and entities. Commercial Fuel cell technology was boosted during the “space race” in the late 1950’s, when NASA was looking for auxiliary power technology that was lightweight and efficient. The first fuel cell of major significance was developed by General Electric in 1955. It used a hydrocarbon-based polymer as electrolyte.3 This electrolyte was developed initially for ion exchange membrane processes. This technology was improved in 1962 during the US Gemini program, but fuel cell devices suffered many drawbacks such as their high cost, high operational

1 temperature, low efficiency, poor electrolyte stability, and the need for a humidification system. There are numerous types of fuel cell as listed in Table 1.

Anionic Fuel Cells (AFC), Proton Exchange Membrane Fuel Cells (PEMFC), Direct Methanol Fuel Cells (DMFC), Phosphoric Acid Fuel Cells (PAFC), Molten Carbonate Fuel Cells (MCFC) and Solid Oxide Fuel Cells (SOFC) are examples. They may use different fuels, operate at different temperatures and they may have different reactions at each electrode. A major discerning feature is the ion carrier or type of electrolyte. The hydronium + - ion (H3O ) in a PEM, while corrosive, can be easily made, however the hydroxide ion (HO ) is less corrosive to metals but is a strong nucleophile and highly reactive to organic 2- 2- molecules and are more challenging. Carbonate (CO3 ) and O require high temperatures. AFC, PEMFC and DMFC thus operate at low-to-medium temperatures and do not require an expensive heating system such as that required for PAFC, MCFM and SOFC.

An example of a PEMFC is shown in Figure 1.1. The components are built around the electrolyte. On each side of the electrolyte is deposed the catalyst.

The high level focus of this thesis is proton exchange membranes, specifically the organic chemistry surrounding the synthesis of new polymers for proton exchange membranes. The operation of DMFC, PAFC, MCFC and SOFC is not be discuss in this work but further information can be found in the literature.5,2,6–9,10

1.2. Polymer Electrolyte Membranes

There are many different components of a PEM fuel cell, but the main ones are: the catalyst, the gas diffusion layer, and the membrane. The membrane is required to be chemically and mechanically stable, exhibit low hydrogen and oxygen permeability, high ionic conductivity and be as inexpensive as possible.11

3 1.2.1. Proton Exchange Membrane for Fuel Cell (PEM-FC)

The transport of protons in a PEM requires the presence of an acid tethered to a polymer backbone. Three common acid groups are carboxylic, sulphuric and phosphoric acid. Carboxylic acids are weak acids, which means that the concentration of free, mobile protons is low and the conductivity of carboxylic acid groups is low. Phosphoric acids unfortunately form anhydrides under low humidity, which lowers their conductivity unless the temperature is sufficiently high. Sulfonic acid is the acid group of choice for proton exchange membranes.12

Sulfonated polymers are of common interest. Despite their use in biology,13,14 where the sulfonate group serves as an anchor, or as a host-guest group, the most common use of sulfonated polymers is as an ion exchange material. The proton of the sulfonic acid group can be substituted by a different cations - sodium, lithium15, and ammonium16 or polyvalent cations. Depending on the cation, the sulfonated polymer can be water soluble or insoluble. Furthermore, the flexibility and the plasticity of the polymer backbone can be tuned in order to change the physical properties of the polymer. For example, a poly-alkylene polymer will be more flexible than a poly-phenylene based polymer. The molecular weight also impacts mechanical strength, i.e. low molecular weight polymers lead to membranes that are too brittle when cast as a film.11 Ion- containing polymers such as those used in PEMFCs have the added complication of possessing hydrophobic segments and ionic/hydrophilic segments. The hydrophobic segment is typically the polymer backbone, and have included poly(ethers),17 poly(ketones),18 poly(sulfones),19 and partially-fluorinated20 or fully-fluorinated polymers perfluorosulfonated ionomer, the most common of which has the tradename Nafion®.21

1.2.2. Perfluorosulfonated acid ionomer PEMs

The polymer architecture of a proton exchange membrane, particularly the interplay between the hydrophilic and hydrophobic regions, is critical to its properties as discussed in Elab and Hickner’s review on the topic,22 which delineates the different benefits to using block copolymer strategies versus other architectures. High proton conductivity is often achieved when there are sufficient ionic groups and good segregation of the ionic domains. This was demonstrated by Ding et al.23 by comparing the morphology of block and random ionic copolymers. The observations from this study

4 report that ion conductivity, morphology, and hydration number are interrelated and strongly dependent on copolymer architecture. Similarly, the degree of sulfonation or ion exchange capacity (IEC) play a strong role on hydration level and ion conductivity. The morphology of the polymers can also change depending on the ion exchange capacity.24 Peckham et al.25 reported that when IEC is increased, the conductivity of the membrane typically increases due to the increasing acid concentration. In the case of low IEC polymers, the acid groups are too dispersed to create connected regions for the proton transport, and hydration remains low. The dissociation of the acid group depends of the amount of water absorbed by the polymer membrane, which is why the vast majority of PEMs require constant exposure to high relative humidity for their operation. It has to be mentioned that these properties can be modified with different acid groups.26 For all of the above reasons, membrane properties are known to be highly dependent on their molecular architecture and resultant morphology, and on the ionic and water content. All these properties together control ion conductivity in the material.

Nafion®, created the in the nineteen sixties by Dupont, is the most widely studied ion containing polymer for proton exchange membranes.21 Nafion is synthesized from the highly reactive monomer, tetrafluoroethylene. It is classified as a perfluorosulfonated ionomer, for which there are various versions and derivatives as reported in Figure 1.2.

CF2 CF2 CF2 CF x y

O CF2 CF O CF2 SO3H m n CF3 Figure 1.2: Chemical structure of perfluorosulfonated acid ionomer (PFSA).

Many perfluorinated materials have been developed and made commercially available. The Table 2 below lists different examples of Nafion® material and some other perfluorosulfonated acid ionomers and their characteristics.

5 Table 2: Different Examples and their Composition of Perfluorinated Polymers Containing Sulfonic Acids on the Side Chain Currently Used in Fuel Cells. Name Stoichiometry Equivalent weight Thickness (µm) Nafion® 112 m =1; x=5-13.5, n = 2; y = 1 1100 80 Nafion® 115 m = 1; x = 5-13.5, n = 2; y = 1 1100 125 Nafion® 117 m = 1; x = 5-13.5, n = 2; y = 1 1100 175 Nafion® 120 m = 1; x = 5-13.5, n = 2; y = 1 1200 260 Flemion® m = 0-1; n = 1-5 1000 50-120 Aciplex® m = 0; x = 1.5-14, n = 2-5 1000-1200 25-100 Dow Chemical m = 0; x = 3.6-10, n = 2 800 125

Despite the exceptional properties and ubiquity of perfluorosulfonic acid ionomers, they are very expensive to prepare, they utilize hazardous reagents, and there is growing concern about their recycling and disposal.17,27 Non-fluorinated analogues are thus of considerable interest.

1.2.3. Non-Fluorinated PEMs

The vast majority of ionic polymers investigated as a potential replacement to perfluorosulfonic acid ionomers contain aromatics moieties onto which acid groups are attached. Common polymer backbones are shown in Figure 1.3. A common route of introducing the acid group is post-sulfonation, i.e., covalently attaching the acid functionality onto a prepared polymer. Numerous of procedures for this process exist. Maier and Meier-Haack12 have reviewed the different types of sulfonated agents and these will be discussed in the section 1.5.5.

6 O O O S S O Poly(ether) Poly(ketone) Poly(sulﬁde) Poly(sulfone)

O H N N N O Poly(amide) Poly(benzimidazole) Poly(arylene) Figure 1.3: Different building blocks used to create poly(arylenes).

Poly(arylene-ethers) (sPAEs) are an interesting class of polymer and can be readily synthesized. Asano et al.28 report a rigid road polymer backbone based on polyamide and an alkyl ether sulfonated ether as a pendant group. The polymer decomposes at 150 °C, due to desulfurization. The ether function is the weak link in this polymer family.29 Sulfonated polymers without ether links is a topic of growing interest. Jannasch et al. report on the modification of poly(sulphide)-co-poly(sulfone) using a tetrasulfonated monomer 4,4’-bis[(4-chlorophenyl)sulfonyl]-1,1’-biphenyl (BCPSBP).30 Yoon et al.31 report the use of a poly(ketone), functionalized using chlorosulfonic acid to obtain a polymer with high thermal stability, up to 280 °C, and with high proton conductivity. Jouanneau et al. functionalized poly(benzimidazole) by introducing pendant sulfonated phenylenes.32 This strategy was the second generation of the sPBI first made by Glipa et al. where they doped PBI with sulphuric acid or phosphoric acid. The polymer possesses a proton conductivity of 4.0 mS/cm,33 and proved to be stable as a membrane in fuel cell operation for up to 10,000 hours at 160 oC.34 Poly(sulfones) also show very good potential to replace the poly(ether). Schuster et al. reports a poly(phenylene sulfone) which exhibits enhanced stability decreased desulfonation at elevated temperatures.35,36

1.2.4. Poly(phenylene) PEMs

Poly(phenylenes) contain primarily phenylene linkages and are devoid of weaker heteroatom linkages. A cross-coupling approach to sulfonated poly(p-phenylene) was developed. Si et al. and Granados-Focil et al. using the Ullmann reaction reported the polymerization of the sulfonated 1,4-dibromobenzene or the sulfonated 4,4’- dibromobiphenyl analogues.37,38 The resultant polymer was highly rigid and had poor

7 mechanical properties. A crosslinker was used to enhance its conductivity and mechanical properties.37 Using a similar cross-coupling route Mochizuki et al. reported the synthesis of partially fluorinated polyphenylene containing sulfonic acid sPAF, which exhibits good conductivity and mechanical stability but is partially fluorinated.39

An alternative route that leads to a poly(phenylenes), involves [4+2] Diels-Alder cycloaddition. This method, developed in the late 1920’s by Otto Diels and Kurt Alder, requires a diene and a dienophile.40–42 This reaction will be discussed in more detail in section 1.5.6. The Diels-Alder reaction was modified by Dilthey et al. in the early thirties, when they reported the use of a cyclic diene (tetracyclopentadienone) which prevents the retro Diels-Alder reaction.43 Ried and Frietag, thirty years later, applied this reaction to a di- and tetra-substituted dienophile,44,45 and prepared the first polymer using a bistetracyclone (BTC) and a bis dienophile (1,4-diethynylbenzene). Characterization of the resultant polymer revealed a melting point of 420 °C.46 The high stability of the poly(phenylene) attracted the interest of J. K. Stille, who studied and characterized this new class of polymer extensively. Mukamal et al. first reported the polymerization in toluene, whereas Ried et al. used cis-β-dekalol for 24 hours under pressure at 200 °C to yield 91% as a white polymer.47 Thermogravimetric analysis of the polymer revealed the poly(phenylene) was stable to 550 °C under air atmosphere and to 575 °C under nitrogen. The drawback of this particular reaction is that is impossible to control the regiochemistry of the product,48 because during the addition of the dienophile with the diene, two configurationally isomers might be obtained per diene. VanKerckhoven et al. first attempted postfunctionalization of the poly(phenylene) using harsh conditions: sulphuric acid, at 250 °C for 120 hr.49 Later, Kallitsis and Naarmann50 used the Yamamoto coupling reaction to realize one of the first poly(p-terphenylene) polymers, using nickel, triphenylphosphine and zinc as a reducing agent to couple dichloro or dibromo monomer derivatives earlier reported by Arnold and Wolf.51,52 These polymers also exhibited high thermal stability. Kallitsis et al. reported the polymerization of a pentaphenylene with an ester link between the phenylenes to increase solubility. The addition of alkyl chains also increased solubility of the polymer.53 Mullens et al. investigated polymers prepared by Diels-Alder polymerization, and Shifrina et al. quantified the ratio of isomers.54

Fujimoto et al. at the Sandia National Laboratory reported the post- functionalization of a poly(phenylene) to yield a sulfonated derivative, sPP,55 which was subsequently used as a polymer electrolyte membrane (PEM). The extent of sulfonation

8 was estimated to be between 50 to 80%. The polymer became soluble in polar solvents such as DMSO, NMP with increasing sulfonation content, but remained insoluble in water. The polymer was stable up to 285 °C.56 This polymer has been studied in depth,57–59 and more recently quaternary ammonium derivatives of these polymers have been explored as anion conducting polymers.60–62

The main drawback of sulfonated poly(phenylenes) to date is that they were prepared by post sulfonation of a pre-prepared polymer. Post-sulfonation is known to be difficult to reproduce since the sulfonate groups can be attached to different segments of the polymer chain and there is little control of their sequence distribution. Assuring more precise control of polymer structure and architecture would be highly desirable as doing so has been shown to leading to enhancements in polymer properties.

1.3. Electrochemistry of PEMFCs

Proton conductivity is a critical property to consider in the design of proton exchange membranes as it supports proton transport from the anode to the cathode in operating fuel cells. Proton conductivity is directly related to aspects of the polymer structure such as self-organisation in film, the quantity and nature of the acid group, the morphology, and the phase segregation.63,64,65 This section describes some of the pertinent considerations and measurements of proton transport.

1.3.1. Proton Transport Mechanism

Phase segregation plays an important role in the proton transport. The hydrophilic domains of the polymer structure self-assemble during the membrane formation as ionic clusters. Proton conduction is enhanced in the presence of water and the clusters hydrate to form percolated pathways for proton transport. Proton conduction is strongly correlated to the level of hydration (water uptake). The mechanism of proton conduction in PEMs can be similar to the mechanism of proton conduction in bulk water. Protons (H+) are strongly + + associated with surrounding water and form hydronium ions (H3O ), Zundel ions (H5O3 ) + 66,67 and the Eigen ions (H9O4 ). Three mechanisms of proton transport in the PEMFC are proposed: the vehicular mechanism, the Grotthuss mechanism, and a surface mechanism, as shown in Figure 1.4. The vehicular mechanism explains the proton transport as a movement from one entity through the ionic domain due to the high

9 hydration of the channel. The proposed Grotthuss mechanism shows that the protons are transferred from one entity to another followed by a reorientation of the water molecules. The surface mechanism explains the transport in low relative humidity when the number of water molecules per sulfonic acids are low (l = 1 to 2), wherein protons “hop” from one molecule of water on one side of the channel to one sulfonate group on the other side.

Figure 1.4: Simplified mechanisms of proton transport in an hydrated PEM references nb. Adapted with permission authors Journal of Polymer Science, Part B Polymer Physics (2006), 44(16), 2183, © 2006 John Wiley & Sons, Inc.68

Zawodzinski et al.69 suggested that at high relative humidity every mechanism participates in the proton transport but the Grotthuss mechanism is predominant. When the relative humidity decreases, the vehicular mechanism becomes predominant. At low water contents, the ionic groups are in close proximity to each other and in this instance the surface mechanism is the primary mechanism. The protons repeatedly “hop” from a water molecule to a sulfonic acid along the wall of the ionic channel.70

10 1.4. Degradation: Oxidative Stability

Degradation of PEMs in fuel cell primarily occurs due to the presence of hydroxyl radicals generated during the course of the oxygen reduction reaction. One source of hydroxyl radicals is hydrogen peroxide which is generated via the two-electron reduction mechanism, as opposed to the desirable four-electron mechanism as shown in Figure 1.5.71

Gubler et al. reported a list of potential radicals which can be generated during the fuel cell operation, summarized in Table 3.72 After its formation, hydrogen peroxide may decompose into HO• (the hydroxyl radical) which can then react with hydrogen peroxide to form hydrogen gas and the peroxyl radical (HOO•). Peroxo radicals may also react with hydrogen peroxide to form water, oxygen gas, and hydroxo radicals. Hydrogen radicals (H•) can be formed via the reaction between hydroxo radicals and hydrogen gas. Peroxo radicals react iron(III), which is often present as an impurity, to form iron(II) which participates in further reaction pathways.

11 Table 3: Proposed Radical Formation During the Fuel Cell Operation, with and without the Presence of Iron. Reprint with Permission from Lorenz Gubler, Sindy M. Dockheer, and Willem H. Koppenol, Journal of The Electrochemical Society, 158(7), B755-B769, Copyright (2011) The Electrochemical Society.73 # Reaction ∙ 1 �� → 2�� . . 2 �� + �� → �� + � . . 3 �� + �� → �� + �� + � . . 4 �� + � → � + � . . 5 � + � → �� . 6 2�� → �� + � . 7 �� + �� + � → �� + �� + � . 8 �� + �� + � → �� + � . 9 �� + �� + � → �� + �� . 10 �� + �� → �� + � + � . 11 �� + �� → �� + �� + �

Hydrogen radicals, peroxyl radicals, and hydroxyl radicals are highly reactive and act as reagents for the membrane degradation. Using a stable material that is less susceptible to attack by free radicals which is important for operating fuel cells. Ex situ tests are performed in the laboratory to qualify the stability of the membrane. The oxidative test or Fenton’s Reagent test generates radicals through a reaction of iron(III) with hydrogen peroxide at 80°C.74,75 This reaction decomposes hydrogen peroxide into radicals in the presence of iron(III). The proposed mechanisms of these reactions are listed in Table 4. In Table 4, it is shown that iron(III) reacts with hydrogen peroxide to form a peroxide radical and iron(II). Iron(II) decomposes hydrogen peroxide to form a hydroxo radical. Iron(III) and iron(II) act as catalysts in the production of radicals and allow the formation of the same radicals as those present during the fuel cell operation.

Table 4: Mechanism of Decomposition of Hydrogen Peroxide in the Presence of Iron(III). Adapted with Permission from Joseph De Laat, Hervé Gallard, Environmental Science and Technology, 33 (16), 2726-2732, Copyright (1999) American Chemical Society.74 # Reaction . 1 �� + �� → �� + �� + � . 2 �� + �� → �� + �� + �� . 3 �� + �� → �� + �� . . 4 �� + �� → �� + �� . 5 �� + �� + � → �� + �� . 6 �� + �� → �� + � + �

12 In a typical ex situ reaction procedure a source of iron(III) is mixed with hydrogen peroxide in water at 80 °C and the material of interest is submerged.76 It is important to examine the material and after the oxidative test. In reality, these oxidative tests performed in the laboratory are much harsher than those found during the fuel cell operation.77 A computational study reports that the aryl sulfonyl radical has a long life time which prevents the fragment SO3 from being created. In perfluorosulfonic acid ionomer films, the C-S bond is believe to be the weak link.75

1.5. Synthetic routes

1.5.1. Organometallic Cross-Couplings: Sonogashira Cross-coupling

The 70’s was the golden age for inorganic catalysis – this period revolutionised organic synthesis. Tamara et al. reported the modification of the Grignard reaction using an addition of a metal such as silver for homo-coupling, and copper for cross-coupling in 1971.78,79 Tamao et al. published “Selective Carbon-Carbon Bond Formation by Cross- Coupling of Grignard Reagents with Organic Halides: Catalyzed by Nickel-Phosphine Coupling”.80 According to the authors, in this route, a di(halo)(organo)nickel complex

((L)2Ni(X)2 is first generated, shown in Figure 1.6, compound 1; where L is typically a phosphine. In the presence of two equivalents of the Grignard Reagent (R1-Mg-X’), the transmetallation occurs: an exchange of the halide X and the R1 group is made the between the (organo)nickel and the magnesium. The nickel becomes (L)2Ni(R1)2, as shown in Figure 1.6 compound 2. The next step is the reaction of the new nickel complex with one molecule of the reagent R2-X2, which leads to an oxidative addition (structure of the nickel complex is not shown) and release of one molecule R1-R2. The nickel complex possess at this step one group R1 and one group X: [(L)2Ni(R1)(X2)], compound 3. In the presence of a Grignard reagent, R1-Mg-Br, the nickel complex becomes (L)2Ni(R1)(R2), compound 4. A catalytic cycle is achieved between compound 3 and 4 as long as the nickel is fed with Grignard reagent (R1-Mg-Br) or a second reagent (R2-X2), the cycle can continue, as shown in Figure 1.6.

13 2 R1-Mg-Br 2 X-Mg-Br R2-X2 R1-R2 R1-Mg-Br X2-Mg-Br L L L L L : Ligand X Ni L R1 Ni L R1 Ni L R2 Ni L X R1 X2 R1 1 2 3 R1-R2 R2-X2 4 Figure 1.6: Proposed mechanism for the Kumada reaction.

The nickel does not need to be present in stoichiometric amounts. The above was the first report to readily produce a-vinylnaphtalene from vinyl chloride and a- naphtylmagnesium bromide. A few years later, Neigishi reported a new organometallic cross-coupling between two alkenyl derivatives using palladium or nickel coupling.81 This work reported coupling using vinylalane, an alkyl aluminium derivative, and an haloalkenyl. Miyaura, Yamada, and Suzuki reported their discovery of a new cross-coupling where alkyl-borane reacted with alkyl-halide in presence of catalytic amount of tetrakis(triphenylphosphine) palladium.82 The authors were interested in the chemistry of the triple bond; until that point in time only allylic and aromatic derivatives had been reported. Catalytic coupling between an allyl and alkyne was achieved, as for example the cross-coupling between an alkyne-halide and an vinyl-borane, in presence of base. This work was impactful because boronic derivatives and halide derivatives are easy to synthesized. Furthermore, the derivative could be expanded to alkenyl,82 alkynyl,82 aryl,83 allyl,84 or benzyl84 and the reagent can be a simple boronic acid.85

It is long known that copper can catalyze the coupling between two aromatic 86–88 moieties. This discovery was made by Ullmann in 1903. In 1975, Tohda et al. reported in 1975 the insertion of an alkyne into a s-alkenyl palladium complex.89 The same group reported the synthesis of an acetylene derivative base on the insertion previously mentioned, and this reaction was given the name of his inventor, Sonogashira.90 The same principle is observed as in the Kumada cross-coupling: a palladium(0) species is required for this reaction and oxidative addition of an halide reagent (R-X) is observed on the catalyst. An alkynyl reagent (R’-CC-H) in the vicinity is inserted In the palladium complex, the transmetallation step. The following reducing elimination releases the product R-CC- R’ and the palladium recovers its initial oxidation state, as shown in Figure 1.7.

14 (0) Pd L4

L = P(C6H5)3

2 L R-X R-CC-R' (0) L2Pd

Reductive Oxidative elimination addition

L L L Pd(2) CC-R' R Pd(2) X R L

Trans-cis Transmetallation isomerization Cu-CC-R' + L HNR3 R Pd(2) CC-R' L NR3 Cu+ I-

H R'

Cu+ I- H-CC-R' Figure 1.7: Proposed mechanism for Sonogashira cross-coupling.

In this mechanism, the key step is generation of Pd(0) and copper-acetylide. The presence of a nitrogen base is important. The base helps reduce the palladium and activate the alkyne. The same conclusion can be made as for the Kumada cross-coupling, the reaction continues until the source of alkyne or halide is depleted. Different parameters can be adjusted for the Sonogashira cross-coupling such as exact nature of the palladium catalyst, the halide, the alkyne, the base, and the co-catalyst. One of the most common and most broadly used catalysts is tetrakis(triphenylphosphine)palladium91 which is unstable in air, and when exposed to moisture. The dichlorobis(triphenylphosphine)- palladium92,93 is a safe alternative, air and moisture stable, and is cheaper and easy to store. Two other alternatives are the palladium diacetate,94 and palladium dichloride.95 The halogenated reagent is normally an aromatic molecule, as the aromaticity of the benzene ring allows oxidative addition to occur. However in 2013, Fu et al. reported the first Sonogashira cross-coupling with an alkyl halide using a N-heterocyclic carbene ligand.96 Iodine and bromide are good leaving groups. In this case, the iodide will react first, and then the bromide and chloride.97 When a substrate has two different halides, it is possible

15 to selectively functionalized the reagent step by step.95,98 Different leaving groups or substituted forms of the halides are possible and may be excellent leaving groups, these include triflate99 and tosylate. The alkyne must to possess a hydrogen atom, in other words it has to be terminal. No reaction with acetylene gas has been reported, but when the alkyne possesses a substituent the reaction becomes possible. Many substituents for the other side can be used such as aliphatic,100 aromatic,101 or protected with silanes functions102 such as trimethylsilyl,103 triisopropylsilyl,104 carboxylic acid105 or esters. The base must be a nitrogen base due to the poor nucleophilic character of the amine and its ability to form a complex with the copper. This enhances the solubility of the copper co- catalyst system, and allows deprotonation of the alkyne. Diethylamine, triethylamine, diisopropyl and triisopropyl amine are the most common bases used. In the past, copper- iodide was widely used in the reaction but due to increases in the price of copper, some efforts were made to avoid the used of this metal in reactions.106 Recently, Sonogashira cross-coupling was achieved in aqueous solution,107 and at room temperature,108 as well as using microwave-assisted reactions. Despite the fact that the mechanism is not yet fully understood, the use of microwave assisted reaction allows a shorter reaction times and higher yield.109 The use of this technique also seems to enhance the yield when aryl- bromide is involved in the reaction using heterogeneous catalysis at a high temperature (120 °C) for a short amount of time (10 to 30 min).110

The review of Chinchilla and Nàjera can be used as a source of further detail and explanation about the Sonogashira cross-coupling.111

1.5.2. Oxidation of the Carbon-Carbon Triple Bonds

The selective oxidation of the carbon-carbon triple bonds or C(sp)-C(sp) to obtain the desired product is a complex route and only a few successful methods have been reported. In this work, an attempt was made to oxidize the alkyne to benzil, or a 1,2- diketone, shown in Figure 1.8.

16 O

O 1,2-diphenylethyne benzil Figure 1.8: Oxidative product expected from the oxidation of the 1,2- diphenylethyne.

One method of interest was proposed by Ren et al. where the oxidation of the alkyne was successful using palladium dichloride and copper dichloride in “catalytic” amounts with dioxane and oxygen gas as source of oxygen atoms.112 Another route was proposed by Rogatchov et al.,113 where oxidation took place using sulfur trioxide in dioxane. These two mentioned methods were not selected for this thesis for two main reasons: 1) the catalysts cannot be recycled and 2) the sulfur trioxide is not easy to handle as it needs to be treated with extreme caution. Instead, two other methods were found that worked successfully with moderate to satisfactory yields: the oxidation with DMSO/iodine and the oxidation using potassium permanganate. Rusanov et al.114 proposed two methods of oxidation: the first one consisted of the oxidation of a non- terminal alkyne using DMSO and iodine at a high temperature; shown in Figure 1.9; the second one was similar but used hydrobromic acid instead of iodine. The authors claim no further oxidation after the benzil function was made whereas when potassium permanganate (KMnO4), thallium nitrate, selenium dioxide, ozone are used, the oxidation continued all the way to the carboxylic acid.

S I I2 O

O I S I- 1,2-diphenylethyne I

- CH3-S-CH3

S I- O O I S O - (CH ) IS+ I- O 3 2 I O I- O benzil Figure 1.9: Proposed mechanism for the oxidation of the 1,2-diphenylethyne with I2-DMSO.

17 In the proposed mechanism in Figure 1.9, the iodine is present in stoichiometric amounts, or in excess, and forms a cycloiodotriene adduct wherein dimethylsulfoxide (DMSO) attacks one of the carbons. The formed product is a sulfonium derivative where the iodide (I-) is the counter ion. With tautomeric rearrangement, the dimethylsulfite molecule is eliminated so that another DMSO molecule can attack the second carbon and form a second sulfonium derivative. After a second elimination, benzil is formed and an iodo dimethyliodosulfonium is released. According to the authors,114 the reaction may not stop at the alpha diketone and continues to oxidize up to the alcohol or carboxylic acid.115 In 2008, Chen et al.116 proposed an advancement of this reaction wherein microwave irradiation enhanced the reaction, however this work was difficult to scale-up. The reaction was only attempted to 2-to-5 mL reactor vessels.

The last method for oxidizing the alkyne to benzyl consider uses potassium 117 permanganate (KMnO4) in the oxidation, shown in Figure 1.10. Lee and Chang proposed the oxidation where KMnO4 is used the reaction in stoichiometric amounts and which leads to the benzil but does not proceed to the carboxylic acid.

O O- Mn O - MnO4 O O - MnO2

O 1,2-diphenylethyne benzil Figure 1.10: Proposed oxidation mechanism of the 1,2-diphenylethyne using permanganate.

In the proposed mechanism, shown in Figure 1.10, the stoichiometry has to be carefully monitored as it can run out of control due to the high reactivity of the permanganate ion. The permanganate ion is attaching to one side of the alkyne bond, forming a five membered-ring manganese adduct. Via tautomerism, manganese dioxide is eliminated to produces benzil. The work of Lee and Chang117 proposed the stoichiometry is the key to preventing over-oxidation to the aldehyde, carboxylic acid and carboxylate. It should be noted that potassium permanganate is a strong oxidizing reagent which does not require elevated temperatures for reaction.117

18 1.5.3. Protiodesilylation of Alkynes

An important functional group used in this work is the terminal alkyne group, which is unstable with prolonged time, elevated temperature, and light, due to the acidity of the proton. The most commonly used protecting groups for alkynes are silanes, which are easy to insert and to remove. The products can easily be purified by chromatography or distillation. The protection of the terminal alkyne of the propargyl alcohol with a silane, via lithiation118 or the Grignard formation119 are examples, as shown in Figure 1.11.

1) Cl Si Li Si a) BuLi O Li + OH 2) H3O 3-(trimethylsilyl)prop-2-yn-1-ol OH

b) EtMgBr 1) Cl Si BrMg Si O MgBr 2) + OH H3O Figure 1.11: Two synthetic routes to protect the propargyl alcohol with trimethylsilane: a): via lithiation and pathway, b): via Grignard reagent.

In pathway a) above, butyllithium (pKa »50)120 reacts with the alkyne and the alcohol and creates a di-lithiated intermediate. The addition of one equivalent of chlorotrimethylsilane reacts faster with the acetylide ion (pKa » 24 in DMSO) rather than with the alkoxide (pKa » 15 in DMSO). After quenching the reaction with dilute acid or water, 3-(trimethylsilyl)prop-2-yn-1-ol is obtained. A similar mechanism is observed for the pathway (b). The Grignard reagent is first generated using magnesium metal in an anhydrous solvent such as THF or diethyl ether, and bromoethane is slowly added. This first reagent, CH3-CH2-Mg-Br, pKa » 50, must be prepared in excess to be able to deprotonate the acetylide and the alcohol. After the reaction of the Grignard reagent and the propargyl alcohol, one equivalent of the trimethylsilyl chloride is added following by quenching with dilute acid or water.

Numerous silyl protective groups are available and can be used. Figure 1.12 reports a few examples of silane groups with more or less bulk: trimethylsilane (TMS), triethylsilane (TES), triispropylsilane (TIPS), and the biphenyl-diisopropylsilane (BDIPS).

19 R TMS TMS : R' Si TES : R' Si R TES

R TIPS TIPS : R' Si BDIPS : R' Si R BDIPS Figure 1.12: Examples of silane protecting groups used for the protection of alkynes.

Releasing the proton of the alkyne is called the protiodesilylation. The reaction conditions vary from a number of milder conditions to harsh conditions. The cleavage of the group can be achieved in acidic or basic media and the less steric hindrance associated with the silane, the easier the protiodesilylation. As an example, the Figure 1.13 lists some methods of deprotection for each of the functional groups presented in Figure 1.12.

K2CO3 R TMS R H MeOH, RT

TBAF R TES R H THF, -23°C

KOH R TIPS R H MeOH, 50°C

NaF R BDIPS R H THF, reﬂux Figure 1.13: Protiodesilylation of the TMS, TES, TIPS, and BDIPS protecting groups.

As shown on the Figure 1.13, protiodesilylation occurs in basic media, but the acidic route is also possible.121 Though unfortunately not common for the acetylenes, the risk of addition is possible with sulfuric acid and hydrochloric acid. The proposed methods are not restrictive as, for example, the trimethylsilyl-ynil function, that can be cleaved using silver nitrate in a water/ethanol medium.122

In this work, the alkynes were attached to an aromatic backbone, and the protiodesilylation for aryl-alkyne was the only type of reaction employed. Figure 1.14

20 proposes an appropriate means of releasing the terminal alkyne using a base, a nucleophile, or a Lewis base.

+ Nu- - H3O Si Si H + Nu Si + H2O Nu Figure 1.14: Proposed mechanism for the protiodesilylation of the 1-trimethylsilyl- 2-phenyl-acetylene.

According to the work of Dietze123 on a mechanistic study of the hydrolysis of alkoxy-silane, the silane becomes pentavalent and so anionic. With the use of a base (potassium carbonate, potassium hydroxide), a nucleophile (TBAF, NaF), or a Lewis base

(AgNO3) the electronegative ion attacks the silane and becomes pentavalent. The compound is stable. In the presence of water or dilute acid the acetylide gains a proton and the silane side product is eliminated.

Furthermore, based on the difference of reactivity between the different silyl protecting groups, it is possible to selectively deprotonate one alkyne from another one, judiciously.124 Ivachtchenko et al. proposed an elegant way to selectively release one terminal alkyne from a symmetric compound using a methyllithium-lithiumbromide complex in diethyl-ether.125 The size and the strength of the nucleophile or the Lewis base has a big impact on the reaction. For example, the TMS group is cleaved more easily than the TIPS group. Using this logic, Höger et al. reported a selective deprotection using potassium carbonate in a bicomponent solvent mixture,126 with a resulting 89% yield of the expected product. Figure 1.15 shows three different cases of protiodesilylation. Note, when a fluorine source is used, such as TBAF, the nucleophile F- is too strong and both terminal acetylenes are released, the 1,4-diethynylbenzene is obtained.

21 i) a) Si Si Si H

ii) Si H

b) Si Si

iii) H H

Figure 1.15: a) Examples of selective deprotection used by Ivachtchenko et al.125, i)MeLi-LiBr, Et2O, RT, 15h; b) impact of the nucleophile used for the selective deprotection of a terminal acetylene, ii) was used by Höger 127 et al. : K2CO3, MeOH/THF, 8h, iii) TBAF, THF, 4h.

Acetylenes compounds can be unstable as terminal or protected, as reported in 1988 by Neeman et al.128 regarding the preparation of acetylenic precursors and their oligomers. It is mentioned twice in their report that “our initial attempt to distill 1 (1,3- diethynylbenzene) at temperatures up to 110°C and at aspirator pressures resulted in an exothermic reaction followed by an explosion.” The same observation was made by Perepichka et al. during a Glaser-Hay coupling and an explosion which injured a labworker.129 Finally, the terminal acetylenes usually have poor stability which can lead to decomposition, oxidation and oligomerization, and are required to be stored in brown glass jar, in an argon atmosphere, and at low temperature.

1.5.4. Knoevenagel Condensation

The Knoevenagel condensation is well known coupling reaction between an activated methylene compound and a carbonyl compound. The reaction allows the formation of a geminal alkene product, as shown in Figure 1.16.

R R O H R4 B- 2 4 + + BH + HO- R R H R 1 2 3 R1 R3 Figure 1.16: Knoevenagel condensation.

The reaction occurs under basic conditions. The bases used are usually weak bases such as piperidine or acetate ion although stronger bases such as potassium hydroxide or sodium ethoxide can also be used. The base needs to be strong enough to

22 deprotonate the activated methylene. As an example, Formentin et al. reported the reaction of benzaldehyde with malononitrile, as shown in Figure 1.17.130

O CN KOH H + CN CN H CN - HO -H2O Δ -H O CN 2 - CN CN H H O- CN H+ CN OH H CN

Figure 1.17: Proposed Knoevenagel reaction mechanism between benzaldehyde and malononitrile under basic conditions, reported by Formentin et al.130

The potassium hydroxide has an estimated pKa range of 15.7 to 31 in DMSO,131,132 and the methylene of the malononitrile has an estimated pKa of 11.1, whereas piperidine has a pKa of 11.2, which is too low to deprotonate the methylene proton. The proposed mechanism for the reaction is shown at the bottom of Figure 1.17. The hydroxide deprotonates one of the protons on the methylene of the malononitrile. This nucleophile attacks the base of the carbonyl of the acetophenone and forms an alkoxide via tautomerism. In basic media, this entity is stable, and/but in the vicinity of an acidic proton, an alcohol is formed. Under heating, water is eliminated and the germinal compound is formed.

In this thesis, the product is obtained by a double Knoevenagel condensation between 1,3-diphenylacetone and the benzil or bisbenzil to lead to a five member rings called tetracyclone or bistetracylone (see details in Section 3.2.5). Figure 1.18 shows a proposed mechanism of the reaction to form the tetracyclone.

23 O O O KOH + EtOH, reﬂux H O HO- -H2O -

O O-

H O- OH O O O- - O O

HO-

H O - O O - O O O OH

Figure 1.18: Proposed mechanism for the synthesis of the tetracyclone.

Benzylic protons are acidic, and under the action of a base the methylene is deprotonated and an enone is formed. The activated methylene is able to attack one of the ketones of the benzil and form an alkoxide. This alkoxide can be reorganized due to the presence of the second proton from the methylene and the first alkene is formed after eliminating the hydroxide. The base will attack the second methylene and form water. With a similar mechanism the activated methylene will attack the second carbonyl of the benzil and after the alkoxide is formed and reorganized, the second alkene is formed. These compounds are aromatic and fully delocalized along the structure.133 The resonance structures indicated that there are at least four possibilities for the functionalization of the

24 tetracyclone and six possibilities for the bistetracyclone.134 This compound and the dimer, synthesized form the bisbenzil instead of the benzil, are heavily used in this work, and the ability to form derivatives were therefore very important.

1.5.5. Electrophilic Aromatic Substitution

Electrophilic aromatic substitution (EAS) is a common way to functionalize an aromatic ring. This reaction replaces one hydrogen of the ring with one functional group. A few examples of the aromatic substitution are nitration, sulfonation, halogenation, and alkylation. These reactions are also dependant on the electronic effect on the benzene ring. The mechanism involves an attack of a positive ion from the aromatic ring. A cation is formed as a Wheland intermediate, then a rearrangement releases a proton and the aromaticity is recovered. Figure 1.19 shows the mechanism of the nitration of a benzene ring.

H - -O H O O + + + - +N O O S O N O HSO4 H O+ O OH H

-O + O N O + + H2O + N H O O H

H O H - H+ NO2 N+ + NO O 2 Wheland intermediate Figure 1.19: Proposed mechanism for the nitration of an aromatic ring.

The electrophile has to be formed first prior to the reaction with the benzene ring, thus the nitric acid gains one proton of the sulfuric acid and creates a nitronium after losing a water molecule. This nitronium is electron deficient and in the presence of an electron rich molecule such as benzene, EAS will easily occur. After losing one proton from the transition state, which is called a Wheland intermediate, the nitrobenzene is formed. For the transport of protons, the hydrocarbon material needs to possess a source of protons, such as sulfonic acid, which can be easily inserted on aromatic rings using the EAS. Figure

25 1.20 shows the mechanism of the sulfonation. One molecule of sulfuric acid will gain a proton from another molecule and after reorganization and the loss of a water molecule, the electrophile is formed. In the vicinity of a benzene ring, the double bond attacks the sulfur on the electrophile and creates the Wheland complex. The elimination of a proton allows the recovery of the aromaticity and the formation of the benzene sulfonic acid.

H H - O + O O - HSO4 H - H2O O O + + H S O S O O S O O S O H H O OH OH O

H H SO H O - H+ 3 + S O + SO3H O+ H Wheland intermediate Figure 1.20: Proposed mechanism for the sulfonation of a benzene ring by EAS.

Sulfuric acid is not the only reagent which allows the functionalization of a benzene ring. Maier and Maier-Haack12 reported the most common ways to obtain a sulfonated product as listed in Table 5.

Table 5: Examples of Sulfonating Reagents and some of their Reactivity Properties. Reprinted with Permission of Maier, G.; Meier-Haack, J. Adv. Polym. Sci., 216: 1–62, ©2008 Springer.135 Reagent Reactivity Site of reaction Observation Chlorosulfonic acid High Electron-rich Cheap, side reaction Fuming H2SO4 (Oleum) High Electron-rich Inexpensive, crosslinking H2SO4 High Electron-rich Inexpensive, low reactivity* SO3/TEP Medium – Electron-rich Inexpensive, reactivity can be High controlled** Trimethylsilylsulfonyl Medium Electron-rich Relatively expensive*** Chloride Acetylsulfate Low Aliphatic, double Cheap bonds * During the functionalization, the side product formed is water, the water decreases the reactivity of the sulfuric acid. ** The triethylphosphate concentration can be judiciously adjusted to maintain the reactivity relatively high. *** During the EAS and before quenching the reaction, the presence of trimethylsilyl ester prevent side reaction such as crosslinking or degradation. Chlorosulfonic acid is a strong reagent that allows functionalization of a benzene ring, similar to oleum and sulfuric acid. These reagents are used for the functionalization

26 of polysulfone,136 poly(arylene ether sulfone),137 poly(ether ether ketone),138 and poly(arylene ether).139 Triethylphosphate and sulfur trioxide are used to obtain the sulfonated poly(sulfone)-poly(phenylenesulfidesulfone),140,141 and poly(phenylene ether).142 Sulfur trioxide can be used but its melting point is at 17 °C and is toxic and difficult to handle, has a melting point of 44.5 °C and its reaction with water is exothermic, thus the reaction needs to be keep below 0°C for safety and control.143,144 Trimethylsilyl chlorosulfonate (TMSO-SO2Cl) is a reagent made by the reaction between trimethychlorosilane and chlorosulfonic acid, and this reagent can be prepared or purchased.145,146 This reagent has been heavily used for the functionalization of polysulfone,141 poly(phenyl sulfone),147 and polysulfone-block-poly(vinylidene fluoride).148 The use of this reagent provides an excellent advantage which is that the sulfonate group is protected as trimethylsilyl ester until quenching or hydrolysis, as shown in Figure 1.21.

O O O O OSiMe OSiMe ROH OH S 3 S 3 S + + Cl S OSiMe3 HO O O O -ROSiMe3

Figure 1.21: Proposed mechanism for the sulfonation of benzene using trimethylsilyl chlorosulfonate.

These examples are not exhaustive and other reagents such as alkylsulfate,149 sulfur trioxide complex such as dioxane, can be used with similar results.150,151 Electron withdrawing and electron donating groups affect EAS and their presence will alter the reactivity of the benzene ring, and the position of the sulfonic acid may be different, as illustrated in Table 6.152 The functionalization of the toluene with sulfuric acid, for example, leads only to the para-toluene sulfonic acid (PTSA) and not the ortho-toluene sulfonic acid due to the previously named steric effects.

