Design, Synthesis and Properties of -Fused Azaacenes and Their Applications in Organic Electronics

INAUGURALDISSERTATION zur Erlangung des Doktorgrades der Fakultät für Chemie, Pharmazie und Geowissenschaften der Freiburg Institute of Advanced Studies, Soft Matter Research der Albert-Ludwigs-Universität Freiburg im Breisgau

Vorgelegt von Sandeep Pandharinathrao More aus Jamb Nanded (India) 2013

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Vorsitzender des Promotionsausschusses: Prof. Dr. Thorsten Koslowski Referent: Prof. Dr. Dietmar Plattner Korreferent: Prof. Dr. A. Mateo-Alonso Datum der Promotion: 21.10.2013

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Teile dieser Dissertation wurden Veröffenlich:

Publikationen:

1. "Versatile 2,7-substituted pyrene synthons for the synthesis of pyrene-fused azaacenes", Sandeep More, Rajesh Bhosale, Sunil Choudhray, Aurelio Mateo- Alonso, Org. Lett., 2012, 14, 4170-73.

2. “A tetraalkylated pyrene building block for the synthesis of pyrene fused azaacenes with enhanced solubility”, Niksa Kulisic, Sandeep More, Aurelio Mateo-Alonso, Chem. Comm. 2011, 47, 514-517.

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To my teachers

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- 8 - Acknowledgements

This thesis has been conducted in the Department of Organic Chemistry, Albert- Luwigs University, Freiburg under the direction of Prof. Aurelio Mateo-Alonso. I wish to express my sincere gratitude for giving me the opportunity to get into research in his group. During my work I enjoyed the untiring discussion with my supervisor. Much helpful advice and the moral support from Prof. Mateo-Alonso lead to success of my dissertation work in time.

My gratitude also goes to Prof. Dr. Dietmar Plattner, who agreed to read my thesis and participated in as a referee.

I also wish to convey my thanks to Dr. Keller, Mr. Reinbold and Ms. Schonhard from NMR department. Thanks also to Mr. Warth and Mr. Wörth for the MS, Dr. Thomann for TEM images and finally to Mr. Bär for the computer service.

Special thanks to our collaborators, Prof. Ingo Krossing (Albert-Luwigs University, Freiburg) for the crystal structures and Prof. Emilio Palomares (ICIQ, Spain), Prof. Franco Cacialli (UCL, United Kingdom) and Prof. Dago De Leeuv (University of Groningen, The Netherlands) for the device studies of my molecules.

Completion of this thesis would not have been possible without the wonderful skills and valuable advices of Dr. Niksa Kulisic and Dr. Rajesh Bhosale. I would also like to thank my colleagues Francesco Scarel, Sunil Choudhary, David Boschert, Sudhakar Gaikwad, Cinzia Spinato, Burkhardt Possel, Mads Grueninger for maintaining a congenial, fun filled atmosphere in the lab.

Life in Freiburg would never been as great without Gaurima, Sachin, Sarika, Deblina, Vignesh, Rajeevan, Bobby, Pradipta and Bachhi who have been like a family to me.

My deep gratitude goes to my teachers Dr. R. P. Pawar, Dr. W. N. Jadhav, Dr. H. B. Borate, Mr. V. N. Sonnekar, Mr. C. V. Magar, Mr. T. N. Dalave, Mr. B. P. Shinde, Mr. S. T. Chavan and Mr. Narwade without whom I could never be here.

I would like to thank all my friends in Parbhani and Pune for their continuous encouragement and support.

Finally, I extend enormous thanks to my father Dr. Pandharinathrao, my mother Late Mrs. Mitravrinda, my brother Mr. Sudarshanrao, my sister-in-law Mrs. Pratibha and my sister Dr. Archanadevi for their support, love and care. Last but not the least, with a warm heart, I would like to thank my nephews and nieces Somnath, Shambhavi, Shivani and Malhar for keeping me cheerful throughout the PhD.

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Contents

1. Small molecules for organic electronics 19 1.1 Introduction 21 1.1.1 Organic field effect transistors (OFETs) 21 1.1.1.1 Working principle 23 1.1.1.2 Use of organic molecules in OFETs 26 A. Use of conjugated polymers in OFETs 26 B. Use of small molecules in OFETs 27 1.1.2 Organic light emitting diodes (OLEDs) 36 1.1.2.1. Material used in OLEDs 38 A) Use of conjugated polymers in OLEDs 38 B) Use of small molecules in OLEDs 38 Use of in OLEDs 39 Use of N containing PAHs in OLEDs 40 1.1.3 Organic photovoltaics (OPVs) 40 1.1.3.1 Use of organic material in OPVs 41 A) Use of conjugated polymers in OPVs 41 B) Use of small molecules in OPVs 42 Use of acenes in OPVs 43 Use of other PAHs in OPVs 44 1.2 References 47

2. Design, synthesis and properties of pyrene fused azaacenes 53 2.1 Introduction 55 2.1.1 Bandgap 56 2.1.2 Stability of acenes 57 2.1.3 Synthesis of acenes with greater stability 58 2.2 Heteroacenes 61 2.2.1 Introduction 61 2.2.2 Smaller azaacenes and oligo-azaacenes 61 2.2.3 Pyrene fused azaacenes 64 2.3 Synthesis of pyrene fused oligoacenes 70 2.3.1 Objective 70 2.3.2 Synthesis of non-substituted pyrene fused oligoacenes 71 2.3.2.1 Attempts to synthesize 5,6-dihydro-3b,7a-(epoxyethanooxy) [1,4] dioxino[ 2',3':9,10] phenanthro [4,5-abc]phenazine-13,14-diamine 71 Ist strategy 71 IInd strategy 72 2.3.2.2 Stepwise cyclocondensation from pyrene diketone or tetraketone 74 Ist strategy 74 IInd strategy 75 2.3.3 Attempts to synthesize di-tert.-butyl pyrene fused oligoazaacenes 75

- 11 - 2.3.3.1 Synthesis of 2,7-di-tert-butylphenanthro[4,5-abc]phenazine-11,12- diamine and further cyclocondensation 75 2.3.3.2 Attempt to synthesize 2,7-di-tert-butylpyrene fused octaazadodecacene 77 2.3.3.3 Synthesis of 5,6-dihydro-3b,7a-(epoxyethanooxy) [1,4]dioxino[2',3':9,10] 2,7-di-tert-butylphenanthro [4,5-abc]phenazine-13,14-diamine 78 Ist strategy 78 IInd strategy 79 IIIrd strategy 80 2.3.3.4 Attempts to synthesis of 2,7-di-tert-butylpyrene-4,5-diketals fused octaazadodecacene 82 2.6 Conclusion 84 2.7 References 85

3. Design, synthesis and properties of versatile 2,7-substituted pyrene fused azaacenes as low LUMO materials for OPVs 89 3.1 Introduction 91 3.1.1 1-Substituted pyrene 91 3.1.2 1,3,6,8-Substituted pyrene 92 3.1.3 4,5,9,10-Substituted pyrene 94 3.1.4 2,7-Substituted pyrene 95 3.2 Synthesis of 2,7-substituted pyrene-fused azaacenes 98 3.2.1 Objectives 98 3.2.2 Synthesis of 2,7-substituted pyrene tetraketone 99 3.2.3 Utilization of 2,7-substituted pyrene tetraketones for azaacene synthesis 100 3.2.4 Optical properties 101 3.2.5 Electrochemical properties 102 3.3 Low LUMO azaacene material synthesis 104 3.3.1 Optical properties of low LUMO azaacenes 105 3.3.2 Electrochemical properties of low LUMO materials 106 3.3.3 Photocurrent-Voltage Curves (J-V Profile) of 247 108 3.4 References 109

4. Synthesis and properties of “twisted” pyrene fused azaacenes 111 4.1 Introduction 113 4.2 Synthesis of Twistazaacene using bulky substituents 117 4.2.1 Objectives 117 4.2.2 Attempts to synthesize trimethylsillyl acetylene (TMS) substituted tetraazahexacene 117 Ist attempt 117 IInd attempt 118 4.2.3 Synthesis and crystal structure study of tri-isopropylsilyl (TIPS) acetylene substituted tetraazahexacene 119

- 12 - 4.2.4 Synthesis and crystal structure study of tri-isobutylsilyl (TIBS) acetylene substituted tetraazahexacene 121 4.2.5 Synthesis and crystal structure study of tri-phenylsilyl (TPS) acetylene substituted tetraazahexacene 123 4.3 Optical properties 125 4.4 Conclusion 126 4.5 References 127

5. Self-assembling properties of 2,7-substituted pyrene fused azaacenes 129 5.1 Introduction 131 5.2 Supramolecular self-assemblies of 2,7-substituted pyrene azaacenes 133 5.2.1 Self assemblies of compound 241a 134 5.2.2 Self assemblies of compound 241b 138 5.3 Conclusion 139 5.4 References 140

Experimental Procedures 143

Appendix 181

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- 14 - Abbreviations

AcOH Acetic Acid °C Centigrade degree C-C Carbon-carbon C-N Carbon-nitrogen

CHCl3 Chloroform d Doublet DCM DFT Density Functional Theory

DIPA di-iPropyl Amine

DIPEA di-iPropylethyl Amine DMF Dimethylformamide EA Ethyl Acetate EI Electronic Impact eq Equivalent ESI Electrospray Ionization Et Ethyl EtOH Ethanol hrs Hours HCL Hydrochloric Acid HOMO Highest Occupied Molecular Orbital Hz Hertz i-Pr iso-Propyl J Coupling constant LUMO Lowest Unoccupoed Molecular Orbital m Multiplet Me Methyl mmol Milimolar MS Mass spectrommetry NMR Nuclear magnetic resonance NIR Near infrared ODCB o-Dichlorobenzene OFET Organic Field Effect Transistor OLED Organic Light Emitting Diode

- 15 - OPV Organic Photovoltaic PE Petrolium Ether (40-60oC) Ph Phenyl PAH Polycyclic Aromatic ppm Parts per million PTSA p-Toluenesulphonic Acid PTSCl p-Toluenesulphonyl Chlorid rt Room temperature s Singlet T Temperature t Triplet TFA THF Tetrahydrofuran

TIBS tri-iButylsilyl

TIPS tri-iPropylsilyl TLC Thin layer chromatography TMS Trimethylsilyl TPS Triphenylsilyl UV-Vis Ultraviolet-visible V Volts

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Chapter: 1

Small Molecules for Organic Electronics

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- 20 - 1.1. Introduction: The use of organic materials in electronic devices is motivated by their ease in tuning electronic and processing properties by chemical design and synthesis, relatively low cost processing, mechanical flexibility, and compatibility with flexible substrates. Among these electronic products, organic light-emitting diode (OLED) technology is already used in commercial applications such as displays for mobile phones and portable digital media players, car radios and digital cameras, while other technologies with great potential are under development such as organic field-effect transistors (OFET) and photovoltaic (OPV) solar cells. Nevertheless some device OFET and OPV prototypes are on the edge for market entry. Organic materials are also proving their economic and ecological benefits along with design and application options such as in large-area lighting, flexible displays, etc.1 Different types of organic material have been used in electronics in the form of conjugated polymers and small molecules. The conjugated polymer implemented electronics is also known as “plastic electronics” which flourished in the 1970s with the seminal discovery of iodine doped semiconducting polyacetylene.6 It has showed advantages over silicon regarding the cost and processing and the efficiency is now competing in the technologies where amorphous silicon is currently used. But still there are some drawbacks regarding solubility and batch-batch variation in molecular weight and purity that varies the device performance.2 The formation of oligomers and the catalysts used during polymerization are difficult to separate which drops the purity of polymeric material. The implementation of small molecules in organic electronics started in 1963 when Pope and co-workers studied the electroluminescence of .52b It has been now refocused due to their advantages over polymers such as comparatively easy purification and in some cases easier synthesis. With small molecules the molecular precision is greater than that of synthetic polymers. However to make the field competitive regarding the cost and efficiency it still needs more research efforts in material efficiency and process technology.

1.1.1. Organic Field Effect Transistors: Since the 1950’s metal oxide semiconductor field effect transistors (MOSFET) are used in processors of daily electronic appliances. MOSFETs are made of silicon and/or gallium arsenide as semiconductor. Since last decade the focus on using organic semiconducting materials instead of silicon in field effect transistors is due to the low cost processing and compatibility with flexible substrates as well as easily tunable electronic properties by chemical design and synthesis.

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Fig. 1: Display made out of flexible OFET. (Source: http://www.techspot.com)

Historically organic materials were known as insulators and were commonly used in containers, packing, molding, coating, etc. Several attempts to prepare “conducting organic material” were carried out such as the synthesis of polyaniline by F. Goppelsroeder.3 The view towards organic molecules as “electronic material” was advanced in 1940s when Mulliken came up with the self-consistent field (SCF) molecular orbital theory for which he got Nobel Prize in 1966. But apart from the technical contribution he directly contributed by the study of donor-acceptor or charge transfer complexes. Further in compendious study of these charge transfer complexes was done in 1961 by Briegleb.4 The metallic complex of tetrathiofulvalene (TTF) and tetracyanoquinonedimethane (TCNQ) with maximum conductivity came up in 1973 (Fig. 2a and 2b).5 In this complex TTF works as stong electron donor and TCNQ as strong electron acceptor. Depending on the TTF-TCNQ charge transfer complex, in 1974 Aviram and Ratner from IBM proposed the molecular rectifier consisting donor π system (TTF) and acceptor π system (TCNQ), separated by a sigma-bonded bridge (Fig. 2c). They calculated response of the molecule to an applied field and found rectifier properties.6

a) b) S S NC CN

S S NC CN

TTF TCNQ

c) NC CN

S S

S S

NC CN

Fig. 2: a) TTF as donar b) TCNQ as acceptor c) Molecule rectifier proposed by Aviram and Ratner

- 22 - Shirakava along with Heeger and Mac Diarmid’s group reported the conductivity of polyacetylene upon doping with iodine (Fig. 3).7

Fig. 3: Schematic representation of device reported by Heeger and co-workers.

This discovery of highly conductive polymers boosted research in the field, which contemplated on the synthesis and evaluation of π-conjugated systems. As a result in 1986, A. Tsumura and co-workers came up with first organic field effect transistor (OFET) in which polythiophene was used as semiconductor with mobility -10-5 cm2/(V.s).8

1.1.1.1. Working Principle: The OFETs consists of three terminals i.e. drain, source and gate electrode, a gate insulator and organic semiconducting layer. Depending on the positions of these terminals there are four types of OFETs (Fig. 4), top contact (2a), bottom contact (2b), top gate/bottom contact (2c) and top gate/top contact (2d). The path in organic semiconductor along which the current flows or the area between source and drain electrode is called channel and at the ends of channel there are two electrodes, they are called as source and drain respectively. There is also a control electrode which helps to change the diameter of channel on applied voltage is called as gate. Usualy the diameter of channel is fixed but it can be varied with the help of gate in order to get better conductivity.

