Synthesis and Characterization of Novel Imine-Linked Covalent Organic Frameworks THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Toni Beirl Graduate Program in Chemistry The Ohio State University 2015 Master's Examination Master's Examination Committee: Professor Psaras McGrier, Advisor Professor Jovica D. Badjic Copyrighted by Toni M.Beirl 2015 Abstract Covalent organic frameworks (COFs) are a class of porous crystalline materials composed of light elements (such as H, B, C, N, and O) that are linked by covalent bonds. The modular nature of COFs permits the integration of various π-conjugated molecular building blocks into highly ordered polymeric structures with low densities and high thermal stabilities making them suitable for applications related to energy storage and conversion, catalysis, and gas storage. Since a majority of the early examples of COFs contained boroxine or boronate esters linkages, many of these materials were often susceptible to hydrolysis when exposed to aqueous conditions resulting in decomposition of the framework. The recent discovery of imine-linked COFs has sparked the creation of COFs with superior chemical stability on account of an intramolecular hydrogen bond between the hydroxyl and imine functional groups, which enhances their stability in aqueous and acidic environments. Utilizing this feature, this thesis examines the synthesis and gas adsorption properties of novel imine-linked COFs that contain 1,3,5-tris(styryl)benzene and 1,3,5– tris(arylethynyl)benzene π-conjugated units. By creating analogs which were fluorescent in both solution and solid-state, studies were conducted to determine their ability to serve as chemical sensors for explosives. These studies highlight the potential benefits of utilizing both monomers for the development of COFs for gas storage and sensory applications. ii Dedication: This is dedicated to all my friends, family, and mentors who have all helped me throughout the years iii Acknowledgements I would like to thank Professor Psaras McGrier for accepting me into his group. His mentorship and guidance taught me to love chemistry and to become a better problem solver. I have learned a lot about myself and about my chemistry skills from working with him. I would also like to thank my fellow group members. Luke Baldwin and Jon Crowe were always willing to help with any problem and listen if I was having issues with an experiment. They were very helpful with learning the new instrumentation I was unfamiliar with when entering the group. Grace Eder was accepted into the group as a fellow first year with me and was always there to listen to any problems going on. My family has helped keep me grounded and focused through the time I was in graduate school. I appreciated their ability to listen to whatever I was going through. All of my friends, outside the department and within, were instrumental in my work here. They helped remind me to enjoy my time and learn as much as I could. I would like to thank all the faculty whom helped me at The Ohio State University. Dr. Chris Callam and Dr. Noel Paul allowed me to teach for them, whether it be in the teaching labs or being a head TA for them, something I learned much from. I would like to thank Tanya Young for running my solid state data for me, Cameron Begg for taking my SEMs, and Steven Bright for taking my TGAs. I would also like to thank Dr. Jovica iv Badjic for being on my committee, as well as being an incredibly helpful professor in my time here, especially when taking classes. v Vita May 2009……………………………………Ashland High School, Ashland, Wisconsin May 2013……………………………………B.S. in Chemistry, University of Louisville August 2013 to Present………………………Graduate Teaching Associate, Department of Chemistry and Biochemistry, The Ohio State University Fields of Study: Chemistry vi Table of Contents Abstract………………………………………………………………………………....ii Dedication……………………………………………………………………………....iii Acknowledgements……………………………………………………………………..iv Vita……………………………………………………………………………………...vi Table of Contents……………………………………………………………………….vii List of Tables…………………………………………………………………………....x List of Figures…………………………………………………………………………..xi List of Schemes…………………………………………………………………………xiv List of Abbreviations…………………………………………………………………...xv Chapter 1: Synthesis and Characterization Imine-Linked COFs....……........................1 1.1 Abstract……………………………………………………………………..1 1.2 Introduction…………………………………………………………………2 1.3 Results and Discussion……………………………………………………...7 1.4 Future Plans…………………………………………………………………26 vii 1.5 Conclusions……………………………………………………………….....27 Chapter 2: Gas Adsorption Studies of Imine-Linked COFs..........................