27 Table 6: Effect of Electronic Substituents on a Benzene Ring and their Strength as Donating or Withdrawing Groups . Electronic effect strength Substituents effects Orientation Electron donating* Alkoxide EDG Amine and alkylamine Ether, alcohol, amide Ester, thiol Aryl Alkyl, carboxylate Reference Proton Alkylhalide EWG Halides Amonium, trialkylammonium Ketone, aldehyde Nitrile, sulfonic acid Electron withdrawing Nitro * In the case of the donating effect, the substitution will happen initially on the para position due to the absence of steric effects due to the donor group. The post functionalization of the polymer is a crucial step in the PEM FC research and a few synthetic routes were developed by different research groups. A derivative of a poly(ether sulfone) was developed by Wang et al.153 in which the use of 1,4-butanesultone was used for the post sulfonation.154 Whereas the early method used halogenated solvent, this reagent required a polar and a protic solvent such as dimethylsulfoxide (DMSO) due to the mechanism, which needed to generate a strong electrophile for the ring opening reaction of the 1,4-butanesultone. Like the previous method, the use of 1,4-butanesultone allowed the functionalization of the polymer with different degrees of sulfonation. The authors report an IEC range from 1.42 to 1.97 mequiv./g based on titration. A similar approach is reported by Kulkarni et al. for the post functonalization of the alkyl-grafted, sulfonated, ether-containing polybenzimidazole (GSOPBI).155 Another approach is reported by Jutemar et al. for the functionalization of poly(arylene ether sulfone) (PSU), in which case the sulfonation was appended in two steps.156 The first one consisted, after dissolving the polymer in a polar solvent under a neutral atmosphere, the generation of the nucleophile using butyllithium, and the subsequent exchange of the neutral atmosphere with sulfur dioxide, which created a sulfinated polymer (Ar-SO2-R). The last step consisted of the oxidation of the polymer using hydrogen peroxide. This route was efficient for the functionalization of the sulfone moiety, because of the sulfone is a strong electron withdrawing group. The protons alpha to the sulfone are more acidic, and so the reactivity of this position is increased. This method allowed the authors to reach a range of polymer with an IEC from 1.3 to 4.00 mequiv./g. Another method, reported the use of

28 oleum at room temperature for the functionalization of a derivative of poly(ether sulfone).17,157 Bae et al. developed the sPAESK (sulfonated poly(arylene ether sulfone ketone) which was post functionalized using similar method such as earlier mentioned, chlorosulfonic acid and halogenated solvent.158 A similar structure was functionalized using oleum, fuming sulfuric acid, on a polymer having the acronym sPEASK by Miyatake et al.159

Lulianelli and Basil29 reported a possible issue of crosslinking which could occur during the sulfonation of the PEEK, and which can be applied to all polymers containing ether linkages. When concentrated sulfuric or chlorosulfonic acid is used for the substitution, a similar mechanism of the EAS could occur. In this case, the sulfone function is formed by the dehydration between two sulfonic acids. Furthermore, the ether bond between two aryls may be susceptible for hydrolysis.

The attachment of sulfonic acids is reversible. In most cases the EAS can be performed under a low temperature such as -20°C using sulfur trioxide-diethyl ether, or at 50°C using sulfur trioxide-DMF. The desulfonation can happened at high temperature. Asano et al. reported the desulfonation of polyimide ionomers at temperatures higher than

200°C. The analysis of the volatile formed compounds formed showed traces of SO2, 160 SO3. In other instances, the presence of a sulfone group enhances the reactivity of the protons in b of the the sulfone and the EAS become less difficult. This is because a sulfone is a stronger electron withdrawing group (EWD) than an ether linkage. EWD groups destabilize the σ-complex and leads to a quick sulfonation mechanism, but also prevents the desulfonation and the hydrolysis mechanism.36

Until recently, the only way to functionalize the tetracyclone and the bistetracyclone was to use the TMSO-SO2Cl and this reagent was used extensively in this work. Despite the high price of the reagent, the substitution of these substrates works at room temperature, and after the stoichiometry was adjusted acceptable yields were obtained, and the products were obtained without the need for further purification.

1.5.6. [4+2] Diels-Alder Cycloaddition

Otto Diels and Kurt Alder reported the condensation of a diene and a dienophile for the first time in 1928 in the journal Justus Liebigs Annalen der Chemie.42 Their research

29 at this time focused on quinone synthesis where they attempted to increase the fused ring backbone around the quinone block. Their discovery came from the reaction of buta-1,3- diene with naphthalene-1,4-dione, as shown in Figure 1.22.

O O

O O buta-1,3-diene naphthalene-1,4-dione 1,4,4a,9a-tetrahydroanthracene-9,10-dione Figure 1.22: Condensation of the buta-1,3-diene with the naphthalene-1,4-dione which lead to the discovery of Diels and Alder.42

Their surprise was that the final compound was partially hydrogenated. The authors decided to investigated the reaction of buta-1,3-diene with different structures such as diazo ester, quinone, and maleic anhydride amongst others. Their observation was similar to earlier observations: the obtained product was partially hydrogenated and contained remaining unsaturation. In the first half of the 20th century, chemists did not have access to nuclear magnetic resonance and infrared spectroscopies, or single crystal X- ray diffraction, but Diels and Alder were still able to correctly identify the structures of their products. Their paper ended with a note that “these observations show no doubts that the obtained hydrocarbons show an extension of conjugation”. Otto Diels and Kurt Alder received the Nobel Prize in chemistry in 1950 “for their discovery and development of the diene synthesis”.

This reaction is well known as a cycloaddition between a diene and a dienophile. The diene is a conjugated compound with a bond sequence p-s-p, the most common one being the buta-1,3-diene, and the dienophile is a compound which has at least one p bond. The simplest dienophile is ethene, as shows Figure 1.23. In some cases, heteroatoms can be present in the diene and the dienophile and the reaction is then called the hetero-Diels- Alder reaction.

Diene Dienophyle Figure 1.23: Elementary structure of a diene and dienophile.

30 The reaction is classified as a [p4s+p2s] cycloaddition. The 4 and 2 are related to the number of p electrons involved in the rearrangement. The “s” means that the reaction is suprafacial. These days there are exhaustive varieties of dienes and dienophiles available. The dienes can be classified in categories as reported in the following

Figure 1.24. Dienes that are reactive possess the cisoid geometry, not transoid. In

Figure 1.24, the compounds in cisoid geometry are reported in green and those in transoid geometry are reported in red. The transoid compounds are usually unreactive or poorly reactive in the case of an open chain, and unreactive in the case of a ring. The cyclic dienes are usually more reactive than the open chain ones. Another important aspect is the electronic effects of the substituents. Electron-donating substituents on the diene accelerate the reaction with electron withdrawing groups in the diene: this case is called a normal electron demand Diels-Alder. Electron-withdrawing substituents on the diene accelerate the reaction with electron donating groups present on the diene; this case is called a inverse electron demand Diels-Alder. Finally, the reactions where the substituents have no effect on the diene or the dienophile are called neutral.

Open chain Outer ring Inner-outer ring Across ring Inner ring

O TMS O O O

O O O O Figure 1.24: Structures of dienes and their configuration, which modify their reactivity for [4+2] Diels-Alder cycloaddition.161

Dienophiles are molecules possessing at least one double bond or a triple bond, as shown in Figure 1.25. Ethene, the simplest dienophile, has poor reactivity. Electron- withdrawing and electron-donating groups, on one carbon atom of the double bond,

31 activates the double bond in both normal and reverse electron-demand Diels-Alder reaction.

Dienophiles

Acyclic Cyclic

O O CN OMe O

O O

O O NC CN CO Me 2 N N Ph N NC CN MeO2C O

Ph S N N O CN Figure 1.25: Dienophiles with and without heteroatoms.

The Diels-Alder reaction is a pericyclic concerted reaction of cycloaddition forming a six membered ring, as shown in Figure 1.26. A concerted synchronous transition state and asynchronous transition state have been proposed. The nature of the reagents, the solvent, and the conditions have a strong impact on the reaction. The synchronous transition state is when the new bonds are formed simultaneously, as opposed to the asynchronous transition state where one bond is formed prior to the other.

O O H O

+ O O O

O O H O

Figure 1.26: Proposed intermediate state during the cycloadditon of the buta-1,3- diene and the maleic anhydride.

The regio-chemistry is important in this reaction as when an unsymmetrical diene and an unsymmetrical dienophile react together, two regio-isomer adducts are formed, as

32 reported in Figure 1.27. It is called a regio-specific reaction when one possible isomer is mostly, or only, produced.162

CO Me CO Me + 2 2 +

CO2Me

CO Me CO2Me + 2 + CO2Me Figure 1.27: Scheme showing that different regio-isomers can be formedduring the [4+2] Diels-Alder cycloaddition.

Nonetheless, the regioselectivity depends on the number and nature of substituents on both the diene and dienophile, as well as the reaction conditions. In the simpler instance where two different substituents are present on the diene, one substituent works as regio-director and controls the regio-chemistry of the reaction.163 Trost et al.164 reported interesting results regarding the cycloaddition of the 2-methoxy-3- thiophenylbutadiene with methylvinylketone, and Proteau et al.165 reported on the impact of sulfur and its derivatives on the regioselectivity of the Diels-Alder cycloaddition. The regioselectivity of the Diels-Alder reaction was explained using the Frontier Molecular Orbital Theory166 and will be discussed further below. Briefly, the stronger the electronic effect of a substituent, the more regioselective the reaction will be.

The Diels Alder is a pericyclic reaction and is suprafacial, which means the same side of the p orbital will react together on the diene and the dienophile, as shown in Figure 1.28.

Suprafacial Antarafacial

Dienophile LUMO Dienophile LUMO

Diene HOMO Diene HOMO

Figure 1.28: Proposed addition mechanism of the dienophile on the diene, based on suprafacial or antarafacial addition.

33 There are two possible approaches of the diene on the dienophile which are named endo and exo. The endo attack is the configuration where the bulkiest side of the diene and the dienophile lie one above each other. The exo attack is where the bulkier side of one reagent is under the smaller part of the other reagent. Figure 1.29 reports the four possible configurations based on two orientations of the dienophile in relation with the diene, in both the exo and endo attack modes. In this example four regio-isomers can be formed.

R R endo-ortho

R +

R R

exo-ortho R = CO2Pr endo-meta

R R

exo-meta Figure 1.29: Four addition mechanisms for [4+2] Diels-Alder cycloaddition for the reaction between the penta-1,3-diene and the propyl-acrylate.

The exo is the expected mode of addition because it suffers from less steric repulsive interactions than the endo. The endo adduct is usually the main product because of the stability of the secondary orbital interaction in the transition state. This preference is known as Alder’s rule. One good example of the Adler’s rule is the cycloaddition of maleic anhydride and the cyclopentadiene,167 as shown in Figure 1.30.

34 O

O +

H H O O O O O endo exo O O O H O O O O H Figure 1.30: Additons mechanisms between the maleic anhydride and the cyclopentadiene.

The reaction at room temperature leads to the endo product, which is the kinetic product. As mentioned, the kinetic product is the product that is made the quickest. As a kinetic product, the compound is less stable over time than the thermodynamic product. This is why the endo product can leads to a retro-Diels-Alder. If the same reaction is run at high temperature, the first product which will be formed will be the kinetic one, but with higher energy, or heat, the endo adduct will be converted in the exo adduct according to the Figure 1.30.

The majority of Diels-Alder reactions are reversible. However, this work focused on a small sub-category of the Diels-Alder reagents that does not allow the retro-Diels- Alder reaction under these operating condition. This topic, the retro Diels-Alder, will not be discussed but interesting works can be found in the literature.168,169

Multiple cycloadditions can be achieved at the same time or in consecutive reactions. These steps can occur without isolating the different products. This is called a domino reaction, as shown in Figure 1.31.170 The reaction is between two unsymmetrical bis-dienes and a bis-dienophiles. As the Diels-Alder is regioselective, at room temperature the reaction works in two consecutives steps. The first step is the intermolecular reaction between the 2-(dimethyl-tert-butylsiloxy)-1,3,5,7-nonatetraene and the 1-phenyl-4- penten-1-yn-3-one. The trimethylsilyl-oxy group activates the diene in the same manner, and the conjugated vinylketone activates the dienophile. In Figure 1.31, the first six membered ring is formed and the second reaction, the intramolecular reaction, occurs

35 under gentle heat. This second step is the consequence of the functionality of the previous reaction.

OTMS OTMS OTMS Δ

CCl4 C H C6H5 6 5 C6H5 O O O Figure 1.31: Example of a “domino” reaction between a double diene and a double dienophile.

Fleming first proposed the theory of the frontier molecular orbital (FMO) in 1978.166 This theory provided an explanation of the regiochemistry and the stereochemistry of the Diels-Alder reaction. The mechanism is based on the superfacial interaction and the reaction between the highest occupied molecular orbital (HOMO) of one component and the lowest unoccupied molecular orbital (LUMO) of the other one.

To briefly summarise the Diels Alder reaction mechanism, the frontier molecular orbitals are the only orbitals which participate in the reaction. The numbers of molecular energy levels are based on the number of p-electrons involved in the system. The electrons are reported as a single head arrow, the head direction reported the spin orientation. On the same energy level, the electrons must have an opposite spin. In the case of buta-1,3-diene, there are four p-electrons which mean four levels, and for ethene, there are two electrons and two energy levels. The HOMO level is the highest energy molecular orbital which contains electron(s) and the LUMO is the next orbital with higher energy that has by definition no electrons, as shown in

Figure 1.32. The ethene and buta-1,3-diene are represented on the same energy level.

36 LUMO ΔE ΔE' 1π bonds 2 bonds HOMO π 2 e- 4 e-

Figure 1.32: Energy diagrams of a diene and dienophile.

The Diels-Alder reaction is a suprafacial reaction between the HOMO and the LUMO of the diene and the dienophile. Two cases are possible: engagement of the HOMO of the diene and the LUMO of the dienophile which is the normal cycloaddition, or engagement of the LUMO of the dienophile and the HOMO of the diene which is the inverse electron demand, This is shown in Figure 1.33. It should be noted that the reaction depends of the HOMO-LUMO energy gap. The lower the energy difference, the lower is the transition state energy of the reaction will be. In the case of the Diels-Alder reaction, the substituent plays an important role. Electron withdrawing substituents lower the energy of both the HOMO and the LUMO, while the electron-donating substituents increases their energies. The reaction with dienes with an electron-withdrawing substituent and a dienophile with an electron-donating group react faster: this is a normal electron demand Diels-Alder reaction.

Diene LUMO LUMO Dienophile LUMO

HOMO Dienophile HOMO Diene HOMO

Inverse Normal Figure 1.33: Inverse and normal Diels-Alder reactions based on the energy levels engaged in the reaction

The ortho-para rules are explained by the orbital coefficient of the four atoms which form the two s bonds. The regiochemistry is determined by the overlap of the orbitals that have larger coefficients. The greater is the difference between the orbital coefficients of

37 the two atoms at the end of each reagent, the greater the regioselectivity the cycloaddition is. Electron-withdrawing substituents decrease the size of the atoms which will form the p orbital whereas electron-donating substituents increase the size of their orbitals.

The theory of the FMO explains the stereoselectivity using an additional non- bonding interaction. This extra interaction does not favour a bond but lowers the energy of the endo transition state. When the orbital lobes are larger, the overlap will be better, the extra interaction will be stronger, and it will be easier to form the endo adduct, as shown in Figure 1.33-b with the example of acrolein and the piperylene.

Due to time constraints, this thesis work focused on the thermal Diels-Alder cycloaddition and the un-catalyzed reaction. The synthesis of polymeric materials were the priority of this thesis and many aspects of the reactions were necessarily glossed over, such as the use of catalysts, and the effects of irradiation with high energy photons on the reaction.

1.6. Thesis Scope

The purpose of this thesis was to design a new sterically encumbered, pre- sulfonated difunctionalized monomer which could be polymerized via DA coupling as a diene with a dienophyle, as shown in Figure 1.34. The initial plan was to functionalize the reagents of the tetracyclone but this failed for reasons which will not be discussed in this thesis.

SO3H

HO3S

SO3H

HO3S Figure 1.34: Proposed structure of a new sterically encumbered, pre-sulfonated difunctionalized monomer: sBTC(H+)

38 The synthesis of the monomer began with commercial compounds and was prepared in five main steps. The first step was Sonogashira cross-coupling, following to the oxidation of the triple bond, followed by the Knoevenagel condensation, by electrophilic aromatic substitution, and finally [4+2] Diels-Alder cycloaddition reaction.

In Chapter 2, short explanations of the different techniques used in this work is provided. In Chapter 3 the entire synthesis of the monomer, the diene and the dienophile and the model compounds, as well as their characterizations using NMR, IR, MS and single crystal X-ray diffraction is discussed.Also discussed are some of the difficulties encountered in this work due to the absence of regioselectivity. In Chapter 4 studies on the homopolymerization of the monomer, the characterization of the homopolymer, and its reveals its shortcoming- the polymer was soluble in hot water - is described. In Chapter 5 a strategy to decrease the swelling of the polymer by tuning the hydrophobicity/hydrophilicity of the polymers via copolymerization is proposed, and characteristics of membranes prepared therefrom is discussed. In Chapter 6 future work and ideas are proposed, including introduction of ionic and covalent brenching. Chapter 7 provides an overall conclusion of this work.

39 Chapter 2.

Techniques and Methods

2.1. Nuclear Magnetic Resonance (NMR)

The NMR spectroscopy is based on the principles of magnetization of nuclei of molecules in an intense magnetic field, radio-frequencies, and their relaxation. In this work, proton and carbon NMR spectroscopies were used as well as two other techniques which are less known and therefore described below.

2.1.1. 1D NOE

The Nuclear Overhauser Effect (NOE) is an example of polarization transfers between nuclei. There are two possible polarization transfers possible: heteronuclear and homonuclear. In heteronuclear transfers, the signal of one nucleus is transferred to another nuclei family. When the concentration of a sample is low, NOE can be used to enhance the signal of other nuclei. For carbon NMR spectroscopy, it is only possible to observe 13C which has a natural abundance of 1.108%. This is because this carbon isotope has an odd number of protons and/or an odd number of neutrons, which was discovered by the Nobel prize Laureate P. Zeeman in 1902. The theoretical NOE signal enhancement in an experiment like this one can enhance the carbon signal by 200%. The homonuclear effect, for example proton-proton, can also be very useful for molecular identification through-space. After irradiation and saturation of one nucleus, the polarization is transfered to nearby nuclei. Only the nearby nuclei through-space will exhibit a NOE effect. For complex molecules such as mentioned above, this technique was useful for the identification of the molecules in a solution.

The NOE technique requires the use of two coils: one for the irradiating field of the signal and one for the observing field. The first coil is set up on the frequency of the desired nucleus (proton) to be studied. The irradiation continues until magnetic saturation of the nucleus occurs and a 90° pulse is applied to allow the reading of the second coil. The signal is then recorded. This procedure is repeated until the signal-to-noise is appreciable. Then a similar procedure is run but the frequency of irradiation is further away from the

40 desired nucleus than in the previous procedure, and this similar procedure is repeated for an equal number of times. The final spectrum is obtained from the remaining FID (free induction decay) which is calculated by subtracting the FID of the first experiment from the FID of the second experiment.

This one dimensional (1D) experiment is a powerful tool when only limited information is needed. The irradiated proton will be exhibited as a negative multiplet signal. The 1D NOE spectrum shows only the close neighbouring nucleus (i) (proton[s]) through space within a range of 5 angstroms, i.e., those that are affected by the NOE effect.171 The nucleus (i) affected by the NOE effect will retain their coupling constants and multiplicities.172

2.1.2. 2D COSY

The 2D COSY, or homonuclear shift correlation spectroscopy, is an technique which provides information about the structure of the molecule through the molecular bonds. A 2D COSY spectrum is represented by a square whereas normal 1H spectra are represented on both the vertical and horizontal sides but also on the diagonal of the square. The 2D COSY experiment can identify neighbouring protons through bonds with a maximum of three bonds (3J). The cross-peaks (peaks off-diagonal) indicate the proximity and connection of the protons. In some instances is it possible to observe the 2J, e.g., dissymmetric hydrogens.172 One 2D COSY spectrum allows an observation of the whole coupling network of a molecule.173

Figure 2.1 shows an example of 2D COSY spectrum of an aromatic molecule. On the left and the top the 1H spectrum can be observed and because of the symmetry it can also be observed on the diagonal. The cross-peaks on both sides of the diagonal reflect the interaction between two signals.

Figure 2.1: Example of 2D COSY NMR spectrum of nitrobenzene in DCM-d2.

The sequence for a 2D COSY is more complicated than the 1D NOE because it depends on two time scales (t1 and t2) and two steps. The sample is first excited by a pulse(s) and then the resulting magnetization slowly decreases during time t1, longitudinal relaxation. A second period, called the mixing time, starts when the sample is excited again by a pulse(s) and then the signal is recorded during time t2. If, during time t1, a signal is observed at a frequency F1 and if, during time t2, the same signal is observed at a frequency F2, this means the signal was transferred in some way to F2 and was affected by the mixing period. More information about this mechanism can be found in the literature.173 The spectrum in Figure 2.1 can be understood as: proton A and C have a cross-peak between each other, which means they are connected with a 3J bond. Proton C also has a cross-peak with proton B, but B does not have a cross-peak with A (marked with a X). The conclusion of this spectrum is that proton A only correlates with C, proton B only correlates with C, and proton C correlates with A and B.

42 2.2. Size Exclusion Chromatography

Gel permeation chromatography (GPC), also known as size exclusion chromatography (SEC), is a technique that allows the separation of molecules based on their size. This method is widely used to quantify the molecular weight of polymers. The separation of the polymers occurs due to differences in mobility in a mobile phase which depend on the length of the backbone, e.g., the hydrodynamic volume.

A polymer in solution is injected through an injector connected to a pump fed by a solvent tank. The sample flows through a system containing at least one separation column and then on to various detectors. The columns are packed with porous particles of polystyrene gel. The small molecules are able to move into each pore along their route. The medium molecules will only be able to access pores of medium sizes and higher,and the large polymers will not penetrate into the pores and hence flow faster through the columns and will reach the detectors at an earlier time. The larger the molecular weight, the shorter the retention time compared to smaller polymer chains. Effective separation usually uses more than one column connected in a series with different pore size.

The polymer chains eluted from the column are detected by a sensor. Common sensors are based on the difference of the refractive index (RI) and the ultraviolet absorption (UV). Both sensors are differential which means they measure the difference of the RI or the UV between the solvent and the flowing sample as a function of time. The UV detector is set at a specific wavelength and measures the absorbance of the solution based on time.

Molecular weights are obtained by a comparison based on a calibration curve. A series of polymer standards with a known molecular weight are injected and analyzed. A calibration curve is obtained wherein the logarithm of the molecular weight is a function of the retention time. The obtained molecular weight of the polymer is based on standards and a calibration curve.

A sample containing polymers is a mixture of macromolecules with different lengths. The molecular weight of a sample is based on an average of the molecular weight of the chains and theirmolar fractions:

43 � � � = = � ∑ �

Equation 2-1

where � is the molar fraction containing i repeating units, Ni is the quantity of macromolecules containing i repeating units, and N is the total quantity of macromolecules.

The degree of polymerization in number (DPn) is defined as:

∑ � � �� = � × � = ∑ �

Equation 2-2

The average molecular weight in number Mn is defined as:

∑ �� = �� = = �� × � ∑ �

Equation 2-3

where Mn is the average molecular weight in number in g/mol, and M0 is the molecular weight of a repeating unit in g/mol.

The weight (wi) fraction is expressed as:

� � �� = = = = � ∑ � ∑ �� ∑ � �

Equation 2-4

where m is the total weight of the sample defined as:

� = � = �� = � ��

Equation 2-5

44 where mi is the total weight of the macromolecules with a molecular weight Mi defined as:

� = � × � = � × � × �

Equation 2-6

The degree of polymerization in weight is expressed as:

∑ � � ∑ � �� ∑ � � �� = � � = = = ∑ � ∑ �� ∑ � �

Equation 2-7

The average molecular weight, in weight Mw, is obtained as:

∑ �� ∑ �� = �� = = = �� × � ∑ � ∑ ��

Equation 2-8

Mn is the quotient of the total weight m over the number of macromolecules N and:

� > �

Equation 2-9

The polydispersity index (PDI) is defined as:

� �� = = � ��

Equation 2-10

The polydispersity index reveals the distribution of the polymer chain lengths in the polymer sample. If all the chains have the same length, then PDI = 1.

45 2.3. Polycondensation of AA and BB Monomers

Polycondensation uses bifunctional monomers (AA and BB for example) which react with each other. During polycondensation one functional group of one monomer will react with a functional group of a second monomer and then form a dimer. A dimer can then react with a monomer and form a trimer, or two dimers can react together and form a tetramer, as shown in Equation 2-11. Ideally, the monomer concentration rapidly decreases due to the formation of oligomers.

� �� + � �� → � mer �� + �� → � − � − � �� + � − � − � → � − � − � − � �� + � − � − � → � − � − � − � �� − � − � + � − � − � → � − � − � − � − � ��

Equation 2-11

If the reaction is quantitative, only one large macromolecule should be obtained. However, the polymerization can terminate prematurely for different reasons, such as when the thermodynamic equilibrium is reached (an example is the condensation between a diacid and a diol). A second reason is when an increase in viscosity leads to difficulties in the ability of two functional groups to react with each other. In some cases, the end groups may react with each other and form a ring. For a stoichiometric mixture of AA and BB the degree of polymerization is given by:

1 �� = 1 − �

Equation 2-12

where p is the monomer conversion.

To obtain a high molecular weight the conversion needs to reach 99%, which means the reaction needs to be quantitative. Polydispersity index for a polycondensation is typically 2, due to the larger difference in chain lengths.

46 2.4. Properties of Polymer Membrane

2.4.1. Polymer Casting

All polymer solutions for membrane casting were prepared from 10% w/w solutions in hot DMSO at 50 to 80°C. After complete dissolution, each solution was filtered through a Buchner funnel equipped with a glass fiber filter paper (G8 from Fisher Scientific). The filtered solution was then coated onto a glass plate at room temperature supported upon a K202 Control Coater casting table and a previously calibrated adjustable doctor blade (RK PrintCoat Instrument Ltd.). The blade height was set at 400 µm with the blade moving using gear 2. The glass plate was then transferred to an oven previously equilibrated using a spirit level and heated at 86 °C for 8 hours. The glass plate and the membrane were cooled down to room temperature, then the membrane was released from the glass plate by immersion in an aqueous bath containing 0.5 M H2SO4(aq). The membrane was then soaked in a 2.0 M H2SO4 bath for 1 h and in deionized water for 24 h, before drying for 1.5 h at room temperature on Kimtech® lab wipes. Finally, the membrane was compressed between two glass plates protected with Kimtech® lab wipes and dried overnight at 80 °C under vacuum, followed by cooling to room temperature under vacuum. The obtained thickness was measured using a caliper in multiple places (at least 6 places) on the film.

2.4.2. Ion Exchange Capacity (IEC)

Ion exchange capacity values for the membranes were obtained via automatic titration using a standard 0.01 M NaOH(aq) solution as a titrant. The titrant solution was verified against an aqueous solution of 0.01 M potassium hydrophthalate (KHP), which was previously dried overnight under vacuum at 80°C, using Equation 2-13. [KHP]aq represents the potassium hydrophthalate solution in mol/L, V(KHP) is the volume of the KHP solution used in L, V(NaOH) is the titration volume used during the titration in L, and[NaOH]aq is the resulting real concentration of sodium hydroxide solution in mol/L.

[��] × �() [��] = �()

Equation 2-13

47 Membrane samples averaging 20 x 20 mm were dried under vacuum at 80 °C overnight. Before releasing the vacuum, the oven was cooled down to room temperature. Sample masses were recorded thrice for accuracy. Each sample was then immersed overnight in 2.00 M NaCl (20 mL), the pH of which was previously adjusted to 7.00 – 7.05 using 0.01 M HCl(aq) or 0.01 M NaOH(aq). The membrane samples were then removed, and the remaining solution was titrated using the previously standardized NaOH solution. The -1 experimental IEC (IECxp, in meq. g ) can be obtained according to Equation 2-14, where

[NaOH]aq is the previously determined aqueous concentration of sodium hydroxide in mol/L, Veq is the titrant volume required to reach the equivalence point in L, and m(polymer) or m(sPPP(m)(H+) is the dry membrane weight in g.

[��] × �() [��] × �() �� = � 100 = � 100 �() �(()())

Equation 2-14

According to the theoretical composition of the polymer, the molecular weight can be calculated for 100 repeat units (Mn 100u, see Figure A 112 and Figure A 113). The number of sulfonic acid moieties therein can be obtained by multiplying the number of hydrophilic repeat units present (# Hydrophilic) by 4, which is number of acid functional groups per hydrophilic repeat unit. This yields the statistical number of sulfonic acid groups per 100 repeat units of polymer, nb(SO3H)100u. From this, the theoretical IEC (IECth, in meq. g-1) can be estimated, as per Equation 2-15.

��(��) �� = × 100 ��

Equation 2-15

The value of IECth and the IECxp can be compared as a measure of experimental accuracy and to provide insight into the availability of protons within the polymer membranes (Figure A 113).

48 2.4.3. Hydrolytic Stability

A dissolution test was used to determine polymer integrity and hydrolytic stability at elevated temperatures in water. A piece of polymer membrane was immersed in water at room temperature, after which the temperature was increased to 80°C.

2.4.4. Water Uptake (WU) and Water Content (WC)

To accurately determine membrane water uptake and content, a comparison between a fully dried and a fully hydrated (wet) state must be made. To accomplish this, membrane samples were first soaked in deionized water for a minimum of 16 h. The wet mass (mwet), thickness (Twet), and length (Lwet) and width (Wwet) were then measured. After drying at room temperature for 1 h, the polymer samples were further dried in an oven at 80 °C under vacuum for 16 h. The temperature was cooled to room temperature prior to releasing the vacuum, after which the sample dry mass (mdry), thickness (Tdry), and length

(Ldry) and width (Wdry) were immediately determined. Membrane samples mass measurements were repeated a minimum of three times per sample, until a constant sample mass, within the analytical balance error, was obtained.

The water uptake ratio, expressed as a percentage (WU%), can be obtained according to Equation 2-16-a, where mwet and mdry are in g. Membrane water content, expressed as a percentage (WC%), can be obtained according to Equation 2-16-b.

m − m m − m �) WU% = x 100% �) WC% = x 100% m m

Equation 2-16

2.4.5. Volume Uptake (VU)

The volume uptake percentage (VU%) was determined using the expression of the volume (V = L x W x T) of a given sample, where L is the length, W is the width and T refers to the thickness, wet or dry, as described above. These parameters are measured in the same unit of length (mm). In this way, the difference in volume (VU%) of a 3 3 membrane sample when dry (Vdry, in mm ) vs. wet (Vwet, in mm ) was obtained, as per Equation 2-17.

49 (L × W × T) − (L × W × T) V − V VU% = x 100% = x 100% (L × W × T) V

Equation 2-17

2.4.6. Water Sorption (λ)

The water sorption, λ (mol H2O / mol SO3H), represents the number of water molecules per sulfonic group within a membrane. It was determined according to Equation

2-18, in which, VU is the volume uptake, MH2O is the molecular weight of water in g/mol, and IECxp in mequiv./g which is the experimentally determined in mequiv/g or mmol/g. VU% λ = 10 M × IEC

Equation 2-18

2.4.7. Acid Concentration ([SO3H])

The analytical concentration of acid within a wet polymer membrane, [SO3H], was determined using Equation 2-19, where mdry is the dry mass of the polymer in g, Vwet is the volume of the wet polymer in cm3, and IEC is expressed in mmol g-1.

m [−SOH] = × IEC V

Equation 2-19

2.4.8. Effective Proton Mobility (μeff)

Using the measured membrane acid concentration (mol L-1) and Faraday constant -1 (F = 96485 C mol ), effective proton mobility (µeff) was calculated according to Equation 2-20, where σ is the proton conductivity of the polymer in water, in Scm-1.

σ µ = F × [−SOH]

Equation 2-20

50 2.4.9. Proton Conductivity (σ)

Three parameters must be considered and these cannot be measured independently of each other: the interfacial contact resistance or membrane resistance

(Rel), the membrane bulk capacitance (Cdl), and the membrane bulk resistance (Rct). The interfacial contact resistance is the resistance created by the contact between the electrolyte and the electrode. The membrane bulk capacitance is the capacitance of the double layer: this is the charge between the two electrodes. The membrane bulk resistance is the charge transfer resistance.

Impedance spectra are usually presented using a Nyquist plot. The impedance is represented as a function of the frequency and each point represent the real and imaginary parts at one frequency wi. A Nyquist plot is usually a semicircle with the high- frequency part (y axis) giving the resistance Rel (membrane resistance) and the radius (x axis) giving the charge transfer resistance, as shown in Figure 2.2.

Figure 2.2: Example of a Nyquist plot. Modified with permission Spinger Nature, © 2010, PEM Fuel Cells and their Related Electrochemical Fundamentals. In: Electrochemical Impedance Spectroscopy in PEM Fuel Cells. Springer, London.4

A Randles circuit can be used to easily explain the relationship between Rel, Cdl, 174 and Rct and the equivalent circuit is shown in Figure 2.3.

Figure 2.3: Schematic representation of a Randles cell with electronic componants.

Information can be extracted at different positions on the semi-circle of the Randles

Nyquist plot. At high frequencies, the impedance of Cdl is low and the impedance can be assumed to be close to Rel. At low frequencies, Cdl becomes high and the measured impedance tends to be Rel + Rct. If at low frequencies the intercept is the Rct, and at high frequencies the intercept is Rct + Rel, then the diameter of the semi-circle is the Rel or the resistance of the membrane.

The impedance can be measured in situ (membrane with electrodes) or ex situ (membrane alone). The Randles circuit previously mentioned demonstrates an example of ex situ measurement. During the measurement, the membrane is maintained between two Teflon® blocks and two electrodes made of platinum as shown in Figure 2.4.

Figure 2.4: Set up for measuring the EIS. Modified with permission from Journal of electroanalytical Society, Soboleva, T.; Xie, Z.; Shi, Z.; Tsang, E., Navessin, T.; Holdcroft, S. 622, 145, © 2008, Elsevier B.V.175

The conductance of the membrane is obtained using the following equation:

� � � = = � × � � × � × �

Equation 2-21

52 where s is the conductivity in S/cm, L is the length of the sample in m, Rel is the membrane resistance in W, and A is the cross sectional area in m2 which is the product of the thickness T and the width W in m.

Membranes were soaked in deionized water (16 h), and their dimensions (thickness and width) measured prior to resistance experiments. The in-plane proton conductivity was measured by AC impedance spectroscopy with a Solartron 1260 frequency response analyzer (FRA), employing a two-electrode configuration, according to a procedure described in the literature.176 Proton conductivities at variable relative humidities RH) were measured by placing a conductivity cell inside an Espec model SH- 241 humidity chamber held at a given temperature. Proton conductivity was measured at 30 °C and at 80 °C at various RH: 95% RH, 90% RH, 70% RH, 50 % RH, 30% RH. Resistance data were outputted in the form of a Nyquist plot, which was fit to a Randles equivalent electrical circuit to calculate a value for membrane ionic resistance, Rp. Proton conductivity (σ) was calculated according to Equation 2-22, where L (cm) is the distance between electrode, and A (cm2) is the cross-sectional area of the membrane (T x W, in cm).

L L σ = = R × � R × � × �

Equation 2-22

2.4.10. Polarization Curve and Fuel Cell Efficiency

The efficiency of the fuel cell is obtained by running the polarization curve. The theoretical maximum voltage which can be obtained for PEMFC for one cell is 1.23 V, which is calculated by subtracting the value of the HOR from the ORR, see Equation 1-1. The polarization means the potential is shifting from its equilibrium value which leads to an electrochemical reaction(s). The curve reports the voltage change with the current density. A good device is expected to exhibit a polarization curve with high current density 0 (close to the theoretical E cell = 1.23V) at high cell voltage, see Figure 2.5.

Three regimes can be observed on a polarization curve: the kinetic region, the Ohmic region, and the mass transfer region. The kinetic loss is the diminution of the cell voltage due to the relatively slow electrochemical reduction of O2. Ohmic losses cause the cell voltage to decrease almost linearly and is due to the resistance of the internal components, primarily the ionic resistance of the PEM, but also the catalyst layer, and the contact resistance. The proton resistance has an important impact on the Ohmic region. The mass transfer losses can be a consequence of many factors that reduce the rate at which the reactant gases reach the catalyst sites.

54 Chapter 3.

Model Compounds

In this work, a critical challenge was to successfully prepare sulfonated monomers and examine its reactivity. Before starting large-scale synthesis of the monomer, cautious exploratory approaches were attempted on small model compounds. This section reports the approach, the synthesis and the characterization done on various small model molecules. Part of this work was published in the Journal of the American Chemical Society: T. J. G. Skalski, B. Britton, T. J. Peckham, S. Holdcroft, “Structurally-Defined, Sulfo-Phenylated, Oligophenylenes and Polyphenylenes”, J. Am. Chem. Soc, 2015, 137, 12223-12226 and in Angewandte Chemie International Edition: Michael Adamski, Thomas J. G. Skalski, Benjamin Britton, Timothy J. Peckham and Steven Holdcroft, “Highly Stable, Low Gas Crossover, Proton-Conducting Phenylated Polyphenylenes”, Angew. Chem. Int. Ed., 2017, 56, 9058-9061. My contributions to the section below included the entire synthetic sections and the molecular structure characterizations; Dr. Dev Sharma performed thermogravimetric analyses; Ania Sergeenko helped characterize the crystal structure, and Dr. Andrew Lewis ran the high temperature 1H NMR and the 1D NOE sequences.

3.1. An Introduction to Tetracyclones and Bistetracyclones

2,3,4,5-Tetraphenylcyclopenta-2,4-dienone (tetracyclone or TC) could have been discovered earlier if, in 1901, Henderson et al. had used a reflux bath instead of a warm bath when they first mixed benzil with dibenzyl ketone in a basic medium. The lower temperature allowed them to discover the tetraphenylcyclopentenolone.178 According to the literature and knowledge at this time, the first report of the synthesis of the TC was made in 1925 in two different laboratories, by Ziegler et al.179 and Loewenbein et al.180, shown in Figure 3.1. Later, Dilthey et al. reported new derivatives of the TC,181 and the condensation of the TC with maleic anhydride using the [4+2] Diels-Alder reaction. They proposed for the first time the two steps reaction, when the adduct is formed and then the carbon monoxide is extruded at a higher temperature to form the expected product.181 Three years later, Dilthey et al. published the first investigation of the [4+2] Diels-Alder cycloaddition reaction between TC and a series of vinylene, acetylene and ethynyl

55 derivatives. The conclusion appeared to be that the reaction was irreversible under their conditions.182 Thirty years later, Ried et al. applied this reaction on a di- and trisubstituted dienophile45 and made the first polymer from a bistetracyclone (BTC) and the bis- dienophile the 1,4-diethynylbenzene.44

The first characterization of this polymer reveals a melting point of this compound at a higher temperature of 420 °C.183 The high stability attracted the interest of J. K. Stille, who thoroughly characterized this new class of polymer. Harold et al. firstly report the non- expensive polymerization in toluene whereas Ried and coworkers used the cis-β-dekalol: the reaction took 24 h under pressure at 200°C and produced a white polymer in a 91 % yield.47 This last information also enhances the strength of the Diels-Alder reaction and the potential of these compounds, which usually give quantitative yields; this can be a strength for industry. The thermogravimetric analysis study revealed that a degradation occurred at 550 °C under an air atmosphere and at 575 °C under nitrogen. The drawback of the reaction is that it is impossible to control the regiochemistry of the product,48 as the dienophile is added to the diene, two configurationally isomers might be obtained per diene, as shown in Figure 3.2.

O H

KOH HO Warm Bath

O Tetraphenylcyclopentenolone + O KOH O O Reﬂux

2,3,4,5-tetraphenylcyclopenta-2,4-dienone Figure 3.1: Schematic preparation of the tetraphenylcyclopentenolone (upper product) proposed by Henderson et al. in 1901 and the 2,3,4,5- tetraphenylcyclopenta-2,4-dienone (lower product) by Ziegler et al. and Loewenbein et al in 1925.

VanKerckhoven et al. realized the first post functionalization of the poly(phenylene) under harsh conditions: sulphuric acid, 250 °C for 120 h, as shown in Figure 3.3.49 Later, Kallitsis and Naarmann50 used the Yamamoto coupling to realize one of the first poly(p-

56 terphenylene)s using nickel, triphenylphosphine and zinc as reducing agent with the dichloro or dibromo monomer derivatives that were made by Arnold and Wolf.51,52 These polymers, like the one made by Stille and Ried, shows high thermal stability. Another attempt was made by Kallitsis et al. when they polymerized a pentaphenylene; however, to ensure the polymer would remain soluble, the link between the monomeric units was an ester bond, which increased the polarity and induced flexibility in the polymer chain. Some alkyl chains were also added and the solubility increase drastically.53 Mullens et al. investigated the properties and the product of the polymerization using the Diels-Alder reaction, and Shifrina et al., quantified the ratio of the isomers using a small molecule as model. 54 Based on the crystal structure of the main product, they concluded that the main isomer was the meta-meta product after the addition of phenylacetylene on the BTC, as shown in Figure 3.3.

R R R

H O + O + O H

Figure 3.2: Adducts and intermediates (isomers of position) obtained by the Diels-Alder reaction from the TC and the phenylacetylene before the carbon monoxide extrusion.

After the first attempt to functionalize the poly(phenylenes) (PPP) in 1972 using sulfuric acid at 250 °C, as shown in Figure 3.3,49 Fujimoto et al. reported the efficient functionalization of the PPP in 2005 using chlorosulfonic acid and obtained a sulfonated poly(phenylene), sPP.55 For the first time the sPP was used as a polymer electrolyte membrane (PEM), and the sulfonation efficiency was estimated between 80 to 50%, based on the different samples as shown in Figure 3.3. The polymer was soluble in polar solvents, such as DMSO and NMP, but remained insoluble in water. The thermal stability was lower than that the PPP but it remained at 285 °C for the first 5% weight loss, which 184 is often related to the SO3 cleavage in the highly encumbered aromatic polymer and in the sulfonated arylene. Because of the high stability of the backbone and how easy it is to make the polymer, the sPP was broadly studied.57,58,185 Cornelius et al. also applied this backbone to the rival of the PEMFC, the AEMFC, by post-functionalizing the polymer with quaternary ammonium: BTC has initially one methoxy group in para positon on each

57 phenyl rings close to two ketones which was then converted after the polymerization to N,N,N-trimethylmethanamonium, and this derivative exhibited high performance for AEMFC.60–62

Unfortunately, despite the fact that these materials seem to be chemically robust and electrochemical efficient in fuel cells, this strategy, i.e., polymerization and post- sulfonation, may cause some issues. An expert in polymer chemist might see an important limitations for a realizable material, that functionalization might may on different sites and the polymers prepared are likely moleculary irreproducible. This is due to the synthetic strategy of post-functionalization, as shown in Figure 3.3.