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Fig. 4: Types of OFET device.

The charge carrier mobility is one of the crucial paramaeter in the OFETs it can be explained as the drift of electrons or holes through the semiconductor when applying electric field. The charge carrier mobility is calculated by the equation below.

WC i 2 IDS = µ (VG - V0) 2L where, IDS is the current measured between source and drain, W is the channel width i. e. gap between source and drain, the capacitance of gate insulator per unit area is denoted by Ci, L is the length of channel i.e. distance between source and drain electrode, µ is the field effect mobility, VG is the applied gate voltage. The charge carrier mobility is reported as cm2V-1s-1, it is clearly the ratio of the drift velocity of the charge carrier (cm s-1) to the applied electric field (cm V-1). The mobility in the magnitude of 1 cm2V-1s-1 is essential in order to get mobility in competence with amorphous silicon with on/off ratio greater than 105. There are several factors affecting the performance of the OFET devices and interface interaction is also one of them. According to literature, bottom gate / top contact (2b) and top gate / bottom contact (2c) showed better results than the other two, might be due to the improved interface between the semiconductor layer and the electrodes9. Apart from the engineering of the device there are two more key factors affecting the mobility, which are taken into consideration. The first is transfer integral i. e. the splitting of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and secondly, the energy loss when charge carrier passes through molecule known as recognition energy. Both these parameters depends on packing of the molecule, π-conjugation length and degree of conjugation.10 The molecular packing is the arrangement or ordering of the molecules in solid

- 24 - state. There are two main types of packing motifs i. e. herringbone and lamellar as shown in Fig. 5. In herringbone arrangement the molecules are face to edge arranged (Fig. 5a-b), in the lamellar type of motifs the arrangement of molecule is face to face as shown in Fig. 5c-d.

Fig. 5: Molecular packing motifs in crystals. (A) Herringbone packing (face-to-edge) without π overlap (face-to-face) between adjacent molecules; (B) herringbone packing with π overlap between adjacent molecules; (C) lamellar motif, 1-D π stacking; (D) lamellar motif, 2-D π stacking.

The lamellar motif is proved to be significant for the better charge mobility11 may be due to the face to face interaction increased which makes the charge to move along the shortest distance and the transfer integral goes to its maximum. As we have discussed briefly about the charge carrier mobility, these charges can be electrons (negative charge), holes (positive charge) or both. Depending on the charge carrier, OFETs are divided mainly into three types, n-type, p-type and ambipolar. In n-type electrons are the majority carrier whereas in p-type holes are carried with majority and in ambipolar both electrons and holes are charge carriers. In p-type the Fermi level of source-drain metal is close to the highest occupied molecular orbital (HOMO) level of the organic semiconductor (Fig. 6a) and when negative gate voltage is applied, positive charges are induced at the organic semiconductors which can be extracted by the electrodes on applying a voltage, VDS between drain and source. Such organic semiconductor conducts positive charge or holes with majority. Whereas in n-type semiconductors the Fermi level of source-drain electrodes is

- 25 - close to lowest unoccupied molecular orbital (LUMO) of the semiconducting material (Fig. 6b). On applying positive gate voltage, the negative charges are induced at the semiconductor, can be extracted by applying voltage between source and drain.

Fig. 6: Schematic representation of n-type and p-type semiconductors.

Investigations are currently carried out all over the world on the synthesis of semiconducting organic material among which there are small molecules, oligomers as well as polymeric material. All these kind of materials have their own advantageous properties in order to get better performance.

1.1.1.2. Use of organic molecules in OFET: There are two distinct classes of the organic material used for OFETs such as conjugated polymers and small molecules and they have their own advantages that makes them ideal candidate for OFET device.

A. Use of conjugated polymers in OFET: Derivatives of conjugated polymers such as polythiophene (1),12 polyarylamines (2),13 polyfluorene (3)14 have been implemented in OFETs.

- 26 - C10H21

S S S S S S S S n C10H21

1, µ = 0.003 cm2/(V·s)

X X

C8H17 C8H17 N n

n

3, µ = 10-3cm2/(V·s) 2, µ = >0.003 cm2/(V·s)

Fig. 7: Polymers used for OFET and their mobilities.

There is plenty of literature available on the polymer based OFET but it is not mentioned here as the objective of this thesis is applications of small molecules in organic electronics.

B. Use of small molecules in OFET: Polyaromatic (PAH) such as acenes, azaacenes, oligomers, etc. are examples of small molecule semiconductors. There are some advantages such as comparatively easy synthetic and purification protocol, defined geometry and more molecular precision than the conjugated polymers. These small molecules are usually vacuum-deposited and the channels formed are either polycrystalline or monocrystalline. Usually the single crystal or monocrystalline channels exhibit high carrier mobility and reproducibility of properties. The small molecules are devided into two main classes i. e. p-type and n-type depending on the charge carriers.

a. Use of small molecules as hole carriers in OFET (p-type): The small molecules, which conduct positive charge or holes with majority, are known to be p-type molecules. There are different types of such small molecules, among those selected examples of PAHs including small acenes and azacenes has been briefly explained.

i) Use of acenes as hole carriers in OFET (p-type): Aromatic hydrocarbons like acenes are used in OFETs as the semiconducting layer. Acenes are class of aromatic hydrocarbons made up of linearly fused rings. The π electron cloud in fused benzene rings makes them promising candidate for transistors. In this section implementation of small acenes like, , anthracene, and in OFET along with their charge carrier mobilities has been

- 27 - explained briefly. The analogues of small acenes showed wide range of bangaps and tunable colour and packing morphology, which was advantageous for their implementation in OFETs.

Use of naphthalene derivatives as hole carriers in OFETs: Thiophene15 (4) and thenothiophene16 (5) substituted naphthalene (Fig. 8) derivatives were synthesized and studied, which have shown mobilities 0.14 cm2/(V·s) and 0.084 cm2/(V·s) respectively. There are several reports on anthracene analogues for OFETs may be because of the more mobility than naphthalene and higher stability than higher acenes such as tetracene, pentacene.

S C6H13

C8H17 S S S S C8H17

4 C6H13 S 5 µ = 0.14 cm2/(V·s) µ = 0.084 cm2/(V·s)

Fig. 8: Naphthalene derivatives used for OFET and their mobilities.

Use of anthracene derivatives as hole carriers in OFETs: The monomer anthracene has shown the time of flight mobility reaching upto 3 cm2/(V·s). In order get more extended π conjugation and planarity 2,6-oligoanthrylenes were reported by Suzuki. Dimer 6 has shown mobility 0.01 cm2/(V·s) without any substituent and after alkyl substitution (Fig. 9) the mobility is 0.13 cm2/(V·s). Anthracene trimer such as 7 with and without alkyl substitution shows mobility 0.07 and 0.18 cm2/(V·s).17 But the mobilities reported here are obtained with substrate at 175oC that limits the number of different substrates. Apart from these oligomers there are also anthracene derivatives in which the 2,6 position substitutions are other aromatic molecules like thienyl 8, thienothiophene 9. Alkyl substitution display enhanced mobility as compared to their non alkylated analogues.

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R 6 R 7

R = H, µ = 0.01 cm2/(V·s) R = H, µ = 0.07 cm2/(V·s) 2 2 R = C6H13, µ = 0.13 cm /(V·s) R = C6H13, µ = 0.18 cm /(V·s)

S C6H13

R S S S S R 8 C6H13 S 9 R = H, µ = 0.06 cm2/(V·s) µ = 0.14 cm2/(V·s) 2 R = C6H13, µ = 0.5 cm /(V·s)

Fig. 9: Anthracene derivatives used in OFETs and their mobilities.

18 2,6-Substituted are almost planar. It has been reported that, if there is substitution at 9,10 position (Fig. 10) like 9,10-diphenylanthracene (DPA) 10, it is very difficult to get crystalline thin film. Because of this single crystal of DPA exhibit hole mobility of 3.7 cm2/(V.s)19 and the nanoribbon obtained from DPA gives only 0.16 cm2/(V.s).20 Instead of phenyl substitution 10, phenyl acetylene substitution 11 raised mobility of device up to 0.5 cm2/(V.s).21 The dimer via 9,10 substitution 1222 exhibit mobility of 0.8 cm2/(V.s). The trimer 13 was also synthesized with long alkyl chains in order to increase the solubility. The 13 showed mobility upto 0.055 cm2/(V.s) and 0.0025 cm2/(V.s) after annelation.23

10 12 11 0.16 cm2/(V·s) µ = 0.8 cm2/(V·s) µ = µ = 0.5 cm2/(V·s)

C10H21 C10H21

13 µ = 2.5x10-3 cm2/(V·s)

Fig. 10: 9,10-substituted naphthalene and their mobilities.

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Use of tetracene as hole carriers in OFETs: Tetracene (14) and its derivatives has not been studied extensively as anthracene. The reason might be the low reactivity of terminal carbons or less stability than anthracene.24 But still tetracene has been used in FET with hole mobility of 0.1 2 25 2 26 cm /(V·s) whereas the tetracene single crystal showed mobility upto 1.3 cm /(V·s). The thiophene-tetracene hybrid 15 was synthesized and used for OFET, showed high mobility 0.5 cm2/(V·s) and it exhibits more thermal and oxidation stability.27 The most studied analogue of tetracene studied is rubrene (5,6,11,12-tetraphenyl tetracene) 16 as shown in Fig. 11 which is now a criterion for single crystal mobility in OFETs. Rubrene exhibits mobility of 20 cm2/(V·s).28 But the thin film mobility of rubrene is 0.7 cm2/(V·s) with improved method for thin film formation.29 This difference in the mobility of rubrene crystal and thin film is due to the lack of good planarity in rubrene which prevents formation of good thin film. There are also halogen substituted tetracene derivatives 17-19 reported in the literature by Bao and co-workers30. The monochloro and mono bromo analogue of tetracene 17 and 18 shows mobility of 1.4x10-4 and 2.4x10-3 cm2/(V·s) respectively. The dichloro derivative 19 exhibits mobility of 1.6 cm2/(V·s). The 17, 18 shows herringbone motif and 19 slipped π-stack motif. May be because of this changed motif π-π interaction in 19 is increased, which resulted in the increase in mobility. As mentioned already the rubrene showed good results, by taking into consideration the properties of simple rubrene, substituted rubrene is also studied. The crystal of tert- butyl substituted rubrene 20 showed mobility of 12 cm2/(V·s) where as the tert-butyl substitution on tetracene core (21) exhibit mobility of 2x10-3 cm2/(V·s). This difference might be due to the bulky tert-butyl groups on tetracene core which disturbed the intermolecular π-π stacking.

S

14 S µ = 0.1 cm2/(V·s) 15 µ = 0.5 cm2/(V·s)

R

R3

R R 3 17 = R = Cl, R' = H µ = 1.4x10-4 cm2/(V·s) 18 = R = Br, R' = H µ = 2.4x10-3 cm2/(V·s) 19 = R = R' = Cl µ = 1.6 cm2/(V·s) 16 R1 R2 µ = 0.7 cm2/(V·s) 20 = R = R = H, R = t-Bu µ = 12 cm2/(V·s) µ = 15.4 cm2/(V·s) 1 3 2 -3 2 21 = R1 = H, R2 = R3 = t-Bu µ = 2x10 cm /(V·s)

Fig. 11: Tetracene and its analogues used for OFET.

- 30 - Use of pentacene as hole carriers in OFETs: 31 Pentacene 22 crystallizes in typical herringbone motif but its potential polymorphic nature complicates further the device studies. After numerous studies on the vapor deposited thin films of pentacene, it showed mobility more than 1.5 cm2/(V·s)32 which was improved to 5 cm2/(V·s).33 On reducing the impurity of pentacenequinone the pure pentacene crystal showed mobility of 35 cm2/(V·s).34 There have also been studies on the improvement of thermal stabiliy and solubility of pentacene. To achieve more solubility and thermal stability the were substituted at the terminal carbons with different groups like methyl, alkyl chains, halogens, as shown in Fig. 12. The tetramethyl pentacene 23 exhibits mobility upto 0.3 2 35 cm /(V·s) and it was more stable thermally than pentacene 22. The dimethyl analogue 2436 showed more mobility i. e. 2.5 cm2/(V·s) than 23. The mobility was decreased to 0.5 cm2/(V·s) on putting long chain so Bao and co-workers came up with electron withdrawing substituents which were helpful to reduce the HOMO of pentacene core and also resulted in stable devices in air and light.37 Among all the compounds mono- bromo derivatives showed mobility upto 0.13 cm2/(V·s). The nitrile substituted 27 and trifluoromethyl substituted 28 pentacene showed almost similar mobility up to 0.3 cm2/(V·s). The dibromo derivative 29 showed maximum mobility up to 0.23 cm2/(V·s). Similary, the bromo substitution at the end positions of pentacene was done and studied the OFET devices made out of the respective products. For the dibromo analogue 31 the mobility found was 0.06 cm2/(V·s). But the device making out of tetrabromo derivative 30 was not carried out due to the elimination of bromine at 150oC that was confirmed by TGA and elemental analysis.

R R'

R' R 22 2 23 = R = R' = CH3, µ = 0.3 cm /(V·s) µ = 1.5 cm2/(V·s) 2 24 = R = CH3, R' = H, µ = 2.5 cm /(V·s) 2 25 = R = C6H13, R' = H, µ = 0.5 cm /(V·s)

R R R'

R' R' R 2 26 = R = Br, R' = H, µ = 0.13 cm /(V·s) 30 = R = R = Br, 2 27 = R = CN, R' = H, µ = 0.03 cm /(V·s) 31 = R = Br, R' = H,µ = 0.06 cm2/(V·s) 2 28 = R = CF3, R' = H, µ = 0.03 cm /(V·s) 2 29 = R = R' = Br, µ = 0.23 cm /(V·s)

Fig. 12: Pentacene and its “end” substituted analogues used for OFET with their mobilities.