……….......29 2.1 Abstract……………………………………………………………………...29 2.2 Introduction……………………………………………………………….....29 2.3 Results and Discussion…………………………………………………........35 2.4 Future Plans………………………………………………………………….45 2.5 Conclusions………………………………………………………………….45 Chapter 3: Analog Synthesis and Fluorescence Quenching….........................................47 3.1 Abstract………………………………………………………………….......47 3.2 Introduction………………………………………………………………….47 3.3 Results and Discussion………………………………………………………52 3.4 Future Plans……………………………………………………………….…60 3.5 Conclusions………………………………………………………………….60 Chapter 4: Experimental Data……………………………………………….………......62 4.1 General Methods………………………………………………………….…62 4.2 Experimental Data for Linker, Vertex A, and Vertex B………………….…64 4.3 Synthesis of Alkene and Alkyne Analog and DhaTas and DhaTae………...74 viii References and Notes…………………………………………………………….......…78 Appendix A: 1H and 13C NMR Spectra for Synthesized Compounds…………………..81 ix List of Tables Table 1: DhaTas Attempts to Increase Surface Area.....................................................12 Table 2: DhaTae Attempts to Increase Surface Area.....................................................17 Table 3: Comparison of Surface Area and Distributional Pore Volume for DhaTab, DhaTas, and DhaTae......................................................................................................44 Table 4: Percentage Fluorescence Quenching...............................................................59 x List of Figures Figure 1: Crystallinity of DhaTph after Water and Acid Treatment.............................6 Figure 2: N2 Isotherm of DhaTas..................................................................................13 Figure 3: Pore Distribution of DhaTas..........................................................................13 Figure 4: PXRD of Trial 4 of DhaTas...........................................................................14 Figure 5: PXRD for DhaTas Comparing Reaction Times............................................14 Figure 6: N2 Isotherm of DhaTae..................................................................................18 Figure 7: Pore Distribution of DhaTae..........................................................................18 Figure 8: PXRD of DhaTae...........................................................................................19 Figure 9: FTIR of DhaTas.............................................................................................20 Figure 10: FTIR of DhaTae...........................................................................................21 Figure 11: Solid State 13C NMR of a) DhaTas b) DhaTae............................................23 Figure 12: TGA of a) DhaTas b) DhaTae......................................................................24 Figure 13: SEMs of a) DhaTas b) DhaTae....................................................................25 Figure 14: COF-102 and COF-108...............................................................................31 xi Figure 15: a) CO2 uptake of DhaTas at 273 K and 298 K b) H2 uptake of DhaTas at 77 K and 87 K.........................................................................................................................36 Figure 16: a) Heat of Adsorption for CO2 of the DhaTas b) Heat of Adsorption for H2 of the DhaTas......................................................................................................................37 Figure 17: a) CO2 uptake of DhaTae at 273 K and 298 K b) H2 uptake of DhaTae at 77 K and 87 K.........................................................................................................................38 Figure 18: a) Heat of Adsorption for CO2 of the DhaTae b) Heat of Adsorption for H2 of the DhaTae.....................................................................................................................39 Figure 19: a) CO2 Uptake for all COFs b) H2 Uptake for all COFs..............................43 Figure 20: Common Nitroaromatics..............................................................................49 Figure 21: Electron-transfer Fluorescence Quenching Mechanism..............................50 Figure 22: a) COF Py-Azine b) Fluorescence Quenching using PA of COF Py-Azine..51 Figure 23: Images of Fluorescent a) Alkene and b) Alkyne Analogs.............................54 Figure 24: a) Absorbance of Alkene Analog in DMSO b) Emission of Alkene Analog in DMSO c) Emission of Alkene Analog in Solid State......................................................54 Figure 25: a) Absorbance of Alkyne Analog in DMSO b) Emission of Alkyne Analog in DMSO c) Emission of Alkyne Analog in Solid State......................................................55 Figure 26: a) Fluorescence