+ n cis-β-dekalol, 200°C

BTC 1,4-diethynylbenzene poly-para-phenylene PPP Ried et al. 1966

ClSO3H H SO 250°C CHCl3, RT 2 4, 8h 120h X X

X X X X

n n

X X X X

X X Fujimoto et al., 2005 X = SO3H or H VanKerckhoven et al. 1972 Figure 3.3: Synthesis of the poly-para-phenylene (PPP) firstly made by Reid et al. using cis-b-dekalol for 24h and the two further post functionalization made by VanKerckoven et al49 and Fujimoto et al.55

58 The [4+2] Diels-Alder cycloaddition requires a diene, TC or BTC, and a dienophile, as shown in Figure 3.3. The above were prepared with an acetylene to yield an aromatic compound after the cycloaddition reaction. The chemistry of the alkyne has been known for more than a century, and Kenkichi Sonogashira played a big part in this domain. Even though the Grignard reaction allows the addition of the alkyne-Grignard on sp3 or sp2 carbons (alkyl, aldehyde, ketone), the addition is not allowed on aromatic substrates. In 1975, Sonogashira et al. reported the first substitution of acetylenic hydrogen with halide.90 As mentioned before, an aryl halide and a true acetylene react together in the presence of an amine, and two catalysts. This reaction is one example of organometallic cross- coupling and similar to the Suzuki-Miyaura reaction82,85, the Heck reaction,186 or the Negishi reaction187 just to name a few. Four dienophiles were made using the Sonogashira cross-coupling and the protiodesilylation reactions.

The ring closing, or [4+2] Diels-Alder cycloaddition was mostly run with an apolar aprotic solvent under reflux. However, the carbon monoxide extrusion, in this case, required a higher temperature. Reid et al.45 used cis-b-Dekalol, Mukamal et al.47 used toluene in a Paar pressure reactor at 200 °C for the synthesis of poly(hexaphenylpentaphenyleneoxide). Fujimoto et al.184, Lim et al.188, and Lee et al.142 used diphenylether (DPE) at 180°C to lead the SDAPP0. Dong et al.189 used sulfolane for the synthesis of 1,2-bis(4-hydroxybenzene)-3,4,5,6-tetraphenyl-benzene (BHPTPB), and 1,2-bis(difluorobenzoy1)-3,4,5,6-tetraphenylbenzene, (BFBTPB). The cycloaddition involving the carbon monoxide extrusion reaction has always been run using an unsubstituted diene, i.e., no substitution, such as EAS, were made after the synthesis of the tetracyclone.

3.2. Synthesis of the Diene: Sulfonation of the Tetracyclone

This section reports the challenging work to synthesize a prefunctionalized diene with a sulfonic acid reagent and the step-by-step process to characterize the new compounds. Section 3.2 first reports the synthesis of the disulfonated tetracyclone and its + + + protection, sTC(H ) and sTC(HNEt3 ), as well work related to the monomer, sBTC(H ). This section reports the synthesis of different dienophiles and the last section reports the synthesis and characterization of model compounds.

59 3.2.1. Materials

Triethylamine (NEt3, 99%), activated charcoal (G-60), hydrochloric acid (ACS reagent, 36.5-38% content) were purchased from Anachemia Science. 1,4-Diodobenzene (98%) and phenylacetylene (98%) were purchased from Combi-Blocks, Inc and use without purification.

Acetone (Certified ACS), dichloromethane (DCM, Certified ACS stabilized), methanol (MeOH, reagent grade), pentane (reagent grade), ethyl acetate (Certified ACS), silica gel (S825-1, 230-400 mesh, grade 60), neutral alumina (60-325 mesh, Brockman Activity I), anhydrous magnesium sulfate (Certified Powder) and Celite™ (545 Filter aid, not Acid-washed powder) were purchased from Fisher Scientific and used without further purifications.

Nitrobenzene (98%, reagent plus), diethylamine (reagent plus, 98%), dimethyformamide (DMF, Chromatosolv® HPCL grade), trimethylsilyl-chlorosulfonate (99%), lithium bromide (reagentPlus® >99%), triisopropylsilyl-acetylene (95%), benzil (>97%) were purchased from Sigma-Aldrich Canada Co. Diethylamine and nitrobenzene were degassed with argon before each use; all other compounds were used without any further purification.

Ethanol (99%) was purchased from Commercial Alcohols

Trimethylsilylacetylene (lot number 003013I12J) was purchased from Oakwood.

Diethyl ether anhydrous (reagent ACS), sodium chloride (reagent ACS), potassium carbonate Anhydrous (ACS grade), sodium thiosulfate anhydrous (reagent grade) and tetrabutylammonium fluoride (hexahydrate, 95%) were purchased form ACF Montreal and used without further purification.

Chloroform (ACS grade), dimethylsulfoxide (ACS grade), sodium hydroxide (ACS grade) and iodine (analytical reagent) were purchased from BDH

Petroleum ether (reagent grade), n-butanol (reagent grade), potassium hydroxide (reagent grade, min 85%), sulfuric acid (reagent grade, 95-98%), potassium permanganate (KMnO4, reagent ACS, min 99%), potassium carbonate anhydrous (K2CO3,

Reagent ACS, min 99%) and sodium sulphite anhydrous (Na2SO3, reagent chemical

60 grade, meets ACS specifications) and tetrahydrofuran (ACS grade) were purchased from Caledon Laboratory Chemical.

1,3-diphenylacetone (ACS reagent, 98%) was purchased from Tokyo Chemical Industry Co., Ltd.

Argon (PP 4.8) was purchased from Praxair.

Diphenylphosphine palladium dichloride (Pd(PPh3)2Cl2, 97%) and copper(I) iodide (>99.9%) were purchased from Strem Chemicals.

Dimethylsulfoxide-d6 (D, 99.9%), acetone-d6 (D, 99.9%) and methylene chloride- d2 (D, 99.8%, CD2Cl2) were purchased from Cambridge Isotope Laboratories, Inc.

3.2.2. Equipment

The syntheses were performed according the regular use of a manifold and Schlenk line.

The 1H and 13C NMR spectra were recorded on a Bruker AVANCE III 500 MHz spectrometer equipped with a 5-mm TXI Inverse probe at room temperature (T = 298 K). 2D (COSY) and 1D NOE were recorded on Bruker a AVANCE II 600 MHz “TCI 600” spectrometer equipped with a 5mm TCI cryoprobe.

Mass spectra were recorded for the dienes on an AB Sciex 4000 Q TRAP spectrometer (ESI mode) at SFU. For all the other molecules, accurate mass measurements were performed on an LC-TOF instrument from Agilent Technologies in positive APPI mode. Molecular ion (M+) or protonated molecular ions (M+H)+ were used for empirical formula confirmation, and were carried out at the Centre Régional de Spectrometry de Masse at the Université de Montréal.

Size-exclusion chromatography analyses were obtained using Water HPLC HR 5, HR 4 and HR 3 columns with HPLC grade DMF (containing 0.010 M LiBr) as eluent. Polystyrene samples, purchased from Waters Associates Inc., were used as standards for the calibration.

61 Microwave-assisted reactions were carried out using a Biotage® initiator+ microwave reactor using a 20-mL reactor equipped with a stirring bar.

Thermogravimetric analysis (TGA) was performed using a PerkinElmer STA6000 heating at a rate of 2 °C/min from room temperature (30°C) to 600 °C under a nitrogen atmosphere to assess the thermal stability of molecules.

Infrared spectra were record on a PerkinElmer UATR FT IR spectrometer at room temperature.

3.2.3. Strategy

The strategy used in this work required the synthesis of two main components prior to attempting polymerization using the Diels-Alder [4+2] cycloaddition: The first components were tetracyclones and bistetracyclones. The second components contain an alkyne group, as shown in Figure 3.4. The diene used in this study contained a carbonyl which, after the cycloaddition, is released as carbon monoxide, preventing the retro-Diels- Alder reaction.

R R

Diene Dienophile Figure 3.4: General structure of the diene (red) and dienophile (green) used in this work.

3.2.4. Synthesis of Tetracyclone (TC)

O O O KOH + Reﬂux O

Benzil 1,3-diphenylpropan-2-one TC Figure 3.5: Synthesis of tetracyclone.

62 TC was synthesized according to a literature45,190 procedure with the following modifications. To a 500-mL, two-neck, round-bottom flask containing 300 mL of absolute ethanol and equipped with a condenser, septum and stir bar were added 1,3- (diphenyl)propan-2-one (19.99 g, 95.1 mmol, 1.00 eq), and benzil (20.00 g, 95.1 mmol, 1,00 equiv.). The solution was refluxed for 0.5 hour. KOH (3.81 g, 95.1 mmol, 1.0 equiv. dissolved in 5 mL of water) was added dropwise to the warm solution through the septum using a syringe. The solution was refluxed for an additional 45 min before being cooled to 0 °C using an ice bath. After 2 h, the solution was filtered and the precipitate was washed twice with cold methanol to yield the TC (33,1 g, 95.0 mmol, >99%.) as a purple crystalline 1 powder. H NMR (500 MHz, CD2Cl2) δ (ppm): 6.95 (d, J = 7.01 Hz, 4 H), 7.18 (t, J = 7.47 13 Hz, 4 H), 7.21-7.27 (m, 12 H), see Figure A 1. C NMR (125 MHz, CD2Cl2) δ (ppm): 200.86, 155.33, 133.77, 131.54, 130.68, 129.80, 129.00, 128.51, 128.00, 126.01, see Figure A 2. FTIR-ATR (cm-1): 3060, 1709, 1494, 1444, see Figure A 4. HRMS [M+H]+: calcd for

C29H20O 385.1583, found 385.1583, see Figure A 5.

3.2.5. Functionalization of TC

The functionalization of the tetracyclone was not as easy as it could have been. Ogliaruso et al. reviewed the synthesis and the possible reactions in the “Chemistry of the Cyclopentadienones”.191 At this time, the functionalization was difficult and no electrophilic aromatic substitutions were successful. This presented a significant challenge to this thesis work.

The electrophilic aromatic substitution on TC was attempted with different reagents, solvents, and temperatures reported by Maier et al.192 Based on the resonance structure of the TC, the EAR could occur on the four benzene rings, in ortho and para positions, see Figure 3.6. EAS at the ortho position was difficult because of the steric hindrance between the cyclopenta-2,4-dienone and the phenyl rings.

63 Two possible paths

O O O O

O O

Figure 3.6: Resonance structures of tetracyclone.

EAS was successfully performed using trimethylsilyl-chlorosulfonate (TMSO-

SO2Cl) at room temperature. Surprisingly, the product was obtained in almost quantitative yield. The stoichiometry was adjusted to yield the pure product, see Table 7.

Table 7: Adjustment of the Stoichiometry using TMSO-SO2Cl for EAS of the TC

TC:TMSO-SO2-Cl (equiv.) Product(s) observed 1:2 Reagent and monosubstituted 1:3 Reagent and monosubstituted 1:4 Monosubstituted and disubstituted 1:5 Monosubstituted and disubstituted 1:6 Disubstituted 1:7 Disubstituted

Table 7 reports the associated results for EAS using TMSO-SO2Cl for the functionalization of TC. Best yields were observed using 6 equiv. of reagent for 1 equiv. of TC.

64 3.2.6. Synthesis of 4,4’-(2-oxo-4,(-diphenylcyclopenta-3,5-diene-1,3- diyl)dibenzenesulfonic acid (sTC(H+))

O HO S O 3 SO3H

TMSO-SO2Cl

DCE

TC + sTC(H ) Figure 3.7: Synthesis of 4,4’-(2-oxo-4,(-diphenylcyclopenta-3,5-diene-1,3- diyl)dibenzenesulfonic acid (sTC(H+)).

TC (20.00 g, 51.9 mmol, 1 equiv.) was dissolved in a 1.0-L two-neck round-bottom flask equipped with a stir bar and containing 500 mL of dichloroethane degassed with argon for 30 min. Trimethylsilyl chlorosulfonate (48.1 mL, 311.8 mmol, 6 equiv. was diluted in 55 mL of degassed dichloroethane and added dropwise to the flask. The solution was stirred for 12 h. Ethanol (5 mL) was added to initiate precipitation and quench the reaction. The reaction mixture was stirred for an additional 2 h, then poured into 1.0 L of diethyl ether, filtered and washed several times with cold diethyl ether. The precipitate was recovered and dried under vacuum at 60 °C for 8 h to yield quantitatively sTC(H+) (28.1 g, 51.6 mmol) as a bright purple powder. FTIR-ATR (cm-1): 3404, 1711, 1350, 1133, 1032, 1 983, shown in Figure A 7. H NMR (500 MHz, CD2Cl2) δ (ppm): 3.86 (s, H2O/H3O+), 6.95 (d, J = 7.24 Hz, 4 H), 7.11 (d, J = 8.38 Hz, 4 H), 7.22-7.29 (m, 6 H), 7.46 (d, J = 8.38 Hz, 13 4 H), shown in Figure 3.8. C NMR (125 MHz, CD2Cl2) δ (ppm): 199.48, 155.08, 147.05, 132.63, 130.68, 129.25, 128.90, 128.72, 128.16, 125.23, 124.60, shown in Figure A 9. - 2- HRMS [M-e] : calcd for C29H20O7S2 543.0577, found 543.0564, [M-e] 271.0231, shown in Figure A 6.

3.2.7. Characterization of sTC(H+)

TC was soluble in acetone, dichloromethane (DCM), chloroform and dichloroethane (DCE). After the sulfonation, sTC(H+) precipitated in dichloroethane, and was soluble in boiling acetone and DCM, insoluble in chloroform but became soluble in water, methanol, ethanol, DMF and DMSO. This change in the solubility behaviour indicates a change in the hydrophilicity. Furthermore, it was impossible to observe the

65 ionisation using positive mode from the mass spectrometry (MS) indicating that it was not possible to observe the ionisation. The ionisation in negative mode shows the mono- ionized (M/z with z = 1) molecular ion corresponding to the sTC(H+) containing two sulfonic acids. The mass spectrum also shows a molecular ion with two charges (M/z with z = 2) corresponding to a double ionisation of the sTC(H+), see Figure A 6. Additionally, infrared

-1 (IR) spectroscopy reveals a broad u(OH), stretching band, from 3800 to 2800 cm , see Figure A 7 related to the H+, which was not present on the IR spectrum of the TC, see

Figure A 4. The fingerprint of the sulfonic acid is also present: 1350 cm-1 (uS=O), 983 cm-

1 (uS-O). According to the resonance structure in Figure 3.6, it is not possible to confirm the structure of the sTC(H+).

The 1H NMR spectroscopy and 2D NMR spectroscopy were used to identify the + structure of the sTC(H ). Two doublets are observed in deuterated DMSO (DMSO-d6) (see Figure 3.8); protons 1 and 2 correlated together based on the COSY spectrum (see Figure A 8). These two doublets show that the sulfonation occurred in para position of the phenyl ring and not in the ortho position, as shown in Figure 3.6. The third doublet 4 and the triplets 3 and 5 correlated together and corresponded to a phenyl ring. Based on the chemical shift of protons 1,protons 1 are in alpha position of the sulfonic acid, the protons 2 are in too high field to compare to a regular phenyl ring, which means that this para substituted benzene ring are in alpha position of the ketone. Furthermore, the 13C NMR spectrum (see Figure A 9) shows the remaining signal of the ketone (peak at 199.48 ppm), which proves that the sulfonated reagent is not destructive for TC. The abbreviation of this compound, sTC(H+), does not refer to the stoichiometry of the acidic proton, i.e., two protons are present. The acidic proton (H+) is overlapping with the water contained in the solvent at 3.86 ppm, so that the integration does not match because of the exchange + between the D and the H in the solvent (DMSO-d6) and the sulfonic acid sTC(H ).

66 1 HO3S 2 O

3 SO3H 4

5 + H2O/H

1 2 4 3

1 + Figure 3.8: H NMR (DMSO-d6) spectrum of sTC(H ).

3.2.8. Crystal Structure of the sTC(H+)

The crystal structure of the sTC(H+) was obtained by slow evaporation of DMAc at 80°C. DMAC slowly decomposes at high temperature in presence of a strong acid to form diethylamine, which is incorporated into the structure. The crystal structure proved the structure of the disubstituted TC in both para position of the rings adjacent to the ketone of the TC, as shown in Figure 3.9. The compound crystalized in the monoclinic crystal system in a C2/c group, as shown in Table A 1. The molecules exhibit a head-to-tail arrangement in the crystal structure with a range of distances from 4.150 Å to 4.504 Å between each cyclopentadienone.

Figure 3.9: X-ray crystal structure of the sTC(H+) co-crystalized with diethylamine (ellipsoids set at 50% probability).

The sulfonic acid formed hydrogen bonding with the solvent from the sulfonic acid O3 to H1A of the diethylamonium in a distance of 1.916 Å and O2 and H1B with in a distance of 1.924 Å. Each sulfonic acid forms two hydrogen bonding from two oxygen of the sulfonate group with the diethylamonium molecule. Both ammonium protons of the diethylamonium are involved in a hydrogen bonding, as well. The molecules are organized as rows along the b axis, where the sTC are organized as a head-to-tail alignment, and in between are rows of diethylamonium.

3.2.9. Protection of the Sulfonic Acid: Synthesis of bis + triethylammonium Tetracyclone Disulfonate (sTC(HNEt3 ))

The next step should be the Diels-Alder reaction at high temperature. Based on the literature the desulfonation, e.g., the loss of the sulfonic acid, may occur at a high temperature of 300 °C.56 The chosen strategy was to convert sulfonic acid to a salt form to enhance the chemical stability for the next step. The sodium form was difficult to obtain in a good yield. An alternative approach was to use an amine so triethylamine was used. + The abbreviation for this compound, sTC(HNEt3 ), does not refer to the stoichiometry of the salt as two ammonium cations are present.

68 O O HO S -O S - 3 SO3H 3 SO3 NEt3 H H N N n-BuOH

+ + sTC(H ) sTC(HNEt3 ) Figure 3.10: Synthesis of bis triethylammonium cyclone disulfonate.

In a 500 mL round-bottom flask equipped with a stir bar and containing 150 mL of n-butanol was dissolved 4 (4.00 g, 3.52 mmol, 1 equiv.) then 100 mL of triethylamine was added. The solution was stirring for 12 h, then filtered and wash several times with cold ethyl acetate or diethyl ether. The precipitate was recovered and dried under vacuum at 1 100 °C overnight to yielded 5 (4.56 g, 6.12 mmol, 83%). H NMR (500 MHz, CD2Cl2) δ

(ppm): 1.17 (t, Jt = 7.10 Hz, 36 H), 3.09 (m, two overlapped quadruplets, 12 H), 6.97 (d,

Jd = 6.93 Hz, 4 H), 7.11 (d, Jd = 8.29 Hz, 4 H), 7.22-7.29 (m, 6 H), 7.46 (d, Jd = 8.29Hz, 4 13 H), 8.85 (s, 4 H), see Figure A 10. C NMR (125 MHz, CD2Cl2) δ (ppm): 199.46, 155.00, 147.19, 132.61, 130.55, 129.17, 128.86, 128.66, 128.11, 125.18, 124.57, 45.78, 8.65, see

Figure A 11. FT-IR is shown in Figure A 13. HRMS [M-e]-: calcd for C29H20O7S2 543.0578, 2- + found 543.0595, [M-e] 271.0231. [M+H] : calcd for C6H16N 102.1277, found 102.1278.

The stacked1 H NMR spectra show no differences in chemical shifts for the acid form and the salt form, as shown Figure 3.11. The hydrated acidic peak at 3.84 ppm disappears when the triethylamine is added and is converted into the triethylammonium + (HNEt3 ); the ammonium proton (NH) shows up at 8.86 ppm.

DCM-d2

+ H2O/H

DMSO-d6

H2O

+ H-N Et3

1 + Figure 3.11: Stack of H NMR spectra of the TC (DCM-d2), sTC(H ) (DMSO-d6) and + sTC(HNEt3 ) (DMSO-d6).

Thermogravimetric analysis was performed under a nitrogen atmosphere between + + room temperature and 600°C. Both sTC(H ) and sTC(HNEt3 ) revealed a two-step thermal decomposition mechanism wherein desulfonation occurred first, as shown in Figure 3.12.

70 100 + sTC(H ) sTC(HNEt +) 3

40 Normalized Weight Loss (%) Loss Weight Normalized 20

0 0 100 200 300 400 500 600 Temperature (°C)

+ + Figure 3.12: Thermogram of sTC(H ) and sTC(HNEt3 ) under nitrogen between ambient temperature and 600°C using a heating rate of 2°C/min.

In the case of sTC(H+) between room temperature to 110°C, an additional mass loss is observed, which is the evaporation of water surrounding the sulfonic acids. The first 5% weight loss from the acid occurs between 236 and 286 °C. At the end of this process, at 400°C, the compound lost ~ 34% by weight, which corresponds to the composition (in weight percent) of the sulfonic acid (-SO3H) in the compound. The second major loss of mass, due to decomposition of the hydrocarbon backbone which occurred at 443°C. The ammonium derivative does not contain water. The first 5% weight loss for the sulfonate group appears between 243 and 289°C. The decomposition of the backbone begins at the same temperature as the acid form, at 445°C.

3.3. Synthesis of the Bis-diene: Functionalization of Tetrasulfonated Bistetracyclone

The functionalization of the tetracyclone yields a disulfonated compound substituted in the para position of phenyl ring 1 and 4. Obtaining the bis-diene or the monomer requires modification of the parameters from that optimized for the tetrasubstituted bistetracyclone.

71 3.3.1. Synthetic Plan

A strategy was developed to synthesize a bis-diene as a monomer according to the following Figure 3.13.

Sonogashira I I + 2 equiv. cross-coupling 1,4-bis(phenylethynyl)benzene

Oxidation

O O Knoevenagel O Condensation O O O Bisbenzil

BTC

EAS

SO H SO - 3 H 3 4 equiv. N - SO3H SO3

O O Acid-base

Reaction O O

- HO3S O3S

+ + sBTC(H ) sBTC(HNEt3 ) + Figure 3.13: Synthetic route to sBTC(HNET3 ).

3.3.2. 1,4-Bis(phenylethynyl)benzene

Pd(P(C6H5)3)Cl2, CuI I I + 2 equiv. HNEt2 1,4-bis(phenylethynyl)benzene Figure 3.14: Synthetic route to 1,4-bis(phenylethynyl)benzene.

A 2-L, three-necked round-bottom flask previously dried in an oven at 105°C was equipped with a stir bar, a stopper and two taps, and purged with argon. Under a gentle flux of argon, the following compounds were introduced: 1,4-diiodobenzene (250 g, 0.74 mol, 1 equiv.), trans(triphenylphosphine) palladium (II) dichloride (0.263 g, 0.371 mmol, 0.0005 equiv.), argon-degassed tetrahydrofuran (1.0 L), diethylamine (250 mL) and

72 phenylacetylene (175 mL, 1.56 mol, 2.1 equiv.). The reaction mixture was stirred for 15 min. Meanwhile, to a 60 mL Schlenck tube, purged thrice with vacuum and argon, was introduced copper(I) iodide (72.1 mg, 0.371 mmol, 0.0005 equiv.) and diethylamine (5.0 mL). After complete copper(I) iodide dissolution (indicated by a purple solution colour), the mixture was transferred into the 2-L reactor using a PEEK cannula. The reaction was slowly heated to 56 °C in an oil bath, and reacted for 6 h. After cooling to room temperature, the solution was cautiously poured into a 4-L beaker containing a stirring bar and 10% HCl(aq) solution (2 L). The precipitate was removed by vacuum filtration, then successively washed with water (150 mL) and methanol (until the filtrate ran clear, approx. 2 L). The 1,4-bis(phenylethynyl)benzene, was obtained as an off-white to yellowish powder, and was used without further purification. Yield: 195.6 g (94.7%). 1H NMR

(500MHz, CD2Cl2) d (ppm): 7.36-7.40 (m, 6H), 7.53 (s, 4H), 7.54-7.56 (m, 4H), see Figure

13 A 14. C NMR (125 MHz, CD2Cl2) d (ppm): 89.47(b), 91.70(a), 123.52(e), 123.68(c), 129.02(g), 129.12(h), 132.09(f), 132.13(d), see Figure A 16. HRMS [M+H]+: calcd for + C22H14 178.1096, found [M+H] : 278.1085.

3.3.3. Oxidation of the 1,4-Bis-(phenylethynyl)benzene

Part A: Oxidation Using Iodine/DMSO

I2 O DMSO O O 1,4-bis(phenylethynyl)benzene Bisbenzil Figure 3.15: Synthesis of bisbenzil using iodine/dimethylsulfoxide.

To a two-neck 250-mL round-bottom flask equipped with a stir bar and a water condenser were added 1,4-bis(phenylethynyl)benzene (7.5 g, 26.9 mmol, 1 equiv.), DMSO (128 mL) and iodine (13.69 g, 53.9 mmol, 2 equiv.). The mixture was refluxed at

150 °C for 8 h, cooled, and poured into a stirring Na2S2O3(aq) solution (15 wt%, 1.0 L). After vigorously stirring for 30 min (until a bright yellow color was observed in the precipitate), the precipitate was collected by vacuum filtration, washed with water (3 x 100 mL), dissolved in chloroform, and filtered through a silica plug (height: 10-15 cm). The bright yellow collected eluent was concentrated under reduced pressure, and the resulting yellow

73 solid was recrystallized twice from absolute ethanol (approx. 70-130 mL) to yield bisbenzil, as bright yellow needles. Yield: 5.99 g (65.0 %).

Part B: Oxidation Using KMnO4/DCM

KMnO4 O DCM O O 1,4-bis(phenylethynyl)benzene Bisbenzil Figure 3.16 Synthesis of bisbenzil using potassium permanganate/ dichloromethane.

To a two-neck 250-mL round-bottom flask, equipped with a stir bar and a water condenser, were added 1,4-bis(phenylethynyl)benzene (1.00 g, 1.0 equiv., 3.59 mmol), dichloromethane (20 mL), KMnO4 (1.70 g, 3.0 equiv., 10.8 mmol), NaHCO3 (0.67 g, 2.21 equiv., 7.94 mmol), water (20 mL), and tetra-n-butylammonium bromide (0.15 g, 0.20 equiv., 0.718 mmol) as the phase transfer agent. The second neck was sealed with a glass stopper, and the reaction was left to stir on high at room temperature for 8 h. With moderate stirring, the reaction was then quenched by adding 1 M HCl (25 mL), followed by Na2SO3 until the organic layer became bright yellow. Further additions of HCl facilitated dissolution of the manganese salts, evidenced when the aqueous layer became colorless.

The organic layer was extracted, washed with 0.5 M NaHCO3(aq) (40 mL), and brine (40 mL), dried with MgSO4, and concentrated under reduced pressure to yield bisbenzil as a bright yellow powder. Yield: 0.66 g (53.5%). 1H NMR was used to verify the purity, and the

1 compound was used without further purification. H NMR (500 MHz, CD2Cl2) d (ppm): 7.56 (t, J = 8.03 Hz, 4H,), 7.71 (t, J= 7.42 Hz, 2H), 7.97 (d, J = 7.29 Hz, 4H), 8.11 (s, 4H), see

13 Figure A 17. C NMR (125 MHz, CD2Cl2) d (ppm): 129.71(f), 130.46(g), 130.76(b), 133.15(e), 135.84(h), 137.69(a), 194.01(c), 194.10(d), see Figure A 19. HRMS [M+H]: calcd for C22H14O4 342.0892, found [M+H]: 343.0962, [M+Na]: 365.0784.

74 3.3.4. Bistetracyclone (BTC)

O O O KOH O 2 equiv. O Ethanol + O O

Bisbenzil BTC Figure 3.17: Synthesis of bistetracyclone.

To a 250 mL two-neck, round-bottom flask equipped with a condenser, stir bar and septum, containing 275 mL of anhydrous ethanol was added 1,3-(diphenyl)propan-2-one (4.00 g, 19.1 mmol, 2.1 equiv.) and bisbenzil (3.10 g, 9.07 mmol, 1 equiv.), the solution was then refluxed. After 15 min, KOH (1.02 g, 18.1 mmol, 2.0 eq) was dissolved in 2.0 mL of ethanol and added drop-wise to the refluxed solution. The solution was refluxed for other 45 min and then the solution was cooled at 0 °C for 1 h using an ice bath. The solution was then filtered, wash with ethanol (50 mL) and cold methanol (0 to 4 °C, 200 mL), and the precipitate was dissolved in boiling DCM, filtrated and then recrystallized as 1 purpled needles at 4°C. (5.5 g, 7.97 mol, 88%). H NMR (500 MHz, CD2Cl2) δ (ppm): 6.78 13 (s),6.92 (d, Jd= 7.06 Hz, 4 H),7.19-7.30 (m, 26H), see Figure A 20. C NMR (126 MHz,

CD2Cl2) δ 200.60, 154.93, 154.66, 134.11, 133.50, 130.65, 130.59, 129.77, 129.51, 129.05, 128.53, 128.12, 128.07, see Figure A 22.

3.3.5. Synthesis of Tetrasulfonic Acid Bistetracyclone (sBTC(H+))

SO3H

SO3H Cl O O O S O + 16 equiv. O O Si DCE O

HO3S

HO3S BTC sBTC(H+) Figure 3.18: Synthesis of tetrasulfonic acid bistetracyclone (sBTC(H+)).

In a 1000-mL two-necked, round-bottom flask equipped with a stir bar and containing 400 mL of dichloroethane degassed with argon, was dissolved BTC (14.19 g, 20.7 mmol, 1 equiv.) Trimethylsilyl chlorosulfonate (57.3 mL, 372.2 mmol, 18 equiv.) in

75 250 mL of degassed dichloroethane was added drop-wise to the round-bottom flask. The solution was then stirred for 12 h. The precipitation was initiated with 100 mL of pentane, which also quench the reaction. After an additional 30 min of stirring, the reaction mixture was poured into 1.5 L of pentane and then filtered and washed several times with cold diethyl ether. The precipitate was recovered and dried under vacuum at 60 °C for 8 h to + 1 yield sBTC(H ) (20.5g g, 20.3 mmol, 98.1%.) H NMR (500 MHz, DMSO-d6) δ (ppm): 6.87

(s, 4 Hcore), 6.92 (d, Jd= 7.40 Hz, 4 Ho), 7.10 (d, Jd= 8.16 Hz 4 Hb1), 7.16 (d, J = 8.50 Hz,

4 Hb2), 7.25 (t, Jt= 7.74 Hz, 4 Hm), 7.33 (m, 2Hp), 7.50 (D, JD= 8.32 Hz, 4 Ha2), 7.55 (D,

+ 13 JD= 8.54 Hz, 4 Ha1), 7.57 (s, 4H, H20/H3O ), see Figure 3.19. C NMR (151 MHz, DMSO- d6) δ: 199.45, 155.13, 155.00, 146.56, 146.46, 133.35, 132.22, 131.15, 130.84, 129.53, 129.30, 128.98, 128.84, 128.36, 125.48, 125.45, 124.63, 124.35, see Figure A 24. HRMS - 2- 3- [M-e] : calcd for C52H34O14S4 1010.0831, found 1009.0768, [M-e] 504.0358, [M-e] 335.6890. [M+H]+: calcd for C6H16N 102.1277, found 102.1278.

3.3.6. Characterization of sBTC(H+)

To obtained a pure tetra-functionalized bistetracyclone without di and tri substituted side products, the stoichiometry of the sulfonating reagent had to be adjusted or the tri substituted (M-= 929.12 g/mol) product could be observed, shown in Figure A 25. Several attempts were made to obtained the desired product; it was observed that at least 16 equiv. of the reagent must be used with respect to the substrate, BTC, shown in Table A 2. Furthermore, the tetra-sulfonated product is still obtained when 25 equiv. of TMSO-

SO2Cl is used with respect to the substrate; if the excess is more than 30 equiv., the workup of the reaction becomes difficult to process due to the amount of sulfuric acid produced during the quenching of the reaction.

As reported below, the 1H NMR spectrum shows the presence of doublets and triplets exclusively, shown in Figure 3.19. This indicates that the BTC and the TC are functionalized in the para position shown in Figure 3.8. One singlet is observed at 6.87 ppm which corresponds to the phenyl ring in the center of sBTC(H+). In the high field, two doublets are observed and are attributed to the protons in the alpha position of the sulfonic acid, Ha1 and Ha2. The chemical shift of Ha1 and Ha2 changed because of the difference in the close neighbour and the lack of symmetry of the molecule across the C=O bond.

76 The first phenyl ring is close to the ketone and the core of the BTC and the second one is close to the ketone and the last non-sulfonated phenyl ring.

HO S Ha2 3 Hb2 O Hb1 Ha1

Ho SO3H Hm

Hp Hcore

HO3S

SO3H

Hcore

Ha1 Ha2 Hb2 Hb1 Hm Ho + H Hp

1 + Figure 3.19: H NMR (DMSO-d6) spectrum of sBTC(H ).

The 2D COSY sequence allows the identification of the proton in the same vicinity, shown in Figure 3.20. The Ha1 and Hb1 protons correlated together, d: 7.55 ppm and d: 7.16 ppm respectively. In a similar way, Ha2 correlated with Hb2 and Ho, Hm and Hp correlated together. One singlet appears without correlation, this is attributed to Hcore or the ring in the center of the sBTC(H+), shown in the Figure 3.19 and Figure 3.20.

77 Hcore Ho

Hb1

Hb2 Hm

HO S Ha2 3 Hb2 O Hp Hb1 Ha1 Ho SO3H Hm

Hp Hcore

H a2 HO3S Ha1 O

SO3H

+ Figure 3.20: COSY (2D) NMR (DMSO-d6) spectrum of sBTC(H ).

The mass spectrum shows three charged isotopic ions corresponding to the sBTC(H+) with two, three and four charges, shown in Figure A 26. As an example, the heaviest observed ion is sBTC(H+) without the four protons that exhibit four charges. This ion has a molecular weight of 1006.0540 g/mol (M) and four charges (z= 4) so the m/z= 251.5135 g/mol, 251.5060 g/mol is observed, shown in Table 8 entry 4. This also prove the ionization of the molecule with “losing” its acidic protons is easy, the compound with two and three charges were observed, shown in Table 8.

78 Table 8: Mono and Poly Ionized Ions of the sBTC(H+) Observed by High Resolution Mass Spectrometry. Z mz Theoretical molecular weight Experimental molecular weight Observed 0 1010.0831 1010.0831 none no 1 1009.0759 1009.0759 none no 2 1008.0686 504.0343 504.0352 yes 3 1007.0613 335.6871 335.6874 yes 4 1006.0540 251.5135 251.5060 yes

The conformation of sBTC(H+) in solution was also investigated using the 1D NOE sequence. The 1D NOE sequence irradiated one selected frequency by the operator, as discuss in 2.1.1, and the resulting spectrum shows the proton in the nearby vicinity up to 3.5 Å. This molecule can possibly adopt two conformations in solution as shown in Figure 3.21. The “H” configuration can be described, where the four sulfonic acids are far from each other or at the extremities of the molecule. The “A” configuration is where two sulfonic acids formed hydrogen bonding and the two other sulfonic acids are further away.

SO3H

Hp Ha2 SO3H SO3H HO3S Hm Hb2 Ha1 Ha1 Ho a b b H 1 O H 1 H 1 Hb1 O Hcore O Hb1 O Hcore Hb2 Hb2 Ho Ha1 Ha2 Ha2 Hm Hb2 SO H Ho Ho 3 HO3S SO3H Ha2 Hp Hm Hm Hp Hp

HO3S "H" conformation "A" conformation H A+ Figure 3.21: Possible conformation of sBTC(H ) in solution.

The 1D NOE reveals the correlation in space of the Hcore with Hb1 and Ho, and no correlation between the Hcore and the Hb2 which prove the configuration in “A”, shown in Figure A 27. The rotation of this compound was also investigated using 1H NMR at different temperatures to try to observe proof of atropoisomerism.

79 SO3H SO3H HO3S

SO3H

O O O ?

ΔT O

HO3S HO3S SO3H HO3S Figure 3.22: Possible intramolecular rotation of sBTC(H+).

Unfortunately, no significant signs of rotation are observed inside of the sBTC(H+). However, when the temperature increases, the chemical shift of the protons Ha1, Ha2, Hb1 and Hb2 are deshielded, shown in Figure 3.23.

T=353K

T=343K

T=333K

T=323K

T=313K

T=303K

+ H /H2O T=298K

Ha1 Ha2 Hp Hm Hb2 Hb1 Ho Hcore

1 + Figure 3.23: H NMR (DMSO-d6) stack spectra of sBTC(H ) from 298 K to 353K.

+ The water and acidic peak (H /H2O) shielded from 6.01 ppm to 5.69 ppm with the increasing of the temperature. This is explained by the higher solvation of the acidic proton with the water in the sample. The protons of the sulfonated phenyl rings are deshielded

80 from 0.3 to 0.4 ppm for the Ha as well for the Hb. Finally, the non-sulfonated phenyl rings remains aproximately in the same environment. This behavior is explained by the higher solvation in higher temperature from the sBTC(H+) by the solvent and the water. The Table 9 reports the difference in chemical shift of the protons of the sBTC(H+) between 298 K and 353 K.

+ Table 9: Chemical Shift of the Proton of sBTC(H ) in DMSO-d6 from 298K to 353K. Protons d at 298 K (ppm) d at 353 K (ppm) Ha1 7.53 7.56 Ha2 7.49 7.53 Hp 7.34 7.34 Hm 7.26 7.25 Hb2 7.15 7.18 Hb1 7.09 7.13 Ho 6.93 6.95 Hcore 6.86 6.88 + H /H2O 6.01 5.69

+ + 3.3.7. Protection of sBTC(H ): Synthesis of sBTC(HNEt3 )

SO H SO - 3 H 3 4 equiv. N - SO3H SO3

O O

+ excess NEt3 O n-BuOH O

- HO3S O3S

- HO3S O3S + + sBTC(H ) sBTC(HNEt3 ) + Figure 3.24: Synthesis of sBTC(HNEt3 ).

In a 1000-mL round-bottom flask containing 550 mL of n-butanol was dissolved sBTC(H+) (20.5 g, 20.3 mmol, 1 equiv.) after which 212 mL of triethylamine was added. The solution was stirred for 4 h, then filtered and washed once with n-butanol (120 mL), and several times with cold ethyl acetate or diethyl ether. The precipitate was recovered + and dried under vacuum at 100 °C overnight to yielded sBTC(HNEt3 ) (24.6 g, 17.4 mmol, 1 85.5%). H NMR (600 MHz, DMSO-d6) δ (ppm): 1.16 (t, Jt = 7.20 Hz, 36H, 1 or CH3), 3.09 and 3.10 (2 d, Jd = 4.71Hz, 24H, 2 or –CH2-), 6.86 (s, 4 H, Hcore), 6.93 (d, Jd= 7.35 Hz, 4

H, Ho), 7.08 (d, Jd= 8.42 Hz 4 H, Hb1), 7.14 (D, JD= 8.54 Hz, 4 H, Hb2), 7.26 (t, Jt= 7.15

81 Hz, 4 H, Hm), 7.34 (m, 2H, Hp),7.48 (D, JD= 8.42 Hz, 4 H, Ha2), 7.52 (D, JD= 8.54 Hz, 4 H, Ha1), 8.88 (s, 4H, 3 or NH+), see Figure A 29. 13C NMR (151 MHz, DMSO) δ 199.37, 154.81, 154.64, 147.06, 147.05, 133.18, 132.08, 130.61, 130.24, 129.20, 129.04, 128.95, 128.81, 128.78, 128.74, 128.61, 128.11, 128.04, 125.24, 125.20, 124.43, 124.16, 45.78, - 1- 8.61, see Figure A 30. HRMS [M-e] : calcd for C52H34O14S4 1010.0831, [M-e] was not observed, [M-e]2- 504.0358, [M-e]3- 335.6884, [M-e]4- 251.5147. HRMS [M+H] calcd for + C6H16N 102.1277, observed [M+H]+ 102.1277, see Figure A 33.

+ 3.3.8. Characterization of sBTC(HNEt3 )

The 1H NMR spectrum reveals a small difference in the chemical shift of the protons of the sulfonated phenyl rings, Ha and Hb, from the acid form to the triethylammonium form. The unsulfonated phenylenes remained at the same chemical + shift. The acidic proton appearing on the sBTC(H ) reacted with the triethylamine (NEt3) + and form the triethylammonium (HNEt3 ), where the triethylammonium proton shows up at 8.88 ppm, shown in Figure 3.25.

BTC

SO3H

HO3S

+ HO3S H /H2O sBTC(H+)

SO - H 3 4 equiv. N - SO3

- O3S

+ -O S HNEt3 3 + sBTC(HNEt3 )

1 Figure 3.25: H NMR stack (DCM-d2 in red, DMSO-d6 in green and blue) of BTC, + + sBTC(H ) and sBTC(HNEt3 ).

1D NOE was also performed on the ammonium compound, shown in Figure A 32. The behavior of the ammonium salt was similar to that for the acid precursor, i.e. the “A” conformation was observed.

The FTIR spectrum of the tetra-acid from, shown in Figure A 28, was compared to that for the triethylammonium form, shown in Figure A 34. The uOH of the water and the acid, between 3640 cm-1 and 2499 cm-1 is absent for the ammonium derivative and the

-1 - uN-H can be observed at 3419 cm . The uS=O of the sulfonic acid at 1469 cm 1 and 1175 cm-1 shifts to 1469 cm-1 and 1175 cm-1, and no significant changes were observed for the

-1 uC=O at 1700 cm .

The thermogravimetric analysis is report for the BTC, sBTC(H+) and the + sBTC(HNEt3 ), shown in Figure 3.26.

83 100

40 Normalized Weight Loss (%) Loss Weight Normalized 20 BTC sBTC(H+) sBTC(HNEt +) 3 0 100 200 300 400 500 600 Temperature (°C)

+ + Figure 3.26: Stacked of thermograms of BTC, sBTC(H ) and sBTC(HNEt3 ) between 30°C and 600°C under a nitrogen atmosphere.

The BTC shows a two-steps degradation starting at 378 °C, which represents the first 5% of weight loss, where cyclopentadienone first decomposed followed by decomposition of the remaining aromatic structure. The sBTC(H+) shows a three-step degradation pattern. The first step between room temperature and 130°C is due to residual water which is removed from the sample; then at 283 °C the first 5% of the weight loss + from the polymer skeleton is observed, due to desulfonation. Finally, sBTC(HNEt3 ) a two- step degradation pattern is observed at 289 °C, the decomposition starts following the same process as that for sBTC(H+). The both forms of the monomer show a high thermal stability and both are suitable for the next step: the [4+2] Diels-Alder cycloaddition.

3.4. Synthesis of Dienophiles

Dienophiles are the second important component in this research. The synthesis route used Sonogashira cross-coupling193,194,195,196 followed by protiodesilylation. Most of the syntheses have been published, but they were modified and improved in some cases as follows.