Functionalization on the peri position avoids dimerization of pentacene. By using these substitution strategies dimers or “oligomers” of pentacene have been syntheisized.38 Before this the phenyl substitution was done first at the peri positions39 following which, different type of substituents were used. The tert-butyl acetylene substituted pentacene 32 showed mobility around 10-4 cm2/(V·s). This pentacene

- 31 - showed slipped π-stacking may be due to the shorter length of substituents than the pentacene core that underlines the assumptions in the literature,40 which arose equivocal thoughts that the motif changes from, herringbone to lamellar if the length of substituents is almost the half of core. The TMS substituted pentacene 33 exhibits mobility upto 10-5 cm2/(V·s) which was not improved than 32 but the mobility of 34 reached upto 1.8 cm2/(V·s).41 Quian and co-workers synthesized some biphenyl 35 and thienyl 36 substituted pentacene (Fig. 13) which showed mobility upto 8x10-5 and 0.1 cm2/(V·s) respectively. As like in tetracene the acetylene substituted analogues for pentacene are available.42 Then the derivatives like 38 were reported which were having good solubility and mobility around 10-5 cm2/(V·s).43 Later on the same type of analogue with alkyl chain was reported by Ong et al. which exhibit mobility up to 0.08 cm2/(V·s) with spin coated film and was up to 0.52 cm2/(V·s) with drop casted single crystal or nanoribbon.44 Recently the dimer, trimer and tetramers of pentacene with solubilising group were synthesized and studied their crystal properties by Tykwinski and co-workers.45 Among these derivatives the dimer with TIPS substitution 37 showed mobility of 0.11 cm2/(V·s).

R

R

R

R -5 2 32 = R = t-Bu, µ = 10-4 cm2/(V·s) 35 = R = Phenyl, µ = 8x10 cm /(V·s) -5 2 2 33 = R = SiMe3, µ = 10 cm /(V·s) 36 = R = 2-Thienyl, µ = 0.1 cm /(V·s) 2 34 = R = Si(i-pr)3, µ = 1.8 cm /(V·s)

R' R R Si

Si R R R'

37, µ = 0.1 cm2/(V·s) 38 = R = R' = OMe, µ = 10-5 cm2/(V·s) 0.1 cm2/(V·s) 39 = R' = C5H11, R = H, µ =

Fig. 13: Pentacene and its “peri” substituted analogues used for OFET with their mobilities.

- 32 - Higher acenes and angular acenes for OFETs: The synthesis of analogues of higher acenes like, 40 and heptacene 41 and 42 as shown in Fig. 14 have been reported,46 which is very impressive but they have not been studied (for OFETs) because of the lack of stability.

Si SiR3

Si SiR3

41 = R = SiMe3 42 = R = t-Bu 40

Fig. 14: Hexacene and heptacene derivatives.

There are also some acenes, which are not linearly fused but used for OFETs. The (isomer of anthracene) analogues 43, 44 were synthesized and used for 47 o FET. The analogues 43 was fabricated at Ts (substrate temperature) 150 C and showed saturation region mobility up to 1.1x10-2 cm2/(V·s) and 44 showed 2.5x10-2 cm2/(V·s).

S S

43 44 µ = 1.1x10-2 cm2/(V·s) µ = 2.5x10-2 cm2/(V·s)

Fig. 15: Non-linearly fused acenes used for OFET with their mobilities.

ii) Use of Azaacenes as hole carriers in OFET (p-type): In addition to simple acenes, heteroacenes constituting nitrogen as heteroatom i.e. azaacenes were also implemented in organic semiconductors. The azacenes were found to be more stable than their simple acene analogues and exchange of carbon with nitrogen atom does not affect the aromaticity. In some cases the synthesis of heteroacenes found to be easier than simple acenes. The dihydro derivatives of diazapentacene and diazahexacene (Fig. 16) were reported by Nuckolls and workers,48 among those derivatives, 45 exhibit mobility up to 0.45 cm2/(V·s) and the other dihydrodiazapentacene derivatives 49 and 50 showed similar mobility upto 10-3. The dihydrodiazahecacene 48 showed mobility 5x10-5 cm2/(V·s). The chloro derivatives of diazapentacene 101g and dihydrodiazapentacene 46 were also implemented in OFET that showed mobility up to 0.13 and 1.4 cm2/(V·s) respectively.49 Liu and co-workers reported the OFET performance of tetraazapentacene derivatives 51, 52 and 53.50 Among these the tetraazahexacenes 51 and 52 exhibited mobilities upto 0.02 and 0.01 cm2/(V·s) respectively where as 53 showed very low mobility upto 10-5 cm2/(V·s).

- 33 -

R R Cl Cl H H N N N

N N N H H R R Cl Cl

45 = R = H, µ = 0.45 cm2/(V·s) 47, µ = 0.13 cm2/(V·s) 48, µ = 5 x 10-4 cm2/(V·s)

46 = R = Cl, µ = 1.4 cm2/(V·s)

R'' H N R R N N R'

N R R' N N R H R'' 49 = R = H, µ = 10-3 cm2/(V·s) 51 = R = R' = R'' = H, µ = 0.02 cm2/(V·s) 50 = R = CH 3 2 52 = R = R'' = H; R' = CH3, µ = 0.01 cm /(V·s) -5 2 53 = R = R'' = CH3; R' = H, µ = 10 cm /(V·s)

Fig. 16: Linearly fused azaacenes used for OFET with their mobilities.

Apart from these linearly fused azaacenes, the tetraphenylbisindoloquinoline 54 also showed properties of p-type semiconductor material with mobility upto 1 cm2/(V·s).51 The pyrene fused azaacene 55 was also implemented in OFET and showed mobility upto 10-3 cm2/(V·s).52

N C12H25S N N SC12H25 N C12H25S N N SC12H25

-3 2 54, µ = 1 cm2/(V·s) 55, µ = 10 cm /(V·s)

Fig. 17: Examples angular and pyrene fused azaacenes b) Use of small molecules as electron carrier in OFET (n-type):- The small molecules, which conduct negative charge or electrons with majority, are known to be n-type molecules. There are different types of such small molecules, among those selected examples of PAHs including small acenes and azacenes has been briefly explained.

i) Use of acenes as electron carrier in OFET (n-type):- The general requirement for a molecule to implement as n-type material is LUMO level close to work function of the source and drain electrodes. Using electron withdrawing substituents like halogenes, cyano, nitro, etc can decrease the LUMO of respective material.

- 34 - There are not many reports on n-type acene semiconductor material as like in p- type acenes. The different substituted acenes used for n-type OFETs are briefly explained here. For n-type semiconductors fluorine is one of the most used substituent as shown in Fig. 18. The n-type semiconductor with anthracene unit 56 was prepared in order to study the effect of functional groups on anthracene terminal by Yamashita and co- workers and the compound 56 exhibit mobility up to 0.0034 cm2/(Vs).53 The pentacene derivaties 57 and perfluorinated pentacene 58 exhibit electron mobility around 0.0017 and 0.11 cm2/(V·s) respectively.54

F C 3 F F F F F C4F9 F F

C4F9 F F F F F F F CF3 56, µ = 3.4x10-3 cm2/(V·s) 57, µ = 1.7x10-3 cm2/(V·s) 58, µ = 0.11 cm2/(V·s)

Fig. 18: Examples of n-type semiconductor acenes used for OFET with their mobilities.

ii) Use of azaacenes as electron carrier in OFET (n-type): As like in simple acenes, the most applied method for the preparation of n-type azaacene material is by using electron withdrawing substituents like trifloromethyl, cyano, etc. Here, examples of such azacenes constituting pyrazine are mentioned briefly. The use of trifluoromethylphenyl as electron withdrawing group gave the molecules 59-61 that showed n-type semiconducting properties (Fig. 19). The molecule 59 and 60 exhibited mobilities upto 0.03 and 0.01 cm2/(V·s) respectively where as the molecule 61 didn’t show any mobility.55 Similarly, the azacenes with cyano substitution 62-65 were synthesized and checked FET device properties but showed very low mobilities in the range of 10-8-10-6 cm2/(V·s).56

- 35 - F3C F3C CF3 N CF3 N N N N N N F3C N F3C CF3 CF3 59, µ = 0.03 cm2/(V·s) 60, µ = 0.01 cm2/(V·s)

R1 R N N CN CF3 2

R3 N N CN F3C R4 N N 62 = R1 = R2 = R3 = R4 = H, µ = 3.6 x 10-6 cm2/(V·s)

N 63 = R1 = R4 = H; R2 = R3 = CH3, µ = 1.0 x 10-8 cm2/(V·s) 64 = R1 = R4 = H; R2 = R3 = OCH3, µ = 2.1 x 10-7 cm2/(V·s) F3C 65 = R1 = R4 = OCH3; R2 = R3 = H, µ = 2.5 x 10-7 cm2/(V·s) 61 CF3

Fig. 19: Examples of n-type azaacenes used for OFET with their mobilities.

1.1. 2. Organic light emitting diodes: The light emitting diodes in which organic material is used as an electroluminescent layer are typically known as organic light emitting diodes (OLEDs). These materials are used popularly now days in TV screens, digital displays, mobile screens, computer screens, etc. (Fig. 20) due to their light weigth, flexibility, faster response and improved brightness.

Fig. 20: Flexible OLED and implementation in display. (Source: http://www.charterworld.com; http://www.attendconference.com)

Electroluminescenece means the phenomenon where fluorescent material emits light in response to electric field. This was observed and studided extensively in

- 36 - 1960s.57 The first organic light emitting diode (OLED) was prepared first by Chin Tang in Kodak using modern thin film deposition technique with commodious material and structure.58 The advantages of using organic material are like, greater brightness, fast response time, low power consumption, thin and more flexible devices, etc. There are different types of OLED structures depending on the number of layers. In the single layer OLED (Fig. 21) the organic layer (EML) is sandwiched between cathode and anode. This organic layer should have higher quantum efficiency as well as ability to transport both holes and electrons. In two layer OLED, there are two separate layers transporting hole and electrons. At the interface of these layers the charge recombination takes place and generates electroluminescence. In three layers OLED there is one additional luminescent layer in between hole transporting and electron transporting layer. This system allows optimization of hole transporting, electron transporting and luminescent properties independently. This helps to improve the luminescence or to choose desired color of luminescence. These OLEDs are useful for the emissive materials not having desirable charge transport properties. In case of multi layered OLED electron injection layer is also introduced which helps to prevent leakage of charge carriers and prevents the quenching of excitons. Now days the multiple layer design is being popular among the material chemists.

Fig. 21. Structure of different OLEDs. ( C = cathode; EL = emitting layer; ETL = electron transport layer; HTL = hole transport layer; HIL = holeinjection layer; A = anode small molecules)

The functioning of OLEDs can be explained briefly as, electrons are injected from cathode to the LUMO of the electron transport layer (ETL) and holes are injected by anode to the HOMO of hole transport layer (HTL). These holes and electrons starts to move under high potential towards the opposite charged electrodes. The holes get injected in the HOMO and electrons in the LUMO of the emissive layer (EML). In the

- 37 - EML the charge recombination takes place and excitons are formed. These excitons jumps back from excited state to ground state and emission of light takes place with color depending on the type of molecule used in EML.

1.1.2.1. Material used in OLEDs: There are mainly two types of material used in OLED, polymer and small molecules. The conjugated polymers are also known to be semiconducting and this conductivity of conjugated polymers is associated with the delocalized π molecular orbitals.

A. Use of conjugated polymers in OLEDs: The conjugated materials got attraction due to their properties such as, flexibility, easy film forming capability, solution processability, etc which were suitable for device making. Conjugated PPV polymer 66 (Fig. 22) was reported by Burroughes and co- workers in 1990 and also reported the photoluminiscenece quantum yield around 8%.59 Pyrene based deep blue emitting polymers 67 and 68 were reported by Müllen and co- workers. The photoluminniscence quantum yields for these blue emitting polymers was 88% and 77% respectively.60 Recently benzimidazole and based copolymer 69 has been reported as blue light emitting material.61

N

n n m

n 66

67 68

N N

N N C H R R 8 17 C8H17 n 69 = R = H 70 = R = C8H17

Fig. 22: Examples of conjugated polymers used for OLEDs.

There are many reports on cojugated polymers used in OLED62 but only few are mentioned here, as main focus of the thesis is on applications of small molecules in organic electronics.

B. Use of small molecules in OLEDs:- There are lots of examples of small molecules used in light emitting devices as electroluminescent layer. In this section, PAHs such as acenes and some heteroacenes

- 38 - comprising imidazole used in OLEDs are mentioned. a. Use of acenes in OLEDs: There are many reports on acenes used for OLEDs, selected examples of small acenes such as anthracene, tetracene and pentacenes are choosen and explained briefly. Anthracene is used due to its strong fluorescence. The triisopropylsilylacetylene substitution on anthracene 71 shown in Fig. 23 gives an amorphous material. The TIPS acetylene substitution, which is electronically an insulator, keeps the chromophore isolated from each other. When crystalline films of this material were used in LED, it gives bright blue emission63 at the display intensity of 100 Cd/m2 and emission can be reached maximum to 1000 Cd/m2. The sustituion of methoxy groups as like 72 didn’t chage much the intensity or colour of emission from 71. There are several methods in literature to put bulky groups at the 9,10 positions of anthracene.64 If the substitutents on anthracene chromophore are bulky groups as in 73, it breaks the aggregation of the molecules in the solid state. The aggregates usually supposed to quinch the emission. So with the help of bulky groups the chromophores got very well isolated and produced amorphous compound with bright blue electroluminescence.65 Tetracenes are not very much explored for OLEDs. But the substituted tetracene 74 can work as both light emitting diode as well as field effect transistor (LEFET) due to its hole mobility.66 The compound 74 emits red but due strong π-π interactions the emission is low. Similarly the aryl substitution at 6,13-positions of pentacene 75 was used in LED and gave nice red emission out of the device.67

Si Si

OCH3

H3CO

Si Si

71 72 73

Si

S

OCH3

OCH3

S

Si 75

74

Fig. 23: Examples of acenes used for OLEDs.

- 39 -

Different types of aryl substitutions such as 76, 77 (Fig. 24) have been prepared to improve solubility to ease purification. Some of them display very good solubility and gave nice red electroluminescence even with low concentrations.68 The pentacne 78 showed bright red emission with quantum yield of 3.3 % when used used with an Alq3 host and 78 guest.69 R Si

R' R' O O

O O R' R'

Si R

76 = R = H, R' = CH3 78 77 = R = t-Bu, R' = H

Fig. 24: Examples of pentacenes used for OLEDs. b. Use of N containing PAHs in OLEDs:- There are not many reports available on implementation of azaacenes in OLEDs, the reason might be the change in electronic properties after introducing nitrogen in acene. Here are some very recent examples of nitrogen containing polyaromatic hydrocarbons mentioned briefly in Fig. 25. Blue light emitting material has been derived from phenanthro[9,10-d]imidazole building block 79-81, among which, 81 showed very low efficiency and the other two, 79 and 80 showed maximum luminescence of 40000 and 10000 Cd/m2 respectively.70

N N

N N N

N N N

81 80 N N

N N

79

Fig. 25: Examples of nitrogen containing PAHs used for OLEDs.

1.1.3. Organic photovoltaics (OPVs): - Organic photovoltaic cells have shown their advantages with low weight, low cost processing and flexibility. OPV cell consists of four basic units as, substrate, anode, active layer and cathode. The active layer is basically heterojunction of electron donor

- 40 - (D) and electron acceptor (A) material. When light photon enters, the creation of excitons takes place that dissociate at the D/A interface and formation of holes and electrons. These charges flow towards their oppositely charged electrodes which generates the electric power. The architecture of the OPV is as shown in Fig. 26, based on the arrangement of donor and acceptor, there are two main types of heterojunction, a) bilayer heterojunction b) bulk heterojunction.71 Before these techniques, single layer of organic material use to be sandwiched between two electrodes with different work functions.72 The photovoltaic properties were counted on the nature of the electrodes and efficiency was also very low. The bilayer heterojunction in solar cell was first used by Tang in 1986 and obtained efficiency around 1%. Since then there is extensive research going for the development of the bilayer heterojunction. The limitation of this type is the short exciton diffusion length. The diffusion takes place at the interface of the D/A layers and not all the excitons will be able to reach the interfacial zone that limits the maximum thickness of active layers.

Fig. 26: The architecture structure of bilayer heterojunction (left) and BHJ (right) OPV devices.

Later in 1992 Heeger and Wudl succeed to get highly efficient photoinduced 73 electron transfer by blending donor (conjugated polymer) and acceptor (C60). But the terminology of bulk heterojunction (BHJ) was introduced by Alan Heeger and Fred Wudl74 in 1995 which was further utilised (Fig. 26).75 In BHJ the donor-acceptor are the parts of the interpenetrating blend in bulk volume. As compared to the bilayer heterojunction, BHJ has more interfacial area, which results into enhanced efficiency of the device.76

1.1.3.1. Use of organic material in OPVs: The main drawback using inorganic material in solar cell is the difficult purification and fabrication methods, which increases the cost. Organic material not only provided a cheaper option but also pointed out possibility to prepare flexible, lightweight solar cells with tunable properties. In the same way organic material can be in form of polymer or small molecules as shown below.

A. Use of conjugated polymers in OPVs: There are different types of polymers used for OPVs depending on the electronic

- 41 - properties of constituting monomer units such as donar, acceptor and donor-acceptor. There are many reports available on the use of polymers in OPV but only selected examples are briefly mentioned here (Fig 27). For the preparation of donor polymer electron rich monomeric units are needed. The donor copolymer 82 comprising fluorene and thiophene units showed high hole mobility with PCE about 2.7% out of 82:PCBM (1:4, w/w) blend film.77 Another example of such donor polymer is quadrathienonathalene based copolymer 83 with large π conjugated area that is beneficial for better hole mobility, showed PCE more than 2%.78 For the preparation of acceptor polymer, monomeric units with strong electron withdrawing nature are needed as in case of 84, the isoindigo is perfectly planal π-conjugated molecule with strong electron withdrawing indolin-2-one units. The copolymer 84 has LUMO levels around 3.9 eV and showed PCE up to 3%.79 The combination of donor and acceptor units in same copolymer leads to the formation of donor-acceptor polymers as shown in Fig. 27. The s-tetrazine based polymer 85 was first solution processable, tetrazine based conjugated polymer. It showed good thermal stability and broad absorption range 450- 700 nm with PCE of 5.4%.80 Similarly donor-acceütor copolymer 86 comprising dithienogermole and N-octyldithienopyrrolodione was implemented in OPVs with PCE up to 7.3%.81

R R

S S R N O C6H13 C6H13

S S S S S O N n n n R R = 2-hexyldecyl R = 2-hexyldecyl

82 83 84

R1 C H C H 6 13 6 13 O N C H R R O 6 13 C6H13 Ge N N

S S S S S N N n S S n 85 86

Fig. 27: Examples of polymers used for OPVs.

As seen from the examples above, the polymers performed well enough to use in OPVs extensively but despite of the better PCE, there are certain drawbacks such as betch-to-batch variation in molecular weight, solubility as well as purity that can severely affect the performance of the solar cell.82

B. Use of small molecules in OPVs: In order to avoid these complecation the implementation of small molecules in solar cell was reemerged. Small molecules showed significance over polymeric material in terms of purity and better understanding of structure property relationships. Their

- 42 - well defined dimension and molecular precision gave rise to more reproducible fabrication protocol and avoided the batch-to-batch variation as in case of polymeric material. There are plenty of examples of different types of small molecules implemented successfully in OPVs83 but selected examples of small acenes and other PAHs used for OPVs has been briefly explained here.

a. Use of acenes in OPVs: There are number of examples of organic molecules used in OPVs but brief explanation about the substituted acenes such as anthracene, tetracenes and pentacene used in OPVs is given here. The small acenes used in OPVs as donor or acceptors are either hole transporting (p-type) or electrons transporting (n-type).

i) Use of acenes as donor (p-type): There are many examples of small molecules as p-type semiconductors used for OPVs in the literature.84 Fused acenes are also used as donor in the active layer of OPVs. The anthracene derivative 87 was used along with PC61BM in BHJ solar cell with D/A ratio (1:1.17) gives PCE of 1.12 %85 where as the change in D/A ration to 2:1 the PCE reached upto 1.27%.86 Another derivative of anthracene 88 (Fig. 28) was belended with PC61BM (D:A-1:4), yielded PCE of 1.4% which was best among all the D/A ratios reported for 88 in BHJ OPVs.87 The tetracene and its analogues are also used in active layer of OPVs. In bilayer heterojunction OPV plain tetracene 89 was used with C60 and 2.3% of PCE was delivered.88 As like in anthracene, substituted tetracenes were also implemented in OPVs. The triethylsilyl acetylene substituted tetracene 90 and C60 composed bilayer heterojunction OPV gave PCE of 0.5%. But the dimer tetracene 91 was having even lower PCE of 0.2%, may be due to the higher HOMO (-5.16 eV) than 90 (-5.36 eV).89

OC6H13 Si OC6H13 S Si S S

S

Si

88 Si

C6H13O 90 OC6H13

87 89

Fig. 28: Examples of small acenes used for OPVs.

Pentacene was first used in OPV by Kippelen in 2004 on bilayer heterojunction of

- 43 - 90 crystalline pentacene 92 and C60 that gave PCE of 2.75%. Later on Anthony and co- workers prepared the substituted pentacene 93 shown in Fig 29 gave PCE of 0.5%.91

Si

92

Si

Si Si

91 93

Fig. 29: Examples of tetracene & pentacenes used for OPVs.

Use of other PAHs as donors in OPVs: Apart from these small acenes, fused acenes, some PAHs as shown in Fig. 30 were also used as donors in the active layer of OPVs. Recently triisopropylsilylethynyl substituted dibenzochrysene 94 has been synthesized and used for OPV device using 92 bulk heterojunction with PC71BM and 1.9% of PCE was obtained. The hexaperihexabenzocoronene 95 was also used as donor in OPV and obtained PCE of 1.95%.93

C12H25

Si

C12H25 C12H25

Si C12H25 C12H25

94

C12H25 95

C8H17 C8H17

C8H17 C8H17

96

Fig. 30: Examples of PAHs used for OPVs.

- 44 -

Acenes were moderate PCE with bilayer heterojunction but the crystalline nature of acenes is limitation in BHJ due to the phase separation on blending with fullerene (acceptor). So it needs to tune the properties using different substitution in order to achieve high performance.

ii) Use of Acenes as Acceptor (n-type): Same like these p-type acene molecules n-type acenes are also used in active layer as acceptor. In general the pentacene derivatives are known as donors in the OPV devices. But Anthony and co-workers synthesized some pentacene derivatives and used it as acceptor in OPV. The cyano substitution on pentacene core lowered the LUMO and monocyano 97 and dicyano pentacene 98 as shown in Fig. 31 were synthesized.94 The 97 showed -2 performance with, JSC of 3.72 mAcm , VOC of 0.84 V, FF of 0.41 and PCE up to 1.29%. The dicyano derovative of pentacene 98 showed PCE of 0.43% and the chloro derivative 99 showed PCE of 1.00%. In this way the properties pentacne were reverted from donor to acceptor by electron withdrawing groups on pentacene core. Apart from these cyano substitution there is also pentacene 100 with trifluoromethyl substitution that showed PCE of 1.26% when it was blended with P3HT. There are also some other examples apart from the linearly fused acenes. Wudl and co-workers reported 9-9´- bifluorenylidene polycycles 101 in OPV along with P3HT donor and obtained PCE 1.7%.95

Si Si

R F3C

R'

Si Si H3CO OCH3

100 101 97 = R = CN, R' = H 98 = R = R' = CN 99 = R = Cl, R' = H

Fig. 31: Examples of fused n-type acenes used for OPVs.

In this way there are different molecules synthesized and used in OPVs as acceptor. Although the molecules are not as efficient as fullerene and its derivatives especially in BHJ OPVs. But still there are possibilities of improvement by introducing different kinds of versatile substituents. From all the investigations done on synthesis of organic material comprising acenes or azaacenes and their implementation in electronic devices it clear that, there is no any material or protocol for design and synthesis of such material that can be

- 45 - universally used in OLEDs, OPVs and OFETs, as there are a series of requirements for each of these applications. Nevertheless there are certain characteristics that can be fundamental requirements for the preparation of a reliable material for organic electronics, such as high mobility, ease of synthesis, material stability (prolonged lifetime), and compatibility with types of techniques used for specific application. All these properties can have an important impact on the whole field of organic electronics since they are essential for developing low- cost and better perfomable material for large-area applications.

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- 51 -

- 52 -

Chapter: 2

Design, synthesis and properties of pyrene fused azaacenes

- 53 -

- 54 - 2.1. Introduction Azaacenes: The aromaticity of benzene and its analogues is one of the most fascinating topics in science. The hexagonal structure of benzene 102 was first published by Kekule in 1865.1 Later on he also introduced oscillation hypothesis, which states that the positions of double bonds in benzene ring are continuously changing. The oscillation hypothesis was put forward to explain the structures like as, “isomeric” forms of ortho substituted benzene 103 and 104 as shown in the Fig. 32. The benzene molecule basically represents two resonance structures. The resonance structure is not a digital phenomenon in which bonding jumps from one discrete state to another but it is representation of superimposition of many states in a pictorial model of the chemical structure and these states are not bounded rigidly but they enjoy a versatile degree of freedom or delocalization.

R R

R R 102 103 104

Fig. 32: Kekule’s structure of benzene.

There are several studies done to explain the aromaticity of organic compounds. The Hückel’s law of [4n + 2] π electrons is based on Hückel’s molecular orbital theory which explains aromaticity and predicts the stability of all cyclic sytems possessing [4n+2] π electrons where “n” being an integer.2 There are few examples proved with this rule like benzene, nathalene, anthracene, tetracene, etc. The Hückel’s theory had limitations as, it does not discriminate between simple acenes (22) and angular acenes (106) having [4n+2] number of π electrons and greater stability. Also the hydrocarbons with multiples of six π electrons (107) can not be explained by Hückels theory. So it was limited to very few aromatic systems and there are many attempts done to expand the Hückel’s rule to the polycyclic aromatic systems metioned above.3

22 106 107

Fig. 33: Molecule explained by Hückel’s law (4) and limitations (5,6).

The simplest and most studied structure to prove the sextet theory is benzene. The representation of benzene with ring inside denoting the π electrons was first put forward by Robinson.4 Later Clar came up with aromatic sextet rule5 which was derived from Robinson’s aromatic sextet. Clar proposed that the sextet in aromatic system is shared

- 55 - through the conjugated system. As shown in Fig. 34 the only sextet in 110 is shared by the other two rings as well and showed by arrow. The stability of fully benzoid hydrocarbons or polycyclic hydrocarbons can be also explained using Clar’s aromatic sextet rule.

108 109 110

106 112 113

Fig. 34: Molecules explained by Clar’s sextet rule.

2.1.1. Bandgap: The delocalization of π electrons forms the different energy levels. In an isolated aromatic system these energy levels are discrete and also known as molecular orbitals. In ground state lower energy levels are filled with electrons and higher energy levels are empty. The most representative levels or molecular orbitals represents HOMO and LUMO. After applying external energy the electrons in ground state jumps into the excited state this phenomenon is call as absorption. The electrons from excited state jumps back to ground state with emission of energy which gives rise to fluorescence. The phenomenon of absorption and fluorescence can be explained as in Fig. 35. The difference in between HOMO and LUMO is known as band gap. The band gap decreases as we increase the number of linearly fused aromatic rings and it is seen by the bathochromic shift in the absorption spectra6 and earlier with the decreasing singlet- triplet energy splitting.7

- 56 - Absorption Fluorescenece

Fig 35: Absorption and fluorescence graphical representation.

2.1.2. Stability of Acenes: Molecules composed of linearly annealated benzene rings has fascinated organic chemist for more than a century.8 These compounds also known as acenes and has interesting properties which drove it into the different field like material science with a broad range of applications as we have seen in Chapter 1. But with the increasing number of fused benzene rings the stability of acenes decreases. The tetracene in solution dimerizes to colourless “butterfly dimer” as shown in Fig. 36.9 Pentacene is unstable in air and photosensitive.10 Hexacene decomposes at room temperature in solution. Due to this instability only acenes with up to six fused rings have been characterized thoroughly.11

hν

O 2 O O

Fig. 36: Instability of tetracene & pentacene in the presence of air and light.

Such lack of stability is due the increase in reactivity of acenes. The most common pathway of decomposition of acenes is dimerization which takes place through the “butterfly dimer” formation reaction when exposed to light.12 The most stable acene uptill now is the tetracene. The synthesis of the highest known acenes i.e. pentacene, hexacene and heptacene was carried out under the conditions of matrix isolation using the Strating-Zwanenburg reaction13 as shown in Fig. 37. The hexacene and heptacene showed lifetime approximately 12 and 4 hours respectively under specific conditions.14

- 57 -

n=0, n'=0 Egap=3.24

n=0, n'=1 Egap=2.58 O O n=1, n'=1 Egap=2.08

n n' n=1, n'=2 Egap=1.71

n=2, n'=2 Egap=1.40

Fig. 37: Synthesis of acenes using Strating-Zwanenburg reaction and their band-gaps.

As shown above, increasing the number of fused benzene rings causes fall in band gap and at the same time the stability decreases. There are a few examples that illustrates, how substitutents can be used to produce more stable acenes.

2.1.3. Synthesis of acenes with enhanced stability: To overcome the stability issues, acenes with substitution at selected position were synthesized. In previously (Chapter-1) the examples of halogen, silyls substituted acenes are explained and here some examples of pentacene onwards are mentioned briefly. Miller and co-workers reported the library of substituted pentacenes. The most stable pentacenes 114 and 115 (Fig. 38) showed stability respectively around 19 and 12 hrs in solution under ambident temperature, air and light.15

O SR

1) NaBH4, MeOH

2) R-SH, CH2Cl2 O 3) p-chloranil, C6H6 SR

114 = R = Ph

115 = R = C10H21

Fig. 38: Synthesis of substituted pentacenes.