84 3.4.1. 1,4-Bis(trimethylsilylethynyl)-benzene

TMS I Pd(dppf)Cl /CuI TMS 2 + 2 Equiv. I HNEt2 TMS Figure 3.27: Synthesis of 1,4-bis(trimethylsilylethynyl)-benzene.

In a 1000-mL Schlenk flask equipped with a stir bar, previously degassed three times with argon/vacuum, were add 1,4-diiodobenzene (129.2 g, 384.7 mmol, 1 equiv.), diphenylphosphineferrocene palladium dichloride (0.1583 g, 0.192 mmol, 0.05 mol%), diethylamine (300 mL) and trimethylsilylacetylene (121.7 mL, 844.2 mmol, 2.2 equiv.). The solution was stirred for 10 min. To a second Schlenk tube equipped with a stir bar, degassed as noted previously, were added CuI (0.0369 g, 0.191 mmol, 0.05 mol%), and diethylamine (4 mL, 1 mL/0.05 g of CuI); the solution was stirred for 10 min or until full dissolution of the cuprous salt. The contents of the second Schlenk tube were then transferred to the first Schlenk tube using a PEEK cannula. The combined reaction mixture was vigorously stirred for 5 min at room temperature during which time a precipitate start to appear. The mixture was subsequently heated at 50 °C for 4h and then allowed to cool to room temperature. The solution was filtered and washed several times with diethyl ether. The filtrate was washed sequentially with saturated ammonium chloride, 5.0 M hydrochloric acid and brine, dried over MgSO4 and then filtered. After concentration of the filtrate using a rotary evaporator, white to yellow crystals were obtained. The product was purified by sublimation or recrystallization in cold petroleum ether to give 1,4- bis(trimethylsilylethynyl)-benzene (101.9 g, 98.3% using the sublimation technic).1H NMR 13 (500 MHz, acetone-d6) δ (ppm): 0.23 (s, 18H), 7.45 (s, 4H), see Figure A 35. C NMR (125

MHz, acetone-d6) δ (ppm): δ 132.66, 124.18, 105.20, 96.89, -0.11, see Figure A 36. HRMS + + [M+H] : calcd for C16H22Si2 270.1260, [M+H] 270.1256.

85 3.4.2. 1,4-Diethynylbenzene

TMS

K2CO3

MeOH/DEE TMS Figure 3.28: Synthesis of 1,4-diethynylbenzene.

To a 500-mL round-bottom flask equipped with a stirring bar, previously degassed for 20 min with argon and protected from light using aluminum foil, was added 300 mL of diethyl ether, 70 mL of methanol and 1,4-bis(trimethylsilylethynyl)-benzene (10.0 g, 36.2 mmol, 1 equiv.). K2CO3 (15.2. g, 79.7 mmol, 2.2 equiv.) was added quickly and the reaction mixture was stirred for 3 h. The solution was opened and 100 mL of water was added; the solution was then washed twice with water. The aqueous layer was washed once time with DCM, and the combined organic layers were dried with MgSO4, filtered and concentrated using a rotary evaporator at room temperature to yield white-yellowish crystals. The final product was purified by sublimation and give 1,4-diethynylbenzene (3.72 g, 81.5%). The compound is stable up to 2 months under argon atmosphere when 1 protected from the light at -20 °C. H NMR (500 MHz, acetone-d6) δ (ppm): 3.81 (s, 2 H), 13 7.50 (s, 4 H), see Figure A 37. C NMR (125 MHz, acetone-d6) δ (ppm): 132.88, 123.64, + + 83.49, 81.21, see Figure A 38. HRMS [M+H] : calcd for C10H6 126.0470, [M+H] 127.0541.

3.4.3. 4,4’-Bis((trimethylsilyl)ethynyl)-1,1’-biphenyl

TMS Br Pd(P(C H ) ) Cl /CuI TMS 6 5 3 2 2 + 2 Equiv. HNEt2 Br TMS Figure 3.29: Synthesis of 4,4’-bis((trimethylsilyl)ethynyl)-1,1’-biphenyl.

In a 100-mL Schlenk flask equipped with a stir bar, previously degassed three times with argon/vacuum, were add 4,4’-dibromo-1,1’-biphenyl (6.83 g, 22.0 mmol, 1 equiv.), 15 mL of anhydrous toluene, diphenylphosphineferrocene palladium dichloride (0.090 g, 0.11 mmol, 0.5 mol%) and trimethylsilylacetylene (6.24 mL, 45.2 mmol, 2.05 equiv.). The solution was stirred for 10 min. To a second Schlenk tube equipped with a

86 stir bar, degassed as noted previously, were added CuI (0.021 g, 0.11 mmol, 0.5 mol%), and triethylamine (6 mL, 1 mL/0.007 g of CuI), the solution was stirred for 20 min. The contents of the second Schlenk tube were then transferred to the first Schlenk tube using a PEEK cannula. The combined reaction mixture was vigorously stirred for 15 min at room temperature during which time it turned black. The mixture was subsequently heated at 91 °C for 2 h and then allowed to cool to room temperature. The solution was filtered and washed several times with diethyl ether. The filtrate was washed sequentially with saturated ammonium chloride, 5.0 M hydrochloric acid and brine, dried over MgSO4 and then filtered. After concentrating the filtrate using a rotary evaporator, dark orange amorphous crystals were obtained. The crystals were dissolved in petroleum ether (50 mL) and activated carbon (3.5 g) was added, the solution was then refluxed for 4 h. The hot solution was quickly filtered over Celite® and rinsed four times with boiling petroleum ether (4 x 50 mL). The solution was concentrated using a rotary evaporator and the purity was verified by 1H NMR and was used without further purification to yield 4,4’- bis((trimethylsilyl)ethynyl)-1,1’-biphenyl as white long crystals (5.22 g, 68.5%). 1H NMR

(500 MHz, acetone-d6) δ (ppm): 7.71 (d, Jd = 8.79 Hz, 4 H), 7.55 (d, Jd = 8.79 Hz, 4H), 13 0.25 (s, 18H), see Figure A 39. C NMR (125 MHz, acetone-d6) δ (ppm): 140.90, 133.23, 127.73, 123.40, 105.67, 95.61, 0.00, see Figure A 40.

3.4.4. 4,4’-Diethynyl-1,1’-biphenyl

TMS

K2CO3

MeOH/DEE

TMS Figure 3.30: Synthesis of 4,4’-diethynyl-1,1’-biphenyl.

To a 125-mL HDPE flask equipped with a stirring bar, was add 20 mL of THF. The flask was degassed for 20 min with argon and protected from light using aluminum foil; then 4,4’-bis((trimethylsilyl)ethynyl)-1,1’-biphenyl (1.91 g, 5.58 mmol, 1 equiv.) was added. Under gentle flux of argon, TBAF (5.76 g, 22.0 mmol, 4 equiv.) was added quickly and the reaction mixture was sealed and stirred for 4 h. The solution was filtrated over a plug of alumina and washed three times with THF (3 x 25 mL). The solution was concentrated using a rotary evaporator. The crude material was dissolved into 50 mL of petroleum ether

87 and 1 g of carbon black was add. The solution was refluxed for 4 h and then filtrated over a plug a Celite®. After concentrating using a rotary evaporator, the 4,4’-diethynyl-1,1’- biphenyl was obtained as yellow-white crystals(0.68g, 61.3 %).1H NMR (500 MHz, acetone-d6) δ (ppm): 7.72 (d, J = 8.2 Hz, 4H), 7.60 (d, J = 8.2 Hz, 4H), 3.74 (s, 2H), see 13 Figure A 41. C NMR (125 MHz, acetone-d6) δ (ppm):141.10, 133.39, 127.83, 122.67, 83.90, 80.14, see Figure A 42.

3.4.5. ((4-Bromophenyl)ethynyl)triisopropylsilane

I Pd(P(C6H5)3)2Cl2/CuI Si + Si Br HNEt2 Br Figure 3.31: Synthesis of ((4-bromophenyl)ethynyl)triisopropylsilane.

In a 500-mL Schlenk flask equipped with a stir bar, previously degassed three times with argon/vacuum, were added 1-bromo-4-iodobenzene (49.9 g, 175.0 mmol, 1.00 equiv.), 100 mL of diethylamine, trans-dichlorobis-(triphenylphosphine)palladium(II) (0.124 g, 0.175 mmol, 0.1 mol%) and ethynyltriisopropylsilane (40.4 mL, 175.0 mmol, 1.00 equiv.). The solution was stirred for 10 min at room temperature. To a second Schlenk tube equipped with a stir bar, degassed as noted previously, was added CuI (0.0337 g, 0.175 mmol, 0.1 mol%), and diethylamine (5 mL), the solution was stirred for 20 min. The contents of the second Schlenk tube were then transferred to the first Schlenk tube using a PEEK cannula. The combined reaction mixture was heated at 55 °C for 4 h and then allowed to cool to room temperature. The solution was filtered and washed several times with diethyl ether. The filtrate was washed sequentially with saturated ammonium chloride,

5.0 M hydrochloric acid and brine, dried over MgSO4 and then filtered. After concentrating of the filtrate using a rotary evaporator, a light orange liquid was obtained. The crude liquid was dissolved in petroleum ether (100 mL) and activated carbon (25 g) was added, the solution was then refluxed for 4 h. The hot solution was quickly filtrated over Celite® and rinsed four times with boiling petroleum ether (4 x100 mL). The solution was concentrated using a rotary evaporator. ((4-Bromophenyl)ethynyl)triisopropylsilane was obtained as a 1 colorless liquid (57.3 g, 97.0%). H NMR (500 MHz, acetone-d6) δ (ppm): 7.56 (d, Jd = 8.76 Hz, 2 H), 7.45 (d, Jd = 8.41 Hz, 2H), 1.14 (two singlets, 21H), see Figure A 43. 13C

88 NMR (125 MHz, acetone-d6) δ (ppm): 134.47, 132.65 123.39, 123.29, 107.04, 92.47, 19.02, 12.10, see Figure A 44.

3.4.6. Triisopropyl((4-((trimethylsilyl)ethynyl)phenyl)ethynyl)silane

Si Pd(P(C6H5)3)2Cl2/CuI + TMS HNEt2

Br Si

Figure 3.32: Synthesis of triisopropyl((4-((trimethylsilyl)ethynyl)phenyl)ethynyl)- silane.

In a 250-mL Schlenk flask equipped with a stir bar, previously degassed three times with argon/vacuum, were add ((4-bromophenyl)ethynyl)triisopropylsilane (13.0 g, 38.5 mmol, 1.00 equiv.), 62 mL of diethylamine, dichloro-1,1’- bis(diphenylphosphino)ferrocene palladium (II) dichloromethane, (0.0268 g, 0.0385 mmol, 0.1 mol%) and ethynyltrimethylsilane (6.47 mL, 46.2.0 mmol, 1.20 equiv.). The solution was stirred for 10 min at room temperature. To a second Schlenk tube equipped with a stir bar, degassed as noted previously, was added CuI (0.0073 g, 0.0385 mmol, 0.1 mol%) and diethylamine (2 mL), the solution was stirred for 20 min. The contents of the second Schlenk tube were then transferred to the first Schlenk tube using a PEEK cannula. The combined reaction mixture was heated at 55 °C for 4 h and then allowed to cool to room temperature. The solution was filtered and washed three times with diethyl ether (3 x 50 mL). The filtrate was washed sequentially with saturated ammonium chloride, 5.0 M hydrochloric acid and brine, dried over MgSO4 and then filtered. After concentrating the filtrate using a rotary evaporator, an orange liquid was obtained. The crude liquid was dissolved in petroleum ether (100 mL) and activatedcarbon (25 g) was added; the solution was then reflux for 4 h. The hot solution was quickly filtrated over Celite® and rinsed four times with boiling petroleum ether (4 x100 mL). The solution was concentrated using a rotary evaporator. The compound triisopropyl((4-((trimethylsilyl)ethynyl)phenyl)ethynyl)- silane was obtained as a yellow viscus liquid (13.5 g, 99.4%). 1H NMR (500 MHz, acetone- d6) δ (ppm): 0.23 (s, 9H), 1.14 (two singlets, 21H),7.46 (d, Jd = 8.21 Hz, 2H),7.48 (d, Jd = 13 8.21 Hz, 2 H),see Figure A 45. C NMR (125 MHz, acetone-d6) δ (ppm): 132.77, 132.69,

89 124.32, 124.14, 107.53, 105.24, 96.85, 93.20, 18.97, 12.00, -0.11, see Figure A 46. HRMS + + [M+H] : calcd for C22H34Si2 354.2199, found [M+H] 354.2189.

3.4.7. ((4-Ethynylphenyl)ethynyl)triisopropylsilane

Si Si K2CO3

MeOH/DEE

Figure 3.33: Synthesis of ((4-ethynylphenyl)ethynyl)triisopropylsilane.

To a 1000-mL HDPE flask equipped with a stirring bar, were add 500 mL of methanol and 250 mL of ether. Under stirring, the flask was degassed for 20 min with argon and protected from light using aluminum foil; then triisopropyl((4- ((trimethylsilyl)ethynyl)phenyl)ethynyl)silane (5.00 g, 14.1 mmol, 1 equiv.) was added. Under gentle flux of argon, potassium carbonate (4.87 g, 35.2 mmol, 2.50 equiv.) was added quickly and the reaction mixture was sealed and stirred for 4 h. Then 100mL of water was added to quench the reaction. The organic layer was washed twice with diethyl ether then once with brine then dried with MgSO4 before concentrating using a rotary evaporator. The crude material was dissolved into 50 mL of petroleum ether and 3.5 g of activated carbon was add. The solution was refluxed for 4 hours then filtrated over a plug a Celite®. After concentrating using a rotary evaporator, the ((4- ethynylphenyl)ethynyl)triisopropylsilane was obtained as a bright yellow liquid that 1 solidified at -20°C (4.70g, >99 %). H NMR (500 MHz, acetone-d6) δ (ppm): 7.50 (s, 4H), 3.80 (s, 1H), 1.15-1.14 (two singlets, 21H), see Figure A 47.13C NMR (125 MHz, acetone- d6) δ (ppm): 132.90, 132.80, 124.53, 123.46, 107.47, 93.18, 93.62, 91.21, 18.99, 12.03, see Figure A 48.HRMS [M+H]+: calcd for C19H26Si: 282.1804, found 283.1872.

3.4.8. Characterization of the Dienophiles

As reported earlier, a few dienophiles were designed using the Sonogashira cross- coupling. 1,4-Diethynylbenzene was synthesized in two steps using trans bis(triphenylphosphine)palladium(II) dichloride, copper(I) iodide, and diethylamine followed by potassium carbonate. The precursor, 1,4-bis(trimethylsilylethynyl)benzene,

90 was synthesized in a yield of 98.3 %; the 1H NMR spectrum, shown in Figure A 35, reports the presence of the trimethylsilyl groups at 0.23 ppm, the 13C spectrum showed the same groups at -0.11 ppm, shown in Figure A 36. The protiodesilylation released the alkyne; 1H NMR: 3.81 ppm, shown in Figure A 37 and 13C spectrum: 83.49 and 81.21 ppm, shown in Figure A 38. The same procedures were applied for the synthesis of 4,4’-bis-ethynyl-1,1’- bipenyl, the trimethylsilyl trace is observed at 0.25 ppm, shown in Figure A 39; on the 1H spectrum and the terminal alkynes are released using potassium carbonate, 3.74 ppm on the 1H spectrum, shown in Figure A 41. The last dienophile, was synthesized in three steps. The used strategy was based on the difference in the reactivity of the aryl-halide and two trialkylsilyl groups.197 The first trialkylsilylacetylene group that was added was triisopropylsilylacetylene, followed by (trimethylsilyl)acetylene. The addition of the triisopropylsilylacetylene on the 4-iodo-bromobenzene lead to the ((4- bromophenyl)ethynyl)triisopropylsilane. The presence of the TIPS function is present at 1.14 ppm on the 1H spectrum, shown in Figure A 43, and the alkyne at 123.29 and 123.39 ppm on the 13C spectrum, shown in Figure A 44. The addition of the (trimethylsilyl)acetylene was proved by the presence of the TMS at 0.23 ppm and the TIPS at 1.23 ppm on the 1H spectrum, shown in Figure A 45. The presence of two distinct alkynes can be observed with the four sp carbons at 107.47, 93.18, 93.62, 91.21 ppm the 13C spectrum, shown in Figure A 46. The obtained compound showed the two protecting groups at 0.23 ppm (TMS) and 1.23 ppm (TIPS), shown in Figure A 45. The first alkyne to be released came from the TMS group because of the higher sensitivity of the and the terminal alkyne is at 3.80 ppm, shown in Figure A 47.

3.5. Application of the [4+2] Diels-Alder Cycloaddition for the Synthesis of Model Compounds

Several attempts were made to find the best conditions for successful ring closing + + using the new materials sTC(X) (where X = H or HNEt3 ) as shown in Figure 3.34.

91 XO S O 3 SO3X

+ XO3S SO3X + CO ?

X= H+ sTC(H+) X= H+ DAsTC(H+)Ph + + + + X= HNEt3 sTC(HNEt3 ) X= HNEt3 DAsTC(HNEt3 )Ph Figure 3.34: Synthesis of model compound, DAsTC(X)Ph, and investigation of the parameters for [4+2] Diels-Alder cycloaddtion using sTC(X).

In Table 10 is reported the reaction procedures made using the sTC(X), acid or triethylammonium, and phenylacetylene as reagent.

Table 10: Investigation of [4+2] Diels-Alder Cycloaddtion using the sTC(X) as the Diene and Different Dienophiles at Different Temperature for Different Lenghts of Time. Entry Diene Dienophile T(°C)a Solvent Time (H) Yield (%) 1 sTC(H+) Phenylacetylene 160 DPE 24 None 2 sTC(H+) Phenylacetylene 180 DPE 24 None 3 sTC(H+) Phenylacetylene 200 DPE 24 None 4 sTC(H+) Phenylacetylene 200 DPE 48 None 5 sTC(H+) Phenylacetylene 200 DPE 72 None + 6 sTC(HNEt3 ) Phenylacetylene 160 DPE 48 None + 7 sTC(HNEt3 ) Phenylacetylene 180 DPE 48 None + c 8 sTC(HNEt3 ) Phenylacetylene 200 DPE 48 Traces + c 9 sTC(HNEt3 ) Phenylacetylene 200 DPE 72 Traces + d 10 sTC(HNEt3 ) Phenylacetylene 180 ArNO2 48 50.2 + d 11 sTC(HNEt3 ) Phenylacetylene 200 ArNO2 48 72.3 + d 12 sTC(HNEt3 ) Phenylacetylene 220 ArNO2 48 81.3 + b 13 sTC(HNEt3 ) Phenylacetylene 180 ArNO2 3 47.3 + b 14 sTC(HNEt3 ) Phenylacetylene 200 ArNO2 3 75.7 15 sTC(H+) Phenylacetylene 200b DPE 3 No product + b 16 sTC(HNEt3 ) Phenylacetylene 200 DPE 3 Traces + 17 sTC(H ) Phenylacetylene 200 ArNO2 72 No product + 18 sTC(HNEt3 ) DPA 200 ArNO2 72 No product + 19 sTC(HNEt3 ) Phenylacetylene 200 ArNO2 24 78.2 a: reaction made using a sand bath to reach the desire temperature; b: reaction made using microwave reactor; c: black gummy product obtained; d: yield not improved after an extra 24 hours. There were some risks associated with the regular oil bath reaching a high temperature of 160 °C at the beginning of this work because the flash point of the oil was very close to the required temperature. To increase the safety in this research, a sand bath was used and the temperature was monitored using a thermometer. The use of sTC(H+) did not provide any successful results at any temperature in the presence of DPE, + shown in Table 10, entries 1 to 7; the same results were observed using sTC(HNEt3 ).

92 However, traces of the products appeared, visible by 1H NMR, when the temperature reached 200 °C after 48 h of reaction, shown in Table 10, entries 8 and 9. When DPE is substituted by nitrobenzene (ArNO2), better results were obtained at 180 °C after 48 h; the product is obtained as a white to light brown powder, Table 10 entry 10 to 12. The yield of the product was not improved by increasing the reaction time, but it increased to 81.3% by increasing the temperature. A few tests were performed using a microwave reactor Biotage® Initiator Classic with a 150-mg scale. After 3 h at 180 °C, the solution turns orange and the product is obtained in a 47.3% yield as light brown powder, shown in Table 10, entry 13. Increasing the temperature by 20 °C produced a yellow solution and a white- yellow powder shown in Table 10, entry 14. Diphenylether was also used with the microwave-assisted reactor, as shown in Table 10, entry 15; sTC(H+) did not provide a successful result and gives traces of the product, as shown in Table 10, entry 16. Finally, + after the interesting results with ArNO2, using sand bath with the sTC(HNEt3 ); shown in Table 10, entry 10 to 12; sTC(H+) after 3 days gave no sign of product; as shown in Table + 10, entry 17. A last try was made using sTC(HNEt3 ), a try to observe if a similar product as Ried et al.44 claimed in 1966, shown in Figure 3.35-a. a) O

TC DPA Ried et al. (1966) b)

XO3S XO S O 3

SO3X +

SO3X

+ sTC(X) DPA attemped x : HNEt3 Figure 3.35: Structure made by Ried et al in 1966 and the derivative attemped in this thesis work.

The disulfonated hexaphenylbenzene; shown in Figure 3.35; could have been + made using an internal alkyne, 1,2-diphenylacetylene (DPA) with sTC(HNEt3 ); shown in

93 Table 10 entry 18; but was unsuccessful probably due to the steric hindrance. An additional attempt was made at 200 °C using ArNO2 for 24 h under argon and yielded the compound with 78.2%, as shown in Table 10, entry 19.

This short parametric study indicates that the nitrobenzene can be used as a solvent and the ideal temperature for the reaction must be higher than 180°C. The microwave-assisted strategy was abandoned because at this time the only reactor available had a capacity of only 20 mL; furthermore, the reactor had to be sealed and the reaction produced carbon monoxide so the risk of explosion was too high.

Several model compounds were made for the purpose of this research, just a few are reported in the following section 3.6.

3.6. Synthesis of Model Compounds

A family of compounds were designed to understand the reactivity, solubility properties, structure of the pre-functionalized tetracyclone and bistetracyclones. This part will summarize the most important compounds that were made and characterized.

3.6.1. 2',3',5'-Triphenyl-[1,1':4',1''-terphenyl]-4,4''-Disulfonic Acid + (DAsTC(HNEt3 )-Ph)

- O O3S SO - + + 3 HNEt3 HNEt3

+ -O S SO - HNEt + HNEt + 3 3 3 3 ArNO2, 200°C

Figure 3.36: Synthesis of2',3',5'-triphenyl-[1,1':4',1''-terphenyl]-4,4''-disulfonic + acid (DAsTC(HNEt3 )-Ph

+ To a 60-mL Schlenk tube equipped with a stirring bar were added sTC(HNEt3 ) (1.00 g, 1.19 mmol, 1.0 equiv.), phenylacetylene (0.167mL, 1,49 mmol, 1.12 equiv.) and 8 mL of nitrobenzene. The Schlenk tube was sealed with a septum, and stirred for 10 min and inserted into a sand bath at 200 °C. After 48 hrs, the solution turned yellow; and the tube was cooled to room temperature and the content was transferred to a 250-mL round- bottom flask containing 200 mL of ethyl acetate. The solution turned white and was then

94 refluxed for 4 h, the solution was filtered using a Buchner funnel and washed three time + with boiling ethyl acetate (3 x 20 mL) and yielded DAsTC(HNEt3 )-Ph as a white yellow 1 powder (1.04g, 94.8%). H NMR (500 MHz, DMSO-d6) δ (ppm): 1.15 (t,Jt= 7.36 Hz,18H), 3.08 (two overlapped quadruplets, Jq = 7.20 Hz, 12H), 6.81-6.92 (m, 10H), 6.92-6.99 (m,

2H), 7.11 (D, JD= 8.39 Hz, 2 H), 7.13 (d, Jd = 8.24 Hz, 2 H),7.15-7.19 (m, 5H), 7.36 (d, Jd= 13 8.39Hz, 2H, 7.38 (s, 1H), 8.87 (s, 2H), see Figure A 49. C NMR (151 MHz, DMSO-d6) δ: 146.09, 145.35, 141.73, 141.19, 141.10, 140.36, 139.72, 139.70, 139.60, 139.39, 139.04, 138.55, 131.00, 130.89, 130.78, 130.27, 129.52, 128.91, 127.74, 126.95, 126.59, 126.45, 125.82, 125.63, 124.85, 124.13, 45.75, 8.60, see Figure A 50.HRMS [M-e]-: calcd for - 2- + C36H25Na2O6S2: 663.0882, found, 663.0893 [M-e] , 354.0308 [M-e] , [M+H] ; calculated for - 2- C36H26O6S2: 618.1171 [M-e] , found 617.1084 [M-e]-, 308.0509 [M-2e] ; calcd for C6H16N: 102.1277, found 102.1278.

+ 3.6.2. 2DAsTC(HNEt3 )-1.4-bz

+ - - + HNEt3 SO3 SO3 HNEt3

O -O S - 3 SO3

+ + + 2 Equiv. HNEt3 HNEt3 ArNO2, 200°C

+ - - + HNEt3 SO3 SO3 HNEt3

+ + sTC(HNEt3 ) Linker 2DAsTC(HNEt3 )-1,4-bz + Figure 3.37: Synthesis of 2DAsTC(HNEt3 )-1,4-bz.

+ To a 60-mL Schlenk tube equipped with a stirring bar were added sTC(HNEt3 ) (1.76 g, 2.36 mmol, 2.0 equiv.), freshly sublimated 1,4-diethynylbenzene (0.150 g, 1.19 mmol, 1.0 equiv.), and 5 mL of nitrobenzene. The Schlenk tube was sealed with a septum, and stirred for 10 min and then insert in a sand bath at 200 °C. After 24 h, the solution turned white; and the tube was cooled to room temperature and the content was transferred to a 250-mL round-bottom flask containing 200 mL of ethyl acetate. The solution turned white and was then refluxed for 4 h; then the solution was filtered using a Buchner funnel and washed once with boiling ethyl acetate and twice with boiling acetone + 1 to yielded 2DAsTC(HNEt3 )-1,4-bz (1.76g, 94.7%) as a white powder. H NMR (500 MHz,

DMSO-d6) δ (ppm): 1.14 (t,Jt= 7.26 Hz,36 H), 3.08 (two overlapped quadruplets, 24 H),

95 6.73 (d, Jd= 8.21 Hz, H), 6.83-6.96 (m, 24 H), 7.13 (D, JD= 8.38 Hz, 4 H), 7.23 (d, Jd = 8.27 13 Hz, 4 H), 7.36-7.38 (m, 6H), 8.90 (s, 4H). C NMR (151 MHz, DMSO-d6) δ 145.89, 145.25, 141.74, 141.33, 139.94, 139.77, 139.71, 139.61, 139.45, 139.21, 138.83, 138.43, 131.02, 130.96, 130.47, 130.41, 129.01, 128.94, 126.89, 126.59, 125.81, 125.63, 124.82, 124.17, - 2- 45.78, 8.60.HRMS [M-e] : calcd for C66H46O12S4 1158,1872, found 1157.1811, [M-e] 3- 4- + 578.0868, [M-e] 385.0559, [M-e] 288.5403; [M+H] : calcd for C6H16N 102.1277, found 102.1278.

+ 3.6.3. 2DAsBTC(HNEt3 )-Ph

- SO3 - H O3S N H N O H - H SO3 N - N SO3

+ 2 Equiv. 200°C H ArNO2 N H - O3S N - SO3 H H N O N - SO3 - SO3 2DAsBTC(HNEt +)-Ph + 3 sBTC(HNEt3 ) + Figure 3.38: Synthesis of 2DAsBTC(HNEt3 )-Ph.

+ To a 60-mL Schlenk tube equipped with a stir bar were added sBTC(HNEt3 ) (1.00 g, 0.71 mmol, 1.0 equiv.) and phenylacetylene (0.163mL, 1.485 mmol, 2.1 equiv.) and 10 mL of nitrobenzene. The solution was stirred for 10 min, then was closed with a septum and the content was stirred for 10 min at room temperature then inserted into a sand bath at 190-200 °C. After 8 h, the solution turned orange; the tube was cooled to room temperature and the content was transferred to a 100-mL round-bottom flask containing 50 mL of ethyl acetate whereupon the solution turned white. After refluxing for 4 h, the product was filtered and washed twice with boiling ethyl acetate and twice with acetone. + After drying overnight at 100 °C, compound 2DAsBTC(HNEt3 )-Ph was collected as a light 1 yellow powder. (0.855g, 77.3%). H NMR (500 MHz, DMSO-d6)) δ (ppm): 1.16 (t, Jt =

7.24Hz, 36H), 3.09 (two overlapped quadruplets, Jq = 7.37 Hz, 24 H), 6.46-6.00 (singlets, 13 4H), 7.55-6.54 (m, 38H), 8.89 (s, 4H), see Figure A 56. C NMR (151 MHz, DMSO-d6),

96 - 2- see Figure A 57. HRMS [M-e] : calcd for C66H42O12S4: 1154.1581, found: 578.0840 [M-e] 3- 4- , 285.0539 [M-e] , 288.5385 [M-e] ; calcd for C6H16N 102.1277, found 102.1278.

3.6.4. DATC-TIPS

O Si + Si 200°C DPE

TC DATC-TIPS Figure 3.39: Synthesis of DATC-TIPS.

To a 60-mL Schlenk tube equipped with a stir bar were added TC (1.00 g, 2.60 mmol, 1.0 equiv.), ((4-ethynylphenyl)ethynyl)triisopropylsilane (0.919 g, 3.25 mmol, 1.25 equiv.) and 8 mL of warm diphenylether (35 °C). The solution was stirred for 10 min. The Schlenk tube was closed with a septum, the contents were stirred for 10 min at room temperature and then inserted into a sand bath at 200 °C. After 24 h, the solution turned yellow and the tube was cooled to room temperature and the contents were transferred to a 100-mL round-bottom flask containing 50 mL of methanol whereupon the solution turned light grey. After refluxing for 2 h, the product was filtered and washed twice with boiling methanol. After air-drying overnight, the compound DATC-TIPS was collected as a yellow 1 to light grey powder (1.25g, 75.2%). H NMR (500 MHz, DCM-d2) δ (ppm): 1.12 (s, 21H),

6.83-8.84 (m, 2H), 6.87-6.91 (m, 9H), 6.94-6.95 (m, 2H), 6.97-6.98 (m, 2H), 7.12 (d, Jd = 13 8.38 Hz, 2H), 7.17 (s, 5H), 7.26 (d, jd = 8.38 Hz, 2H), 7.50 (s, 1H) see Figure A 60. C

NMR (151 MHz, DCM-d2) δ (ppm): 142.75, 142.63, 142.42, 141.60, 141.05, 140.76, 140.69, 140.63, 140.37, 139.94, 132.16, 132.10, 131.82, 131.64, 130.56, 130.52, 128.21, 127.63, 127.48, 127.20, 126.95, 126.43, 126.28, 126.01, 122.07, 107.65, 91.50, 19.07, + 19.06, 12.05, see Figure A 61.HRMS [M+H] : calcd for C47H46Si: 638.3359, found: 638.3345 [M+H]+.

97 3.6.5. DATC-CCH

TBAF Si H THF

DATC-TIPS DATC-CCH Figure 3.40: Synthesis of DATC-CCH.

To a 50-mL HDPE flask equipped with a stirring bar, was add 20 mL of THF. Under stirring, the flask was degassed for 20 min with argon and protected from light using aluminum foil, then DATC-TIPS (1.02 g, 1.56 mmol, 1 equiv.) was added. Under gentle flux of argon, TBAF (0.816 g, 3.12 mmol, 2.00 equiv.) was added quickly and the reaction mixture was sealed and stirred for 4 h. Then the solution was poured on a plug of silicate and wash thrice with 20 mL THF then concentrated using a rotary evaporator. The purity was checked by 1H NMR and the product was used without further purification, the DATC- CCH was obtained as white semi-crystalline product (0.753g, 67.5 %). 1H NMR (500 MHz, acetone-d6) δ (ppm): 3.09 (s, 1H), 6.81-6.84 (m, 2H), 6.87-6.89 (m, 7H), 6.93-6.97 (m, 6H), 7.12 (d, Jd = 8.63 Hz, 2H), 7.16 (m, 5H), 7.27 (d, Jd = 8.62 Hz, 2H), 7.50 (s, 1H), see 13 Figure A 63. C NMR (125 MHz, acetone-d6) δ (ppm): 42.97, 142.34, 142.10, 141.33, 140.77, 140.48, 140.34, 140.27, 140.14, 139.68, 131.91, 131.85, 131.78, 131.46, 130.43, 130.36, 128.07, 127.47, 127.33, 127.05, 126.81, 126.26, 126.13, 125.85, 120.29, 83.80, + + 77.78, see Figure A 64. HRMS [M+H] : calcd for C38H26: 482.2035, found 483.2107[M+H] .

98 3.6.6. 2DABTC-TIPS

Si Si + 2 Equiv. DPE, 200°C Si

BTC 2DABTC-TIPS Figure 3.41: Synthesis of 2DABTC-TIPS.

To a 60-mL Schlenk tube equipped with a stir bar were added BTC (1.00 g, 1.45 mmol, 1.0 equiv.), ((4-ethynylphenyl)ethynyl)triisopropylsilane (1.02 g, 3.62 mmol, 2.5 equiv.) and 20 mL of warm diphenylether (35 C°). The solution was stirred for 10 min. The Schlenk tube was closed with a septum, the contents were stirred for 10 min at room temperature and then inserted into a sand bath at 200 °C. After 24 h, the solution turned yellow and the tube was cooled to room temperature; the contents were then transferred to a 250-mL round-bottom flask containing 150 mL of methanol whereupon the solution turned yellow. After refluxing for 2 h, the product was filtered and washed twice with boiling methanol. After air-drying overnight, the compound, 2DABTC-TIPS, was collected as a 1 light yellow powder (1.36 g, 78.3%). H NMR (500 MHz, DCM-d2) δ (ppm): 1.11 (two singlets, 42H), 6.29-6.44 (3 singlets, 4H), 6.65-7.25 (m, 38H), 7,40 (three singlets, 2H), 13 + see Figure A 66. C NMR (151 MHz, DCM-d2) δ (ppm): see Figure A 67. HRMS [M+H] : + calcd for C88H86Si: 1198.6268, found[M+H] .

3.6.7. 2DABTC-CCH

Si TBAF

THF Si

2DABTC-TIPS 2DABTC-TIPS Figure 3.42: Synthesis of 2DABTC-CCH.

99 THF (100 mL) was added to a 250-mL HDPE flask equipped with a stirring bar. Under stirring, the flask was degassed for 20 min with argon and protected from light using aluminum foil; then 2DABTC-TIPS (1.00 g, 0.834 mmol, 1 equiv.) was added. Under gentle flux of argon, TBAF (0.654 g, 2.50 mmol, 3,.00 equiv.) was added quickly and the reaction mixture was sealed and stirred for 4 h. Then the solution was poured on a plug of silicate, washed three time with 50 mL of THF and concentrated using a rotary evaporator. The purity was checked by 1H NMR and the product was used without further purification; the 2DABTC-CCH was obtained as a white semi-crystalline product (0.617g, 83.4 %). 1H NMR

(500 MHz, acetone-d6) δ (ppm):3.08 (m, 2H), 6.65-6.80 (three s, 4H), 6.65-7.26 (m, 38H), 13 7.41-7.43 (three s, 2H), see Figure A 69. C (151 MHz, DCM-d2) δ (ppm): see Figure A 70.

+ 3.6.8. DA-sTC(HNEt3 )-p-DATC

+ - HNEt3 SO3

O -O S - 3 SO3

+ + + HNEt3 HNEt3 200°C ArNO2

- + O3S HNEt3

+ + DATC-CCH sTC(HNEt3 ) DAsTC(HNEt3 )-p-DATC + Figure 3.43: Synthesis of DA-sTC(HNEt3 )-p-DATC.

+ To a 60-mL Schlenk tube equipped with a stir bar were added sTC(HNEt3 ) (0.455 g, 0.610 mmol, 1.0 equiv.), DATC-CCH (0.300 g, 0.622 mmol, 1.02 equiv.) and 12 mL of nitrobenzene. The solution was stirred for 10 min. The Schlenk tube was closed with a septum, the contents were stirred for 10 min at room temperature and then inserted into a sand bath at 190-200 °C. After 8 h, the solution turned pale yellow and the tube was cooled to room temperature. The contents were transferred to a 100-mL round-bottom flask containing 50 mL of ethyl-acetate whereupon the solution turned white. After refluxing for 4 h, the product was filtered and washed twice with boiling ethyl acetate and + twice with acetone. After drying overnight at 100 °C, the compound, DAsTC(HNEt3 )-p- DATC, was collected as a white powder (0.651 g, 87.02%). 1H NMR (500 MHz, DMSO- d6) δ (ppm): 1.16 (t, Jt = 7.05Hz, 18H), 3.08 ( two overlapped q, Jq = 7.05 Hz, 12H), 6.75- 7.02 (m, 32H), 7.10-7.20 (m, 8H), 7.33 (s, 1H), 7.37-7.38 (s + d, Jd = 8.38 Hz, 3H), 8.90

100 13 + 8.22 (two s, 2H). C NMR (151 MHz, DMSO-d6): 146.01, 145.34, 141.76, 141.58, 141.24, 141.15, 140.26, 139.93, 139.86, 139.76, 139.72, 139.64, 139.57, 139.45, 139.39, 139.15, 139.11, 139.09, 139.07, 138.95, 138.50, 131.05, 130.99, 130.94, 130.67, 130.42, 130.30, 129.60, 128.96, 128.93, 128.85, 127.59, 127.04, 126.96, 126.79, 126.60, 126.48, 126.30, 126.00, 125.84, 125.67, 125.64, 125.40, 124.86, 124.20, 45.79, 8.62.HRMS [M- - - 2- e] : calcd for C66H45O12S4 : 997.2663, found: 997.2625 [M-e] , 498.1291; calcd for C6H16N 102.1277, found 102.1278.

+ 3.6.9. 2DATC-sBTC(HNEt3 )

+ - HNEt3 SO3

- + SO3 HNEt3 - + + SO3 HNEt3 HNEt3 O

- O3S 2 Equiv. + - SO3 200°C ArNO2 + HNEt3 O + - HNEt3 SO3 + - HNEt3 O3S

- + SO3 HNEt3

+ + DATC-CCH sBTC(HNEt3 ) 2DATC-sBTC(HNEt3 ) + Figure 3.44: Synthesis of 2DATC-sBTC(HNEt3 ).

To a 60-mL Schlenk tube equipped with a stir bar were added DATC-CCH (0.300 + g, 0.622 mmol, 2.02 equiv.), sBTC(HNEt3 ) (0.436mL, 0.308 mmol, 1.0 equiv.) and 3 mL of nitrobenzene. The solution was stirred for 10 min. The Schlenk tube was closed with a septum, the contents were stirred for 10 min at room temperature and then inserted into a sand bath at 200 °C. After 24 h, the solution turned yellow; the tube was cooled to room temperature and the contents were transferred to a 100-mL round-bottom flask containing 60 mL of ethyl acetate whereupon the solution turned white. After refluxing for 4 h, the product was filtered and washed twice with boiling ethyl acetate and once with acetone. + After drying overnight at 100 °C, compound 2DATC-sBTC(HNEt3 ) was collected as a 1 white powder (0.388 g, 54.34%). H (500 MHz, DMSO-d6) δ (ppm):1.16 (t, Jt = 7.01Hz, 36H), 3.08 (2 overlapped q, Jq = 7.23Hz, 24H), 6.10-6.35 (6 s, 4H), 6.47-7.58 (m, 78H), 13 8.25-8.92 (two s, 4H), see Figure A 76. C (151 MHz, DMSO-d6) δ (ppm): see Figure A - - 77.HRMS [M-e] : calcd for C126H82O12S4: 1918.5002, found 1917.4970 [M-e] ; 958.7443 [M-e]2- (see Figure A 79); 638.8288 [M-e]3-, 478.8702 [M-e]4-. HRMS [M+H]+: Calcd for + + C6H16N : 102.1277, found [M+H] : 102.1278.

101 + 3.6.10. 2DAsTC(HNEt3 )-BTC

+ - HNEt3 SO3

HNEt + - O 3 SO3 -O S - 3 SO3

2 Equiv. + + + HNEt3 HNEt3 200°C ArNO2 - + O3S HNEt3

- + O3S HNEt3 + + sTC(HNEt3 ) 2DABTC-CCH 2DAsTC(HNEt3 )-BTC + Figure 3.45: Synthesis of 2DAsTC(HNEt3 )-BTC.

+ To a 60-mL Schlenk tube equipped with a stir bar were added sTC(HNEt3 ) (0.424 g, 0.569 mmol, 2.02 equiv.), DABTC-CCH (0.250 mL, 0.281 mmol, 1.0 equiv.) and 3 mL of nitrobenzene. The solution was stirred for 10 min. The Schlenk tube was closed with a septum, the contents were stirred for 10 min at room temperature and then inserted into a sand bath at 200 °C. After 24 h, the solution turned yellow, the tube was cooled to room temperature and the contents were transferred to a 100-mL round-bottom flask containing 60 mL of ethyl acetate whereupon the solution turned white. After refluxing for 4 h, the product was filtered and washed twice with boiling ethyl acetate and once with acetone. + After drying overnight at 100 °C, compound 2DAsTC(HNEt3 )-BTC was collected as a light 1 grey powder (0.436 g, 66.7%). H (500 MHz, DMSO-d6) δ (ppm): 1.15 (t, Jt = 7.26Hz, 36H),

3.08 (2 overlapped q, Jq = 7.26Hz, 24H), 6.32-6.46 (6 s, 4H), 6.53-7.39 (m, 78H), 8.23- 13 8.90 (two s, 4H), see Figure A 80. C (151 MHz, DMSO-d6) δ (ppm): see Figure A 81. - - HRMS [M-e] : calcd for C126H82O12S4 : 1918.5002, found: [M-e] none observed; 958.7475 [M-e]2-; 638.8292 [M-e]3-;478.8707 [M-e]4- see Figure A 83 and Figure A 84. HRMS [M+H]+: + + Calcd for C6H16N : 102.1277, found [M+H] : 102.1278.

+ 3.6.11. 2DAsTC(HNEt3 )-Biph

+ - - + HNEt3 SO3 SO3 HNEt3

O -O S - 3 SO3

+ + 2 Equiv. HNEt3 HNEt3 ArNO2, 200°C

+ - - + HNEt3 SO3 SO3 HNEt3 sTC(HNEt +) + 3 2DAsTC(HNEt3 )-Biph + Figure 3.46: Synthesis of 2DAsTC(HNEt3 )-Biph.

102 + The synthesis of the 2DAsTC(HNEt3 )-Biph was similar to the synthesis of the + 2DAsTC(HNEt3 )-1,4-Bz; the compound was obtained as a light grey powder (1.227 g, 1 0.748 mmol, 91.6%). H NMR (500 MHz, DMSO-d6) δ (ppm): 1.14, (t, Jt = 7.26 Hz, 36H),

3.06 (two overlapped quadruplets, Jq = 7.06 Hz, 24 H), 6.83-6.98 (m, 24H), 7.12 (d, Jd =

8.27 Hz, 4H), 7.18 (d, Jd = 8.31 Hz, 4H), 7.20 (d, Jd = 8.45 Hz, 4H), 7.36 (d, Jd = 8.09 Hz, 13 4H), 7.43 (s, 2H), 7.48 (d, Jd = 8.41 Hz, 4H), 8.86 (s, 4H). C NMR (151 MHz, DMSO-d6) δ (ppm): 146.05, 145.23, 141.87, 141.23, 140.21, 139.87, 139.83, 139.77, 139.75, 139.45, 139.19, 138.47, 137.15, 131.05, 130.97, 130.91, 130.46, 130.22, 129.01, 127.02, 126.66,

125.90, 125.70, 124.90, 124.28, 45.72, 8.62. HRMS [M-e]-: Calcd for C72H50O12S4: 1234.2185, [M-e]-, found was not observed, [M-e]2- 616.1012, [M-e]3- 410.3987 [M-e]4- + + + 307.5477. HRMS [M+H] : Calcd for C6H16N : 102.1277, found [M+H] : 102.1278.

3.6.12. 3',6'-Diphenyl-1,1':2',1''-terphenyl (DATC)

+ 200°C DPE

TC Norbornadiene DATC Figure 3.47: Synthesis of 3',6'-diphenyl-1,1':2',1''-terphenyl (DATC).

The synthesis of the DATC-5,6-dihydro was proceed similar to the synthesis of the 2DABTC-TIPS, see 3.6.6. In a 10 mL Biotage® microwave reactor were inserted TC (0.396 g, 1.0 equiv., 1.03 mmol), Norbornadiene (0.120 µL, 1.15 equiv., 1.185 mmol) and 4.2 mL of diphenylether; then the reactor was sealed. The solution was heated in an oil bath at 200 °C for 3 days (until a pale yellow color appeared); the compound was obtained 1 as a white powder (0.075 g, 0.196 mmol, 19.03%). H NMR (500 MHz, DCM-d2) δ (ppm): 6.85-6.86 (m, 4H), 6.94-6.95 (m, 6H), 7.12-7.17 (m, 10H), 7.49 (s, 13 2H). C NMR (151 MHz, DCM-d2) δ (ppm): 142.50, 141.41, 140.88, 140.64, 132.05, 130.39, 129.81, 128.02, 127.31, 126.68, 126.10.

103 3.6.13. 2',3'-Diphenyl-[1,1':4',1''-terphenyl]-4,4''-disulfonic acid, DAsTC(H+)

HO S O 3 SO3H HO3S SO3H + 200°C DMAc

sTC(H+) Norbornadiene sDATC(H+) Figure 3.48: Synthesis of 2',3'-diphenyl-[1,1':4',1''-terphenyl]-4,4''-disulfonic acid, DAsTC(H+).

The synthesis of DAsTC(H+)-5,6-dihydro was similar to the synthesis of + 2DAsTC(HNEt3 )-1,4-bz, see 3.6.2. In a 5 mL Biotage® microwave reactor was inserted sTC(H+) (0.150 g, 1.0 equiv., 0.275 mmol), Norbornadiene (0.032 µL, 1.15 equiv., 0.317 mmol), and 1.9 mL of dimethylacetamide (DMAc); then the reactor was sealed. The solution was heated in an oil bath at 200 °C for 3 days (until a pale yellow color appeared); the compound was obtained as a grey-white powder (0.087 g, 0.161 mmol, 58.48%).1H

NMR (500 MHz, DCM-d2) δ (ppm):6.83 (d, Jd = 6.61 Hz, 4H), 6.95-6.96 (m, 6H), 7.04 (d,

Jd = 8.77 Hz, 4H), 7.36 (d, Jd = 8.77 Hz, 4H), 7.47 (s, 2H), 8.21 (s, 2H). 13 C NMR (151 MHz, DCM-d2) δ (ppm):145.94, 141.58, 140.12, 140.03, 139.43, 131.10,

129.33, 128.90, 127.03, 125.92, 124.89. HRMS [M-e]-: Calcd for C30H22O6S2: 542.0858, - 2- [M-e] was not observed, calcd for C30H20O6S2 : 270.0356, found 270.0348, Calcd for - - C30H20NaO6S2 : 563.0604, [M-e] 563.0585.

3.7. Characterization and Discussion of the Models Compounds.

+ The synthesis of DAsTC(HNEt3 )-Ph reveals the possibility that sulfonic acid could 1 survive the [4+2] Diels-Alder cycloaddition. The H NMR spectrum in DMSO-d6 of the + DAsTC(HNEt3 )-Ph reveals the difference in the chemical shift of the two different sulfonic acids, i.e., two doublets at 7.13 and 7.36 ppm for Ha1 and Ha2, respectively, shown in

Figure A 49. The nomenclature “HDA”, Diels-Alder proton, refered to the proton from the alkyne on the newly formed benzene ring showed as a singlet with a chemical shift of 7.38 ppm, this high chemical shift for a benzenic proton is due to the position of the sulfonated benzene ring 1 (Ha1 and Hb1). The integration of triethylammonium, methyl (-CH3),

104 + methylene (-CH2-) and ammonium (H-N -R3) confirmed the presence of the two sulfonic acid groups. The (2D) COSY reveals the correlation of the protons in the ortho-position (Ha1 and Ha2) of both sulfonic acids with the protons in the meta-position (Hb1 and Hb2), shown in Figure A 51. Finally, the mass spectrometry analysis reported the mass of the expected molecule with a theoretical molecular weight of 618.1171 g/mol, and 617.1284 g/mol was found for the mono-isotopic ion. The di-isotopic ion was also observed, where m/z = 308.0509 g/mol with z = 2.

+ The synthesis of 2DAsTC(HNEt3 )-1,4-bz was attempted with 2 equiv. of + sTC(HNEt3 ) and 1 equiv. of 1,4-diethynylbenzene, which was the base of the research + outlined in Chapter 4. The 2DAsTC(HNEt3 )-1,4-bz was obtained in a yield of 94.7%. This molecule was designed to study the understanding of the future polymer backbone. After the [4+2] Diels-Alder cycloaddition, the sulfonic acid should be reorganized in one or two specific conformations. The sulfonic acid might form hydrogen bonding between themselves or with a solvent; in that case, the small molecule might be bent and show a + similar conformation as that for sBTC(HNEt3 ) in the “A” conformation. In the other conformation, i.e. the “H” conformation, the molecule would be symmetric and all sulfonic acids should be far from each other, shown in Figure 3.49.

+ Figure 3.49: Two H possible conformations Aof the 2DAsTC(HNEt3 ) in solution. Molecules are represented without their cations. The upper right sulfonic acids, on the A, are voluntary bent to facilitated the view.

1 The H NMR spectrum in DMSO-d6 indicated a symmetric compound. Both Ha1 and both Ha2 are deshielded; their respective chemical shifts are 7.38 and 7.23 ppm. The doublet between 7.36 and 7.38 ppm is a singlet that is overlapped with one doublet, as shown in Figure A 52. The COSY sequence, shown in Figure A 54, reveals a correlation between the Ha1 and the Hb1 at 7.13 ppm. A lower chemical shift for the Hb2 (correlated

105 with the Ha2) at 6.73 ppm is due to the extra donating group of the benzene ring in the center; these protons are named Hcore. The same effect is observed for the HDA, 7.38

+ ppm, which is a singlet overlapped with the doublet of the Ha1 for DAsTC(HNEt3 )-Ph and

+ 7.37 ppm for the 2DAsTC(HNEt3 )-1,4-bz. The conformation in solution of this molecule was investigated using the 1D NOE NMR sequence, shown in Figure A 55. Finally, mass spectrometry also revealed that the sulfonic acid remained after the reaction, and the di, tri and tetra isotopic ions are observed. The mono-isotopic ion is not easy to observe because of the presence of the strong acid, which is easily deprotonated.

+ The double cycloaddition of sBTC(HNEt3 ) with 2 equiv. of phenylacetylene yielded + 2DAsBTC(HNEt3 )-Ph as a yellow powder with a yield of 77.3%. This molecule was designed to study the effect on the sulfonate group on the cycloaddition; in other words, to determine if it will be possible to favorably form one product from the mixture of isomers. This reaction is not regioselective, and depending of the addition of the dienophile on the diene, three isomers can be formed based on the [4+2] Diels-Alder cycloaddition, shown in Figure 3.50. The resulting product will be one product with a meta orientation, to the center, core, of the backbone and one para.

- - - SO3 SO3 SO3

- - - O3S O3S O3S O O O + 1 equiv. +

O Core O O

- SO3 - - SO3 SO3

- - - O3S O3S O3S sBTC phenylacetylene meta adduct para adduct Figure 3.50: Two possible additions of the dienophile on the diene on one side of the sBTC. The molecules are represented without their counter ions.

Furthermore, if the rotation is locked, no rotation around the core of the sBTC, it will become an additional mixture of isomers. At a high temperature the rotation of the sBTC might be allowed, then depending on when the addition of the diene occurred, the sBTC might be in the “A” or “H” conformation, and then six isomers are possible, as shown in Figure 3.51; however, this was not examined and purified.

106

- - - SO3 SO3 SO3

- - - SO3 SO3 SO3 p-p'-isomer in H form p-m'-isomer in H form m-m'-isomer in H form

------SO3 SO3 SO3 SO3 SO3 SO3

------O3S SO3 O3S SO3 O3S SO3 p-p'-isomer in A form p-m'-isomer in A form m-m'-isomer in A form Figure 3.51: Six possible isomers of position who could be obtained after the [4+2] Diels Alder cycloaddition and the carbon monoxide extrusion. The molecules are shown without their counter ions. On the bottom row, the sulfonic acids are drawn to provide a better view. The Figure A 56 shows the first difficulty for identifying the disubstituted monomer + 1 product from the sBTC(HNEt3 ). H NMR reveals six different Hcore; none of them are correlated with other based on the 2D COSY, shown in Figure A 58. As a reminder, the reaction was not followed by purifying each isomer but by purifying the residual starting material and solvent. The problem increases with the 13C carbon NMR spectrum, shown in Figure A 57, because of a slight difference in the electronic effect; all the carbons from each isomer can be observed in the spectrum. Figure A 59, the high temperature NMR study, is very useful for characterizing this molecule. The high-temperature NMR allows warming the molecules and the solvent in the spectrometer and resulted in the overlapping of the protons. At room temperature, the presence of the six isomers of position in the mixture is allowed. At 130 °C, it become easier to identified Hcore from the A and H conformations. The identification of the isomer is based on the following study.

The identification of the meta and para protons was done using the result reported by Shifrina et al.171 and is reported below. According to the synthesis, BTC reacts with phenylacetylene to yield 2DABTC-Ph; three positional isomers are possible and are shown in Figure 3.52.

107 O

+ 2 Equiv. 200°C DPE

BTC 2DABTC-Ph

Hcore Hcore Hcore

p,p'-2DABTC-Ph m,p'-2DABTC-Ph m,m'-2DABTC-Ph Figure 3.52: Synthesis of 2DABTC-Ph from Shifrina et al.171 Second row, three different isomers that can be produced: p,p’; m-p’ ; and m,p’.

The authors realized a recrystallization in chloroform/methanol (1:1) and the isomer m-m was obtained by crystallization with a yield of 83%, thereby a crystal structure was obtained. The authors reported the 1H NMR spectrum of the recrystallized m-m compound in tetrachloroethane-d2 at 130 °C. Two singlets were obtained at 7.37 and 6.31 ppm. The first one was named in this manuscript as HDA (integration 2H) or the aromatic proton obtained after the cycloadditon. The second one is the Hcore, in the middle of the phenyl ring. A similar experiment was performed without the purification and 1 recrystallization steps, and a H NMR spectrum was obtained in tetrachloroethane-d2 at 130 °C; shown in Figure 3.53. The area between 6.23 and 6.37 ppm showed two distinct singlets at 6.23 and 6.30 ppm and two overlapped singlets at 6.37 ppm. Based on the previous work, the singlet at 6.30 ppm is the protons of the Hcore for the m-m isomer. The relative intensity of the peak at 6.30 ppm confirms the argument that the m-m isomer was the most favorable isomer and easy to recrystalize. In this study, this compound has a concentration, as determined by 1H NMR, of 47.3%. The two other peaks are one singlet at 6.23 ppm and two overlapped singlets or a doublet at 6.37 ppm has to be identified. In the low field, the peak at 6.37 ppm was attributed to Hcore, shown in Figure 3.53 in red; of the p-p isomer: the molecule contains pentaphenylene as the backbone; Hcore has the effect of two extra benzene rings, which enhance the conjugation and decrease the electron density. This fact enhances the deshielding of these Hcore. This isomer is present

108 in this sample has a concentration of 24.4%. Finally, the singlet at 6.23 ppm is identified as the p-p isomer. For this kind of molecule, the Hcore are under the influence of each side of the molecule, the loss of the symmetry enhances the shielding of these protons and may explain the formation of doublet, not a singlet, at 6.37 ppm. This isomer has a concentration of 28.8 %.

TCE-d2

2DABTC-Ph

1 Figure 3.53: H NMR (TCE-d2) spectrum at 130°C of the mixture of isomers of the 2DABTC-Ph, in the box. The m,m’-2DBTC-Ph was identified by Shifrina et al.54

+ Based on these conclusions, the results were extrapolated for 2DAsBTC(HNEt3 ); the 1H NMR spectrum of the last mentioned compound reveals as well a mixture of isomers. However, at 130 °C; shown in Figure A 59; the spectrum allowed identification of the three isomers. Based on the integration, it was possible to observe in the mixture a concentration of 33.7% for the p-p isomer, 37.5% for the m-m isomer and 28.8% for the m-p isomer.

109 The following three molecules were designed to be incorporated as hydrophilic and hydrophobic segements for polymers described in Chapter 5. Two different hydrophilic blocks are designed to react with sBTC and sTC to form three oligomers, which are studied hereafter. Compound DATC-TIPS was synthesized using a less polar solvent, diphenylether, with 1 equiv. of TC and 1 equiv. of ((4-ethynylphenyl)ethynyl)- triisopropylsilane. After completion, the triisopropylsilyl product was obtained as a yellow to light grey powder in a yield of 75.4%. Similar behaviour is observed in the 1H NMR spectrum for HDA, which is observed in the high field at 7.50 ppm; shown in Figure A 60; and the benzene ring from the ethynyl derivative exhibits two doublets at 7.26 and 7.12 ppm that are correlated; shown in Figure A 62. The benzene ring labeled “e” was identified as a phenylene because of the absence of correlation in space and the integration value of five protons based on the integration of the TIPS group (twenty one hydrogens) at 1.12 ppm, shown in Figure A 60. Finally, the TIPS group exhibits a singlet at 1.12 ppm and exhbits a fingerprint at 19.07, 19.06 and 12.05 ppm in the 13C spectrum; shown in Figure A 61. Furthermore, the carbons from the alkyne show two distinct chemical shifts at 107.65 and 91.50 ppm. The protiodesilylation of this compound released the alkyne and produced DATC-CCH as a white semi-crystalline product with a yield of 67.5%. The protiodesilylation was carried out using TBAF. The elimination of the bulky silicon protecting group requires a strong nucleophile, such as F- or OH-; in most cases, fluoride is used because of its higher reactivity.198 The proton from the alkyne shows up at 3.09 ppm; shown in Figure A 63; and the carbons from the alkyne show up at 83.80 and 77.78 ppm for the alkyne; shown in Figure A 64. The HDA is not affected by the protiodesilylation and still shows up at 7.50 ppm as well as the benzene ring from the acetylene derivative: 7.26 and 7.12 ppm which are correlated together; shown in Figure A 65.

Similar chemistry was made with the BTC and the ((4-ethynylphenyl)ethynyl)- triisopropylsilane to yield 2DABTC-TIPS, see Section 3.6.6. The compound was obtained as a light grey powder. The 1H NMR spectrum shows similar results to those observed previously: a mixture of isomers of position is obtained. Three peaks are observed between 6.29 and 6.44 ppm; shown in Figure A 66. These are not correlated with any other peaks on the 2D COSY; shown in Figure A 68; they are identified as Hcore. At 6.29 ppm, in the aromatic area, the protons are shielded because of the presence of the donating triisopropylsilylethynylgroup, which are the two substituents had on the backbone; this one is identified as the meta-para isomer. The similar identification for

110 + these compounds was made as the identification of the 2DAsBTC(HNEt3 )-Ph; the proton at 6.36 ppm is referred to the Hcore of the meta-meta and those at 6.43 and 6.44 ppm for the para-para, no correlation with these peak were observed on the 2D COSY; shown in Figure A 67. Two observations are made here. First, the presence of three isomers can be detected based on the three peaks of the Hcore between 6.29-6.45 ppm; shown in Figure A 66; but not six, which implies a possible rotation of the molecule around the core (Hcore). Second, the concentration of the isomer in the case of the 2DABTC-TIPS is + different from 2DAsBTC(HNEt3 )-Ph: 20.7% for the meta-para, 50.3% for the meta-meta and 29.0% for the para-para. The 13C carbon; shown in Figure A 68 in the two insets of the alkyne area between 107 and 90.5 ppm reveals of the different positional isomer: two alkyne carbons are observed for each carbon of the alkyne. The protiodesilylation was successful using TBAF as proceed on3.6.5, and the product was obtained in a yield of 83.4% as a white powder. The alkyne protons from both isomers have chemical shifts of

3.07 and 3.08 ppm; shown in Figure A 69. Three different HDA are observed on this spectrum at 7.41 and are not correlated to any other protons on the 2D COSY; shown in Figure A 71. Finally, the 13C spectrum, shown in Figure A 70, reported the alkynyl carbons at 83.9 and 77.7 ppm, which showed the same behaviour as the reagent: two different carbons from each carbon of the alkyne, shown in Figure A 70.

The coupling of the hydrophilic block and the hydrophobic block yielded DA- + + sTC(HNEt3 )-p-DATC that was synthetized using 1.0 equiv. of sTC(HNEt3 ) and 1.02 equiv. of the DATC-CCH. The compound was obtained as a white powder with a yield of 87.02%.

Two other oligomers were prepared using by reacting DATC-CCH with + + sBTC(HNEt3 ) and sTC(HNEt3 ) with 2DABTC-CCH in nitrobenzene at high temperature + + to yield 2DATC-sBTC(HNEt3 ) and 2DAsTC(HNEt3 )-BTC, respectively. Both molecules were obtained in moderate yield, 54.3 and 66.7%, respectively. The first compound exhibits a mixture of six isomers based on the observation of the Hcore between 6.10 and

6.41 ppm (inset, Figure A 76). The two different HDA protons, one connected to the + hydrophilic unit (from the sBTC(HNEt3 )) and one associated with the hydrophobic unit (from the DATC-CCH) possess respective chemical shifts of 7.38 and 7.21 ppm, shown in Figure A 76. In this case, the conjugation is increased, the backbone contains nine phenyl rings and the HDA shifts from 7.49 ppm (in DCM-d2) for DATC-TIPS; shown in

Figure A 60; and DATC-CCH; shown in Figure A 63; to 7.39 ppm (in DMSO-d6) in this

111 new, longer unit; shown in Figure A 76. The hydrophilic HDA proton is observed at 7.21 ppm, and no correlation is observed on the 2D COSY, as shown in Figure A 78, where, + on the 2DAsBTC(HNEt3 )-Ph, the HDA were located at 7.21 ppm, shown in Figure A 56 and Figure A 58. In this case, the chemical shifts of the hydrophobic part decrease because of the presence of the hydrophilic segment, which has an electron-withdrawing effect. The 13C carbon spectrum shows again the presence of the mixture of isomers, shown in Figure A 77. Similar behaviour is observed for Hcore, 6.40 to 6.00 ppm for the + 2DA-sBTC(HNEt3 )-Ph to 6.38 to 6.1 ppm, as shown in Figure A 56. The high resolution mass spectrum successfully reports the expected molecular weight of the compound with a mono isotopic charge: 1917.4970 g/mol with z=1, as shown in Figure A 79. The second molecule reported, as well, the mixture of the six isomers based on the 1H spectrum, shown in Figure A 80, this may be due to the earlier proposed argument. Both HDA protons exhibit chemical shifts of 7.32 and 7.21 ppm, which are for the hydrophilic and hydrophobic protons respectively; as shown in Figure A 80; and as identified on the 2D COSY, shown in Figure A 82. In this case, the chemical shift of the HDA of the hydrophilic part decreases + from 7.39 on the 2DAsTC(HNEt3 )-1,4-bz in 3.6.2 and shown in Figure A 52, to 7.21 ppm on the present molecule, as shown in Figure A 78. Similar to that observed for the hydrophilic part, the HDA of the hydrophobic part showed a decrease in the chemical shift from 7.50 ppm on the 2DABTC-TIPS; as shown in Figure A 66; and 2DABTC-CCH; as shown in Figure A 69 to 7.32 ppm; as shown in Figure A 80. Hcore in this case showed similar chemical shifts at 6.30-6.45 ppm from the 2DABTC-TIPS; as shown in Figure A 66; and 2DABTC-CCH; as shown in Figure A 69; to 6.31-6.46 ppm in this case, as shown in Figure A 80. On the 13C spectrum, as shown in Figure A 81, the pattern is similar to that + observed for the previous compound 2DATC-sBTC(HNET3 ) as shown in Figure A 77.

The use of a single benzene ring between each hydrophilic unit was investigated and reveals an increase in the conjugation. Another attempt was performed using a + biphenyl backbone. Two equivalents of sTC(HNEt3 ) were reacted with 4,4’- diethynylbenzene in the presence of nitrobenzene as a solvent and heated at 200 °C for + two days. The compound, 2DAsTC(HNEt3 )-biph, was obtained as a light grey powder with a yield of 91.6%. The biphenyl linker and co-monomer have the advantage to increase the rigid rod backbone of the small molecule but are also less difficult to handle. While 1,4- diethynylbenzene must be manipulated at a low temperature, stored under argon at -20 °C, stored away from light and purified before each used, 4,4’-diethynylbiphepnyl is more

112 stable and can be store for months in the fridge without any signs of degradation. The second advantage is to increase the distance between each hydrophilic unit. If the sulfonic acids are too close to each other, they might form a hydrogen bond, which can increase the chance of solubility in water by hydration. The 1H NMR spectrum, shown in Figure A

85, shows a well-defined structure where the HAD has now a chemical shift of 7.43 ppm + (7.39 ppm for HAD of the 2DAsTC(HNEt3 )-1,4-bz; there is no correlation with any other proton on the 2D COSY, shown in Figure A 86. As suspected, the hydrophilic segment, e.g., the protons of the sulfonated rings, is deficient in electrons, Ha1 and Ha2 appear, respectively, at 7.48 and 7.18 ppm in this case and 7.36 ppm and 7.23, respectively, for

+ Ha1 and Ha2 of 2DAsTC(HNEt3 )-1,4-bz. Finally, HRMS proves that the compound can be easily deprotonated; the monoisotopic mass was not observed but only the di-, tri- and tetra-isotopic mass, as revealed in Figure A 88: m/z (z=2) = 616.1012, m/z (z=3) = 410.3987, m/z (z=4) = 307.5477, respectively.

Finally, two compounds were made to prove the chemical shifts and the structure of the previously identified compounds. The first one, DATC, was made from the reaction with TC and norbornadiene at 200 °C for three days. This compound was made by a sequence of one Diels-Alder and two retro Diels-Alder reactions between the norbornadiene, and the TC which released cyclopentadiene and carbon monoxide, as shown in Figure 3.54.

O + O O + CO -

TC Norbornadiene DATC Figure 3.54: Proposed mechanism of the Diels-Alder reaction between TC and norbornadiene followed by two retro the Diels-Alder reaction : elimination of cyclopentadiene and CO extrusion.

In the proposed mechanism, the first step is the retro Diels-Alder reaction of norbornadiene, which released cyclopentadiene and acetylene in a concerted mechanism (green arrows). The acetylene reacted with cyclopentadienone to be inserted and created

113 the adduct (red arrows). Finally, the carbon monoxide extrusion reaction takes place to release CO(g) and recover the aromaticity of the central benzene ring.

DATC was obtained in a poor yield but the 1H NMR spectrum and the (2D) COSY show the perfect symmetry of the compound. The higher chemical shift of the HDA reflects the lower electron density from the delocalisation of tetraphenylene; shown in see Figure A 89 and Figure A 90. The 13C spectrum corroborated the perfect symmetry of this compound by only showing eleven carbons over the twenty-two; shown in Figure A 91.

The sulfonated derivative of DATC was also made. DAsTC(H+) was synthesized using the previous method with TC(H+) and norbornadiene. The poor yield and lack of purification was made because of the difficulty of making this compound and the lack of time to complete this manuscript. However, the main compound is the expected product. The 1H NMR spectrum, shown in Figure A 92, showns again perfect symmetry of the compound, the acidic proton has singlet at 8.19 ppm, the singlet at 7.47 ppm is observed for the HDA, the two well defined doublets at 7.36 and 7.04 ppm that correlated together based on the 2D COSY; shown in Figure A 93, then the Ho, Hm and Hp in the multiplet at 6.83 and 6.85 ppm. The 13C spectrum reports again the symmetry of this compound by reporting again eleven carbons on twenty two, shown in Figure A 94.

Finally, the thermal stability of the new sulfonated compounds was studied and compared with that of para-toluene sulfonic acid (PTSA) converted to the triethylammonium form. PTSA was converted to ammonium using a similar synthetic route + + 1 as the conversion of sTC(H ) to sTC (HNEt3 ). In the H NMR spectra; shown in Figure A 96, the acid proton of PTSA was replaced by ammonium one (upper spectra): proton H+, 6.94 ppm; and in the lower spectra: NH+ (2’) appears at 8.88 ppm, methylene (3’) at 3.08 ppm and methyl (4’) at 1.17 ppm.

+ The thermogram of PTSA(HNEt3 ) reveals a two-step decomposition mechanism where the first 5% weight loss appears from 211 to 252°C; shown in Figure A 97. Between 211 and 311°C, the sample loses 81% of its weight, which could be related to the hydrophilic block, sulfonate and ammonium as well as the reduction of the aromatic + moiety. When DAsTC(HNEt3 ) was studied, shown in Figure A 98, the first 5% of the weight loss was apparent at 300 °C, and after a weight loss of 37%, the second thermal + decomposition process occurs at 359 °C. For 2DAsTC(HNEt3 )-biph, the first 5% of

114 decomposition appears at 285°C followed by a weight loss of 39%, shown in Figure A 99. A smooth plateau appears until 477°C where the backbone starts to decompose. Finally, + 2DAsBTC(HNEt3 )-Ph was used for the thermal decomposition; shown in Figure A 100. + Its behaviour is similar to that for 2DAsTC(HNEt3 )-biph: the first 5% loss appears at 297°C, followed by a smooth plateau between 340°C and 477°C, followed by the degradation of the backbone.

3.8. Conclusion

The functionalization of the tetracyclone molecules with multiple sulfonic acid groups to produce sTC(H+) and sBTC(H+) in high yields was successful using trimethylsilyl chlorosulfonate as a reagent. The sTC(H+) compound was successfully crystallised and exhibit hydrogen bonding between each unit. Furthermore, in their network, the solvent is present in channels in the crystal structure, which is an interesting behaviour for the future consideration of their use proton exchange membranes.

The obtained sulfonic acids were converted into ammonium salts using triethylamine. This conversion decreases the hygroscopic property and the intramolecular hydrogen bonding but also increases the thermal stability. Both compounds were reacted with different dienophiles and provided good yields. These compounds can be used as building blocks to make small molecules and oligomers. A family of compounds with molecular weights of 542 to 1918 g/mol were made and characterized using 1H and 2D COSY NMR spectroscopy.

The presence of isomers was observed and proven using 1H NMR spectroscopy at room and high temperature; the isomers were quantified using the previous result from Shifrina et al.54 No attempts to purify each isomer were made because the [4+2] Diels Alder cycloaddition was used in the next chapter for polymerization.

+ Finally, the thermal decomposition study with the PTSA (HNEt3 ), as reference, with models compounds was performed. It was confirmed that the sulfonate groups will decompose first. Secondly, and most importantly, a trend seems to appear toward the thermal stability of the sulfonic acid: when the hydrocarbon skeleton of the molecule increases in molecular weight, the thermal stability of the sulfonic acid increases.

115 Chapter 4.

Structurally-Defined, Sulfo-Phenylated, Oligophenylenes and Polyphenylenes

This chapter is an extention of Chapter 3 and focuses on the synthesis and molecular characterization of structurally-defined sulfo-phenylated, oligo- and polyphenylenes that incorporate a novel tetra-sulfonic acid bistetracyclone monomer. Parts of this chapter was published in the Journal of the American Chemistry Society: T. J. Skalski, B. Britton, T. J. Peckham, S. Holdcroft, “Structurally-Defined, Sulfo-Phenylated, Oligophenylenes and Polyphenylenes”, J. Am. Chem. Soc, 137 (2015) 12223-12226. My contributions to the chapter below include the entire synthetic sections and the molecular characterizations. Dr. Benjamin Britton performed fuel-cell test. Dr. T. J. Peckham provided synthetic insights, and Dr. Holdcroft supervised the work.

4.1. Introduction

Methods to synthesize polyphenylenes,19,42,44,45,47,48,54,199–204 such as those reported by Stille47,48,199,202 and Müllen,54,200,201 have been of significant attention due to the polyphenylene’s inherent chemical stability and mechanical strength. Of more recent interest are routes to branched polyphenylenes bearing ionic functionality. Sulfonated versions of branched polyphenylenes are currently prepared by post-sulfonation of polyphenylenes, for the purpose of preparing polymers for electrochemical membranes.57,60,184 Such membranes are reported to be mechanically robust, and possess high ionic (protonic) conductivity. Recently, they have been examined for use in proton exchange membrane fuel cells (PEMFCs), and post-quaternized ammonium derivatives have been examined in anionic exchange membrane fuel cells (AEMFCs).60– 62,205

Nonetheless, reports of sulfonated polyphenylenes are comparatively sparse because of the difficulty of forming rigid, sterically-encumbered, aryl-aryl linkages and the need to manipulate near-intractable polymers in polar media for the purpose of later introducing ionic functionality. Moreover, current examples of sulfonated polyphenylenes are structurally ill-defined and relatively disorganized due to the uncertainty of meta- vs.

116 para- coupling of the phenyl linkages as well as the multitude of positions available, on multiple phenyl rings, for post-sulfonation.184 As consistently demonstrated for acid- bearing polymers, precise control of the polymer structure and accurate placement of ionic functionality along the polymer backbone enhances short and long range order of ionic channels and thus ionic conductivity.19,25,67,206,207 Ding et al. demonstrated this with block and graft copolymers of sulfonated polystyrene.208 Numerous examples have since been reported for many, primarily aromatic-based classes of ion-containing polymers.17,19,58,185,207,209–216 A high degree of molecular control is primarily achieved by spatially controlling the placement of sulfonic acid groups on the polymer – but such control is difficult, if not impossible, to achieve by post-sulfonation of polyphenylenes. To this end, a strategy leading to the controlled synthesis of novel sulfonated monomers was explored, which demonstrated utility in synthesizing sulfonated, branched oligophenylenes as well as the homopolymer (sPPP-H+), with precise control of the position and number of sulfonic acid groups.

O XO S O XO S O 3 SO3X 3 SO3X (i) (ii) (iii) O O + O

+ + 1 2 3 4(X=H ) 5(X=HNEt3

O XO S O XO S O 3 SO3X 3 SO3X O O (i) (ii) (iii) O +

O O

XO S XO S SO X O 3 O SO3X 3 O 3

+ + 1 6 7 8 (X=H ) 9 (X=HNEt3

SO3H

(iv) (v) (vi) 9 + n

13 SO3H

SO3H sPPP(H+) Figure 4.1: Synthesis of sulfo-phenylated dienes and polyphenylene + homopolymer sPPP(H ). i) KOH/EtOH, reflux; ii) Me3SiOSO2Cl, 1,2- C2H4Cl2; iii) NEt3, n-BuOH; iv) PhNO2: sand bath (180 °C, 12 h) or microwave reactor (195 °C, 2 h) v) 2 M KOH; vi) 0.5 M H2SO4.

117 4.2. Instrumentation and Methods

1H and 13C NMR spectra were recorded on a Bruker AVANCE III 500 MHz equipped with a 5 mm TXI Inverse probe at room temperature (T = 298 K). 2D (COSY) and 1D NOE were recorded on Bruker AVANCE II 600 MHz “TCI 600” spectrometer equipped with a 5 mm TCI cryoprobe.

Mass spectra were recorded for all molecules on an AB Sciex 4000 Q TRAP spectrometer (ESI mode).

Size-exclusion chromatography analyses were obtained using Water HPLC HR 5, HR 4 and HR 3 columns using HPLC grade DMF (containing 0.10 M LiBr) as eluent. Polystyrene samples, purchased from Waters Associates Inc., were used as standards for the calibration.

Microwaves assisted reactions were carried on using microwaves reactor Biotage ® initiator+ with a 20 mL reactor capacity equipped with a stirring bar.

4.3. Materials

Triethylamine (99%, Anachemia Science), and 1,4-diodobenzene (98%) was purchased from Combi-Blocks, Inc. Acetone, dichloromethane (DCM), diethyl ether (reagent grade) methanol (MeOH), petroleum ether (PE), potassium carbonate (reagent grade) and toluene (ACS reagent) were purchased from Thermo Fisher Scientific. n- Butanol, dichloroethane (DCE), dimethylsulfoxide (DMSO),ethyl acetate (AcOEt) and potassium hydroxyde (KOH, reagent grade) was purchased from Caledon Laboratories Ltd. Nitrobenzene (ACS reagent, >99%) and trimethylsilyl chlorosulfonate (99%) were purchased from Sigma Aldrich Canada Co. Dimethylformamide (DMF, anhydrous HPLC grade) was purchased from J&K Scientific. Anhydrous ethanol was purchased from Commercial Alcohols. Diphenylphosphineferrocene palladium dichloride (97%) was purchased from Strem Chemicals, Inc. 1,3-(Diphenyl)propan-2-one (98%), bisbenzyl (98%) and trimethylsilylethynyl (98%) were bought from Tokyo Chemical Industry Co., Ltd. America. Diphenylphosphine palladium dichloride (98%) was purchased from Strem Chemicals, Inc. Copper iodide (99,9%) was purchased from Santa Cruz Biotechnology,

118 Inc. All the previous reagents were used without any further purification. Toluene was degased with argon for 30 min with molecular sieves before being used.

4.4. Synthesis

4.4.1. Tetracyclone 3

O O O KOH + Reﬂux O

1 2 3 Figure 4.2: Synthesis of tetracyclone, 3.

Compound 3 was synthesized according to a literature procedure.45 To a 250 mL, two-neck, round-bottom flask containing 175 mL of anhydrous ethanol and equipped with a condenser, septum and stir bar were added 1,3-(diphenyl)propan-2-one 1 (4.00 g, 19.0 mmol, 1.02 equiv.), and benzyl 2 (3.92 g, 18.7 mmol, 1,00 equiv.). The solution was refluxed for one hour. KOH (1.04 g, 18.7 mmol, 1.0 equiv. dissolved in 5 mL ethanol) was added drop-wise to the warm solution through the septum using a syringe. The solution was refluxed for an additional 45 min before being cooled to 0 °C using an ice bath. After 2 h, the solution was filtered and the precipitate was washed twice with cold methanol to yield the tetracyclone 3 (7.17 g, 15.0 mol, 80.6%) as a purple crystalline powder.1H NMR

(500 MHz, CD2Cl2) δ (ppm): 6.95 (d, Jd = 7.01 Hz, 4 H), 7.18 (t, Jt = 7.47 Hz, 4 H), 7.21- 13 7.27 (m, 12 H). C NMR (125 MHz, CD2Cl2) δ (ppm): 200.86, 155.33, 133.77, 131.54, + 130.68, 129.80, 129.00, 128.51, 128.00, 126.01.HRMS [M+H] : calcd for C29H20O 385.1583, found 385.1587.

119 4.4.2. 4,4'-(2-Oxo-4,5-diphenylcyclopenta-3,5-diene-1,3- diyl)dibenzenesulfonic acid,4.

O HO S O 3 SO3H

TMSO-SO2Cl

DCE

3 4 Figure 4.3: Synthesis of cyclone disulfonic acid, 4.

In a 500 mL round-bottom flask equipped with a stir bar and containing 300 mL of dichloroethane degassed with argon, was dissolved 3 (3.00 g, 7.81 mmol, 1 equiv.). Trimethylsilyl chlorosulfonate (5.57 mL, 31.24 mmol, 4 equiv.) was diluted in 8 mL of degassed dichloroethane and added drop-wise to the flask. The solution was then stirred for 12 h. Ethanol (3 mL) was added to initiate precipitation and quench the reaction. The reaction mixture was stirred for an additional 2 h, then poured into 1.0 L of diethyl ether, filtered and washed several times with cold diethyl ether. The precipitate was recovered and dried under vacuum at 60 °C for 8 h to yield 4 quantitatively (4.25 g, 7.81 mmol,) as 1 + a bright purple powder. H NMR (500 MHz, CD2Cl2) δ (ppm): 3.86 (s, H2O/H3O ), 6.95 (d,

Jd= 7.24 Hz, 4 H), 7.11 (d, Jd= 8.38 Hz, 4 H), 7.22-7.29 (m, 6 H), 7.46 (d, Jd= 8.38 Hz, 4 13 H). C NMR (125 MHz, CD2Cl2) δ (ppm): 199.48, 155.08, 147.05, 132.63, 130.68, 129.25, 128.90, 128.72, 128.16, 125.23, 124.60. HRMS [M-e]-: calcd for C29H20O7S2 543.0577, found 543.0564, [M-e]2- 271.0231.

4.4.3. Bis-triethylammonium cyclone disulfonate, 5:

O O HO S -O S - 3 SO3H 3 SO3

NEt3 n-BuOH H H N N

4 5 Figure 4.4: Synthesis of bis triethylammonium cyclone disulfonate, 5.

120 In a 500 mL round-bottom flask equipped with a stir bar and containing 150 mL of n-butanol was dissolved 4 (4.00 g, 3.52 mmol, 1 equiv.) then 100 mL of triethylamine was added. The solution was stirring for 12 h, then filtered and wash several times with cold ethyl acetate or diethyl ether. The precipitate was recovered and dried under vacuum at 1 100 °C overnight and yielded 5 (4.56 g, 6.12 mmol, 83.1%). H NMR (500 MHz, CD2Cl2)

δ (ppm): 1.17 (t, Jt = 7.10 Hz, 36 H), 3.09 (m, two overlapped quadruplets, 12 H), 6.97 (d,

Jd= 6.93 Hz, 4 H), 7.11 (d, Jd= 8.29 Hz, 4 H), 7.22-7.29 (m, 6 H), 7.46 (d, Jd= 8.29Hz, 4 13 H), 8.85 (s, 4 H). C NMR (125 MHz, CD2Cl2) δ (ppm): 199.46, 155.00, 147.19, 132.61, 130.55, 129.17, 128.86, 128.66, 128.11, 125.18, 124.57, 45.78, 8.65. HRMS [M-e]-: calcd 2- + + for C29H20O7S2 543.0578, found 543.0595, [M-e] 271.0231. [M+H] : calcd for C6H16N 102.1277, found 102.1278.

4.4.4. Bistetracyclone, 7

O O O KOH 2 equiv. O + O Ethanol O O

1 6 7 Figure 4.5: Synthesis of bistetracylcone, 7.

To a 250 mL two-neck, round-bottom flask equipped with a condenser, stir bar and a septum, containing 275 mL of anhydrous ethanol was added 1,3-(diphenyl)propan-2- one 1 (4.00 g, 19.1 mmol, 2.1 equiv.), and bisbenzyl 6 (3.10 g, 9.07 mmol, 1 equiv.), the solution was then refluxed. After 1 h, KOH (1.02 g, 18.1 mmol, 2.0 equiv.) was dissolved in 5.0 mL ethanol and added drop-wise to the refluxed solution. The solution was refluxing for other 45 min then the solution was cooled at 0 °C for 2 h using an ice bath. The solution was then filtered and the precipitate was dissolved in boiling DCM, and then recrystallized 1 as purpled needles at 4°C. (5.5 g, 7.97 mol, 88%.) H NMR (500 MHz, CD2Cl2) δ (ppm): 13 6.78 (s),6.92 (d, Jd= 7.06 Hz, 4 H),7.19-7.30 (m, 26H). C NMR (126 MHz, CD2Cl2) δ 200.60, 154.93, 154.66, 134.11, 133.50, 130.65, 130.59, 129.77, 129.51, 129.05, 128.53, 128.12, 128.07.

121 4.4.5. Tetra(para-sulfonated) Bistetracyclone, 8

3 1 4 2 HO S O 3 SO3H

Cl O O S O 5 + 18 equiv. Hcore O 6 O Si DCE 7

HO S 3 O SO3H 7 8 Figure 4.6: Synthesis of tetra(para-sulfonated) bistetracyclone, 8.

In a 500 mL round-bottom flask equipped with a stir bar and containing 300 mL of dichloroethane degassed with argon, was dissolved 7 (4.00 g, 5.8 mmol, 1 equiv.) Trimethylsilyl chlorosulfonate (16.06 mL, 104.4 mmol, 18 equiv) in 16 mL of degassed dichloroethane was added drop-wise to the round-bottom flask. The solution was then stirred for 12 h. Ethanol (5 mL) was added both to initiate precipitation as well as quench the reaction. After an additional 2 h of stirring, the reaction mixture was poured into 1.5 L of diethyl ether then filtered and washed several times with cold diethyl ether. The precipitate was recovered and dried under vacuum at 60 °C for 8 h to yield 8 (4.74 g, 4.69 1 mmol, 80.9%.) H NMR (500 MHz, DMSO-d6) δ (ppm): 6.87 (s, 4 Hcore),6.92 (d, Jd= 7.40

Hz, 4 Ho),7.10 (d, Jd= 8.16 Hz 4 Hb1),7.16 (d, J = 8.50 Hz, 4 Hb2),7.25 (t, Jt= 7.74 Hz, 4

Hm),7.33 (m, 2Hp),7.50 (D, JD= 8.32 Hz, 4 Ha2), 7.55 (D, JD= 8.54 Hz, 4 Ha1)7.57 (s, 4H,

+. 13 H2O/H3O ) C NMR (151 MHz, DMSO-d6) δ 199.45, 155.13, 155.00, 146.56, 146.46, 133.35, 132.22, 131.15, 130.84, 129.53, 129.30, 128.98, 128.84, 128.36, 125.48, 125.45, - 2- 124.63, 124.35. HRMS [M-e] : calcd for C52H34O14S4 1010.0831, found 1009.0768, [M-e] 504.0358, [M-e]3- 335.6890.