Recently substituted pentacenes (116 and 117) were reported by Matsumara et al. These pentacene derivatives found to be soluble in common organic solvents but stability was not improved significantly.16

- 58 - R R R R

O O

R 1) LiAlH4, TBME

RuH2(CO)(PPh3)3 2) 1M HCl O O

R R R R

116 = R = SiEt3

117 = R = C4H9

Fig. 39: Synthesis of substituted pentacenes by Mastumara et al.

Anthony and co-workers reported the synthesis of functionalized higher acenes like, hexacene and heptacenes (Fig. 40), which were found to be more stable than their no-substituted analogues. Among these hexacene and heptacene analogues the tert.- butyl silyl substituted analogues (119 and 42) were found to be more stable than the i- propyl silyl substituted derivatives (40 and 120) may be due the bulkier substituents. The heptacene 41 was found to be stable only in the crystalline state but it was stable enough to characterize by NMR and Uv-Vis spectroscopy.17

SiR3

O

1) i-Pr3SiCCLi

+ 2) SnCl2 / H3O O

40 = R = i-Propyl SiR3 119 = R = t-Butyl

SiR3

O

1) i-Pr3SiCCLi

+ 2) SnCl2 / H3O O

120 = R = i-Propyl SiR3 42 = R = t-Butyl

41 = R = SiMe3

Fig. 40: Synthesis of substituted higher acenes.

Later in 2008 Wudl and co-workers synthesized more stable heptacene as shown in Fig. 41. The heptacene 123 was not enough soluble where as 124 showed enough solubility in organic solvent was too unstable to characterize fully. The heptacene 125 was soluble and stable for more than 21 days when the mineral oil coated crystals were kept at ambient conditions.18

- 59 -

R 1)5-bromoanthranilic acid R O Ph R Ph N isoamyl nitrile, THF Br diphenylisobenzofuran, LTMP, THF N O Br 2) DCE, reflux O O R R Ph R Ph

Ph R Ph 123 = R = Ph Fe, AcOH, o-DCB O 124 = R = Ph R Ph

Si Si

Ph Ph Ph Ph Zn, AcOH, O O

Ph Ph Ph Ph

Si Si

125

Fig. 41: Synthesis of substituted heptacenes.

Recently the nonacene 126 has been reported by Miller and co-workers which was stable for 24 hrs and six weeks in solution and as solid respectively.19

S S S S S

S S S S S

126

Fig. 42: Miller’s substituted nonacene.

- 60 - 2.2. Heteroacenes: 2.2.1. Introduction: The exchange of a carbon atom by heteroatom on the framework of acenes gives raise to heteroacenes. The structure and properties vary with the heteroatom type, position and number of heteroatoms. If the heteroacene contain N they are known as azaacenes to which this thesis is mostly devoted. The development of straightforward and solid routes to access the synthesis of N- containing polycyclic aromatic hydrocarbons (N-PAH) has permitted study of their properties in great detail. By varying number and position of N atom substitutions on the aromatic core along the π framework it is possible to modulate the electronic structure, stability, solubility and supramolecular organization of corresponding azaacene.20

2.2.2. Smaller azaacenes and oligo-azaacenes: Nitrogen is one of the most used constituting heteroatom in acenes. The exchange of carbon with nitrogen does not affect the degree of aromaticity of the molecule21. In some cases advantage of using N as a heteroatom is the simpler synthetic route followed for the preparation of these acenes. The change in the position of nitrogen also changes the properties of molecule. There is lot of work done and reported on the synthesis and applications of these N-heteroacenes.22 The acenes containing nitrogen heteroatom in the form of pyrazine ring, they are also known as “pyrazinacenes”. The quinaxoline or phenazine fused acenes are also known as pyrazinacene. In order to illustrate some examples, azaacenes with four or five fused aromatic rings constituting pyrazine unit are briefly explained here. The synthesis of such pyrazinacene was started with the synthesis of the tetraazapentacene 127 in 1890 by Fischer and Hepp23 and the oxidation, acylation studies were done by Badger and Pitt in 1951.24 The oxidation of the N,N- dihydroacenes was tried by Hinsberg using potassiumdichromate and sulphuric acid but did not comment on the properties as their dihydro analogues.25 Later in 1967 Kummer and Zimmermann also developed the methods of oxidation using chloranil (129), lead oxide (131) as shown in Fig. 43.26

- 61 - H N N N NH2.HCl H2N + N NH .HCl H N N N 2 2 H 127

H H H H N N N N N N

N N N N N N H H H H 45 O K Cr O K2Cr2O6 Cl Cl 2 2 6 H SO HCl/SnCl2 2 3 PbO2 H2SO4 H2SO4 Cl Cl O

N N N N N N

N N N N N N 128 129 130 131

Fig. 43: Synthesis of N-N-dihydroacene and the oxidation methods.

In 1999 Wudl and co-workers synthesized zwitterionic 5,7-disubstituted quinoxalinophenazines 132 and studied the optical properties.

Ph Ph NH HN Ph Ph H H N N N N 1) H2,Pd/C,3h,RT 2) EtOH,air,reflux H2N NH2 N N Ph Ph 132

Fig. 44: Wudl’s 5,7-disubstituted quinoxalinophenazines.

The simple acenes like pentacene and rubrene used in organic electronics but even after showing better performance, the simple acenes couldn’t be an ideal candidate for organic electronics due to the tedious preparation methods and less stability. To overcome the synthetic and stability issues, Nuckolls and co-workers have also reported the synthesis of N,N-dihydroazaacenes 49, 134 and 135 as shown in Fig. 45 and applied in organic electronics.27 The OFET devices of these molecules showed charge mobilities around 10-2cm2/(V.s) with on/off ratio 8x104. Even though the performance was modest the devices showed remarkable stability. Recently in 2009 Miao and co- workers reported methyl substituted azapentacenes 136 and 137 and checked the OFET performance. The devices showed mobility of 1x10-4 and 5x10-4 cm2/(V.s) respectively.

- 62 - H R OH H2N R' R N R' + R OH H2N R' R N R' H

49 = R = R' = H

134 = R = CH3, R' = H 135 = R = H, R' = OH

H NH2 O OH 0 N N + 180 C 4h NH HO O N N 2 H

1) nBuLi N N N N + 2) CH I 3 N N N N 136 137

Fig. 45: Azaacenes reported by Nuckolls and Miao.

The azaacenes with substitutions on aromatic core (apart from nitrogen) were also reported. The substitution with different types of groups in 138-140 showed improvement in solubility.

SiR3 SiR3

O O

N 1) R SiCCLi N NH2 3 LiAlH4 O S S N 2) NaHPO2/KI N NH2 CH3COOH O

SiR3 SiR3

SiR3

N 138 = R = i-Pr 139 = R = Et N 140 = R = Me

SiR3

Fig. 46: Synthesis of substituted diazatetraacenes.

The molecules 141-146 also showed conducting properties when used in OFETs.28 The 143 and it’s oxidized form 144 was synthesized by Bunz and co-workers as shown in Fig. 47.29 The molecule 143 didn’t show any mobility where as the 144 was n-type material and exhibits mobility up to 3.3 cm2/(V.s). In the same way 142 was prepared from 141, both these molecules used for OFET and showed respective hole mobility of

- 63 - 0.02-0.05 and 0.02-0.07 cm2/(V.s). The 142 functioned as ambipolar material with electron mobility of 2-4 x 10-4 cm2/(V.s). Similarly in case of 145 and 146, it was found that, 145 is p-type material with mobility of 0.3-1.2 cm2/(V.s) and 146 showed ambipolar property with hole and electron mobilities of 0.05-0.22 and 0.3-1.1 cm2/(V.s) respectively.

Sii-Pr3 Sii-Pr3

O H N N 1) i-Pr3Si Li N MnO2 N N 2)SnCl2, HCl N H O

Sii-Pr3 Sii-Pr3 142 141

Sii-Pr3 Sii-Pr3

O H N N 1)i-Pr Si Li N N N N 3 MnO2 2) NaHPO /KI N N 2 N N N N CH3COOH O H

Sii-Pr3 Sii-Pr3 143 144

Sii-Pr3

SiPr3-i O HO N X N X N X i-Pr3Si Li SnCl2, HCl

CF3COOH N X N X N X OH O

i-Pr3Si Sii-Pr3

145 = X = CH 146 = X = N

Fig. 47: Silylethynylated N-heteropentacene used for OFETs.

2.2.3. Pyrene fused azaacenes: From all these examples of azaacenes it can be seen that, the pyrazinacenes have re-emerged as an alternative to acenes due their comparatively enhanced stability and much more straight forward synthesis. The “linear” azaacenes are explained above, but the lateral expansion of these linear azaacenes with extra aromatic rings brings it more stability due the delocalization of π electrons in such rings. One of the best way to prepare pyrene fused azaacenes starts from oxidation of pyrene. The oxidation results into pyrene-4,5-diketone (148) and pyrene-4,5,9,10- tetraketone (149). There were several attempts reported on the oxidation that includes multistep synthesis30 and toxic reagents such as .31 The oxidation of

- 64 - pyrene now a day is carried out popularly by using ruthenium chloride and sodium peroxide in defined mixture of solvent as shown in Fig. 48. This method gives 4,5- diketone 148 or 4,5,9,10-tetraketone 149 in single step depending on the stoichiometry of reaction.32 These molecules 148 and 149 were used as starting material for the synthesis of extended aromatic systems such as 150-161.

RuCl3 RuCl3 O O O H2O H2O

O 4eq. NaIO4 8eq. NaIO4 O O room temp. 30-400C 148 147 149

Fig. 48: Oxidation of pyrene.

The cyclocondensation of pyrene tetraketone 149 with o-phenylenediamine and tetraaminobenzene leads to the pyrene fused azaacenes (150) and the pyrene fused polyacenes (151) respectively.33

NH2 O O N N NH2

O O N N

149 150

H2N NH2 O O N N H2N NH2

O O N N n 149 151

Fig. 49: Stille’s polyquinoxalines.

Other examples of such azacenes are, in 1970 Arnold reported synthesis of pyrene fused ladder polymer 153 in which he used tetraaminodiquinoxalpyrene building block 152 as shown in Fig. 50.34

HOOC COOH O O H N N N NH HOOC COOH 2 2 N N N N

H2N N N NH2 PPA N N N N n 152 153

Fig. 50: Arnold’s ladder type polymers.

- 65 -

The simple route for the preparation of azaacenes is the cyclocondensation of diketone and diamine as shown in Fig. 51. Follwing this route there are many pyrene fused azaacenes prepared and some of them are discussed here. The solution processable pyrene based organic semiconductor 55 was synthesized.35 The molecular orientation and packing style in the thin film was also studied by using various techniques.36

H2N Cl O O Cl N N Cl H2N Cl C12H25SH, K2CO3, 0 AcOH/EtOH, 120 C 0 O O Cl N N Cl DMF, 80 C

C12H25S N N SC12H25

C12H25S N N SC12H25

55

Fig. 51: Pyrene fused azaacene prepared by Kaafarani and co-workers.

In 2009 Wang and co-workers reported pyrene fused azaacenes 155-156 and tried to lower the LUMO by using usual heterocycles fused to the main azaacene core. These azaacenes showed near IR absoption at 746 nm and 844 nm for 155 and 156 respectively. These molecules also formed donor-acceptor system by attaching different electron donating groups shown in Fig. 52.37

O O Ar Ar Ar Ar O N H N O O 2 N Fe, AcOH 2 N N N N N S S S S N 800C N O2N H2N N N N N Ar Ar Ar Ar

OC8H17

155 = Ar = N 156 = Ar = S

C8H17 C8H17 OC8H17

Fig. 52: Solution processable and NIR absorbing pyrene fused azaacene .

The pyrene fused azacenes 157 also used in single layer electroluminescenece device and checked the performance.38 Kaafarani and co-workers reported the tosylated pyrene fused azaacenes 158 and 159, prepared by following easy condensation protocol and implemented them for anion sensing (Fig. 53).39 The anion binding study was done for various anions including acetate, benzoate, cyanide and fluoride using different

- 66 - spectroscopic methods like UV-vis absorbtion, fluorescence and NMR titration.

TosHN NHTos n N N C6H17 C6H17 N N N N

N N TosHN NHTos

158 N N

TosHN NHTos

C10H21O OC10H21 159 157

Fig. 53: Pyrene fused azacenes used for EL and anion sensors.

Recently pyrene fused azaacene is reported by Tong et al. 160-161, which showed strong tendency of aggregation in solution and thin film so can be used as semiconductor in OFETs.

R

H H R' N N N N N N R'

R' N N N N N N R' H H

160 = R = H R C10H21 O R' = C H 161 = R = tert.-butyl 12 25

Fig. 54: Pyrene fused azacenes prepared by Tong et al.

The longest pyrene fused azaacene till date was reported by Wang and co-workers up-to 16 rectilinearly fused aromatic rings 166 as shown in Fig. 55.40 These molecules 162-166 were synthesized by the condensation coupling of 1,2-diketones and 1,2- diamine. They have also showed the decrease in band gap with increasing number of fused aromatic rings using UV-vis and the n-type nature of molecule by cyclic voltammetry.

- 67 - C10H21O OC10H21 N N

N N

C10H21O OC10H21

162

C10H21O OC10H21 N N N N

N N N N

C10H21O OC10H21

163

C10H21O OC10H21 N N N N

N N N N

C10H21O OC10H21

164

C10H21O OC10H21 N N N N N N

N N N N N N

C10H21O OC10H21

165

C10H21O OC10H21 N N N N N N

N N N N N N

C10H21O OC10H21

166

Fig. 55: Pyrene fused azaacenes reported by Wang et al.

- 68 - The pyrene fused tetraazaheptacene 167 and tetraazaoctacene 168 were synthesized in our laboratory using tetraaminobenzene hydrochloride and naphthalene diamine respectively as shown in Fig. 56.41 The effect of protonation of N atoms on absorption of the molecules was also reported. The main drawback of these molecule found was the less solubility in common organic solvents like DCM, chloroform, DMSO, DMF, etc. In order to overcome the solubility issue we decided to modify the pyrene core with solublizing groups.

H3N NH3

H3N NH3 O N N

O N N 167 148

NH2 O O N N NH2

O O N N

149 168

Fig. 56: Pyrene fused azaacenes synthesized in our lab.

The pyrene fused tetraazaoctacenes 169 and 170 (Fig. 57) with enhanced solubilities have been reported by our group.42 In these molecules number of fused aromatic rings are limited due to the lack of reaction sites at the end of these “octacenes”. A new synthetic route which will make it possible to fuse more aromatic rings via similar reaction sites like 1,2 diketone or 1,2-diamine.