122 4.4.6. Tetra Triethylammonium Tetra(para-sulfonated) Bistetracyclone 9

HO S O -O S O - 3 SO3H 3 SO3 H N

H NEt3 N H n-BuOH N H N HO S -O S - 3 O SO3H 3 O SO3

9 8 Figure 4.7: Synthesis of tetra triethylammonium tetra(para-sulfonated) bistetracyclone, 9.

In a 500 mL round-bottom flask containing 200 mL of n-butanol was dissolved 8 (4.41 g, 4.37 mmol, 1 equiv.) after which 100 mL of triethylamine was added. The solution was stirred for 12 h, then filtered and washed several times with cold ethyl acetate or diethyl ether. The precipitate was recovered and dried under vacuum at 100 °C overnight 1 and yielded 9 (6.08 g, 4.30 mmol, 98.3%.) H NMR (600 MHz, DMSO-d6) δ (ppm): 1.16 (t,

Jt = 7.20 Hz, 36H, 1 or CH3), 3.09 and 3.10 (2 d, Jd = 4.71Hz, 24H, 2 or –CH2-), 6.86 (s, 4

H, Hcore),6.93 (d, Jd= 7.35 Hz, 4 H, Ho), 7.08 (d, Jd= 8.42 Hz 4 H, Hb1),7.14 (D, JD= 8.54

Hz, 4 H, Hb2),7.26 (t, Jt= 7.15 Hz, 4 H, Hm), 7.34 (m, 2H, Hp),7.48 (D, JD= 8.42 Hz, 4 H,

13 Ha2)7.52 (D, JD= 8.54 Hz, 4 H, Ha1), 8.88 (s, 4H, 3 or NH+.) C NMR (151 MHz, DMSO- d6) δ 199.37, 154.81, 154.64, 147.06, 147.05, 133.18, 132.08, 130.61, 130.24, 129.20, 129.04, 128.95, 128.81, 128.78, 128.74, 128.61, 128.11, 128.04, 125.24, 125.20, 124.43, - 124.16, 45.78, 8.61. HRMS [M-e] : calcd for C52H34O14S4 1010.0831, wasn’t observed, [M- e]2- 504.0358, [M-e]3- 335.6884, [M-e]4- 251.5147. [M+H]+: calcd for C6H16N 102.1277, found 102.1278.

Compounds 12 and 13 were synthesized according to literature methods.193–196

123 4.4.7. 1,4-Bis(trimethylsilylethynyl)-benzene, 12

TMS Pd(dppf)Cl2/CuI I HNEt TMS 2 + 2 Equiv. Toluene I TMS 10 11 12 Figure 4.8: Synthesis of 1,4-bis(trimethylsilylethynyl)-benzene, 12.

In a 100 mL Schlenk flaskequipped with a stir bar, previously degased three times with argon/vacuum, was add 1,4-diiodobenzene 10 (14.54 g, 44.1 mmol, 1 equiv.), 45 mL of anhydrous toluene, diphenylphosphineferrocene palladium dichloride (0.180 g, 0.22 mmol, 0.5 mol%) and trimethylsilylacetylene 11 (1.28 mL, 92.6 mmol, 2.1 equiv.). The solution was stirred for 10 min. To a second Schlenk tube equipped with a stir bar, degassed as noted previously, was added CuI (0.042 g, 0.22 mmol, 0.5 mol%), and triethylamine (6 mL, 1 mL/0.007 g of CuI), the solution was stirred for 20 min. The contents of the second Schlenk tube were then transferred to the first Schlenk tube using a PEEK cannula. The combined reaction mixture was vigorously stirred for 15 min at room temperature during which time it turned black. The mixture was subsequently heated at 91 °C for 1 h then allowed to cool to room temperature. The solution was filtered and washed several times with diethyl ether. The filtrate was washed sequentially with saturated ammonium chloride, 5.0 M hydrochloric acid and brine, dried over MgSO4 then filtered. After concentration of the filtrate using a rotary evaporator, yellow crystals were obtained. The product was purified by sublimation or recrystallization in cold petroleum ether and give 12 (11.62 g, 97.6% using recrystallization, 89.0% using the sublimation 1 13 technic). H NMR (500 MHz, acetone-d6) δ (ppm): 0.23 (s, 18H), 7.45 (s, 4H). C NMR

(125 MHz, acetone-d6) δ (ppm): δ 132.66, 124.18, 105.20, 96.89, -0.11.

124 4.4.8. 1,4-Bis-ethynylbenzene, 13.

TMS

K2CO3

THF/MeOH TMS

12 13 Figure 4.9: Synthesis of 1,4-bis-ethynylbenzene, 13.

To a 250 mL round-bottom flask equipped with a stirring bar, previously degassed for 20 min with argon and protected from light using aluminum foil, was added 140 mL of tetrahydrofuran and 70 mL of methanol and 12 (1.92 g, 7.11 mmol, 1 equiv.). K2CO3 (4.48 g, 35.5 mmol, 5 equiv.) was added quickly and the reaction mixture stirred for 3 h. The solution was opened and poured into 200 mL of DCM, then washed three times with water. The aqueous layer was washed one time with DCM and the combined organic layers were dried with MgSO4, filtered and concentrated using a rotary evaporator to yield white- yellowish crystals. The final product can be purify by sublimation and give 13 (0.66 g, 1 13 68.3%.) H NMR (500 MHz, acetone-d6) δ (ppm): 3.81 (s, 2H), 7.50 (s, 4H.) C NMR (125

MHz, acetone-d6) δ (ppm): 132.88, 123.64, 83.49, 81.21.

4.4.9. Compound 14

+ - - + HNEt3 SO3 SO3 HNEt3

2 Equiv. 5 + 9 200°C ArNO2,

+ - - + HNEt3 SO3 SO3 HNEt3

14 Figure 4.10: Synthesis of compound 14.

125 To a 60 mL Schlenk tube equipped with a stirring bar were added 13 (0.150 g, 1.19 mmol, 1.0 equiv.), 5 (1.76 g, 2.36 mmol, 2.0 equiv.) and 5 mL of nitrobenzene. The Schlenk tube was sealed with a septum and stirred for 10 min then insert in a sand bath at 190- 200 °C. After 8 h, the solution turn black and the tube was cooled to room temperature and the contents transferred to a 250 mL round-bottom flask containing 200 mL of ethyl acetate. The solution turned white and was then refluxed for 4 h, the solution was filtered using a Buchner funnel and washed once with boiling ethyl acetate and twice with boiling 1 acetone and yielded 14 (1.76g, 94.7%.) H NMR (500 MHz, DMSO-d6) δ (ppm): 1.14(t, Jt

= 7.26 Hz,36 H), 3.08 (two overlapped quadruplets, 24 H), 6.73 (d, Jd= 8.21 Hz, H), 6.83-

6.96 (m, 24 H), 7.13 (D, JD= 8.38 Hz, 4 H), 7.23 (d, Jd = 8.27 Hz, 4 H), 7.36-7.38 (m, 6H), 13 8.90 (s, 4H.) C NMR (151 MHz, DMSO-d6) δ 145.89, 145.25, 141.74, 141.33, 139.94, 139.77, 139.71, 139.61, 139.45, 139.21, 138.83, 138.43, 131.02, 130.96, 130.47, 130.41, 129.01, 128.94, 126.89, 126.59, 125.81, 125.63, 124.82, 124.17, 45.78, 8.60.HRMS [M- - 2- 3- e] : calcd for C66H46O12S4: 1158,1872, found 1157.1811, [M-e] : 578.0868, [M-e] : 4- + 385.0559 [M-e] : 288.5403; [M+H] : calcd for C6H16N 102.1277, found 102.1278.

4.4.10. Compound 16.

- - - SO3 SO3 SO3 H N SO - - 3 SO3 H SO - N 3

O O

2 Equiv. + 9 H + O O H N H SO - SO - 3 3 SO - H 3 N

- - SO3 SO3 - SO3 15 16 Figure 4.11: Synthesis of compound 16. Transition states in brackets shows two possible additions resulting in a mixture of isomers.

To a 60 mL Schlenk tube equipped with a stir bar were added 9 (1.000 g, 0.707 mmol, 1.0 equiv.) and 15 (0.163mL, 1.485 mmol, 2.1 equiv.) and 6 mL of nitrobenzene. The solution was stirred for 10 min. The Schlenk tube was closed with a septum and the contents stirred for 10 min at room temperature then inserted into a sand bath at 190-200 °C. After 8 h, the solution turned orange and the tube was cooled down to room temperature and the contents transferred to a 100 mL round-bottom flask containing 50 mL of ethyl acetate whereupon the solution turned white. After refluxing for 4 h, the product

126 was filtered and washed twice with boiling ethyl acetate and twice whit acetone. After drying overnight at 100 °C, compound 16 was collected as a light yellow powder (0.855g, 1 77.3%.) H NMR (500 MHz, DMSO-d6)) δ (ppm): 1.16 (t, Jt = 7.24Hz, 36H), 3.09 (two overlapped quadruplets, Jq = 7.37 Hz, 24 H), 6.46-6.00 (singlets, 4H), 7.55-6.54 (m, 38H), 13 - 8.89 (s, 4H). C NMR (151 MHz, DMSO-d6), see Figure A 57. HRMS [M-e] : calcd for 2- 3- 4- C66H42O12S4: 1154.1581, found: 578.0840 [M-e] , 285.0539 [M-e] , 288.5385 [M-e] ; calcd for C6H16N 102.1277, found 102.1278.

+ 4.4.11. sPPP-HNEt3

- H H O3S H N N N O -- SO3 O3S H - N SO3 A H B

+ HDA

G' Hcore

-O S H F' D G 3 N F H O -O S C E SO - N 3 H H 3 - SO3 N N

9 13 + sPPP-HNEt3 + Figure 4.12: Synthesis of polymer sPPP-HNEt3

In a 20 mL microwave reactor Biotage® were introduced 9 (1.2 g, 0.848 mmol, 1 equiv.), 13 (0.108 g, 0.859 mmol, 1.02 equiv.), 10.0 mL of nitrobenzene and the reactor was sealed. After stirring for 10 min, the reaction occur at 195 °C under microwaves activation for 2 h. The solution turned purple to orange, after cooling, the reactor was opened and ethyl acetate was added to precipitate the polymer. The polymer was then refluxed for 4 h in ethyl acetate then washed twice with boiling ethyl acetate and once with + diethyl ether. After drying at 120 °C under vacuum, the polymer sPPP-NHEt3 was -1 obtained as a white powder (1.042 g, 82.8%). GPC analysis: Mn = 186,000 g mol , Mw = 1 1 269,000 g mol- , Mw/Mn = 1.44. H NMR (500 MHz, DMSO-d6)) δ (ppm): 1.12 (t, Jt =

7.29Hz, 36H), 3.05 (two overlapped quadruplets, Jq = 7.26 Hz, 24H), 6.16-7.54 (m, 36H), 8.92 (s, 4H).

127 4.4.12. sPPP-H+

- O3S

z H - - - - O3S O3S O3S O3S

H H H core m-p - SO3

- x O3S Hcore p-p y H H

Hcore m-m - - - - SO3 SO3 SO3 SO3

H + (x+y+z) HNEt3

- SO3 m-m p-p m-p

2 steps

HO3S

z H HO3S HO3S HO3S HO3S

H H Hcore m-p SO3H

x HO3S Hcore p-p y H H

Hcore m-m SO3H SO3H SO3H SO3H

SO3H m-m p-p m-p + + Figure 4.13: Conversion of sPPP-HNEt3 to sPPP-H .

128 + In a bound bottom flask of 200 mL, the polymer sPPP-NHEt3 was dissolved in 100 mL of methanol at room temperature under vigourous stirring. After complete dissolution, 75mL of 2.0 M of NaOH in methanol was added and the polymer sPPP-Na+ precipitated whereupon the solution was stirred for another two hours. The solution was filtered and the polymer washed twice with methanol and diethyl ether. The polymer was + dried overnight at 80°C under vacuum. sPPP-Na was dissolved in 75 mL DI H2O. After full dissolution under vigorous stirring, 75 mL of 2.0 M H2SO4 was added. The solution was stirred for another 2 h then filtered, washed several times with water and twice with ether. sPPP-H+was recovered after drying overnight at 120°C under vacuum. GPC -1 1 1 analysis: Mn = 135,000g mol , Mw = 262,000 g mol- , Mw/Mn = 1.49. H NMR (500 MHz, + DMSO-d6)) δ (ppm): 4.93 (s, H /H2O), 6.16-7.54 (m, 36H), 8.92 (s, 4H)

4.4.13. Membrane Casting

sPPP-H+ membranes were cast from 7 w% DMSO solutions. For example: 0.350g of sPPP-H+ was dissolved in 5.0mL of DMSO at 80°C. The solution was then filtered through a glass fiber filter and poured into a 65 mm diameter flat petri dish. The solution was evaporated slowly in a sealed vacuum oven at atmospheric pressure at 80°C for two days. After two days, the membrane was soaked in 0.5 M H2SO4 in water for 12 hours.

The membrane was soaked/washed four times with DI H2O, then dried under vacuum at 100°C overnight.

4.4.14. Fenton’s Reagent Test Procedure

A piece of membrane dried overnight under vacuum at 80 °C, 0.104 g of sPPP- + H , was placed into a vial containing 20mL of 3.0 % of H2O2 solution in DI H2O under stirring at 80°C. 1.54 mL of 3.0 ppm of FeSO4 was added. The resulting solution was stirred for one hour. After cooling to room temperature, the solution was quenched with sodium sulfite until the solution stopped bubbling. The polymer precipitated, and was recovered by filtration and washed several times with DI water. The polymer is then soaked in 1.0 M of HCl in water followed by six washes with DI water. The resulting polymer was dried overnight at 120 °C. The polymer was analyzed by 1H NMR spectroscopy.

129 4.4.15. Ex-situ Characterization of Membranes

Small pieces (2 cm × 2 cm) of sPPP-H+ membrane were equilibrated in 2 M NaCl overnight to release the protons, which were subsequently titrated with 0.001 M NaOH to a phenolphthalein end point. Acid-base control titrations were performed on 2 M NaCl solutions with no membranes present to determine the blank titration volume. After titration, the membranes were immersed in 2 M HCl for a minimum of 4 h to reprotonate the sulfonic sites. After drying at 120 °C under vacuum overnight, the membranes’ “dry” weight was measured. The ion exchange capacity (IEC, mmol/g) of the membrane was calculated using Equation 4-1:

� × � IEC = �

Equation 4-1

where VNaOH and MNaOH are the blank-corrected volume (mL) and molar concentration (mol/L) of NaOH solution, respectively. Wdry is the dry weight of the membrane.

The membranes were equilibrated in deionized water overnight at room temperature and blotted with a Kimwipe to remove surface water prior to determining the “wet” weight. The water uptake was calculated as the percentage increase in mass over the “dry” weight according to the Equation 4-2. Water uptake is reported as the average value measured for three similar samples.

� − � WU = × 100% � Equation 4-2

where Wwet and Wdry are the wet and dry weight of the membrane, respectively.

Proton conductivity was measured by placing a membrane (10 mm x 5 mm) between two Pt electrodes of a conductivity cell, and a 100 mV sinusoidal ac voltage over a frequency range of 10 MHz-100 Hz was applied by ac impedance spectroscopy with a Solartron 1260 frequency response analyzer (FRA).217 The resulting Nyquist plots were fitted to standard Randles equivalent circuit to determine the membrane resistance. Proton conductivity (σ) was calculated using Equation 4-3:

130 L σ = RA Equation 4-3

where L (cm) is the distance between electrodes, � (Ω) is the membranes ionic resistance, and A (cm2) is the cross-sectional area of the membrane.

Temperature and humidity controlled measurements were run inside an Espec model SH-241 humidity chamber maintained at 30 °C.

The acid concentration (as an approximation of free proton concentration217 for the membranes was calculated according to Equation 4-4:

IEC + W [−SOH] = V Equation 4-4

The effective proton mobility (�) was calculated from Equation 4-5:

σ = F [−SOH]µ Equation 4-5

where F is Faraday’s constant.

In-plane proton conductivity was measured by AC impedance spectroscopy with a Solartron 1260 frequency response analyzer (FRA) employing a two-electrode configuration, according to a procedure described elsewhere.217 Proton conductivity at variable RH were measured by placing a conductivity cell inside an Espec model SH-241 humidity chamber sustained at 30 °C.

4.4.16. Fuel Cell Tests Analyses

Optimized Nafion catalyst inks was performed by Dr. B. Britton, fabricated per conventional methods: water was added to Pt/C powder, and methanol added sufficient ® for a final ratio of 1:1 MeOH:H2O, with ionomer solution (Nafion D520) added dropwise while stirring, to a final 1 wt% solids in solution comprised of 30 wt% ionomer 70 wt% Pt/C (TKK TEC-10E50E, 46.4 wt% Pt on graphitized C). Catalyst ink was applied via spray coater (Sono-Tek ExactaCoat) onto the membrane at 80 °C to an electrode area of 5 cm2.

131 To create hydrocarbon ionomer electrodes, catalyst ink was similarly fabricated with 20 wt% ionomer and a final solvent ratio of 3:1 MeOH:H2O, and similarly applied to a loading of 0.4 mg Pt/cm2 onto Nafion® NR211 with a reference Nafion® D520 anode at a loading of 0.2 mg Pt/cm2.

Resultant MEAs were mounted in fuel cell hardware; MEAs with hydrocarbon membranes were laminated to a final active area of 4 cm2 using a standard 3-mil laminate sheet. Conventional GDLs (Sigracet 29BC) were used, with gasketing sufficient to compress GDLs 20-30% using a torque of 30 in·lbs.

Fuel cell performance was evaluated using a fuel cell test station (Teledyne Medusa RD 890CL, Scribner Associates Inc.). MEAs were conditioned by slowly increasing at 20 mA/cm2 followed by ohmic-region polarization curves until consistent function was achieved, ~6 hours. Polarization curves were obtained by current from zero at 80 ºC under 100% relative humidity (RH) conditions, 0.5/1.0 slpm H2/O2, 5 min/pt at OCV, and 200 mA/cm2 increments until a 0.25 V potential cutoff, including 1 min/pt at 2 mA/cm2 increments from 2-20 mA/cm2 and 5 min/pt at 50, 100, and 150 mA/cm2 to resolve the kinetic region. Membrane conductivity was determined via IR drop in the Ohmic region (current-interrupt method).

For cathode and fully hydrocarbon MEAs, electrochemical characterization was performed subsequent to polarization data via a combined potentiostat/EIS (PARSTAT,

Princeton Applied Research). The cell was equilibrated under 0.25/0.5 slpm H2/N2 to a stable potential ~0.1 V, whereupon chronoamperometry (CA) was performed to determine fuel crossover, linear-sweep voltammetry (LSV) performed to determine electronic shorting, and electrochemical impedance spectroscopy (EIS) to confirm membrane resistance via HFR and determine ionomer conductivity in the cathode catalyst layer by a 218 literature method. Cyclic voltammetry (CV) was taken under 0.25/0.00 slpm H2/N2 for 10 cycles at a rate of 50 mV/s, starting at 0.4 V and thereafter cycling between 0.04 and

0.8 V. ECSA determined from the area of the H2 desorption peaks of all consistent cycles as an average ± population standard deviation.

132 4.5. Results and Discussion

Sulfonated dienes were prepared as shown in Scheme 1. The tetracyclone 345,190 was sulfonated using trimethylsilyl chlorosulfonate to produce the novel disulfonic acid tetracyclone 4. The 1H NMR spectrum of 4; as shown in Figure 3.8; reveals a symmetrical structure, containing one doublet (integration 4 H) at 7.46 ppm. Using COSY, Figure A 8, this doublet correlates with the doublet at 7.11 ppm (4 H). These two doublets indicate desulfonation of 3 at the p-position of the two phenylene rings juxtaposed to the ketone.219 Sulfonation occurs at these positions due to delocalisation of the electronic charge introduced by the ketone.220,221 The remaining ten protons are observed asdoublets at 6.95 ppm and 7.22-7.29 ppm for the unsulfonated phenylenes as well as the multiplet between 7.22 ppm and 7.29 ppm and 6.95 ppm for the unsulfonated phenylene. Additional evidence for -SO3H in 4 can be seen inthe IR spectrum, Figure A 7, with the presence of -OH, absent in 3; as shown in Figure A 4. The acidic protons in 4 were exchanged for triethylammonium cations by treatment with triethylamine to produce 5.

The symmetrical, tetrasulfonated monomer 8 was synthesized in a similar fashion to 4. 1H NMR analysis of 8; as shown in Figure 3.19 ; reveals two doublets at low field (7.55 and 7.50 ppm). Using COSY, Figure 3.20, these protons correlate with doublets at 7.10 ppm and 7.16 ppm, which is consistent with p-substitution of the phenyl ring adjacent to the ketone. The signal for the acidic proton appears at 7.57 ppm. 1H NMR analysis indicates that 8 is symmetrical, with Hcore represented by a singlet peak at 6.87 ppm. COSY, Figure 3.20, and the 1D NOE analysis, Figure 4.14, were used to distinguish whether all four of the sulfonic acid groups are distant to one another (“H” conformation) or whether two are in close proximity (“A” conformation); as shown in Figure 4.15.

133

Hcore

Ha1 Ha2 Hm Hb2 Hb1 H Hp o

SO3H SO3H Ha1 Ha1 Ha1 Ha1 Hb1 Hb1 Hb1 Hb1 O O

Hb2 Hb2

Ha2 Hcore Ha2 Ho Hb2 Hb2 Ho Ho Ho HO3S Ha2 Hm Hm Ha2 SO3H Hm Hm Hp Hp

1 1 1 Figure 4.14: H NMR (DMSO-d6) of compound 8 and D NOE irradiation. Red : H spectrum, olive: 1D NOE: irradiation of the Hm; cyan 1D NOE: irradiation of the Ho; purple: 1D NOE: irradiation of the Hcore.

The Ha1 and Hb1 protons (7.55 and 7.10 ppm, respectively) exhibit no through space correlation with protons (Ho, Hm and Hp) on the unsulfonated phenyl rings, whereas

Ha2 and Hb2 (7.51 and 7.17 ppm respectively) do, indicating 8 exclusively adopts the “A” conformation in solution; as shown in Figure 4.15.

134 SO3H

Hp Ha2 SO3H SO3H HO3S Hm Hb2 Ha1 Ha1 Ho a b b H 1 O H 1 H 1 Hcore Hb1 O O Hb1 O Hcore Hb2 Hb2 Ho Ha1 Ha2 Ha2 Hm Hb2 SO H Ho Ho 3 HO3S SO3H Ha2 Hp Hm Hm Hp Hp

HO3S "H" conformation "A" conformation

H A + Figure 4.15: Two possible configurations for the compound 8 the sBTC(H )

Compound 8 was converted to the ammonium derivative 9 for greater thermal stability, prior to Diels-Alder (D-A) coupling. 1H NMR analysis of 9 revealed additional + + signals resulting from the HNEt3 : HN (8.88 ppm); -CH2- (two overlapping quadruplets at

3.09 and 3.10 ppm); and -CH3 (1.16 ppm); as shown in Figure A 29.

The synthesis of bis-dienophile 13 is described below. Oligomers 14 and 16 were synthesized (Figure 4.16) in order to investigate the mode of D-A coupling of co- monomers 9 and 13.

SO3X

SO3X SO3X

SO3X

SO3X SO3X

SO3X + 14 X = HNEt3 16 Figure 4.16: Chemical structure of compound 14 and 16. The dashed line reports the uncertitude of configuration.

135 Compound 14 was obtained by D-A cycloaddition of dienophile 13 and two molar equivalents of 5. As shown in Figure 3.37, the Diels-Alder protons (HDA) originates from the terminal alkyne of 13, Ha1 and Hb1 are, respectively, protons ortho and meta to the sulfonic acid group of the phenyl ring adjacent HDA, while Ha2 and Hb2 are the analogous protons located on the other sulfonated phenyl ring. The 1H NMR spectrum of 14; as shonw in Figure A 52; reveals the presence of HDA at 7.38 ppm and Hcore of the central phenyl ring at 6.93 ppm. As for the peripheral phenyl rings, the protons on the sulfonated rings reflect the different chemical environments with signals at 7.36 ppm (Ha1) and 7.23 ppm (Ha2) correlated; as shown in Figure A 54; with the peaks at 7.14 (Hb1) and 6.77

(Hb2) ppm, respectively. The signals corresponding to the unsulfonated phenyl rings are observed between 6.96 and 6.83 ppm. The possibility of conformational isomers was investigated using 1D NOE; as shown in Figure 4.17.

Hcore

Hp1 & Hp2

HDA Ha1 Ha2 Hb1 Ho1 & Ho2 Hm1 & Hm2 Hb2

SO - -O S Ha2 3 3 Hm1 Hp1 Ha2 Ho1 Hb2 Hb2 H 2 Hp2 N

HDA Hm2 Hb1 Hcore Ho2 1 Ha1 Hb1 a - H 1 - O3S SO3 14

1 1 Figure 4.17: H NMR (DMSO-d6) and 1D NOE of compound 14. Red: H NMR 1 1 spectrum; olive: D NOE irradiation of the HDA; cyan: D NOE: irradiation of the Hb1; purple: 1D NOE: irradiation of the Hb2.

136 Irradiation of HDA at 7.38 ppm reveals the proximity of Hcore at 6.88 ppm (single peak) as well as Hb1 at 7.11 ppm. By irradiating Hb1 at 7.11 ppm, the proximity of Hcore and HDA is also confirmed. Irradiation of Hb1, however, does not indicate the relative proximity of HDA, but a correlation does exist with the unsulfonated phenylene (6.88 ppm,

1 peak) and Hcore (two peaks). This suggests that compound 14 also adopts the “A” conformation in solution.

Compound 16 was synthesized by D-A cycloaddition of 9 with 15, as shown in Figure 3.38. Protons in 16 originating from the phenyl ring of 15 are observed at 7.00, 6.68 and 6.62 ppm; as shown in Figure A 56. According to the literature,48,54,199 this reaction does not afford a pure isomer as both m- and p- additions can occur as shown in Figure 4.11. As a result, three regio-isomers for 16 are evidenced by three main NMR signals at

6.41, 6.31 and 6.14 ppm for Hcore, which correspond to the p-p, m-m and m-p isomers, respectively. Signals at 7.28 ppm are attributed to HDA protons, according to the lack of correlation on the COSY with other protons of the molecule; as shown in Figure 4.18.

137

3 Hcore

Hb1

Hm1, Hm2, Hp1, Hp2

Hb2

Ho1 & Ho2 - - SO3 SO3 Ha1 Ha1 Hb1 Ha2 H DA Hb2 Hcore 3 Ha1 H HDA Hp2 N Ha2 HDA Ho2 Hm2 2 Hb2 1 Ha2 Ha2 Ho1 Hb1

Hm1 Hp1 Ha1 -O S -O S Ha2 3 3

Figure 4.18: COSY (2D) NMR (DMSO-d6) of the compound 16.

The spectrum for compound 16; as shown in Figure A 56; also shows signals at

7.23 and 7.11 ppm due to Ha1, 6.57 and 6.77 ppm due to Hb1, 7.55 and 7.46 ppm due to

Ha2, and 6.93 and 6.85 ppm due Hb2. COSY was used to established the pairing of Ha1 with Hb1, as well as Ha2 with Hb2, wherein the downfield shift of the Ha proton correlates with the upfield shift of the Hb proton (e.g., the peaks at 7.23 and 6.57 correlate) with a similar situation for the downfield pairs (e.g., the peaks at 7.46 and 6.85 ppm correlate). Compound 16 consists of a mixture of “H” and “A” conformers, in contrast to the almost exclusive formation of the “A” conformer for 14. For each conformer, a set of three regio- isomers can be formed and, thus, a total of six peaks, corresponding to the Hcore protons of the three regio-isomers of each conformer, are observed between 6.00 ppm and 6.50 ppm, as shown in Figure A 56 and Figure 4.18.

+ The protected sulfonated poly(phenylene), sPPP-NHEt3 ; as shown in Figure 4.19, was synthesized via the [4+2] D-A cycloaddition of co-monomers 9 and 13.

138

SO3X -O S 3 4 equiv. NH

- SO X SO3 3

O Micro-Wave + ArNO2, O 195°C n -O S 3 SO3X

- SO3 + SO3X X = HNEt3 + 9 13 sPPP-HNEt3 + Figure 4.19: Synthesis route of the sPPP-HNEt3

GPC analysis indicated a Mn of 186,000 Da and a poly-dispersity index (PDI) of 1 + 1.44, as shown in Figure A 101. H NMR analysis of sPPP-NHEt3 ; as shown in Figure + 4.20; revealed methyl groups of NHEt3 at 1.12 ppm (36 H), which were subsequently used as an internal reference for quantification of the remaining protons. The methylene protons (24 H) are represented as two overlapping quadruplets at 3.05 ppm and the ammonium protons (4 H) are found at 8.92 ppm. Signals for the protons of the polymer backbone are observed in the region between 5.90 ppm and 7.60 ppm. The integration + ratio between the methyl from the NHEt3 salt for one unit and the polymer backbone is observed to be 1:1, proving that the sulfonate group in the salt form remains intact during the D-A reaction. As with the model compounds, the polymer shows evidence for regio- isomers: signals for Hcore are found for the m-m (6.32 ppm), p-p (6.17 ppm) and m-p (5.98 ppm) isomers. Integration of these peaks yields an isomeric composition of 42%, 40% and 18%, respectively, as shown in Figure 4.20.

139 Hlink Ho Hp

Ha1 Hb2 HDA1 Hb1 Ha2 1 Hm Hcore

HDA1

HDA

3 H H 2 N N3 1 2 - - SO3 O3S

Hlink Ha1 Ha1

b b H 1 H 1 HDA

HDA Ho Hcore Ho Hb2 Hb2 Ha2 Hm Ha2

Hm Hp Hp -O S SO - 3 H H 3 N N

3 + sPPP-HNEt3

1 + Figure 4.20: H NMR (DMSO-d6) spectrum of sPPP-HNEt3

The effect of regio-isomerization is also observed for the HDA protons whereby they can be either para (HDA1) or meta (HDA2) to the central phenyl ring (i.e., Hcore) as shown in

Figure A 102, (between 7.60 and 7.45 ppm and the peak at 7.23 ppm). However, the HDA protons are observed as a broad peak in the vicinity of 7.23 ppm due to their low intensity as well as being partially obscured by Ha1 situated at 7.43 ppm (assigned by COSY analysis and from 14 and 16). Model compound 16 shows a signal for Ha1 at 7.43 ppm, according to a COSY analysis; as shown in Figure 4.18; but according to a COSY analysis + of sPPP-NHEt3 on the Figure A 103, the peak at 7.22 ppm does not correlate with any of the other peaks, hence the assignment of this signal to HDA of the polymer. Protons on the sulfonated phenyl rings meta and para to the core phenyl ring appear at 7.43 (Ha2) and

7.18 (Ha1) ppm which, by COSY analysis, are shown to correlate with 6.82 (Hb2) and 6.64

(Hb1) ppm, respectively. The protons on the unsulfonated, outer phenyl rings, namely Ho,

Hm and Hp, have signals at 7.34, 6.53 and 7.02 ppm respectively, as shown in Figure A 103.

140 + + Following conversion of sPPP-NHEt3 to sPPP-H ; as shown in Figure 4.13, films were cast from DMSO, as shown in Figure 4.21. The ion exchange capacity (IEC) was determined by acid-base titration to be 3.47 meq g-1, close to the theoretical value of 3.70 meq g-1. This is a very high IEC value for an aromatic polymer and yet the polymer was found to be insoluble and free-standing in water at room temperature, as shown in Figure 4.21; (water content, 85 wt%). For comparison, a previously reported, post-sulfonated polyphenylene, possessing an average of four sulfonic acid groups per repeat unit and an IEC of 2.2 meq g-1, formed a hydrogel in water.184 sPPP-H+ membranes dissolved when placed into Fenton’s reagent, see Section 4.4.14, but a subsequent 1H NMR analysis revealed no changes in chemical structure, suggesting an extraordinarily high oxidative stability; as shown in Figure A 104. However an interesting trend was observed based on the amount of water present after the oxidating test with the Fenton reagent; as shown in Figure A 105, when the polymer was dried, a water peak shows up at 7.47 ppm, after adding 10 mL of deionized water the water peak shift down to 5.92 ppm, with an extra 10 mL of DI water, the water peak shifted down to 4.56-3.97 ppm. This behaviour depend on the hydration of the sulfonic acids of the molecules, the first example is the APTS, the water peak is at 6.94 ppm in DMSO-d6; as shown in Figure A 106; and 8 the water shows up at 7.57 ppm, finally on 4 the water peak shows up at 3.86 ppm.

141

Figure 4.21: Photograph of sPPP-H+ immersed in deionized water at room temperature.

The proton conductivity of sPPP-H+; as shown in Figure 4.22; was studied at 30 ºC on water-saturated samples and partially hydrated (30 – 95% RH) membranes. As is commonly observed for aromatic membranes, proton conductivity increases as a function of RH from a low of 8.65 mS cm-1 at 40% RH to 106 mS cm-1 at 95% RH. In contrast to most aromatic membranes, however, sPPP-H+exhibits conductivity competitive to NR211 at low RH. The conductivity of sPPP-H+ is reduced when water-saturated (77 mS cm-1 vs. 106 mS cm-1 at 95% RH), which reflects the high water uptake of sPPP-H+ in contact with liquid water and a reduction of the analytical acid concentration, [-SO3H], 0.92 M for sPPP- H+ vs. 1.55 M for N211.67,217

142 120 NR211 sPPP-H+

100

) -1

(mS cm (mS

s 40

0 30 40 50 60 70 80 90 100 Relative Humidity (%)

Figure 4.22: Proton Conductivity of sPPP-H+ and Nafion® 211 at 30 °C as a function of RH (data for Nafion NR 211 taken from Peron et al.)

The preliminary studies of sPPP-H+ incorporated into cathode catalyst layers (CCL) of PEMFCs. A reasonable performance for aromatic ionomer was found for the sPPP-H+-based CCL (at 90 % RH) compared to those in which Nafion® D520 was used in the CCL; as shown in Figure A 107; (in both cases, N211 was used as the membrane). However, when the cathode inlet was reduced to 0% RH, not only does the sPPP-H+- based CCL perform better than at 90% RH, it outperforms Nafion®-based CCLs by a significant margin, e.g., a current density of 3000 mA cm-2 can be extracted for a sPPP- H+-based CCL whereas only 800 mA cm-2 can be achieved for Nafion®-based CCLs. Calculation of in-situ membrane conductivity (using Equation 4-4 and the iR drop in the Ohmic region) (Figure A 108) reveals that sPPP-H+ increases the in-situ conductivity of the membrane by 4-6 times.

143 A preliminary FC analysis of sPPP-H+ as membrane and ionomer (Figure A 109) indicates that sPPP-H+ gave a lower performance compared to N212, but this is due to its three times greater thickness, as an in-situ membrane conductivity calculation (Figure A 110) revealed that sPPP-H+ is six times higher than Nafion NR212 under the FC conditions operated. The results are unprecedented for an aromatic membrane, particularly for a fully aromatic-based MEA, in an operating fuel cell, and suggest that thinner sPPP-H+ membranes would provide competitive, if not greater, performance than Nafion®.

4.6. Conclusion

In summary, through the synthesis of a novel sulfonated diene, 9, well-defined, sulfonated oligophenylenes and a polyphenylene homopolymer were obtained. The stereochemistry of the phenyl-phenyl linkages formed was elucidated using model compounds to be a mixture of m-m, p-p and m-p in a ratio of 42:40:18 for the homopolymer. sPPP-H+ was found to be relatively stable to Fenton’s reagent. Membranes possessed a high IEC, yet remained water-insoluble, and exhibited high proton conductivity. Preliminary studies of fuel cells incorporating sPPP-H+ are highly encouraging. Investigation of copolymer derivatives, with a view to controlling polymer morphology, limiting water sorption, enhancing proton conductivity and strengthening the mechanical properties of thin films are therefore warranted and explored in the next chapter.

144 Chapter 5.

Sulfo-phenylated Terphenylene Copolymer Membranes and Ionomers

This chapter is an extension of Chapter 4 and focuses on the syntheses of structurally-defined copolymers of sulfo-phenylated polyphenylenes. Parts of this chapter was published in ChemSusChem: T.J.G. Skalski, M. Adamski, B. Britton, E.M. Schibli, T.J. Peckham, T. Weissbach, T. Moshisuki, S. Lyonnard, B.J. Frisken, S. Holdcroft, Sulfo- phenylated terphenylene copolymer membranes and ionomers, ChemSusChem, 2018, 11, 4033-4043, doi: 10.1002/cssc.201801965. My contributions to the chapter below include the entire synthetic sections and the molecular characterizations. Dr. Benjamin Britton performed fuel-cell test, Dr. T.J. Peckham provided synthetic insights, Michael Admaski provided insights into the characterization of materials and the mecahanical properties, Dr. Takashi Moshisuki performed provided characterization insights of the membrnes, Drs. Sandrine Lyonnard, Barbara Frisken, and Mr. Eric M. Schibli performed SAXS and SANS measurements, which are not included in this thesis.

5.1. Introduction

Acid-bearing polymers have been of high interest in recent decades due to their potency as ion conducting media in various electrochemical technologies, including the electrolysis of water, water purification, redox flow batteries, and hydrogen fuel cells.222,223 Since their conception in the 1960s, perfluorosulfonic acid (PFSA) ionomers such as Nafion have been the technological and commercial benchmark for ion-conducting polymers. Despite their popularity, these materials suffer from drawbacks, namely: their challenging syntheses and associated costs of production; environmental concerns associated with (per)fluorinated chemicals; and high reactant permeabilities, which may lead to system inefficiencies and failure.224,225,226 Numerous sulfonated polymers have been reported as strategies leading to alternatives to traditional PFSAs, with emphasis on those containing aromatic groups within the polymer main chain.227,211 Materials such as poly(arylene ethers),228,229 poly(arylene ether ketones),230,231,232 poly(arylene sulfones),232,19 and poly(phenylenes),230,233,55,234,235 have been investigated over recent decades.

145 Historically, acid-functionalization in these systems has been achieved through post-functionalization, typically by means of subjecting a polymeric substrate to aggressive sulfonating reagents with variable concentrations or reaction times.230 Although effective, post-functionalization strategies are synonymous with a lack of reproducibility, with limited control over the location of the hydrophilic functional groupon the resulting functionalized polymer, and non-integer degrees of functionalization.55,236,237 Synthesis of ion-conducting polymers utilizing pre-functionalized monomers has been demonstrated to offer a distinct structural advantage over their post-functionalized analogues in that the degree of functionalization and polymeric structure are precisely controllable.230,233,238,239,240

The presence of both hydrophilic and hydrophobic moieties on ion-conducting polymers drives phase segregation into respective domains,211,65,241,242 which facilitates the formation of ionic clusters and channels throughout the materials prepared therefrom. These nano and microscopic morphological features are critical to their properties as ion- conducting media.211,242,243,244,245 A highly prospective approach to emphasizing and exploiting phase behavior in ion-containing polymers is copolymerization, which has been frequently shown to be advantageous for membranes fabricated for electrochemical applications.22,23,240,246 A critical factor for such membranes is the total ion content, or ion exchange capacity (IEC).24 There exists an intimate structure-morphology-property relationship between the IEC, water sorption, connectivity of hydrophilic channels, degree of dissociation of acidic groups, and ultimately, ion conductivity of the membrane.211,247,248 Development of new polymers and related materials with focus on enhancing these aspects in unison are likely to enhance the properties of proton exchange membranes (PEM) to unprecedented levels of performance over current standards.

In the context of electrochemical technologies, equally important to the transport properties of materials is durability and longevity. The incorporation of ion-containing polymers in fuel cells, for example, is considered a particularly harsh application due to the exposure to reactive free radicals at elevated temperatures. The examination of ion- containing polymers in the context of fuel cells (FC) is therefore particularly useful for assessing their chemical stability in addition to being technologically relevant, as these applications are the most demanding on the ion-conducting polymeric medium. Here, chemical stability is typically assessed ex-situ via a Fenton’s reagent test, and in-situ via PEM FC open circuit voltage (OCV) accelerated stress tests (AST).249,250,251

146 With PEMFC technology entering a growth in commercialization, there is significant interest in the design of ion-conducting polymers with improved stabilities,234,252,253,254,255the most promising of which is based on the use of polyarylene backbones devoid of labile linkages, such as poly(phenylene)s.256,257 Functionalized polymers comprised entirely of para-phenylene linkages have been reported by several groups, dating back to Litt’s original polyphenylene sulfonic acid.258 However, the degree of polymerization achievable in such systems appears to be limited, yielding materials with poor mechanical properties and solubility characteristics, preventing critical research in both ex-situ and in-situ characterizations.234,259 An alternative synthetic route to poly(phenylene)s involving two monomers free of additional reagents or catalysts, which may circumvent the molecular weight limitations of polycondensations of dihalogenated aromatics,234 is the [4+2] Diels-Alder cycloaddition.257,260,261 Non-functionalized, phenylated poly(phenylene)s (PPP) prepared by this route possess excellent thermal stability46 up to 550 °C in air and 575 °C under nitrogen atmosphere.256 Typical yields reported are near-quantitative, reinforcing the efficacy and potential industrial feasibility of the synthetic approach.256 The functionalized analogue, sulfonated phenylated poly(phenylene) (sPPP), was first prepared through post-functionalization by Stille et al.49 to enhance the solubility of the highly insoluble PPP, and more recently, by the Sandia National Laboratory group for the purpose of preparing PEMs.55 The latter group demonstrated that post-functionalized sPPPs afford tough membranes possessing considerable electrochemical properties, and the group has made significant contributions towards total polymer morphological characterization.262,263,235,59 Due to the high stability of the backbone, simple synthesis, and promising initial PEM properties, sPPP became a topic of interest.235,262,263,59

Unfortunately, despite promising initial reports, according to published literature the overall synthetic strategy employed possessed several limitations. First, polymerization of the PPP backbone has yielded a wide range of molecular weights (Mw = 12,300 - 172,000 Da) with dispersities (Đ) ranging from 1.9 - 4.0.55,256,54 Second, despite reporting a synthetic approach that allowed for tuning polymer IEC, the random and irreproducible nature of post-sulfonation gave irregular functionalizations on the polymer backbone, in the range of 0.8-2.1 sulfonic acid groups per repeat unit. These irregularities made it difficult to providedefinitive structural characterization. Structural regularity is

147 important in obtaining well-defined, reproducible polymers, as this has been linked to membranes with improved properties.234,264,265

Recently, the synthesis of a pre-functionalized, tetra-sulfonated oligophenylene monomer based on the original bistetracyclone (BTC) was reported,266 which was used to prepare a series of functionalized sPPPs homopolymers and oligomers with precisely defined molecular structure.233,238 Additionally, through modifying the dienophile monomer, homopolymers with different hydrophobic segments were synthesized to control the IEC, lower their water uptake and swelling, and to tune proton conductivity. In this chapter, a copolymer-based approach, as shown in Figure 5.1, to control and tune the properties is reported.