O O N N

O O N N

NH2

NH 2 169

C8H17 C8H17 C8H17 C8H17

O O N N

O O N N

C8H17 C8H17 C8H17 C8H17 170

Fig. 57: Pyrene fused tetraazaoctacenes with enhanced solubilty.

- 69 - 2.3. Synthesis of pyrene fused oligoazaacenes: 2.3.1. Objective: The objective of this projest was to develop a new method for the synthesis of ultralong and discrete pyrene-fused azaacenes to overcome all the above aspects related to their synthesis and solubility. Such novel methodology is based on the synthesis of a series of charged and uncharged building blocks with solubilising groups that can be assembled in a cyclic proccess to yield pyrene-fused azaacenes, facilitating their synthesis and enhancing their semiconducting properties, solubility and processability. By using a series of azatetraacene derivatives presenting both diamine and protected diketone functionalities it will be possible to assemble them in a stepwise and cyclic fashion by means of condensation and deprotection steps as shown in Fig. 58.

R R R R R R R

N N N N N N N N N N N N

N N N N N N N N N N N N

R R R R R R R Target molecule

1) Deprotection 2) Capping

R R R R R R R

N NH2 O N N N N N N N N O H2N N + + N NH2 O N N N N N N N N O H2N N

R R R R R R R

Capping Agent Condensation

R R R R R

O O N N N N N N N N O O O O N N N N N N N N O O

R R R R R

Condensation

R R R R R

O O N NH2 O N N N N O H2N N O + + O O O N NH O N N N N O H N N O 2 2 O

R R R R R

Building Block Building Block Deprotection

R R R

O O N N N N O O O O N N N N O O

R R R

Condensation

R R R

O O N NH2 O O H2N N O + + O O O N NH O O H N N O 2 2 O

R R R = H, tert -butyl R Building Block

Fig. 58: Retro-synthetic analysis of target molecules.

- 70 - 2.3.2. Synthesis of non-substituted pyrene fused oligoazaacenes:- 2.3.2.1. Attempts to synthesize 5,6-dihydro-3b,7a-(epoxyethanooxy) [1,4]dioxino [ 2',3':9,10] phenanthro [4,5-abc]phenazine-13,14-diamine: The oxidation of pyrene was carried out by following the procedure reported by J. 45 Harris and co-workers by using RuCl3 and NaIO4. The reaction was carried out under very mild conditions which gives 148 or 149 as a major product depending on the stoichiometry of the reaction (Scheme 1).

RuCl 3 RuCl3 O O 4eq. NaIO4 8eq. NaIO4 O CH CN, DCM, H O O 3 2 CH3CN, DCM, H2O O O room temp. 30-400C 148 147 149

Scheme: 1

The required amines 171 and 172 were synthesized following reported procedure shown in Scheme 2.46 Firstly the protection of amino groups was carried our by tosylation using p-toluenesulphonyl chloride in pyridine at room temperature. Then the nitration was done by fuming HNO3 in AcOH and obtained compound was used as starting material for the preparation of required amines. Deprotection by concentrated H2SO4 offered diamine 172 where as reduction of nitro groups gave diamine 171.

NH2 NHTos o O2N NHTos PTSCl HNO3, 60 C pyridine AcOH NH2 NHTos O2N NHTos

TosHN NH O2N NHTos O N NH 2 Sn/HCl H2SO4 2 2

TosHN NH2 O2N NHTos O2N NH2 171 172

Scheme: 2

Ist Strategy: The first attempt towards the oligoazaacenes was started from the oxidation of pyrene as shown in Scheme 3. The tetraketopyrene 154 was treated with one equivalent of tosylated diamine 155, which gave monocondensed product 157, but following deprotection of tosyls using conc. H2SO4 failed.

- 71 - H2N NHTos

H N NHTos 2 H SO O N O O 171 O N NHTos 2 4 NH2 EtOH / AcOH, 70% O O O N NHTos O N NH2

149 173 174

Scheme: 3

IInd Strategy: To avoid the harsh deprotection condition of Strategy Ist a new synthetic route was planned (Scheme 4) which involves oxidation of pyrene to diketone, protection, oxidation, cyclocondensation with 172 and reduction NO2 groups.

O O O O Oxidation Ketal Protection O Oxidation O O O O O O O

H N 2 NO2

H2N NO2 O O N NO N NH 172 O 2 Reduction O 2 O N NO O N NH O 2 O 2

Scheme: 4

The synthesis of 176 was achieved in two steps, first the protection of diketone 148 by using ethylene glycol and catalytic amount of PTSA, which afforded the acetal, protected pyrene 175 with 45% yield (Scheme 5).

O ethylene glycol O O O PTSA, benzene, 45% O O

148 175

Scheme: 5

There were two possibilities for the formation of acetal in compound 159 as shown in the Fig. 59, which can not be differentiated by NMR. The structure was assigned by X-ray crystallography as crystals suitable for diffraction were obtained from solvent (DCM : PE). The structure in the form of two, fused 1,4-dioxane A was ruled out by using the crystal structure.

- 72 - O O O O O O O O

A B

Fig. 59: Possible structures after ketal protection and crystal structure.

Further oxidation of 175 by using the same conditions was carried out to get 176 with 20% yield after purification (Scheme 6).

O O O O RuCl3, NaIO4 O O O CH3CN, DCM, H2O O O 20% O 175 176

Scheme: 6

With compounds 176 and 172 in hand, the synthetic route as shown in Scheme 7 was developed. The dinitro phenylenediamine 172 was treated with 176 by refluxing in mixture of acetic acid and ethanol that gave 177. For this reaction the yield was 72% and purification was done by filtration and washing with ethanol. The reduction of nitro groups in compound 177 was failed with conventional methods like catalytic hydrogenation by using Pd/C and also Zn/HCl. Finally it was carried out by using hydrazine hydrate and palladium in which the hydrazine hydrate acts as a hydrogen source in situ offered compound 178 quantitatively.

H N 2 NO2

O H N NO O O 2 2 N NO O 172 O 2 O O O EtOH / AcOH, 72% N NO2 O O

176 177

O NH2NH2.H2O, 10% Pd/C N O NH2 O EtOH, reflux, quant.% N NH O 2

178

Scheme: 7

- 73 - 2.3.2.2. Stepwise cyclocondensation from pyrene diketone or tetraketone: Ist Strategy: Tetraazaheptaacene 179 is first building block for desired long oligoacenes and the proposed synthesis of oligioacenes from the heptacene 179 can be ruled out by deprotection of the acetals and then the coupling of the resulted diketone 180 again with the diamine 178 and further deprotection in order to get 181 as shown in Scheme 8.

O N O NH2 O N NH O O 2 N N O O Deprotection 178 O N N B O A O

148 179

O N N 1) A O N N N N

O N N 2) B O N N N N

180 181

Scheme: 8

In order to check the solubility of non-substituted pyrene azaacene, the obtained compound 178 was refluxed with the diketone 148 in ethanol and acetic acid results in the formation of lot of byproducts, which were difficult to separate by chromatography (Scheme 9). This might be due the deprotection acetals under refluxing acidic conditions. To avoid this we carried out the reaction in pure ethanol, which afforded the heptacene, 179 with 35% yield as bright orange solid. The compound 179 was further characterized by 1H NMR and MS; it was not possible to characterize this compound by 13C-NMR spectroscopy due to the lack of solubility.

O

O O O N N N O NH2 148 O O O N NH N N O 2 EtOH, 35% O

178 179

Scheme: 9

The ketal deprotection of 179 was attempted first by reported conditions, using 47 PTSA and mixture of DCM, CH3CN and water under reflux condition but desired product was not obtained. Finally it was obtained by using TFA and water mixture (9:1) at room temperature,48 after overnight stirring (Scheme 10). The reaction work up

- 74 - was carried out by diluting reaction mixture with water which gave precipitation that was filtered and washed with water.

O N N O TFA : H2O (9:1) O N N O N N O O N N

179 180 Scheme: 10

Unfortunately the obtained compound 180 was not soluble in any solvent in order to characterize by NMR but it was detected by MS. The compound 180 was too insoluble to continue.

IInd Strategy: The solubility of heptacenes can be improved by adding more ketals in compound 179. This could be also achieved by condensation of pyrene-4,5-tetraone-9,10- di(ethyleneglycol)ketal (176) and commercially available tetraamino benzene hydrochloride15 183 as shown in Scheme 11. Refluxing both the starting materials in dry pyridine under degassed condition failed to provide desired compound 182 and the corresponding monocondensation product 178 was obtained.

O N NH O 2 O N NH2 H3N NH3 O 4Cl O H3N NH3 178 O 183 O O o O pyridine, 90 C O O O N N 176 O O O O N N O O

Desired product 182

Scheme: 11

2.3.3. Attempts to synthesize di-tert.-butyl pyrene fused oligoazaacenes:- 2.3.3.1. Synthesis of 2,7-di-tert-butylphenanthro[4,5-abc]phenazine-11,12-diamine and further cyclocondensation: The proposed synthetic scheme started with the Friedel-Crafts alkylation of pyrene to prepare 2,7-di-tert-butyl pyrene (Scheme 12). The obtained compound was then subjected to oxiadation and further cyclocondensation with diamine 171. The tosyl 39 deprotection of obtained product compound was done by conc. H2SO4 to get diamine, which was further cyclocondensed with 2,7-di-tert-butyl pyrene tetraketone to get desired heptacene.

- 75 - H2N NHTos

H2N NHTos N Alkylation Oxidation O 171 NHTos

O N NHTos

O O O O

Deprotection N NH2 N N O

N NH2 N N O

Scheme: 12

As seen in section 2.3.2.2, the non-substituted pyrenetetraazaheptacene diketone 180 does not provide soluble azacenes. To enhance the solubility of pyrene fused azaacenes, tert-butyl groups were introduced at 2,7 position of pyrene 184 via simple Friedel Craft alkylation of pyrene with tert-butyl chloride and AlCl3 following previously reported method.49 The further oxidation reaction was carried out under very mild conditions with specified amount of sodium periodate which gives diketone 185 as shown in Scheme 13. The diamine 171 was refluxed with tert-butyl pyrene diketone 185 in the mixture of ethanol and catalytic amount of acetic acid offered compound 158. The amines were deprotected by heating it in sulphuric acid to give the desired diamine building block 187.

tert. butyl chloride RuCl3, NaIO4 O

AlCl3, pyridine, 62% CH3CN, DCM, H2O O r.t., 40%

147

184 185

H2N NHTos

H2N NHTos 171 N NHTos N NH conc.H2SO4 2

EtOH / AcOH, 40oC, quat. reflux, 52% N NHTos N NH2

158 187

Scheme: 13

- 76 - Diamine 187 was also treated with one equivalent of tetraketone 188 by refluxing it in acetic acid for 24 hrs (Scheme 14). After completion of reaction it was filtered and washed with alcohol, which gave 189 as dark orange solid. As seen here, the heptacene diketone is more soluble than the non-substituted pyrene and it was possible to characterize by 1H and 13C NMR.

O O

O O

N NH2 N N O 188

N NH2 AcOH, reflux, 68% N N O

187 189

Scheme: 14

2.3.3.2. Attempt to synthesize 2,7-di-tert-butylpyrene fused octaazadodecacene: Taking into account the solubility of these tert-butyl substituted pyrene tetraazaheptacene diketone, it was possible to prepare this acene linearly by putting more annelated aromatic rings. To accomplish the long azacenes we treated tert-butyl pyrenetetraketone 188 with excess of diamine 187 as shown in Scheme 15.

N N N N

N N N N O O

O O

N NH2 Desired Product 188 190 N NH2

187 N N O

N N O

Obtained Product 189

Scheme: 15

This reaction was attempted under different conditions but the desired product 190 was not obtained. The conditions we applied and results we got are shown on Table 1.

- 77 - Solvent Temp. Time Result

AcOH Reflux 4 days 189

AcOH/ODCB Reflux 8 days 189

Benzoic Acid 180oC 4 days 189

Phenol 150oC 8 days Decomposed

m-cresol 180oC 7 days Decomposed

Table:1

As seen from Table 1, in the solvents like AcOH, Benzoic Acid and mixture of AcOH and ODCB it was possible to get the mono coupled product i. e. heptacene diketone 189. The first coupling takes place in 24 hrs in these cases but afterwards even after prolonging the reaction time did not allow second condensation. The reason might be the low solubility of the intermediate i.e. tetraazaheptacene diketone 189 due to which it was forming precipitate and avoiding the second cyclocondensation. Solvent with higher boiling pont like m-cresol was also tried but further heating in this case caused decomposition of the material.

2.3.3.3. Synthesis of 5,6-dihydro-3b,7a-(epoxyethanooxy) [1,4]dioxino[2',3':9,10] 2,7-di-tert-butylphenanthro[4,5-abc]phenazine-13,14-diamine:

Ist Strategy: As previously reported, in case of the non-substituted pyrene azaacenes, 179 is more soluble than its diketone analogue 180. Hoping for the same change in solubility, synthesis of dodecacene (201) with ketals at both the ends was attempted. This will also to give additional reaction site for diamines after deprotection of the ketals to add more number of fused rings. In order to synthesize the required building block in minimum steps possible, the di-tert-butyl pyrene tetraketone 188 was used. In first attempt the tetraketone 188 was coupled with one equivalent of diamine 171 obtained compound 191 as pale yellow solid with 64% yield. First tried to deprotect the tosyls by using conc. H2SO4 to get compound 192 but it was encountered same problem as in case of non-substituted pyrene azaacene. Afterwards protection of the ketones by using ethylene glycol was attempted in order to get 193 (Scheme 16). The purification was attempted by chromatography but it was possible characterize only by MS.

- 78 - O N NH2

O N NH2

192

conc.H2SO4 H2N NHTos

H N NHTos 2 N O O 171 O NHTos

O O EtOH / AcOH O N NHTos

191 ethylene glycol PTSA, benzene 188

O N NHTos O O N NHTos O

193

Unable to purify

Scheme: 16

IInd Strategy: The next route was tried using, di-tert-butyl pyrene tetraketone 188 and dinitro- diamino benzene 172. The purpose of this route was to prepare building block (199) with more than one reaction site in minimum synthetic efforts. First, the 2,7-di-tert-butyl pyrene tetraketone 188 was coupled with one equivalent of dinitro-diamino benzene 172 to get the monocondensed product 194. The reaction was done in ethanol/acetic acid mixture, which was completed in an hour. The obtained product was washed with alcohol in order to get pure material (67% yield) as yellow solid. The obtained product 194 was subjected for acetal protection in order to get precursor 195 (Scheme 17). This reaction was done in Dean-Stark apparatus by using ethylene glycol and catalytic amount of PTSA. Purification was carried out by column chromatography.