SO3X sPPP(m)-H+

SO3X

m SO3X

X = H+ SO3X m = 1-n Figure 5.1: Preparation of sPPP(m)-H+ copolymers with tunable IECs through introduction of a hydrophobic monomer.

148 5.2. Experimental

2-A 2 equiv. O

O I O 2 + 2 equiv. O (i) (ii) (iii) I O O

1 O

3 4 5 6

SO Y 3 (iv) SO Y 2 equiv. TMS 3 7 TMS O 9 (v) O

(i) (vi) YO3S 8

YO3S TMS

7 Y = HNEt3 10 11 8 Y = H 2-B

-O S H 3 H N O N O

- SO3

+ m equiv. + x equiv. + m + x equiv. sPPP(m)-HNEt3 vii (viii) H -O S H N 3 N (ix) 11 O 8 O - SO3 sPPP(m)-H+

8 6 Figure 5.2: The synthetic pathways for the syntheses of (a) monomers, and (b) the sPPP(m)-y copolymers. (i) Pd(PPh3)2Cl2, CuI, HNEt2, 56°C, 6 h; (ii) I2, DMSO, 150°C, 8 h; (iii) KOH, EtOH, 80 °C, 3 h; (iv) TMSO-SO2-Cl, DCE, RT, 8 h; (v) NEt3, n-BuOH, 4 h; (vi) K2CO3, Et2O/MeOH (3/1), RT, 6 h; (vii) nitrobenzene, 195-220 °C, 120 h; (viii) NaOH, MeOH, 4 h, RT; (ix) 2.00 M H2SO4(aq), 4h, RT.

The overall synthetic routes for the reported monomers and resulting polymers are outlined in Figure 5.2. The syntheses of compounds 3 and 4 are detailed in Section 4.4, whereas the syntheses of compounds 6, 7, 8, 10, 11 have been reported in Chapter 3. Sonogashira cross-coupling reactions (syntheses of compounds 3 and 10) were

149 conducted using standard Schlenk manifold techniques. Protodesilylation (compound 11) and sulfonation (compound 7) were performed under argon atmosphere.

5.2.1. Methods and Equipment

1H, 13C, COSY NMR spectra were recorded on a Bruker AVANCE III 500MHz equipped with a 5mm TXI Inverse probe at room temperature (T = 298 K). The following terms are defined: s for singlet, d for doublet, t for triplet, q for quadruplet and m for multiplet. Chemical shifts are reported in ppm and J-couplings are reported in Hz. Residual proton and carbon peaks for deuterated solvents were set at, respectively, 2.05 ppm and

29.84 ppm for the acetone-d6, 2.50 ppm and 39.52 ppm for the DMSO-d6, and 5.32 ppm and 54.00 ppm for CD2CL2

Mass spectra were recorded on an AB Sciex 4000 Q TRAP spectrometer and a Bruker micrOTOF in both positive and negative electrospray ionization (ESI) modes for ionic compounds. High accuracy mass measurements were obtained on a LC-TOF instrument from Agilent Technologies in positive APPI mode. Molecular ions [M]+ or protonated molecular ions [M+H]+ were used for empirical formula confirmation, and were performed at the Centre Régional de Spectrometry de Masse de l’Université de Montréal.

Size-exclusion chromatography analyses were obtained using a Water HPLC HR5 system with HR4 and HR3 columns using HPLC-grade dimethylformamide (DMF) containing 0.01 M LiBr as eluent. Polystyrene standards, purchased from Water Associates Inc. and Sigma Aldrich Canada Co., were used for instrument calibration with an elute rate of 1mL min-1, internal column set at 80 °C and refractive index detector at 50 °C.

Deionized water (DI water) was purified to 18.2 MΩ· cm at 25 °C using a Millipore Gradient Milli-Q® water purification system.

Membranes were cast using a K202 Control Coater casting table and an adjustable doctor blade (RK PrintCoat Instruments Ltd.) A film of a given polymer solution with a thickness typically between 0.30 – 0.40 mm was spread onto a levelled glass plate. The polymer film was then dried in an oven at 85 °C for 24 h, peeled off the glass plate, soaked in 2 M H2SO4 for 1 h, deionized water for 24 h, and dried between two glass plates under

150 vacuum at 80 °C for 24 h. The obtained membranes typically measured thicknesses between 30 –60 μm.

Titrations were obtained using a Metrohm 848 Titrino plus equipped with a Metrohm 801 Stirrer stir plate and a Metrohm 6.0262.100 pH meter probe.

Impedance measurements were carried out using a Solartron Impedance SI 1260 impedance gain-phase analyzer using Zview and Zplot software. Humidification and temperature were controlled using two ESPEC SH-241 Temperature & Humidity Chambers.

Infrared spectra were recorded on a Perkin Elmer UATR FT IR spectrometer. Membrane samples were keep dry under argon, and folded to obtain an average thickness of 300±50 μm to allow for adequate signal/noise response.

5.2.2. Materials

Triethylamine (NEt3, 99%), activated charcoal (G-60), Hydrochloric acid (HCl, ACS reagent, 36.5-38% content) were purchased from Anachemia Science. 1,4-diodobenzene (98%), phenylacetylene (98%) were purchased from Combi-Blocks Inc., and use without purification. Acetone (Certified ACS), dichloromethane (DCM, Certified ACS stabilized), diethylamine (97%), methanol (MeOH, reagent grade), pentane (reagent grade), ethyl acetate (Certified ACS), silica gel (S825-1, 230-400 mesh, grade 60), neutral alumina (60-

325 mesh, Brockman Activity I), anhydrous magnesium sulfate (MgSO4, Certified Powder), and Celite™ (545 Filter aid, not Acid-washed powder) were purchased from

Fisher Scientific. Nitrobenzene (PhNO2, 98%, reagent plus), diethylamine (ReagentPlus®, 98%), dimethyformamide (DMF, Chromatosolv® HPCL grade), trimethylsilylchlorosulfonate (TMSO-SO2-Cl, 99%), lithium bromide (LiBr, ReagentPlus®, >99%) were purchased from Sigma-Aldrich Canada Co. While diethylamine and nitrobenzene were degassed with argon before each use, all other compounds were used without any further purification. Ethanol (EtOH, 99%) was purchased from Commercial Alcohols. Trimethylsilylacetylene (lot number 003013I12J) was purchased from Oakwood.

Diethyl ether anhydrous (Et2O, ACS reagent), sodium chloride (NaCl, ACS reagent), potassium carbonate anhydrous (K2CO3, ACS grade), sodium thiosulfate anhydrous

(Na₂S₂O₃,reagent grade) were purchased from ACF Montreal. Chloroform (CHCl3, ACS

151 grade), dimethylsulfoxide (DMSO, ACS grade), sodium hydroxide (NaOH, ACS grade) and iodine (I2, analytical reagent) were bought from BDH. Petroleum ether (reagent grade), n-butanol (n-BuOH, reagent grade), potassium hydroxide (KOH, reagent grade, min 85%), Sulfuric acid (H2SO4, reagent grade, 95-98%), potassium permanganate

(KMnO4, reagent ACS, min 99%), potassium carbonate anhydrous (K2CO3, Reagent ACS, min 99%) and sodium sulphite anhydrous (Na2SO3, reagent chemical grade, meets ACS specifications), tetrahydrofuran (THF, ACS grade) were purchased from Caledon Laboratory Chemical. 1,3-Diphenylacetone (ACS reagent, 98%) was purchased from Tokyo Chemical Industry Co., Ltd. Argon (PP 4.8) was purchased from Praxair.

Diphenylphosphine palladium dichloride (Pd(P(phi)3)2Cl2, 97%) and copper(I) iodide

(>99.9%) were purchased from Strem Chemicals. Dimethylsulfoxide-d6 (D, 99.9%), acetone-d6 (D, 99.9%), methylene chloride-d2 (D, 99.8%, CD2Cl2) were purchased from Cambridge Isotope Laboratories, Inc.

5.2.3. Syntheses

Compounds 3 and 4 were synthesis according to the methods reported in Sections 3.3.2 and 3.3.3. Compounds 6, 7, 8, 10, and 11 were synthesized according to previous work.233 Compound 11 was purified by sublimation yielding purple crystals, which were stored under argon in an amber jar at -20°C. Periodic analyses via 1H NMR found no degradation using these storage conditions.

5.2.4. General Procedure for the Syntheses of sPPP(m)-H+

+ The general synthetic route for sPPP(m)-HNEt3 is shown in Figure 5.2-B. + Optimization of polymerization conditions was study using sPPP(0.8)-HNEt3 . The effects of temperature, time, solvent concentration, and dienophile/diene ratio on polymer yield and molecular weight were investigated. Polymers were analyzed with size exclusion chromatography (SEC) in dimethylformamide (DMF).

To a 250 mL Schlenk flask containing a stir bar, monomers 6 (0.217 g, 0.314 mmol, 0.1 equiv.) and 8 (4.00g, 2.83 mmol, 0.9 equiv.) were added, followed by nitrobenzene (44 mL). The solution was gently stirred at room temperature while being degassed with argon

152 for 30 minutes. Freshly sublimated 1,4-diethynylbenzene 11 (0.402 g, 3.19 mmol, 1.02 equiv.) was added, and the reaction mixture was further stirred at room temperature for 30 min, followed by insertion of the reaction vessel into a sand bath pre-set to 220 °C, with medium stirring, for 120 h. After cooling, the solution was poured into boiling ethyl acetate (400 mL) and refluxed for 4 h. The solution was filtered without cooling, and the collected polymer precipitate washed with boiling ethyl acetate (3 x 100 mL). The obtained brown powder was dissolved in methanol (15 mL) and poured into ethyl acetate (500 mL). The resulting precipitate was collected by filtration and dried under vacuum at 120°C overnight, + to give sPPP(0.9)-HNEt3 as an off-white, fibrous solid product. Yield: 4.17 g (84.7%). Obtained polymers were characterized by 1H NMR spectroscopy and SEC in DMF prior to further use.

+ Figure 5.3: Copolymer sPPP(0.9)-HNEt3 obtained after workup.

The procedure for cation exchange from triethylammonium salt to acid form has 233 - + been outlined in previous works. The triethylammonium salt (-SO3 HNEt3 ) was removed first by soaking the polymer in a basic methanolic solution (NaOH in MeOH), - + resulting in conversion of the polymer to an alkaline form (-SO3 Na ). The polymer was - + then subject to an aqueous acid wash, converting it to its acidic form (-SO3 H ). Following this conversion, the polymer was again characterized using 1H NMR and SEC in DMF.

Membrane Preparation and Characterization The acidic form of the polymer, sPPP(m)-H+, were cast from 7% w/w solutions in DMSO. After complete dissolution of the polymer, each solution was thoroughly filtered

153 through a borosilicate glass filtration Buchner funnel with sintered disc (coarse frit) via vacuum filtration, and the resulting polymer solution coated onto a glass plate using an adjustable doctor blade. After heating in an oven at 86 °C for 8 h to evaporate the DMSO, the glass plate was removed and cooled to ambient conditions. The resulting membrane was released from the glass plate by immersion in dilute acid, rinsed thoroughly with deionized water, and dried overnight at 80 °C under vacuum. Membranes were obtained with an average thickness of 45μm, from which samples were then cut for further characterization.

Mechanical Properties Mechanical properties, such as tensile strength, Young’s modulus, and elongation at break, are typically assessed by a standardized tensile test.267 These parameters are essential in evaluating a membrane material’s overall physical robustness and durability, especially to elastic deformation.267 Barbell-shaped membrane samples were cut using a standard ASTM D638 type IV specimen cutting die from polymer membranes equilibrated at ambient conditions for minimum 24 h. Mechanical strength measurements were obtained on an Instron 3344 Series single column system, with a set operational crosshead speed of 5 mm min-1. Each value represents an average of at minimum three sample measurements. Error is reported as the standard deviation.

Dimensional Stability, Ion Exchange Capacity, and Water Sorption Previously published methodologies268 were used to determine polymer water sorption characteristics, including water uptake, water content, dimensional stability (volumetric expansion, or volume uptake), ion exchange capacity (IEC), number of water molecules per sulfonic group (λ, mol H2O per mol of –SO3H), membrane analytical acid concentration [SO3H], and effective proton mobility (μeff).

Membrane Stability Oxidative stability of the polymers was examined by subjecting membrane samples to Fenton’s reagent test. The metal-catalyzed disproportionation of H2O2 provides an effective means of generating oxygen-containing free radical species in solution, serving as common ex-situ accelerated degradation testing for PEMs. Membrane samples 2+ were exposed to Fenton’s reagent (80 °C, 3% H2O2, 3 ppm Fe ) and removed periodically for analysis, until no membrane visibly remained.

154 Proton Conductivity (σ) In-plane proton conductivity was measured by AC impedance spectroscopy using conductivity cells assembled from membrane samples with a two-electrode configuration, according to a procedure described elsewhere.269 Measurements were performed inside a humidity chamber held at 30 or 80 °C at variable relative humidites (RH): 95%, 90%, 70%, 50 %, and 30% RH. Resistance data were plotted as a Nyquist plot, which was fit to a Randles equivalent electrical circuit to calculate a value for membrane ionic resistance, from which proton conductivity (σ) was calculated.

Fuel Cell Characterization Membrane-electrode assemblies (MEAs) incorporating sPPP(m)-H+ polymers were formed, integrated into fuel cell systems, and characterized in situ as described in section 2.4.9. Polymers sPPP(0.6)-H+, sPPP(0.8)-H+, or sPPP(1.0)-H+ were incorporated into these systems as both ionomer in the catalyst layers (20 wt% ionomer of solids to a total loading of 0.4 mg Pt·cm-2) and membrane, yielding an assessment of each sPPP(0.6)-H+, sPPP(0.8)-H+, and sPPP(1.0)-H+ as fully hydrocarbon solid polymer electrolyte fuel cells. These were compared to a wholly PFSA reference MEA comprised of Nafion D520 in the catalyst layers (30 wt% ionomer of solids to a total loading of 0.4 mg Pt·cm-2) and Nafion 212 membrane.

Electrochemical characterization was performed using a combined potentiostat/frequency-response analyzer (Princeton Applied Research VersaSTAT 4) after equilibration of the fuel cell to a stable low potential < 0.15 V under fully humidified

0.25/0.5 slpm H2/N2 anode/cathode gas feeds. Chronoamperometry was performed at 100 mV·step-1 from 0 to 600 mV at 30 s·step-1, and linear sweep voltammetry at 2 mV·s-1from OCV to 600 mV for the measurement of fuel crossover and detection of shorting, respectively. Cathode ionomer conductivity was measured via electrochemical impedance spectroscopy. Using an inert (0 slpm) N2 feed, cyclic voltammetry was performed from 0.05 to 0.8 V up to 20 cycles or measurement destabilization for the measurement of electrocatalytically active surface area. Electrochemical data was processed as described 218 previously. After disassembly, MEAs were freeze-fractured with liquid N2 and membrane and electrode thicknesses measured by scanning electron microscopy (FEI/Aspex Explorer).

155 5.3. Results and discussion

5.3.1. Synthesis, Casting and Characterizations

+ Five random copolymers sPPP(m)-HNEt3 and one homopolymer sPPP(1.0)- + + HNEt3 were prepared from the pre-sulfonated diene monomer sBTC(HNEt3 ) (8), its unsulfonated diene analogue BTC (6), and dienophile 1,4-diethynylbenzne (11). This study investigated the properties of these polymers, from sPPP(1.0), to the copolymer sPPP(0.5) which contains 50% of each pre-sulfonated and unsulfonated monomers. Optimum polymerization conditions were found to be 120 h reaction time in nitrobenzene solvent at a monomer concentration of 96 g/L and temperature of 220 °C. Numerous other solvents, namely DMSO, DMF, NMP, DMAc and sulfolane, were found to be ineffective at yielding polymers with sufficient molecular weights. The same synthetic strategy was employed for each copolymer synthesized. The yield was found to decrease with increasing hydrophobic content, which could be attributed to poorer solubility of the hydrophobic backbone in nitrobenzene. Polymer purity was assessed via 1H NMR using + the triethylammonium cations on sPPP(m)-HNEt3 as internal probes, Figure 5.4.

156

1 + Figure 5.4: H NMR (DMSO-d6) of the six copolymers sPPP(m)-HNEt3 .

Terminal ethynyl functional groups were observed (singlet at 4.12 ppm), which were used to estimate molecular weight. Triethylammonium cations were removed via a two-step process involving exchange to sodium form sPPP(m)-Na+ by immersion in methanolic sodium hydroxide solution, followed by immersion in an aqueous sulfuric acid solution, yielding the respective acidic forms sPPP(m)-H+. After drying under vacuum at 120 °C to remove the residual water, see Figure 5.5, polymer molecular weights were investigated.

157

1 + Figure 5.5: H NMR (DMSO-d6) of the six ionic copolymers sPPP(m)-H , and sPPP(0.0).

Both triethylammonium and acid forms were characterized using size-exclusion chromatography (SEC) in DMF containing LiBr (0.01 mol L-1). The average molecular weights are reported in Table 11.

+ Table 11: Yield and Molecular Weights (in Daltons) of (a) sPPP(m)-HNEt3 , and (b) sPPP(m)-H+, as Determined by SEC in DMF.

Polymer Yield (%) Mw(a) PDI(a) Yield (%) Mw(b) PDI(b) sPPP(1.0) 89.1 363.000 1.86 92.1 290.900 1.90 sPPP(0.9) 81.1 347.000 2.41 89.2 221.100 1.83 sPPP(0.8) 89.0 240.000 1.96 99 225.000 2.01 sPPP(0.7) 79.1 267.000 2.63 99 176.000 2.43 sPPP(0.6) 85.6 217.000 2.75 93.2 103.550 3.50 sPPP(0.5) 83.2 198.000 3.43 92.8 161.400 2.87 PPP 67.2 77.600 2.57 N/A N/A N/A

158 + These data show that the molecular weights of sPPP(m)-HNEt3 decrease with increasing hydrophobic character. This observation suggests that polymer solubility in the nitrobenzene solvent system may be a limiting factor with increasing hydrophobic character. To further probe this hypothesis, the fully hydrophobic PPP was synthesized from BTC (6) and 1,4-diethynylbenzene (11), which resulted in material with aweight average molecular weight (Mw) of only 77,600 Da. The molecular weights of functionalized polymers decreased after conversion from triethylammonium to acid form for each polymer, supporting a successful exchange to a repeat unit of lower molecular weight (removal of four triethylamine molecules per repeat unit). Figure A 112 shows the theoretical calculation and the approximation to obtained the molecular weight of the polymer based on the 1H NMR spectrum. This approximation is possible due to the small excess of compound 11 used during the polymerizations. The hypothesis is that each chain terminating group is an alkyne moiety, and not a cyclopentadienone, allowing for a comparison of integration ratios between internal aromatic protons and external terminating alkyne protons.

The membranes were analyzed using FTIR, kept under dry argon, and folded to obtain an average thickness of 300±50 μm to allow for adequate signal/noise response over 48 scans on Figure A 111.

Acidic form of the polymer, sPPP(m)-H+, were cast into membranes using aforementioned techniques, and their membrane properties were investigated. Mechanical strength measurement data show that all sPPP(m)-H+ membranes possess similar tensile strength (43.8 ± 5.1 MPa) and Young's modulus (1228 ± 191 MPa), larger than that of Nafion NR-211 (17.3 ± 0.4 MPa and 270 ± 17 MPa, respectively), but display lower elongation at break values as shown Table 12 and Figure 5.6. Polymer membranes were cut into a barbell-shaped samples using a standard ASTM D638 type IV specimen- cutting die. The mechanical properties were measured on an Instron 3344 Series single column system, operating with a crosshead speed 5mm min-1. All measurements were performed under ambient temperature and humidity. The tensile strength, Young’s modulus, and elongation at break data reported all represent the average of at least three sample measurements per polymer.270

159 Table 12: Mechanical Properties of sPPP(m)-H+ Copolymers under Ambient Conditions Compared to Nafion NR-211.

sPPP(1.0)238 sPPP(0.9) sPPP(0.8) sPPP(0.7) sPPP(0.6) sPPP(0.5) NR-211238 Tensile 43.5 ± 39.6 ± 41.8 ± 42.9 ± 51.3 ± 43.4 ± 17.3 ± Strength (MPa) 1.9 3.1 1.1 2.4 3.8 3.7 0.4 Elongation at 29.1 ± 29.2 ± 26.5 ± 31.7 ± 18.6 ± 15.9 ± 148.3 ± Break (%) 1.4 2.7 3.3 6.2 1.8 3.9 3.6 Young's 1059 ± 1008 ± 1407 ± 1281 ± 1393 ± 1220 ± 270 ± 17 Modulus (MPa) 34 53 195 111 11 89

The data obtained from these measurements suggest that the rigid-rod polyphenylene backbone employed provides significant mechanical strength and resistance to elastic deformation,271 properties integral to robustness and longevity in electrochemical device manufacture and operation.250 Ionic content does not appear to significantly affect material mechanical properties. The findings presented herein are consistent with previously published mechanical properties of post-sulfonated phenylated polyphenylenes,55 as well as pre-sulfonated derivatives.238 a) b) 60 60 sPPP(1.0)(H+) sPPP(0.9)(H+) 50 50 sPPP(0.8)(H+) sPPP(0.7)(H+) 40 sPPP(0.6)(H+) 40 sPPP(0.5)(H+) NR-211 30 30 sPPP(1.0)(H+) Strain (MPa) Strain (MPa) Strain 20 20 sPPP(0.9)(H+) sPPP(0.8)(H+) sPPP(0.7)(H+) 10 10 sPPP(0.6)(H+) sPPP(0.5)(H+) 0 0 0% 50% Strain 100% 150% 0% 10% 20%Strain30% 40% 50%

Figure 5.6: a) Representative stress-strain curves of sPPP(m)-H+ membranes, compared to that of NR-211; b) zoom on the sPPP(m)-H+.

The thermogravimetric analysis (TGA) was performed at a 1.0 °C per minute ramp rate from room temperature to 600 °C. The initial sample weight represents a previously dried sample (under vacuum at 80 °C overnight). Each sample mass used for analysis was between 5.0 – 8.0 mg. Data Figure 5.7 show remarkable consistency between

160 polymer samples characterized and are consistent with previously reported observations for both post-sulfonated phenylated polyphenylenes,55 as well as pre-sulfonated counterparts.238 Thermogravimetric Analysis of the sPPP(m)(H+) under Nitrogen 100

sPPP(1.0)(H+) Normalized Weight Loss (%) Loss Weight Normalized 20 sPPP(0.9)(H+) sPPP(0.8)(H+) sPPP(0.7)(H+) sPPP(0.6)(H+) sPPP(0.5)(H+) 0 0 100 200 300 400 500 600 Temperature (°C)

Figure 5.7: Thermograms of sPPP(m)-H+copolymers at 1.0°C per minute under nitrogen.

Theoretical (IECth) and experimental (IECxp) ion exchange capacity values, calculated and determined by titration experiments, respectively, are shown in Figure A + - 112 and Figure A 113. They follow a linear trend from sPPP(0.5)-H (IECth = 2.17 meq. g 1 + -1 ) to the homopolymer sPPP(1.0)-H (IECth = 3.70 meq. g ). The experimental IECs were calculated using Figure A 113 and the Table A 4. The obtained IEC values closely matched their theoretical counterparts, as previously observed.233,238 These data provide insight to polymer tunability according to the ratios of hydrophilic and hydrophobic monomers used. The water uptake (WU%), water content (WC%), volume uptake (VU%), water sorption -1 (λ, number of protons per sulfonic acid: mol H2O · mol SO3H), acid concentration ([- -3 SO3H]), and material densities (g cm ) of each polymer membrane are summarized in Table 13. High hydrophilic content polymers sPPP(1.0)-H+ – sPPP(0.9)-H+ showed excessive swelling and eventual dissolution in water at 80 °C, but remained intact at room temperature. sPPP(0.8)-H+ – sPPP(0.5)-H+ were fully insoluble, as shows Table A 5.

161 4.0

3.5

3.0

2.5

2.0

1.5 Theoretical IEC sPPP(1.0)(H+) sPPP(0.9)(H+) 1.0 sPPP(0.8)(H+) sPPP(0.7)(H+)

Ion Exchange Capacity (mEquiv./g) Capacity Exchange Ion sPPP(0.6)(H+) 0.5 sPPP(0.5)(H+)

0.0 0.0 0.2 0.4 0.6 0.8 1.0 Hydrophilic Molar Composition of the sPPP(m)(H+)

Figure 5.8: Theoretical and experimental ion exchange capacity (IEC) values for sPPP(m)-H+ polymers.

sPPP(1.0)-H+ showed the largest water and volume uptakes, which declined significantly with increasing hydrophobic character. Similarly, polymer water contents show a gradual decline with increasing hydrophobic character from sPPP(1.0)-H+ to sPPP(0.5)-H+, and are reported in Table 13. The number of water molecules per sulfonic acid was highest in sPPP(1.0)-H+, which consequently possessed one of the lowest acid concentrations.

Table 13: Properties of sPPP(m)-H+ Membranes.

-3 Polymer WU (%) WC (%) VU (%) λ [-SO3H] Density(g cm ) sPPP(1.0)(H+) 319.3 76.1 364.3 50.7 0.85 1.17 sPPP(0.9)(H+) 278.3 73.6 348.8 47.2 0.84 1.16 sPPP(0.8)(H+) 191.7 65.7 200.0 37.0 1.10 1.15 sPPP(0.7)(H+) 125.4 55.6 141.9 25.0 1.34 1.11 sPPP(0.6)(H+) 90.5 47.5 93.9 20.2 1.35 1.09 sPPP(0.5)(H+) 65.1 40.3 67.7 19.4 1.51 1.06

162 In-plane ionic conductivity measurements were conducted at 30 and 80 °C between 30% and 95% RH. Data are summarized in Figure 5.9 and Table A 6 and Table A 7 a) b) 120 sPPP(1.0)(H+) 0.1 sPPP(0.9)(H+) 100 sPPP(0.8)(H+) 80 sPPP(0.7)(H+) sPPP(0.6)(H+) 0.01 ) ) 1 1 - - 60 sPPP(0.5)(H+) Nafion 211

40 cm (S σ

σ (mS cm (mS σ 0.001

0 0.0001 30 50 70 90 30 50 70 90 Relative Humidity (%) Relative Humidity (%) c) d) 350 sPPP(1.0)(H+) 300 sPPP(0.9)(H+) sPPP(0.8)(H+) 250 0.1 sPPP(0.7)(H+) sPPP(0.6)(H+) ) 200 ) 1 1 - sPPP(0.5)(H+) - 150 Nafion 211 0.01 σ (S cm (S σ

σ (mS cm (mS σ 100

0 0.001 30 50 70 90 30 50 70 90 Relative Humidity (%) Relative Humidity (%)

Figure 5.9: Proton conductivities of sPPP(m)-H+ and Nafion NRE 211, a) at 30 °C and variable RH and; b) the respective log plot; c) at 80 °C and variable RH and; (b) the respective log plot.

There is a clear trend with increasing hydrophobic character and decreasing proton conductivities in the polymers examined. At 30 °C and 95% RH, sPPP(1.0)-H+ displayed a noteworthy conductivity (120 mS cm-1) compared to Nafion 211 (79 mS cm-1). The conductivity of the highly hydrophobic sPPP(0.5)-H+ (0.5 mS cm-1) was significantly lower under identical conditions. At 80 °C and 95% RH, sPPP(1.0)-H+ showed excellent conductivity (338 mS cm-1), and polymers with increasing hydrophobic character up to sPPP(0.6)-H+ (133 mS cm-1) were higher in conductivity than Nafion 211 (113 mS cm-1).

163 These data, along with the trends observed in polymer water sorption, suggest that introducing hydrophobic co-monomers into the pre-functionalized proton conducting polymers is an effective means of tuning both their physicochemical and electrochemical properties.

5.3.2. Membrane Stability

To demonstrate the resilience of a wholly aromatic polymer backbone, a polymer oxidative stability test was conducted by subjecting membrane samples to Fenton’s reagent. In the case of sPPP(1.0)-H+ and sPPP(0.9)-H+, membrane samples dissolved prior to completion of the analysis, likely due to their high hydrophilic ratios, as previously reported.233 In these instances, however, it was possible to quench the Fenton’s reagent solutions using excess sodium sulfite, which resulted in precipitation of the dissolved polymers from solution and allowed for collection of material for subsequent analysis. After 1 h exposure, all sPPP(m)-H+ membrane samples were visually intact, displayed no observable mass loss, Figure 5.10, and were chemically unchanged when assessed by 1H NMR, Figure A 114 to Figure A 119. After 3 h total exposure time, sample dissolution hindered our ability to accurately determine residual mass for sPPP(1.0)-H+ and sPPP(0.9)-H+ samples, but recovered material further showed no changes to chemical structure when assessed by 1H NMR. The residual masses of membrane samples (excluding precipitated materials) are summarized Figure 5.10.

100% sPPP(1.0)(H+) sPPP(0.9)(H+) sPPP(0.8)(H+) 80% sPPP(0.7)(H+) sPPP(0.6)(H+) 60% sPPP(0.5)(H+)

40% Weight Remaining Weight

20%

0% 0 1 2 3 4 5 6 7 Time (h) Figure 5.10: Residual masses of sPPP(m)-H+ copolymers following immersion in Fenton’s reagent.

164 These data reflect the high oxidative stability of a polyphenylene backbone, and expand on previously published results for these types of systems.233,238,272 In stark contrast, a recently reported class of highly phenylated, post-sulfonated poly(arylene ether)s with similar IECs retained as little as 80% of initial sample masses, or dissolved entirely, after just 1 h under these conditions.273

5.3.3. Analyses in Fuel Cells

Fully hydrocarbon sPPP-based membrane-electrode assemblies (MEAs) and fuel cells were formed and characterized by Dr. B. Britton using sPPP(0.6)-H+,sPPP(0.8)- H+,and sPPP(1.0)-H+ but are included for the sake of continuity of the thesis. sPPP-based membranes exhibited very high in situ ionic conductivity, Figure 5.11-a: for sPPP(0.6)- H+,sPPP(0.8)-H+,and sPPP(1.0)-H+ in situ conductivities at 80 °C, 100% RH were measured to be 74±2, 244±28, and 256±34 mS·cm-1, respectively, compared to 81±1 mS·cm-1 for Nafion 212. These values correspond well to conductivities measured ex situ at 95±5% RH (see Figure 5.9), previous reports,233 and similar materials.238

+ + + H2 fuel crossover currents for sPPP(0.6)-H ,sPPP(0.8)-H ,and sPPP(1.0)-H were very low: 0.41±0.02, 0.57±0.01, and 0.16±0.03 mA·cm-2, respectively, compared to the 3.73±0.06 mA·cm-2 measured for the PFSA reference. Thus, fully hydrocarbon sPPP-type fuel cells exhibited only 4-15% of the fuel (H2) crossover of the PFSA reference membrane of similar thicknesses, as per Figure 5.11-b.

165 a) b) 4.0

300 ) ) 2 - 1 - 3.5

cm 250 · 3.0 200 2.5 150 2.0 1.5 100 1.0 Conductivity (mS Conductivity

50 (mA·cm Fuel Crossover

2 0.5 H

In SituIn 0 0.0 N212 sPPP-60 sPPP-80 sPPP-100 N212 sPPP(0.6) sPPP(0.8) sPPP(1.0) 50 µm 56 µm 37 µm 49 µm

Figure 5.11: Membrane data for sPPP-based systems compared to a PFSA reference for a) membrane conductivity from in situ data (iR drop method) and b) hydrogen fuel crossover data determined by chronoamperometry.

Polarization data were collected with cathode gas feeds of oxygen, Figure 5.12-a, and air, Figure 5.12-b. For sPPP(0.6)-H+,sPPP(0.8)-H+,and sPPP(1.0)-H+, peak power densities in PFSA-optimized conditions in oxygen were 500, 770, and 418 mW·cm-2, respectively, compared to 792 mW·cm-2 for the PFSA reference (Figure 5.13-b); in air, 244, 456, and 256 mW·cm-2, respectively, compared to 455 mW·cm-2 for the PFSA reference (Figure 5.13-c).

166 a) b)

1.0 N212 50 µm 1.0 N212 50 µm sPPP(1.0) 48 µm sPPP(1.0) 48 µm sPPP(0.8) 37 µm sPPP(0.8) 37 µm 0.8 sPPP(0.6) 56 µm 0.8 sPPP(0.6) 56 µm

0.6 0.6

0.4 0.4

Potential, E (|V|)E Potential, (|V|)E Potential, 0.2 0.2

0.0 0.0 0 500 1000 1500 2000 2500 0 500 1000 1500 -2 -2 Current Density, j (mA·cm ) Current Density, j (mA·cm ) Figure 5.12: PPP(1.0)-H+, sPPP-(0.8)-H+, and sPPP(0.6)-H+ as both membrane and ionomer in the catalyst layer, i.e., hydrocarbon-based fuel cells, compared to a standard Nafion reference, operating at zero backpressure (100 kPaabs) and conditions optimized for the Nafion reference: 95% RH, 80 °C, 0.5/1.0 slpm gas flows of H2/O2 (a) or air (b) at the anode/cathode; all data 5 min·pt-1 at 100-200 mA·cm-2 intervals with 1 min·pt-1 at mA·cm-2 intervals to resolve the kinetic region; 0.4 mg Pt·cm-2 cathode/anode catalyst loadings with composition and conditioning as described above and in the supporting information. with composition and conditioning as described in Fuel Cell section.

Time scales relevant to the determination of equilibrated water transport (5 min·pt- 1), and all sPPP-based systems show equivalent water transport to PFSAs, thus showing stability, repeatability, and equal or lower mass-transport losses for equivalent non-MEA components. Both sPPP(0.8)-H+,and sPPP(1.0)-H+ formed low-resistance membranes (see Figure 5.13-a). However, sPPP(1.0)-H+ exhibited significant kinetic-region losses which is attributed to significant in situ swelling of ionomer in the catalyst layer. Full polarization for fully hydrocarbon systems is rare in the literature, and the equivalence of the fully sPPP(0.8)-H+ system to the PFSA reference in all of the kinetic, Ohmic, and mass transport regimes is a very promising result for future development.

167 a)

1.0 N212 50 µm sPPP(1.0) 48 µm sPPP(0.8) 37 µm 0.8 sPPP(0.6) 56 µm

0.6

0.4

100 )

Potential, E (|V|)E Potential, ·cm

Ω 50 m

0.2 ( iR iR

0 0 500 1000 1500 2000 2500 3000 -2 0.0 j (mA·cm ) 0 500 1000 1500 2000 2500 Current Density, j (mA·cm-2) b) c)

1000 750

1.0 N212 50 µm 1.0 N212 50 µm )

sPPP(1.0) 48 µm ) sPPP(1.0) 48 µm -2 sPPP(0.8) 37 µm -2 sPPP(0.8) 37 µm sPPP(0.6) 56 µm sPPP(0.6) 56 µm 0.8 750 0.8 500 0.6 0.6 500

0.4 0.4

250 Potential, E (|V|)E Potential, Potential, E (|V|)E Potential, 250

0.2 0.2

PowerDensity (mW·cm PowerDensity (mW·cm

0.0 0 0.0 0 0 500 1000 1500 2000 2500 0 500 1000 1500 -2 -2 Current Density, j (mA·cm ) Current Density, j (mA·cm )

Figure 5.13: Polarization data (IVs) from in situ fuel cell tests for of sPPP(0.6)-H+, sPPP(0.8)-H+, and sPPP(1.0)-H+ as fully hydrocarbon, homogeneous fuel cells (i.e. same polymer employed as both membrane and ionomer in the catalyst layer) compared to a standard Nafion reference (N212 membrane / ND520 ionomer in catalyst layer); all polarization data at 80 °C, 95% RH (optimized for Nafion), zero backpressure, 0.5/1.0 slpm hydrogen/oxygen or air as anode/cathode gas feeds at zero backpressure, showing polarization data from operation in oxygen: a) Including in situ membrane resistance (iR) as a function of current density (inset); b) Including power density (y2- axis); and c) Polarization data from operation in air including power density (y2-axis).

168 5.4. Conclusions

The control and tunability of physical and electrochemical properties of sulphonated, phenylated polyphenylenes was demonstrated via copolymerization of ion- containing pre-functionalized, and non-functionalized monomers. Varied ratios of monomers resulted in changes in polymeric structure, which were elucidated through small angle x-ray and neutron scattering experiments. sPPP(m)-H+ polymers with weight average molecular weights up to 291 kDa were achieved (DPn = 269), from which tough yet flexible membranes were prepared and characterized for their physicochemical and electrochemical properties. Experimental ion exchange capacities from 1.86 to 3.50 meq g-1, corresponding to 50 to 100% functionalized monomers were observed, which displayed ex-situ proton conductivities from 62 up to 338 mS cm-1 at 80 °C and 95% relative humidity. Ex-situ oxidative stability measurements highlighted the chemical integrity of the purely aromatic backbone free of labile linkages employed- after 3 h total exposure time, no changes to chemical structure were observed. In-situ fuel cell characterization yielded a promising assessment of sPPP(m)-H+ efficacy as fully hydrocarbon solid polymer electrolyte fuel cells, as judged by the peak power densities measuring 770 mW·cm-2 in oxygen, and 456 mW·cm-2 in air. Cumulatively, the work reported demonstrates the feasibility of purely hydrocarbon approaches to electrochemical systems, such as fuel cells, as a competitor to traditional PFSA-based materials.

169 Chapter 6.

Exploratory Projects and Future Work

One of the discoveries of this research was the high solubility of sPPP(H+) in hot water, as discussed in Chapter 4. In Chapter 5, one proposed strategy to increase the molecular weight and to decrease the IEC by introducing a hydrophobic unit into the polymer backbone, with the intent of rendering the polymer insoluble in hot water. In collaboration with M. Adamski of the Holdcroft group, an investigation of different monomeric linkers was undertaken. It was found that monomers 4,4’-diethynyl-1,1- biphenyl and 1,4-diethynylnaphtalene yield polymers that were stable in hot water, and the fuel cell performances were enhanced.268 However, the introduction of an additional monomer had two drawbacks: differences in monomer reactivity and the difficulty in setting up the reaction - as three reagents had to be accurately weighed to obtain an accurate stoichiometry. Chapter 5 reports that when the hydrophobic content increased, the molecular weight of the polymer tends to decrease. This is likely due to the difference of solubility and the difference of reactivity during the polymerization. A kinetic study to investigate the polymerization constants for each monomer using the Mayo-Lewis equation would be useful, though this task may require an incredible amount of time to determine the polymerization constant.

Two other possible routes are proposed below, to decrease the solubility of the polymer in hot water and simplify the syntheses procedures.

6.1. Ionic and Covalent Crosslinking

Ionic crosslinking can be performed by adding a specific percentage of crosslinking reagents.

6.1.1. Ionic Crosslinker in the Polymeric Backbone

sPPP(m)(H+) possesses acidic segments. Ionic crosslinking can be achieved using a monomer containing a base, such as an amine. Diphenylamine appears to be a good candidate for this purpose, and is demonstrated in Figure 6.1. It is important to note that

170 the linker used as a crosslinker has to be in sufficient quantities to enhance the mechanical properties but not so much that it renders the polymer insoluble.

TMS TMS H H i I I ii

N N H H N H 1 2 3

iii

iv crosskinked sPPP(m)(H+) N H 4 Figure 6.1: Proposed synthesis route 1 to obtain the crosslinking linker: i: N- iodosuccinimde, ii: Sonogashira cross-coupling with trimethylsilylacetylene, iii: protiodesilylation, iv: added in a solution of monomer(s).

This above synthesis is based on the synthesis of 1,4-diethynylbenzene but with an additional step of halogenation of the diphenylamine. A small quantity of this linker (compound 4 in Figure 6.1) can be sufficient to decease the IEC or it can be used as a new linker as shown in Figure 6.2.

SO3H SO3H

H H H N N

SO3H SO3H

- SO3H SO3 Figure 6.2: Proposed structure of the ionic crosslinked sPPP with the diethylamine linker derivative and the charge balance on the polymer backbone.

171 6.1.2. Ionic Crosslinker as an Additive.

Following the same logic as above, a base can be added during the casting to partially crosslink the polymer film. A diamino derivative such as 1,4-diaminobenzene or the 1,3-diaminobenzene can be used. When the polymer sPPP is converted into its acid form, 0.1% to 5% of the crosslinker can be added to the casting solution prior to the casting. This method is currently the easiest strategy to prevent solubility in hot water. This method also has an advantage in that an accurate amount of crosslinking can be quantified by 1H NMR due to the ratio between the tertiary ammonium and the proton of the polymer. Figure 6.3 proposes a theoretical structure of the use of 1,3-diaminobenzene. In an intramolecular reaction, two sulfonic acids of two different repeating units will be quenched by the crosslinker.

NH3 - O3S SO3H

NH3 - HO3S SO3

HO3S SO3H

Figure 6.3: Example of the possible ionic crosslinking in the film using 1,3- diaminobenzene as a crosslinker.

6.1.3. Covalent Crosslinking

The covalent crosslinking has the disadvantage of being introduced during the polymerization step. This strategy implies that the synthesis of a new molecule, such as 1,3,5-tris((trimethylsilyl)ethynyl)benzene, for which the proposed synthetic route follows the synthesis of previously mentioned acetylene derivatives or linkers, as shown in Figure 6.4.

172 Si

I ii) iii)

I I

Si Si

5 6 7 Figure 6.4: Proposed synthetic route for 1,3,5-triethynylbenzene; i) Sonogashira cross-coupling using trimethylsilylacetylene, ii) protiodesilylation.

The content of compound 7 will have to be adjusted to obtain a processible polymer and not an insoluble polymer. The ionic crosslinking strategy was demonstrated by Weissbach et al.274 for the work on poly(benzimidazolium) and for the use of a-a’-dichloro- p-xylene which crosslinked during the casting of the membrane.

6.2. Reviewing the Polymerization of sPPP(m)(y)

The polymerization of sPPP(m)(y) was perfromed using the [4+2] Diels-Alder reaction, which requires two reagents, a diene and a dienophile (as discussed in Chapter 4). In this work, a second diene was added to the reactor, as discussed in Chapter 5. Furthermore, the stoichiometry needs to be adjusted to obtain a processible polymer. It may be possible to simplify the polymerization step by changing the polymerization route. This proposed strategy can be performed in two steps, as shown in Figure 6.5.