H N 2 NO2

H N NO O O O 2 2 O N N 172 NO2 ethylene glycol O NO2 O O O EtOH / AcOH O N NO PTSA, toluene N NO 2 O 2

188 194 195

- 79 - Scheme: 17

Different solvent conditions for the acetal protection as shown in Table: 2 were tried but yield not higher than 8%.

Solvent Catalyst Temp/Time Result Benzene PTSA Reflux/72 hrs. No Reaction Toluene PTSA Reflux/96 hrs. 195

Xylene PTSA 140oC/72 hrs. No Reaction THF CSA Reflux/48 hrs. No Reaction

CHCl3 CSA Reflux/72 hrs. No Reaction

CHCl3 PTSA Reflux/72 hrs. 195

Table:2

An explaination for the low yields comes from the low solubility of 194. In fact it was not soluble in solvents like, benzene, xylene even at reflux conditions. In case of THF it was not soluble either and there was no evolution after 2 days of reflux. The compound 194 was sparingly soluble in chloroform in which, it worked on adding catalytic amount of PTSA than that of camphor sulphonic acid. The case was same with toluene as well but yield of 195 was very low. Due to the lack of solubility of starting compound 194 the yield of product 195 dramatically dropped. Hence we decided to follow the same route we developed during the synthesis of non-substituted pyrene azaacenes.

IIIrd Stratagy: The second strategy starts with the oxidation of 2,7-di-tert-butyl pyrene to the diketone which on ketal protection, oxidized further to diketone. Then obtained diketone was cyclosondensed with 172. The reduction of nitro groups to amine offered the desired compound (Scheme 18).

- 80 - H N 2 NO2

O O H2N NO2 O O oxidation ketal-protection O O 172 O O O O O O

O N NO O N NH O 2 reduction O 2 O O O N NO2 O N NH2

Scheme: 18

2,4-di-tert-butylpyrene-4,5-dione 180 was prepared as previously reported procedures by using NaIO4, RuCl3 with specified stoichiometry and solvent conditions. Further protection the diketones was carried out in Dean-Stark apparatus by using ethylene glycol and catalytic amount of PTSA, in refluxing benzene. This reaction was worked well as the diketone was completely soluble in refluxing benzene. After completion of reaction the crude was purified by column chromatography in order to get 196 as off white powder with 42% yield (Scheme 19). This ketal pyrene 196 was again subjected to oxidation to prepare compound 197. The obtained diketone 197 was then coupled with 172 by refluxing in EtOH/AcOH mixture for overnight. The reaction worked nicely and the product got precipitated in the schlenk which was separated by filtration and washed with alcohol. After drying 198 obtained as yellow powder (68% yield) which was characterized and used for next step. The next step was reduction of nitro groups by slow addition of hydrazine hydrate in the reaction mixture containing 198 and Pd/C at 800C. After completion of reaction the catalyst was filtered off and solvent was removed under reduced pressure. The obtained crude product 199 was used as it is for next step.

- 81 - O ethylene glycol O O O O RuCl3, NaIO4 O O O O PTSA, benzene, 43% CH CN, DCM, H O O 3 2 O O 35%

180 196 197

H N 2 NO2 NH2NH2.H2O, H2N NO2 O N NO O N NH 172 O 2 10% Pd/C O 2 O O EtOH / AcOH, 85% O N NO2 EtOH, reflux O N NH2

198 199

Scheme: 19

2.3.3.4. Attempts to synthesis of 2,7-di-tert-butylpyrene-4,5-diketals fused octaazadodecacene: The synthesis of heptacene 200 was attempted by refluxing the mixture of obtained diamine 199 and the diketone 180 in EtOH/AcOH (Scheme 20). The reaction was monitored by TLC and after consumption of starting material the reaction was stopped. Methanol was added in the reaction mixture and then it was filtered and washed with methanol. After washing bright orange compound was obtained but in NMR it showed peaks for 8 aromatic protons that were unable to assign.

O

O

O N NH2 O N N O 180 O O O O N NH2 EtOH/AcOH O N N

200 199 Scheme: 20

In the same way attempts to couple the diamine 199 with tetraketone 188 were carried out to get the dodecacene 201 but failed to give the desired product (Scheme 21).

- 82 - O O N N N N O O O O N N N N O O O O

O O

O Desired Product N O NH2 188 201 O N NH O 2

199 O N N O O O N N O O

202

Product detected by Mass Spectroscopy

Scheme: 21

Mostly complex mixture with lot of by products was obtained, which were difficult to separate by column chromatography and characterize by 1H NMR. From mass spectroscopy, it was possible to detect only mono coupled product 202 in the reaction mixture AcOH/ODCB (Table 3). Solvent with higher boiling point like m-cresol was also tried but further heating in this case caused decomposition of the material.

Solvent Temp. Time Result

AcOH Reflux 5 days Complex mixture

Phenol 150oC 8 days Complex mixture

AcOH/ODCB Reflux 6 days 202

m-cresol 180oC 5 days Decomposed

Table: 3

By taking into consideration all the results from 2,7-di-tert-butyl-pyrene azaacenes it can be concluded that the tert-butyl groups on the pyrene are not enough to make higher azaacenes soluble.

- 83 -

2.4. Conclusions: Attempts to develop new synthetic strategy have been carried out. The synthesis was attempted first with non-substituted pyrene but due to the lack of solubilizing groups, failed to obtain desired oligoacenes. Secondly, to overcome the solubility issues, tert-butyl groups were introduced as solubilizing groups. Unfortunately the tert- butyl groups did not improve much the solubility but azaacene with up to seven linearly fused aromatic rings i.e. “heptacene” (202) was prepared successfully. The attempts to synthesize longer oligoacenes were failed, as the tert-butyl groups did not provide enough solubility. The synthetic strategy includes simple cyclocondensation ptotocol for the preparation of long oligoacenes and building blocks prepared for this were with more than one reaction sites for such condensations. These building blocks after modification can be used for the stepwise synthesis of long oligoazaacenes with enhanced solubility and tunable properties.

- 84 - 2.5. References:

1) A. Kekule, Bull. Soc. Chem. (NS) 3, 98, (1865); Zeit. Chem. (NF), 1865, 1, 277; Bull. Acad. Roy. Belg., 1865, 19, 551. 2) E. Hückel, Z. Physik., 1931, 70, 204.; 1931, 72, 310.; 1932, 76, 628.; 1933, 83, 632. 3) (a) Armitt, T. W.; Robinson, R. J. Chem. Soc. 1925, 1604-1618. (b) Clar, E. The Aromatic Sextet; John Wiley & Sons: London; 1972. (c) Kruszewski, J.; Krygowski, T. M. Tetrahedron Lett. 1972, 36, 3839-3842. (d)Schleyer, P.; Maerker, C.; Dransfeld, A.; Jiao, H.; van Eikema Hommes, N. J. R. J. Am. Chem. Soc. 1996, 118, 6317-6318. (e) Poater, J.; Fradera, X.; Duran, M.; Sola, M. Chem. Eur. J. 2003, 9, 400. (f) Bader, R. F. W.; Streitwieser, A.; Neuhaus, A.; Laidig, E.; Speers, P. J. Am. Chem. Soc. 1996, 118, 4959. 4) Armitt, T. W.; Robinson, R. J. Chem. Soc. 1925, 1604-1618 5) Clar, E. The Aromatic Sextet; John Wiley & Sons: London; 1972. 6) Clar, E. Polycyclic Hydrocarbons; Academic press: New York, 1964; vol. 1. 7) Hachmann, J.; Dorando, J. J.; Aviles, M.; Chan, G. K. L.; J. Chem. Phys. 2007, 127, 134309. 8) R. Mondal, C. Tönshoff, D. Khon, D. C. Neckers and H. F. Bettinger J. Am. Chem. Soc., 2009, 131, 14281–14289. 9) Bouas-Luarent, H.; Dürr, H. Pure Appl. Chem. 2001, 73, 639. 10) (a) M. Yamada, I. Ikemoto and H. Kuroda, Bull. Chem. Soc. Jpn., 1988, 61, 1057. (b) A. Maliakal, K. Raghavachari, H. Katz, E. Chandross and T. Siegrist, Chem. Mater., 2004, 16, 4980. 11) Watanabe, M.; Chang, Y. J.; Liu, S. W.; Chao, T. H.; Goto, K.; Islam, M. M.; Yuan, C. H.; Tao, Y. T.; Shinmyozu, T.; Chow, T. J. Nature Chem., 2012, 4, 574. 12) Biermann, D.; Schmidt, W. J. Am. Chem. Soc.; 1980, 102, 3163. 13) (a)Strating, J.; Zwanenburg, B.; Wagenaar, A.; Udding, A. C. Tetrahedron Lett. 1969, 125-129. (b) R. Mondal, C. Tönshoff, D. Khon, D. C. Neckers and H. F. Bettinger J. Am. Chem. Soc., 2009, 131, 14281–14289. 14) (a) R. Mondal, R. M. Adhikari, B. K. Shah, D. C. Neckers, Org. Lett. 2007, 9, 2505. (b) R. Mondal, B. K. Shah, D. C. Neckers, J. Am. Chem. Soc. 2006, 128, 9612. 15) Kaur, I., Jia, W., Kopreski, R., Selvarasah, S., Dokmeci, M. R., McGruer, N. and Miller, G. P., J. Am. Chem. Soc., 2008, 130, 16274–16286. 16) Daiki Matsumura, D.; Kitazawa, K.; Terai, S.; Kochi, T.; Ie, Y.; Nitani, M.; Aso, Y.; Kakiuchi, F.; Org. Lett., 2012, 14, 3882-3885. 17) Payne, M. M.; Parkin, S. R.; Anthony, J. E. J. Am. Chem. Soc. 2005, 127, 8028. 18) Doris Chun, Yang Cheng, and Fred Wudl; Angew. Chem. Int. Ed. 2008, 47, 8380 –8385. 19) Kaur, M. Jazdzyk, N. N. Stein, P. Prusevich, G. P. Miller, J. Am. Chem. Soc. 2010, 132, 1261-1263. 20) (a) Liang, Z.; Tang, Q.; Xu, J.; Miao, Q. Adv. Mater., 2011, 23, 1535–1539. (b) Liang, Z.; Tang, Q.; Mao, R.; Liu, D.; Xu, J.; Miao, Q. Adv. Mater., 2011, 23,

- 85 - 5514. (c) Appleton, A. L.; Brombosz, S. M.; Barlow, S.; Sears, J. S.; Bredas, J.- L.; Marder, S. R.; Bunz, U. H. F. Nature Comm., 2010, 1, 91. 21) U. H. F. Bunz, Chem. Eur. J., 2009, 15, 6780–6789. 22) (a) J. E. Anthony, Chem. Rev., 2006, 106, 5028. (b) U. H. F. Bunz, Chem. Eur. J., 2009, 15, 6780. (c) U. H. F. Bunz, Pure Appl. Chem., 2010, 82, 953. (c) Richards, G. J.; Jonathan P. Hill, J. P.; Morib, T.; Katsuhiko Ariga, K.; Org. Biomol. Chem., 2011, 9, 5005–5017. 23) (a) O. Fischer and E. Hepp, Chem. Ber., 1890, 23, 2789. (b) Fischer, O.; Hepp, E.; Chem. Ber., 1895, 28, 293. 24) Badger, G. M.; Pettit, R.; J. Chem. Soc., 1951, 3211. 25) Hinsberg, O.; Liebigs, J.; Ann. Chem., 1901, 319, 257. 26) Kummer, F.; Zimmermann, H.; Ber. Bunsenges. 1967, 71, 1119. 27) Miao, Q.; Nguyen, T. Q.; Someya, T.; Blanchet, G. B.; Nuckolls, C.; J.Am. Chem. Soc., 2003, 125, 10284. 28) (a) Liang, Z.; Tang, Q.; Xu, J.; Miao, Q. Adv. Mater. 2011, 23, 1535. (b) Wang, C.; Liang, Z.; Liu, Y.; Wang, X.; Zhao, N.; Miao, Q.; Hu, W.; Xu, J. J. Mater. Chem. 2011, 21, 15201. (c) Liang, Z.; Tang, Q.; Mao, R.; Liu, D.; Xu, J.; Miao, Q. Adv. Mater. 2011, 23, 5514. 29) Miao, S.; Appleton, A. L.; Berger, N.; Barlow, S.; Marder, S. R.; Hardcastle, K. I.; Bunz, U. H. F. Chem. Eur. J. 2009, 15, 4990. 30) (a) Stille, J. K.; Mainen, E. L. Macromolecules 1968, 1, 36. (b) Young, E. R. R.; Funk, R. L. J. Org. Chem. 1998, 63, 9995. (c) Cho, H.; Harvey, R. G. Tetrahedron Lett. 1974, 1491. 31) Oberender, F. G.; Dixon, J. A. J. Org. Chem. 1959, 24, 1226. 32) Hu, J.; Zhang, D.; Harris, F. W. J. Org. Chem. 2005, 70, 707. 33) Stille, J. K.; Mainen, E. L J. Polym. Sci., Part B, 1966, 4, 665–667. 34) Arnold, F. E. J. Polym. Sci., Part A-1: 1970, 8, 2079–2089. 35) Kaafarani, B. R.; Lucas, L. A.; Wex, B.; Jabbour, g. E. Tetrahedron Letters 2007, 48, 5995–5998. 36) Lucas, L. A.; DeLongchamp, D. M.; Richter, L. J.; Kline, R. J.; Fischer, D. A.; Kaafarani, B. R.; Jabbour, G. E. Chem. Mat. 2008, 20, 5743-5749. 37) Luo, M.; Shadnia, H.; Qian, G.; Du, X.; Yu, D.; Ma, D.; Wright, J.; Wang, Z. Chem.Eur. J. 2009, 15, 8902-8908. 38) Wang, M.; Tong, H.; Cheng, Y.; Xie, Z.; Wang, L.; Jing, X.; Wang, F. Journal of Polymer Science Part A: Polymer Chemistry 2010, 48, 1990–1999. 39) Raad, F. S.; El-Ballouli, A. O.; Moustafa, R. M.; Kaafarani, B. R.; Al-Sayah, M. H. Tetrahedron, 2010, 66, 2944 – 2952. 40) Gao, B.; Wang, M.; Cheng, Y.; Wang, L.; Jing, X.; Wang, F. J. Am. Chem. Soc. 2008, 130, 8297-8306. 41) Mateo-Alonso, A.; Kulisic, N.; Valenti, G.; Marcaccio, M.; Paolucci, F.; Prato, M. Chem. As. J. 2010, 5, 482-485. 42) Kulisic, N.; More, S.; Mateo-Alonso, A. Chem. Commun. 2011, 47, 514–516. 43) Oberender, F. G.; Dixon, J. A. J. Org. Chem. 1959, 24, 1226.