173 SO3X

XO3S

O SO3X

SO3X Br + iv) XO3S Br Br O

X = NEt3 SO3X X = NEt3 SO3X

sBTC(X) 8 SO3X 9

SO3X SO3X

Br vi)

vii) Br

SO3X X = H SO3X X = Na

SO3X sPPB(X) SO3X 10 Figure 6.5: Proposed alternative route to polymerize sBTC(X): iv) Diels-Alder reaction; v) cation exchange with 1.0 mol/L sodium hydroxide; vi) polymerization; vii) cation exchange to the acid form.

This proposed polymerization route can be acheived by different strategies. One alternative is the Yamamoto cross-coupling using nickel as a catalyst. Miyake et al.275 reported the use of Ni(COD)2 in the polymerization of sodium 2,5- dichlorobenzenesulfonate with quinquephenylene, however this source of catalyst is expensive, unstable in light and oxygen, needs to be stored below 0°C, and is used in stoichiometric amounts or in excess. A cheaper alternative is the use of nickel in catalytic amounts where bis(triphenylphosphine)nickel(II) dichloride is used in conjunction with zinc and sodium iodide to regenerate the catalyst. The triethylammonium salt is the conjugated acid of the triethylamine and for this new polymerization route, the reagent needs to be neutral, and why the cation needs to be exchanged to sodium. Ullmann coupling can also be applied and requires metallic copper.37

In a quick investigation, the use of compound 10 with the catalytic system

Ni(COD)2/bipyridine in NMP for 3 days gave a polymer with a Mn of 72,000. Unfortunately,

174 this molecular weight is insufficient to form strong membranes and further research should be done to improve the polymer synthesis.

175 Chapter 7.

Conclusion

In this thesis, studies on the synthesis of the new pre-sulfonated monomers, its polymerization, and an examination of properties of membranes prepared therefrom are reported.

In Chapter 3, the synthesis of tetracyclone (TC) and its sulfonation to sTC(H+) using trimethylsilyl chlorosulfonate is reported. The conversion of sTC(H+) into its + triethylammonium derivative, sTC(HNEt3 ), was successfully achieved. The same strategy + was applied to the conversion of bistetracyclone (BTc) to sBTC(HNEt3 ). These two new molecules were investigated using 1H, 2D COSY, 13C, and 1D NOE spectroscopy in order to elucidate their molecular structures. The fingerprint patterns of the molecules were observed in 1H NMR, infra-red spectroscopy, mass spectrometry, and single X ray crystal. The thermogravimetric study showed that the thermal stability of the monomer is + + enhanced in its triethylammonium form. Both sTC(HNEt3 ) and sBTC(HNEt3 ) were used in the [4+2] Diels-Alder cycloaddition with various dienes. Several model compounds were made in good yield, and with molecular weights of up to 1918 g/mol. In each case, the sulfonic acids remained intact after the reaction, and confirmed by 1H NMR, mass spectrometry, and infrared spectroscopy.

+ In Chapter 4, sBTC(HNET3 ) containing four sulfonate groups per monomer, is used in the [4+2] Diels-Alder cycloaddition with 1,4-diethynylbenzene to yield the polymer + sPPP-HNEt3 . The polymer was obtained in the triethylammonium form and successfully converted into its acidic form, sPPP-H+. This polymer exhibited a high IEC of 3.49 mequiv./g, close to the theoretical value of 3.70. The polymer with a molecular weight of 192,000 g/mol formed a free-standing membrane that exhibited a proton conductivity of 108 mS/cm at 30°C at 95% RH. A dimensional study revealed intense swelling due to the high IEC value. sPPP-H+ did not exhibit signs of degradation in an oxidative test but was revealed to be soluble in hot water. These membranes could be formed into a membrane- electrode-assembly and examined in a hydrogen/oxygen fuel cell.

In Chapter 5, a strategy is demonstrated to address the polymer’s dissolution in hot water. Namely, the introduction of additional hydrophobic segements into the polymer

176 backbone. Six random co-polymers were designed and prepared by polymerizing + sBTC(HNEt3 ) with varying amounts of 1,4-diethynylbenzene and BTC as hydrophobic + monomers to form sPPP(y)(HNEt3 ). Their compositions ranged from 50% to 100% hydrophilic content (y value). The IEC ranged from 1.88 to 3.50 mequiv./g. The molecular weight of the polymers from 161,400 g/mol to 290,900 g/mol. All polymers were insoluble in hot water and stable during an oxidative test. The ex situ proton conductivity was between 14 mS/cm and 349 mS/cm. sPPP(0.8)H+ and sPPP(1.0) showed an in situ conductivity three times higher than NR212. sPPP(0.8), examined as a membrane in a fuel cell analyses provided peak of current at 770 mA/cm2, which is promising for the future of the use of this polymer in hydrogen/oxygen fuel cells.

177 References

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200 Appendix.

Supporting Information

1,2,3,6

5 4

2 3 1 O

4 5

1 Figure A 1: H NMR (CD2Cl2) spectrum of TC.

201 e i f & j

g k

d h c

f g e d O b a

i c j h

f & j

e i

d & h b c

13 Figure A 2: C NMR (CD2Cl2) spectrum of TC.

202

2 3 1 O 1, 2, 3, 6

4 5

Figure A 3: COSY (2D) NMR (CD2Cl2) spectrum of TC.

203 90

60 Transmittance (%) Transmittance 50

TC 30 4000 3500 3000 2500 2000 1500 1000 500 Wavenumber (cm-1)

Figure A 4 : FT-IR spectrum of the TC.

Figure A 5: MS spectrum of TC.

204

Figure A 6: MS spectrum of sTC(H+).

205 100

50 Transmittance (%) Transmittance 40

20 + sTC(H )

4000 3500 3000 2500 2000 1500 1000 500 Wavenumber (cm-1)

Figure A 7: FT IR of the sTC(H+).

206 3

2 4

1 HO3S 2 O

3 SO3H 4

2 4 5 1

+ Figure A 8: COSY (2D) NMR (DMSO-d6) spectrum of sTC(H ).

207 f e

i j

f HO S g 3 e O d h k c d b a

i c SO3H h j

f e

i j

a b g d h c

13 + Figure A 9: C NMR (DMSO-d6) spectrum of sTC(H ).

208 Table A 1: Crystallographic Information for compound sTC(H+).

sTC(H+)

molecular formula C33H34N7O7S2 formula weight (g mol–1) 634.74 crystal dimensions (mm) 0.032, 0.055, 0.456 crystal system monoclinic space group C2/c a (Å) 35.0306(10) b (Å) 10.4945(3) c (Å) 8.5064(2) α (deg) 90 β (deg) 93.955(2) γ (deg) 90 V (Å3) 3119.75(15) Z 8 T (K) 150(2) –3 ρcalcd (g cm ) 1.351 μ (mm) 1.975

2θmax (deg.) 66.658 total/unique reflections 2720/2544

obsd reflns [I0 ≥ 2σ(I0)] 2544 a R1, wR2 [I0 ≥ 2σ(I0)] 0.0306, 0.0824 GOF 1.064 largest difference 0.250/ -0.367 peak/hole (e–/ Å3)

209 1 2 4 3

1 - O3S 2 O 9

- H 3 SO3 N 4 7 5 8

7 1 2 4 3

5 9

1 + Figure A 10: H NMR (DMSO-d6) spectrum of sTC(HNEt3 ).

210 f e i j

d h k c

-O S g f 3 e g d O b a f f H i c SO - g h 3 N j

f e

i j

a b g d h c

13 + Figure A 11: C NMR (DMSO-d6) spectrum of sTC(HNEt3 ).

211 3 8 2

4 5

1 - O3S 2 O 9 - H 3 SO3 N 4 7 5 8

4 2 3 5 1

+ Figure A 12: COSY (2D) NMR (DMSO-d6) spectrum of sTC(HNEt3 ).

212 100

60 Transmittance (%) Transmittance 50

sTC(HNEt +) 3 30 4000 3500 3000 2500 2000 1500 1000 500 Wavenumber (cm-1)

+ Figure A 13: FTIR of sTC(HNEt3 ).

213 Hcore

1 & 3

2 2 1 Hcore

Hcore

1 & 3

1 Figure A 14: H NMR (DCM-d2) spectrum of 1,4-bis(phenylethynyl)benzene.

214

Figure A 15: COSY (2D) NMR (DCMO-d2) spectrum of 1,4-bis(phenylethynyl)- benzene.

215 f d g

h c e a b

g f d b a e c h

13 Figure A 16: C NMR(DCM-d2) spectrum of 1,4-bis(phenylethynyl)benzene.

216 Hcore

1 2 3

Hcore

1 2

Hcore 3

3 DCM-D2

1 Figure A 17: H NMR (DCM-d2) spectrum of bisbenzil.

217 2

Hcore 1

Hcore

1 2

Figure A 18: COSY (2D) NMR (DCM-d2) spectrum of bisbenzil.

218 b g f h b b a d g c e f e c h d

d c h f a e g

13 Figure A 19: C NMR spectrum (DCM-d2) of bisbenzil.

219 Hcore

5 1, 4 2

9 8 7 2 3 3 & 6 1 O 4 5

8 Hcore 9 7

Hcore

1, 2, 3, 4, 5, 6, 9

8 7

1 Figure A 20: H NMR (DCM-d2) spectrum of bistetracyclone.

220 Hcore

2 1, 2, 4 8 3 1 O 4 5 5 6 3 & 6 9

8 Hcore 9 7

Hcore 7

3 & 6 9

Figure A 21: COSY (2D) NMR (DCM-d2) spectrum of bistetracyclone.

221 g

iqm n j r

s k o e d l h p f c b

j k i O h m n b a c l o q d p e r f s g

a e & d c & b

13 Figure A 22: C NMR (DCM-d2) spectrum of bistetracyclone.

222 100

Transmitance (%) Transmitance 60

BTC 40 4000 3500 3000 2500 2000 1500 1000 500 Wavenumber (cm-1)

Figure A 23: FT-IR spectrum of BTC.

223 g im q j HO3S k s i n j O h r a m n ed o k l h p f c b b c l o q SO3H p d e r f s g

HO3S

SO3H

s & g

i, m & q

n, r, & j

a o & k e & d p & f h c & b l

13 + Figure A 24: C NMR (DMSO-d6) spectrum of sBTC(H ).

Figure A 25: MS spectrum of the mixture containing tri (M = 930.13g/mol) and tetrasulfonated sBTC(H+) (M = 1010.08 g/mol)

224 Table A 2: Adjustement of the stoichiometry of the TMSO-SO2Cl to obtained the pure tetra functionalized sBTC(H+)

Equivalent of BTC Equivalent of TMSO-SO2Cl Substituted products obtained 1.0 equiv. 8 equiv. tri and tetra 1.0 equiv. 10 equiv. tri and tetra 1.0 equiv. 12 equiv. tri and tetra 1.0 equiv. 13 equiv. tri and tetra 1.0 equiv. 14 equiv. tri and tetra 1.0 equiv. 15 equiv. tri and tetra 1.0 equiv. 16 equiv. tri and tetra 1.0 equiv. 17 equiv. tri and tetra 1.0 equiv. 18 equiv. tetra 1.0 equiv. 20 equiv. tetra 1.0 equiv. 25 equiv. tetra

Figure A 26: Mass spectrum of sBTC(H+).

225 Hcore H H H H H a1 a2 m b2 b1 H Hp o

SO3H SO3H Ha1 Ha1 Ha1 Ha1 Hb1 Hb1 Hb1 Hb1 O O

Hb2 Hb2 Ha2 Hcore Ha2 Ho Ho Hb2 Hb2 Ho Ho HO3S Ha2 Hm Hm Ha2 SO3H Hm Hm Hp Hp

+ Figure A 27: 1D NOE irradiation of sBTC(H ) (DMSO-d6), red: 1H proton, green: irradiation of the Hm, cyan: irradiation of the Hp, fushia: irradiation of the Hcore.

226 100

Transmitance (%) Transmitance 60

sBTC(H+) 40 4000 3500 3000 2500 2000 1500 1000 500 Wavenumber (cm-1)

Figure A 28: FT-IR spectrum of sBTC(H+).

227 Hcore 2 1

Ha1 Ha2 Hb2 Hb1

Hm Ho

-O S Ha2 3 Hb2

O Hb1 Ha1 1 - Ho SO3 Hm 3 Hp Hcore H N 2 1 -O S 3 2

O - SO3

Ha1 & Ha2

1 + Figure A 29: H NMR (DMSO-d6) spectrum of sBTC(HNEt3 ).

228 j -O S k 3 i g O im h m n q b a c l o - s q SO3 n j p d e r r l h p f c b f s g H N u t - O3S

O - t SO3

a e & d o & k

13 + Figure A 30: C NMR (DMSO-d6) spectrum of sBTC(HNEt3 )

229 Hcore

Ho 1

Hb1

Hb2

Ha2

Ha1

- Ha2 O3S Hb2

O Hb1 Ha1

- Ho SO3 Hm 3 Hp Hcore H N 2 1

- O3S

O - SO3

+ Figure A 31: COSY (2D) NMR (DMSO-d6) spectrum of sBTC(HNEt3 ).

230 -O S Ha2 3 Hb2

O Hb1 Ha1

- Ho SO3 Hm 2 3 Hp Hcore H N

- O3S

O - SO3

+ Figure A 32: 1D NOE irradiation of sBTC(HNEt3 ) (DMSO-d6), red: 1H proton, green: irradiation of the Hm, olive: irradiation of the Hp, fushia: irradiation of the methylene of the triethylammonium.

+ Figure A 33: Mass spectrum of the triethylammonium cation HNEt3 .

231 100

60 Transmitance (%) Transmitance

40 sBTC (HNEt +) 3

4000 3500 3000 2500 2000 1500 1000 500 Wavenumber (cm-1)

+ Figure A 34: FT-IR spectrum of sBTC(HNEt3 ).

232 Si Har

HTMS Si 12

Har

1 Figure A 35: H NMR (Acetone-d6) spectrum of 1,4-bis(trimethylsilylethynyl)- benzene.

233 e e Si a c e a d b c b a e a Si d e e 12

b c d

13 Figure A 36: C NMR (Acetone-d6) spectrum of 1,4-bis(trimethylsilylethynyl)- benzene.

234 Har H1

Har

1 Figure A 37: H NMR (Acetone-d6) spectrum of 1,4-diethynylbenzene.

235 a c a d b c a b a d 13

b c

13 Figure A 38: C NMR (Acetone-d6) spectrum of the 1,4-diethynylbenzene.

236 b a c

c c

b c a a a b b b a a c b c c

1 Figure A 39: H NMR (Acetone-d6) spectrum of 4,4'-bis((trimethylsilyl)ethynyl)-1,1'- biphenyl.

237 g g f c g b d e b a a c

e g d f g g

c b

a d e f

13 Figure A 40: C NMR (Acetone-d6) spectrum of 4,4'-bis((trimethylsilyl)ethynyl)- 1,1'-biphenyl.

238 b a

c b a a b b a a b c

b a c

1 Figure A 41: H NMR (Acetone-d6) spectrum of 4,4'-diethynyl-1,1'-biphenyl.

239 c f b d e b a a c e d f

c b

f a d e

13 Figure A 42: C NMR (Acetone-d6) spectrum of 4,4'-diethynyl-1,1'-biphenyl.

240 d

a b

d d c c d c b d a c d d

a b

1 Figure A 43: H NMR (Acetone-d6) spectrum of ((4-bromophenyl)ethynyl)- triisopropylsilane.

241 a d

h h

g g h h f c e b g d h h h a c b

b c

a d e f

13 Figure A 44: C NMR (Acetone-d6) spectrum of ((4-bromophenyl)ethynyl)- triisopropylsilane.

242 d

d e

b a e

d d c c d c b d a c d d

e e

b a

1 Figure A 45: H NMR (Acetone-d6) spectrum of triisopropyl((4-((trimethylsilyl)- ethynyl)phenyl)ethynyl)silane.

243 c b

d a e i f j

h h g g h h f h c e b g d h h i a c k b j k k g

c b

a d e i f j

13 Figure A 46: C NMR (Acetone-d6) spectrum of triisopropyl((4-((trimethylsilyl)- ethynyl)phenyl)ethynyl)silane.

244 d

a b

d d

c c d c b d a c d d

a b

1 Figure A 47: H NMR (Acetone-d6) spectrum of ((4-ethynylphenyl)ethynyl)- triisopropylsilane.

245 c b

h h g g h f h c e b g d h h i a c b j

c b j da f e i

13 Figure A 48: C NMR (Acetone-d6) spectrum of ((4-ethynylphenyl)ethynyl)- triisopropylsilane.

246 HDA HPh Hb1 Hb2

Hm & Hp Ha1 Ha2 Hp

H-N-(CH2-CH3) 3

HPh HNEt + HNEt + 3 HDA 3

- - O3S SO3 Ha1 Hb1 Hb2 Ha2

Ho Hm Hm Hm Hp Hp

H-N-(CH2-CH3) 3

HDA

Hp H-NEt3 * * *

1 + Figure A 49: H NMR (DMSO-d6) spectrum of DAsTC(HNEt3 )-Ph. (* refers to residual ethyl acetate and acetone.)

247 + + HNEt3 HNEt3

- - O3S SO3

* *

13 + Figure A 50: C NMR (DMSO-d6) spectrum of DAsTC(HNEt3 )-Ph, (* refered to residual ethylacetate)

248 H-N-(CH2-CH3) 3 Hb2 Ha2 Hm & Hp

HPh Hp

Hb1

HDA Ha1

H-N-(CH2-CH3) 3

HPh + + HNEt3 HNEt3 HDA

- - O3S SO3 Ha1 Hb1 Hb2 Ha2

Hm Ho Hm Hm Hp Hp

H-NEt3

+ Figure A 51: COSY (2D) NMR (DMSO-d6) spectrum of DAsTC(HNEt3 )-Ph.

249 HDA SO - -O S Hcore Ha2 3 3 Hm1 Hp1 Hm1 & Hm2 Hp1 & Hp2 Ha2 Ho1 Hb2 Hb2 Ha1 Ha2 3 Hb1 Hb2 H 2 Ho1 & Ho2 Hp2 N

HDA Ho2 Hm2 Hb1 Hcore 1 Ha1 Hb1

Ha1 - - O3S SO3 14 1

Hcore HDA

Ha2 Hb1 Hb2

1 + Figure A 52: H NMR (DMSO-d6) spectrum of 2DAsTC(HNEt3 )-1,4-bz.

250 n o

u,q,f,h,g t x s w p l m i j a k e b c

d r v

z y SO - -O S x w k l 3 3 l k w x

w v j k k j v w

v u i j j i u v y s r g f a a f g r s z c b b c h H z t t y q h q N s r e d a a d e r s z n m m n y o n n o

p o o p - - O3S SO3 14

13 + Figure A 53: C NMR (DMSO-d6) spectrum of 2DAsTC(HNEt3 )-1,4-bz.

251 Hp1 & Hp2 Hb2

Hm1 & Hm2 Ho1 & Ho2

Hb1 1

Ha2

HDA Ha1

SO - -O S Ha2 3 3 Hm1 Hp1

a Ho1 Hb2 H 2 Hb2 H 2 Hp2 N

HDA Ho2 Hm2 Hb1 Hcore 1 Ha1 Hb1

Ha1 - - O3S SO3 14

+ Figure A 54: COSY (2D) NMR (DMSO-d6) spectrum of 2DAsTC(HNEt3 )-1,4-bz.

252 Hcore

Hp1 & Hp2

HDA Ha1 Ha2 Hb1 Ho1 & Ho2 Hm1 & Hm2 Hb2

- - SO3 O3S Ha2 Hm1 Hp1 Ho1 Hb2 Ha2 Hb2 H 2 Hp2 N

HDA Hm2 Hb1 Hcore Ho2 1 Ha1 Hb1 a - H 1 - O3S SO3 14

1 + Figure A 55: H NMR spectrum of 2DAsTC(HNEt3 )-1,4-bz(DMSO-d6) and three 1D 1 NOE spectra. Red: H spectrum; green: irradiation of the HDA at 7.37ppm, close to the HDA; cyan: irradiation of Hb1; purple: irradiation of the Hb2 close to the Hcore.

253 HDA Ho1 & Ho2 Hcore

Ha2 Ha1 Hm1, Hm2, Hp1, Hp2 Hb1

Hb2 Hb2 Hb1 3

- - SO3 SO3 Ha1 Ha2

Hb1 Hb2

Hcore 3 H HDA Hp2 N H Ho2 Hm2 2 Hb2 DA 1 Ha2 Ho1 Hb1

Hm1 Hp1 Ha1 - - O3S O3S

16 2

1 + Figure A 56: H NMR (DMSO-d6) spectrum of 2DAsBTC(HNEt3 )-Ph.

254 - - SO3 SO3 Ha1 Ha2

Hb1 Hb2

Hcore 3 H HDA Hp2 N Ho2 Hm2 2 b HDA H 2 1 Ha2 Ho1 Hb1

Hm1 Hp1 Ha1 - - O3S O3S

13 + Figure A 57: C NMR (DMSO-d6) spectrum of 2DAsBTC(HNEt3 )-Ph.

255 1

3 Hcore

Hb1

Hm1, Hm2, Hp1, Hp2

Hb2

Ho1 & Ho2 - - SO3 SO3 Ha1 Ha1 Hb1 Ha2 HDA Hb2 Hcore 3 Ha1 H HDA Hp2 N Ha2 HDA Ho2Hm2 2 Hb2 1 Ha2 Ha2 Ho1 Hb1 Hm1 Hp1 Ha1 -O S -O S Ha2 3 3

+ Figure A 58: COSY (2D) NMR (DMSO-d6) spectrum of 2DAsBTC(HNEt3 )-Ph.

256 Hcore - - 293K SO3 SO3 Ha1 Ha2

Hb1 Hb2 3 Hcore 3 H HDA Hp2 N H Ho2 Hm2 2 Hb2 DA 313K 1 Ha2 Ho1 Hb1

Hm1 Hp1 Ha1 - - O3S O3S

16 333K

353K

373K

1 + Figure A 59: H NMR (DMSO-d6) spectra of 2DAsBTC(HNEt3 )-Ph at various temperature, fushia; 293K, marine: 313K, olive: 333K, kaki: 353K, red: 373K.

257 e

a f, g, h , j, m

HDA c d i l k, n

a a

h b b g a Si a j f k i a b a

c l d

m HDA

n e

e b e

HDA c d

1 Figure A 60: H NMR (DCM-d2) spectrum of DATC-TIPS.

258 Si

13 Figure A 61: C NMR (DCM-d2) spectrum of DATC-TIPS.

259 a a

h b b g a Si a j f k i a b a

c l d

m HDA

n e

Figure A 62: COSY (2D) NMR (DCM-d2) spectrum of DATC-TIPS.

260 e

g, h, j, m HDA b f, i & l c k & n

h g j a f k i

b l c

m HDA

n e e e

HDA a c b

1 Figure A 63: H NMR (DCM-d2) spectrum of DATC-CCH.

261

13 Figure A 64: C NMR (DCM-d2) spectrum of DATC-CCH.

262

Figure A 65: COSY (2D) (DCM-d2) spectrum of DATC-CCH.

263 HDA Har Hcore a

HDA a

HDA Hcore b b

HDA Har Hcore

1 Figure A 66: H NMR (DCM-d2) spectrum of 2DABTC-TIPS.

264

Figure A 67: COSY (2D) NMR (DCM-d2) spectrum of 2DABTC-TIPS.

265

13 Figure A 68: C NMR (DCM-d2) spectrum of 2DABTC-TIPS.

266 HDA Har Hcore

HDA

HDA Hcore a

Hcore

a HDA

1 Figure A 69: H NMR (DCM-d2) spectrum of 2DABTC-CCH.

267 b a

b a a

a b

13 Figure A 70: C NMR (DCM-d2) spectrum of 2DABTC-CCH.

268 Hcore

HDA

HDA Hcore a

HDA

Figure A 71: COSY (2D) NMR (DCM-d2) spectrum of 2DABTC-CCH.

269 HDA2 H & H C2 c1 Hb2 H Ha1 DA1 Ha2 Hb1

- SO3 H 3 N Ha1 Hb1 HC2 HC1 HDA1 Ho1 Hm1

Hp1

HDA2 Ho2 1 Hm2 H Hb2 2 N 3 - Ha2 Hp2 O3S

1 + Figure A 72: H NMR (DMSO-d6) spectrum of DA-sTC(HNEt3 )-p-DATC.

270 - SO3 H N

H N - O3S

Residual NEt3

13 + Figure A 73: C NMR (DMSO-d6) spectrum of DA-sTC(HNEt3 )-p-DATC.

271 Hb2

Hb1

HC2 & Hc1 HDA1 Ha2

HDA2 Ha1

- SO3 H N Ha1 Hb1 HC2 HC1 HDA1 Ho1 Hm1

Hp1

HDA2 Ho2 1 Hm2 H Hb2 2 N 3 - Ha2 Hp2 O3S

+ Figure A 74: COSY (2D) NMR (DMSO-d6) spectrum of DA-sTC(HNEt3 )-p-DATC.

272

+ Figure A 75: High resolution masse spectrum of DA-sTC(HNEt3 )-p-DATC of the observed monoisotopic ion (997.2625 g/mol) and diisotopic ion (z=2, 498.1291 g/mol).

273 HN-(CH2)3-(CH3)3

HDA1 HDA2

HDA2

- + SO3 HNEt3

- + SO3 HNEt3 HDA1

HDA1

HDA2 HDA2 HN-(CH2)3-(CH3)3

HDA2 + - HNEt3 SO3

- + HN-(CH2)3-(CH3)3 SO3 HNEt3 Residual NEt3

1 + Figure A 76: H NMR (DMSO-d6) spectrum of 2DATC-sBTC(HNEt3 ).

274 - + SO3 HNEt3

- + SO3 HNEt3

+ - HNEt3 SO3

- + Residual NEt3 SO3 HNEt3

13 + Figure A 77: C NMR (DMSO-d6) spectrum of 2DATC-sBTC(HNEt3 ).

275 - + SO3 HNEt3

- + SO3 HNEt3

+ - HNEt3 SO3 Hcore

- + SO3 HNEt3

HDA2

HDA1

+ Figure A 78: COSY (2D) NMR (DMSO-d6) spectrum of 2DATC-sBTC(HNEt3 ).

+ Figure A 79: High resolution masse spectrum of 2DATC-sBTC(HNEt3 ) of the observed monoisotopic ion.

276 HN-(CH2)3-(CH3)3

HDA2 HDA1 Hcore

HDA2 HDA2 HN-(CH2)3-(CH3)3

HDA1

Hcore

HDA1

HN-(CH2)3-(CH3)3 Residual NEt3

1 + Figure A 80: H NMR (DMSO-d6) spectrum of 2DAsTC(HNEt3 )-BTC.

277 Residual NEt3

13 + Figure A 81: C NMR (DMSO-d6) spectrum of 2DAsTC(HNEt3 )-BTC.

278 HDA1

Hcore

HDA1

HDA2

HDA2 HDA2 Hcore HDA1

HDA1

+ Figure A 82: COSY (2D) NMR (DMSO-d6) spectrum of 2DAsTC(HNEt3 )-BTC.

+ Figure A 83: High resolution mass spectrum of 2DAsTC(HNEt3 )-BTC, di, tri and tetra-isotopic ions.

279

+ Figure A 84: High resolution mass spectrum of 2DAsTC(HNEt3 )-BTC: tri-isotopic ion.

Hb2, Hm1, Hm2, Hp1 & Hp2

HDA

Ha1 HB1 Hb1 Ha2 HB2 Ho1, Ho2

3 2

1 Ha1 Ha2

Hb1 HDA HB1 HB2 Hb2 Ho1 Hm1

Hp1

Ho2 Hb2 HDA Hb1

Hm2 Ha2 Ha1 2 Hp2

1 + Figure A 85: H NMR (DMSO-d6) spectrum of 2DAsTC(HNEt3 )-Biph.

280 Hb2

HB2 Hb1 Ha2

HB2 Ha1 HDA

HB2 HB2

3 2

Ha1 1 Ha2

Hb1 HDA HB1 HB2 Hb2 Ho1 Hm1

Hp1

Ho2 Hb2 HDA Hb1

Hm2 Ha2 Ha1

Hp2

+ Figure A 86: COSY (2D) NMR (DMSO-d6) spectrum of 2DAsTC(HNEt3 )-Biph.

281 - - O3S O3S 4 Equiv. NH

- - SO3 SO3

Residual NEt3

13 + Figure A 87: C NMR (DMSO-d6) spectrum of 2DAsTC(HNEt3 )-Biph.

+ Figure A 88: High Resolution mass spectrum of 2DAsTC(HNEt3 )-Biph, di, tri et tera-isotopic ion.

282 Hm1, Ho1, Hp1 Ho2 & Hp2 HDA

Hm2

Hm1 Ho1 HDA HDA

Hp1

Ho2

Hm2 Hm1, Ho1, Hp1 Hp2 Ho2 & Hp1 HDA

Hm2

1 Figure A 89: H NMR (DCM-d2) spectrum of DATC.

283 Hm1 Ho1 HDA HDA

Hp1

Ho2

Hm2

Hp2

Hm1, Ho1, Hp1

Hm2

Hm2 Ho2 & Hp1 Ho2 & Hp2

HDA Hm1, Ho1, Hp1

HDA

Figure A 90: COSY (2D) NMR (DCM-d2) spectrum of DATC.

284

13 Figure A 91: C NMR (DCM-d2) spectrum of DATC.

285 Ho & Hp

HDA Ha Hb Hm1

Ha Hb HDA

HO3S SO3H Ho

Ho & Hp

HDA Ha Hb Hm

H+

1 + Figure A 92: H NMR (DMSO-d6) spectrum of DAsTC(H ).

286 Ho & Hp Ha Hb

HDA Hm H+

Ha Hb HDA HDA

HO3S SO3H Ho

Ha Hb

HDA H+ Hm

Ho & Hp

HDA

+ Figure A 93: COSY (2D) NMR (DMSO-d6) spectrum of DAsTC(H ).

287 HO3S SO3H

13 + Figure A 94: C NMR (DMSO-d6) spectrum of DAsTC(H ).

288

Figure A 95: High resolution mass spectrum of DAsTC(H+) where only the di- 2- isotopic anion is observe, C30H20O6S2 , with in theorie m/z (z=2) = 270.0356, 270.0349 was found.

289 Ha Hb

H+

Ha’ Hb’

Hb 1 1

Ha Hb

4’

2’ Ha’

Hb’ 3’ 4’ 1’ 1’

3’ Ha’ Hb’

2’

1 Figure A 96: H NMR (DMSO-d6) spectra, upper PTSA in the acid form, lower PTSA + (HNEt3 ), inset: zoom of the aromatic area between 7.6 and 6.8 ppm.

290 PTSA(HNEt +) 3 1.0

0.8

0.6

0.4 Normalized Weight Lose (%) Lose Weight Normalized 0.2

0.0 0 100 200 300 400 500 600 Temperature (°C)

+ Figure A 97: Thermogram of the PTSA(HNEt3 ) from room temperature to 500°C, under nitrogen, 1.0°C per minute.

291 DAsTC(HNEt +) 3 1.0

0.8

0.6

0.4 Normalized Weight Loss (%) Loss Weight Normalized 0.2

0.0 0 100 200 300 400 500 600 Temperature (°C)

+ Figure A 98: Thermogram of DAsTC(HNEt3 ) from room temperature to 500°C, under nitrogen, 1.0°C per minute.

292 2DAsTC(HNEt +)-Biph 3 1.0

0.8

0.6

0.4 Normalized Weight Loss (%) Loss Weight Normalized 0.2

0.0 0 100 200 300 400 500 600 Temperature (°C)

+ Figure A 99: Thermogram of 2DAsTC(HNEt3 )-biph from room temperature to 500°C, under nitrogen, 1.0°C per minute.

293 DAsTC(HNEt +)-Ph 3 1.0

0.8

0.6

0.4 Normalized Weight Loss (%) Loss Weight Normalized 0.2

0.0 0 100 200 300 400 500 600 Temperature (°C)

+ Figure A 100: Thermogram of 2DAsBTC(HNEt3 )-Ph from room temperature to 500°C, under nitrogen, 1.0°C per minute.

294 sPPP-HNEt + 3 sPPP-H+ 1.0

0.8

0.6

0.4

0.2 Normalizedrefractive index (a.u.)

0.0 15 20 25 Retention time (min)

+ + Figure A 101: Size extrusion chromatogram of sPPP-HNEt3 and sPPP-H , run in DMF-SEC with 0.01 M LiBr, with a flow rate of 1.0mL/min.

295 - O3S

18% H - - - - O3S O3S O3S O3S

H H H core m-p - SO3

- O3S 42% Hcore p-p 40% H H

Hcore m-m - - - - SO3 SO3 SO3 SO3

- SO3 m-m p-p m-p

HDA

Hcore m-m

Hcore p-p

Hcore m-p

1 + Figure A 102: H NMR (DMSO-d6) spectrum of sPPP-HNEt3 , zoom on the aromatic area: 7.6 ppm to 5.8ppm.

296 Hcore

Hb1

3 H H 2 N N3 1 SO - -O S Hb2 3 3

Hlink Ha1 Ha1

b b H 1 H 1 HDA Hlink

HDA Hp Ho Hcore Ho Hb2 Hb2 Ha2 Hm Ha2

Hm Hp Hp Ha1 - - O3S SO3 HDA H H N N

Ho + sPPP-HNEt3

Ha2

+ Figure A 103: COSY (2D) NMR (DMSO-d6) of sPPP-HNEt3

297 sPPP-H+ before Fenton test

sPPP-H+ after Fenton test

1 + Figure A 104: H NMR (DMSO-d6) spectrum of sPPP-H : red before Fenton test; olive after Fenton test.

298 H O sPPP-H+ before Fenton test 2

H2O

sPPP-H+ after Fenton test

H2O

sPPP-H+ after Fenton test + 10µL of DI water

H2O

sPPP-H+ after Fenton test + 10µL of DI water (total added 20 µL)

1 + Figure A 105: H NMR (DMSO-d6) spectrum of sPPP-H ; red: before oxidation stability test, olive: after the Fenton test; cyan after adding 10µL of DI water in the NMR tube, purpler after adding 10 µL of DI water (total H2O added : 20 µL) in the NMR tube.

299 a b H2O

c a b

b H2O

DMSO-d6

1 Figure A 106: H NMR (DMSO-d6) of APTS.

300

+ Figure A 107: O2/H2Fuel cell performance of sPPP-H as ionomer in cathode catalyst layer at 80 °C for MEAs with Nafion® N211 as membrane, Nafion® D520 as ionomer in cathode catalyst layer is shown for comparison (NOTE: anode RH maintained at 100%).

301

Figure A 108: In situ membrane proton conductivity as a function of RH for MEAs tested as per Figure A 107 where original RH = 100% (D520) or 90% (sPPP-H+)

302

Figure A 109: Fuel cell performance for sPPP-H+ (150 μm thick) and NR212 (50 μm + thick) at 80 °C under O2/H2 at 70% cathode and anode RH. sPPP-H cathode and anode contain sPPP-H+, 0.4 mg cm-2 Pt. NR212 cathode and anode contain Nafion® D520, 0.4 mg cm-2Pt.

303

Figure A 110: In-situ membrane proton conductivity for sPPP-H+ and NR212 as function of RH.

304 Table A 3: Yields and determined molecular weight characteristics (in Daltons) of the reported polymers.

(a) (a) (a) (a) (a)(b) (c) (c) (c) Copolymer Yield(%) MnSEC MwSEC ĐSEC MnNMR Yield(%) MnSEC MwSEC ĐSEC (c) sPPP(1.0) 89.1 274,600 363,800 1.86 371,400 92.1 164,200 290,900 1.90 sPPP(0.9) 81.1 143,000 347,000 2.41 268,900 89.2 121,000 221,100 1.83 sPPP(0.8) 89.0 122,100 240,000 1.96 153,800 >99.9 110,000 225,000 2.01 sPPP(0.7) 79.1 91,700 267,800 2.63 224,400 99.1 91,100 176,000 2.46 sPPP(0.6) 85.6 77,000 217,000 2.75 N/A 93.2 49,700 103,550 3.50 sPPP(0.5) 83.2 75,550 198,000 3.43 49,900 92.8 61,900 161,400 2.87 sPPP(0.25) 74.7 34,700 51,900 1.48 58,700 89.2 34,000 52,900 1.52 sPPP(0.0) 67.2 30,200 77,600 2.57 N/A N/A N/A N/A N/A

(a) Polymer in the triethylammonium form - sPPP(m)-HNEt3+.

(b) Mn obtained by 1H NMR in d6-DMSO. (c) Polymer in the acidic form- sPPP(m)-H+. (d) sPPP(0.0) does not contain ionic groups and therefore has no acid form.

305 Transmittance Infrared Spectrum of the sPPP(m)(H+)

100

75 Transmittance (%) Transmittance 70 sPPP(1.0)(H+) sPPP(0.9)(H+) 65 sPPP(0.8)(H+) sPPP(0.7)(H+) sPPP(0.6)(H+) 60 sPPP(0.5)(H+)

4000 3500 3000 2500 2000 1500 1000 500 Wavenumber (cm-1)

Figure A 111: FT-IR spectra of sPPP(m)-H+.

306

Figure A 112: Theoretical procedure for calculating the number average molecular + 1 weight, Mn, for the reported copolymers sPPP(m)-HNEt3 using H NMR.

307 HO3S

SO3H HO3S

SO3H

Chemical Formula: C H 2• 2• 60 40 Chemical Formula: C60H40O12S4 Molecular Weight: 760,9596 Molecular Weight: 1081,2124 Figure A 113: Molecular weight of hydrophobic and hydrophilic repeat units of found in the sPPP(m)-H+ copolymers.

Table A 4: Theoretical calculations for sPPP(m)-H+ IECs

Copolymer # Hydrophilic # Hydrophobic Mn 100u (Da) nbSO3H100u IECth sPPP(1.0)(H+) 100 0 108,120.80 400 3.70 sPPP(0.9)(H+) 90 10 104,918.52 360 3.43 sPPP(0.8)(H+) 80 20 101,716.24 320 3.15 sPPP(0.7)(H+) 70 30 98,513.96 280 2.84 sPPP(0.6)(H+) 60 40 95,311.68 240 2.52 sPPP(0.5)(H+) 50 50 92,109.40 200 2.17 sPPP(0.4)(H+) 40 60 88,907.12 160 1.80 sPPP(0.3)(H+) 30 70 85,704.84 120 1.40 sPPP(0.2)(H+) 20 80 82,502.56 80 0.97 sPPP(0.1)(H+) 10 90 79,300.28 40 0.50 sPPP(0.0)(H+) 0 100 76,098.00 0 0.00

308 Table A 5: Hydrolytic stability of sPPP(m)-H+ copolymers. Copolymer State at 80°C Dissolution time sPPP(1.0)(H+) Soluble 90 min sPPP(0.9)(H+) Soluble 135 min sPPP(0.8)(H+) Insoluble - sPPP(0.7)(H+) Insoluble - sPPP(0.6)(H+) Insoluble - sPPP(0.5)(H+) Insoluble -

Table A 6: Proton conductivity values of sPPP(m)-H+ copolymers at 30°C at various relative humidities

Proton conductivity values (mS cm-1) at 30 °C Polymer 95% RH 90% RH 70% RH 50% RH 30% RH sPPP(1.0)-H+ 119.8 75.1 27.5 9.3 2.5 sPPP(0.9)-H+ 100.6 70.2 22.9 7.8 2.0 sPPP(0.8)-H+ 85.8 68.7 19.6 3.7 0.6 sPPP(0.7)-H+ 34.0 22.7 6.7 1.7 0.7 sPPP(0.6)-H+ 33.0 22.9 7.7 2.5 0.7 sPPP(0.5)-H+ 5.4 4.4 1.3 0.9 0.2 Nafion 211 78.5 49.4 12.6 1.7 0.1

Table A 7: Proton conductivity values of sPPP(m)-H+ copolymers at 80°C at various relative humidities

Proton conductivity values (mS cm-1) at 80 °C Polymer 95% RH 90% RH 70% RH 50% RH 30% RH sPPP(1.0)-H+ 338.1 211.9 83.4 32.1 6.9 sPPP(0.9)-H+ 283.4 207.3 78.4 28.8 6.7 sPPP(0.8)-H+ 319.8 222.1 84.1 32.3 4.1 sPPP(0.7)-H+ 197.9 134.5 48.4 16.0 3.4 sPPP(0.6)-H+ 133.1 109.5 41.1 12.7 2.2 sPPP(0.5)-H+ 62.0 53.5 19.4 5.6 0.7 Nafion 211 113.0 67.9 31.2 14.7 13.3

309

1 + st Figure A 114: H NMR spectra in DMSO-d6 of sPPP(1.0)-H before (red, 1 spectrum) and after exposure to Fenton’s reagent for 1 h (green, 2nd spectrum) and 3 h (blue, 3rd spectrum). Insets depict superimposed aromatic + regions. The H2O/H3O peak is typically found between 3 and 6 ppm.

310

1 + st Figure A 115: H NMR spectra in DMSO-d6 of sPPP(0.9)-H before (red, 1 spectrum) and after exposure to Fenton’s reagent for 1 h (green, 2nd spectrum) and 3 h (blue, 3rd spectrum). Insets depict superimposed aromatic + regions. The H2O/H3O peak is typically found between 3 and 6 ppm.

311

1 + st Figure A 116: H NMR spectra in DMSO-d6 of sPPP(0.8)-H before (red, 1 spectrum) and after exposure to Fenton’s reagent for 1 h (green, 2nd spectrum) and 3 h (blue, 3rd spectrum). Insets depict superimposed aromatic + regions. The H2O/H3O peak is typically found between 3 and 6 ppm.

312

1 + st Figure A 117: H NMR spectra in DMSO-d6 of sPPP(0.7)-H before (red, 1 spectrum) and after exposure to Fenton’s reagent for 1 h (green, 2nd spectrum) and 3 h (blue, 3rd spectrum). Insets depict superimposed aromatic + regions. The H2O/H3O peak is typically found between 3 and 6 ppm.

313

1 + st Figure A 118: H NMR spectra in DMSO-d6 of sPPP(0.6)-H before (red, 1 spectrum) and after exposure to Fenton’s reagent for 1 h (green, 2nd spectrum) and 3 h (blue, 3rd spectrum). Insets depict superimposed aromatic + regions. The H2O/H3O peak is typically found between 3 and 6 ppm.

314

1 + st Figure A 119: H NMR spectra in DMSO-d6 of sPPP(0.5)-H before (red, 1 spectrum) and after exposure to Fenton’s reagent for 1 h (green, 2nd spectrum) and 3 h (blue, 3rd spectrum). Insets depict superimposed aromatic + regions. The H2O/H3O peak is typically found between 3 and 6 ppm.

315