- 86 - 44) (a) Stille, J. K.; Mainen, E. L. Macromolecules 1968, 1, 36. (b) Young, E. R. R.; Funk, R. L. J. Org. Chem. 1998, 63, 9995. (c) Cho, H.; Harvey, R. G. Tetrahedron Lett. 1974, 1491. 45) J. Hu , D. Zhang, F. W. Harris, J. Org. Chem., 2005, 70, 707–708. 46) (a) Kleineweischede, A.; Mattay, J. European Journal of Organic Chemistry 2006, 4, 947–957. (b) Starnes, S. D.; Arungundram, S.; Saunders, C. H. Tetrahedron Letters, 2002, 43, 7785. 47) Shirai, Y.; Osgood, A. J.; Zhao, Y.; Yao, Y.; Saudan, L.; Yang, H.; Yu-Hung, C.; Alemany, L. B.; Sasaki, T.; Morin, J. F.; Guerrero, J. M.; James, K. F.; Tour, J. J. Am. Chem. Soc., 2006, 128, 4854–4864. 48) Yan, Y. L.; Cohen, S. M. Org. Lett., 2007, 9, 2517. 49) Yamato, T.; Miyazawa, A.; Tashiro, M. Chemisch. Ber. 1993, 126, 2505-2511.

- 87 -

- 88 -

Chapter: 3

Design, synthesis and properties of versatile 2,7- substituted pyrene fused azaacenes as low LUMO materials for OPVs

- 89 -

- 90 - 3.1. Introduction: The chemistry of pyrene has always been attracted chemists due to its interesting electronic and photophysical properties. In 1837 it was discovered by Laurent1 in the destructive distillation of coal tar and since then pyrene has become an important topic for researchers in different fields. In organic electronics pyrene is being very promising building block due to its properties. The blue light emitting pyrene chromophore, along with its high charge carrier mobility and stability should be one of the reliable material for OLEDs, OFETs and semiconducting material for OPVs. The tendency of pyrene to form excimers2 decreases the fluorescence efficiency and puts limitations on the use of pyrene itself as a blue light emitter in OLEDs. The formation of excimers can be avoided by modification of pyrene. Such modified has been used in OLEDs and showed increase in photoluminescence efficiency.3 In order to predict new ideal material for optoelectronics, understanding of the structure property relationship of that material is important. In recent years plenty of research is focused on structural modification and film morphology optimization of pyrene in order to get high-performance devices. There is large scope for modifications on pyrene (Fig. 60) due to the availability of number of sites for substitution. Several reports in literature have successfully demonstrated that the intermolecular interactions can be controlled by manipulating the structure complexity at the molecular level using different types of substituents on different positions.4 The literatured methods used for such modification of pyrene are highlighted briefly in the following sections.

2 1 3

10 4

9 5

8 6 7 147

Fig. 60: Structure of pyrene and the positions for substitution.

3.1.1. 1-substituted pyrene: Modification of pyrene at position-1 has been followed by synthesis of 1- pyreneboronic acid 204 as shown in Fig. 61. The dipyrenylbenzenes 205-207 were prepared by treating 204 with different aryl bromides via Suzuki coupling.5

- 91 - Br B(OH)2

Br2 B(CH3O)3

pyridine n-BuLi

147 203 204

R Br

Br R R Na CO , Pd(PPh ) 2 3 3 4 R

205 = R = H

206 = R = CH3 207 = R = OCH3

Fig. 61: Synthesis of di-pyrenylbenzene via boronic acid precursor.

Similarly, owing to its easy synthetic protocol Sonogashira coupling has been proved to be an important tool for modification of pyrene at position-1. The initial substrate, 1-bromopyrene 203 can be easily prepared by treating one equivalent of bromine at room temperature and Sonogashira coupling with trimethylsilyl (TMS) acetylene gives compound 209 as shown in Fig. 62. Further deprotection of 209 under basic conditions gives 1-ethynylpyrene 210, which has been used as main building block in many Sonogashira coupling reaction and variety of substituted pyrene derivative has been prepared for OFETs.6

TMS Br

H TMS KOH, 86%

PdCl2(PPh3)2 CuI, 80%

203 209 210

Fig. 62: Synthesis of 1-ethynylpyrene via Sonogashira coupling.

3.1.2. 1,3,6,8-substituted pyrene: The bromination of pyrene at high temperature leads to 1,3,6,8-tetrabomopyrene 211, which was also utilized for variety of substitutions via Sonogashira or Suzuki coupling reactions (Fig. 63).7 The Suzuki coupling of tetrabromopyrene 211 with diverse type of boronic acids leads to variety of tetrasubstituted pyrenes like 2138. Tetrasubstitution with bulky group diminishes aggregation leading to much brighter OLEDs. The simple nucleophilic substitution strategy was also applied on the

- 92 - tetrabromopyrene in order to synthesize the polysulphatated derivative 214. In case of 9 214, change in fluorescence upon reversible one electron oxidation were observed. Suzuki coupling of 211 with different types of boronic acids provided library of copounds like 212 and 215-217.10

C6H13 C6H13

C6H13 C6H13

C6H13 C6H13

C6H13 213 212 C6H13

H3C CH3 F3C CF3

S S Br Br

S S

214 F C CF Br Br 3 216 3 H3C CH3 211

S

S

S

S 215 217

Fig. 63: Tetrasubstituted pyrenes synthesized following Suzuki coupling.

Columnar liquid crystals of 218 have also been reported, which were synthesized from 211 by using Sonogashira coupling (Fig. 64).11 Sonogashira coupling of tetrabromopyrene 211 has been also carried out with trimethylsilylacetylene (TMS) and after deprotection afforded 219 which was used as starting material for the synthesis of molecules with interesting supramolecular self-assembling properties in solution and on surface.12 Recently in our lab, the 1,3,6,8-substituted pyrene 208 was implemented as building block in order to prepare pyrene fused azaacenes with improved solubility.13

- 93 - OC12H25 OC12H25

C12H25O OC12H25

C12H25O OC12H25

C12H25O OC12H25

OC H C12H25O 218 12 25 OC12H25 OC12H25

Br Br

Br Br C6H13 C6H13 H H 197

C6H13 C6H13 H H 208 219

Fig. 64: Tetrasubstituted pyrenes synthesized following Sonogashira coupling.

3.1.3. 4,5,9,10-substituted pyrene derivatives: The substitution at 4,5,9,10 positions of pyrene is a very building block that allows the preparation of extended aromatic systems. Pyrene oxidation can be done in order to prepare pyrene-4,5-diketone (148) and pyrene-4,5,9,10-tetraketone (149). The early reports describes the oxidation that includes multistep synthesis14 and toxic reagents such as osmium tetroxide.15 Currently, oxidation of pyrene is carried out commonly by using ruthenium chloride and sodium peroxide. This method yields 4,5-diketone 148 or 4,5,9,10-tetraketone 149 in single step depending on the stoichiometry of reaction.16 These molecules 148 and 149 have been used as starting material for the synthesis of extended aromatic systems such as 220-223 as shown in Fig. 65.17

- 94 - N N

N N

220 221

RuCl3 RuCl3 O O O 4eq. NaIO4 8eq. NaIO4

O DCM/CH3CN/H2O DCM/CH3CN/H2O O O room temp. 30-400C

148 147 149

N N N N

N N N N

222 223

Fig. 65: Oxidation of pyrene.

3.1.4. 2,7-substituted pyrene derivatives: The simplest way of substitution at 2,7-positions of pyrene can be Friedel-Crafts alkylation but there are not many reports on such type substitution other than with tert- butyl groups.18

tert. butyl chloride

AlCl3, pyridine

184

Fig. 66: 2,7-substitution of pyrene using Friedel-Craft alkylation.

The substitution at 2,7-positions of pyrene other than tert-butyl is synthetic challenge because of the presence of nodal planes laying perpendicular to the 2,7- positions in HOMO and LUMO as shown in Fig. 67.

- 95 -

Fig. 67: HOMO (left) and LUMO (right) of pyrene.

There are very few reports on the synthesis of 2,7-substituted pyrene; some of the recent examples are mentioned here. The synthetic route for 2,7 n-hexyl pyrene 227 is as shown in Fig. 68. The synthesis involes Friedel-Craft acylation on tetrahydropyrene 224 and then oxidation of 226 to get the 2,7-n-hexylpyrene 227 .19

O

H2, Pd/C C5H11COCl

EtOAc AlCl3, CH2Cl2

224 O 225

KOH, NH2NH2 DDQ

ethylene glycol 1,4-dioxane

227 226

Fig. 68: Synthesis of 2,7-hexylpyrene.

- 96 - The 2,7-substitution of pyrene via reduction of pyrene and finally the oxidation using DDQ in order to get compound 228 has been reported and also the molecule 228 used as building block by Lambert and co-workers.20

O O C8H17 O O C8H17 Br

Br2/NaOH n-BuLi DDQ Benzene CH3COOH C8H17COOCl

224 Br Br Br 228

Fig. 69: Synthesis of 2,7-substituted pyrene.

Direct substitution on 2,7 positions of pyrene following borylation was reported by Qiao et al. using Iridium catalyst. The borylated product was then used as starting material for Suzuki coupling with different aromatic halides as shown in Fig. 70. The crystal structures of obtained molecules 229-232 were studied and demonstrated the effect of substituent on packing motif of molecule. These moleculers were also applied in OFETs as p-type semiconducting material and checked performance among all the molecule 232 showed mobility upto 0.018 cm2/(V·s).21

229 = Ar = O O B Ar

B pin , dtbpy 2 2 ArBr, Na2CO3 230 = Ar = S [Ir(OMe)COD]2 Pd(PPh3)4

0 N cyclohexane, 80 C toluene, 900C 231 = Ar = S

B Ar O O 232 = Ar = S

Fig. 70: Synthesis of 2,7-substituted pyrene.

Recently Marder and co-workers have reported borylation of pyrene at the 2,7 positions and further utilize the resulted intermediates for different types of reaction like, Suzuki-Miyaura, Sonogashira, Buchwald-Hartwig and Negishi cross coupling as shown in Fig. 71.22

- 97 - Bpin OH OTf

H2O2, NaOH Tf2O pyridine/hexane THF/H2O, RT

Bpin OH OTf

H R NaIO4 [PdCl2(PPh3)2], CuI THF/H2O DMF/Et3N

R

B(OH)2 R-Br

[PdCl2(dppf)]

K3PO4, DMF

B(OH) 2 233 = R = (4-COOC8H17)C6H4 234 = R = [4-B(Mes) ]C H 2 6 4 R 235 = R = (4-NMe2)C6H4 236 = R = Ph; 209 = R TMS

Fig. 71: Synthesis of 2,7-substituted pyrene reported by Marder and Co-workers.

3.2. Synthesis of 2,7-substituted pyrene-fused azaacenes: 3.2.1. Objective: We are interested in synthesizing these compounds to make n-type semiconductors. To overcome the insolubility of tert-butyl substituted pyrene acenes, we have recently developed and implemented in our lab, the 1,3,6,8-tetraoctyl-4,5,9,10- tetraketopyrene 154 as building block in order to prepare tetraazaoctacenes (170) with improved solubility.13 Unfortunately, the synthesis of 170 is tedious due to the lack of reactivity in some cases and also the lack of stability over time which can be explained in terms of steric hinderance caused by the substitutions on positions 1,3,6,8 of pyrene as shown in Fig. 72. Synthesis of low LUMO material was designed with simple cyclocondensation protocol as shown in Fig. 72. In order to lower the LUMO, o-phenylenediamines with electron withdrawing groups were used which also reduced nucleophilicity of diamine and prolonged the reaction time. Due this prolonged reaction time, pyrene tetraketone 154 was not an ideal candidate for the sythesis of low LUMO material as it decomposes over time. In order to enhance the reactivity and overcome the stability issues, synthesis 2,7-substituted pyrene fused azaacenes was carried out.

- 98 - R

RuCl3, 8eq.NaIO4 O O O O o O O 40 C 3 steps 2 steps

O O O O O O

R 154 X X NH EtOH/AcOH H2N 2 reflux H2N X NH2 X R

X X X N N X N N

N N X N N X X X

R = TIPS, Alkyl chain X = H, electron withdrawing group R

170

Fig. 72: Synthesis of 1,3,6,8-substituted pyrene fused azaacene and proposed route for synthesis of low LUMO material.

The objectives of this project were as mentioned below. (a) To overcome the oppressive synthesis of 2,7-substituted pyrene tetraketone and utilization of these 2,7-substituted pyrene tetraketone synthons in the preparation of pyrene-fused azaacenes. (b) Synthesis of potential n-type material for organic electronics.

3.2.2. Synthsis of 2,7-substituted pyrene tetraketone: The synthetic scheme starts from 2,7-diodo-4,5,9,10-tetraketopyrene (3)23 (Scheme 22) that is readily available in two steps from pyrene. First, we attempted to functionalize positions 2,7 of 237 by means of Sonogashira reactions.24 Nevertheless, after screening several standard palladium sources, ligands, and bases for Sonogashira reactions, no evolution toward the desired products was observed. This is consistent with the lack of reactivity of 237 in other C−C forming reactions, such as Suzuki coupling.23 In order to check if the ketone substituents are influencing the reactivity, all ketones were transformed into diketals. This is not only a way to protect ketones but also a way to inverse the polarity of the carbonyl group (umpolung). Compound 238 was easily obtained by refluxing 237 in o-dichlorobenzene (ODCB) in the presence of ethylene glycol and p-toluenesulfonic acid in a Dean-Stark apparatus25. After purification by column chromatography white solid compound 238 was obtained and successfully used for Sonogashira coupling with triisopropylsilyl (TIPS) acetylene which yielded compound 239a with 78% yield. The success of this Sonogashira coupling with compound 238 is explained in terms of inversed polarity (umpolung) of carbonyl groups by ketal formation. This developed protocol was applied for different types of acetylenes containing octyl and dodecyl chains in order prepare

- 99 - library of compounds like 239a-c. All the Sonogashira reactions were done in dry THF under degassed conditions and purification was done by using column chromatography. Obtained 2,7-substituted pyrene derivatives 239a-c were treated with 10% H2O in TFA in order to get the tetraketones 240a-c. The purification of obtained tetraketones 240a-c was done by different ways depending on the substituents. The TIPS acetylene and octyne acetylene substituted pyrene (240a and 240b) were purified by just filtration and washed with water to get pure compounds with good yields. But in case of 240c, purification was done by using column chromatography.

R

I I

ethyleneglycol, O O H R O O O O PTSA, O O o-dichlorobenzene O O O O O O reflux, 51% O O Sonogashira coupling I I 240a= R = TIPS 237 238 240b= R = C6H13 R

240c= R = C12H25 240

R R

R O O TFA:H O, r.t. O O [Pd(PPh3)2Cl2] O O 2 CuI,DIPA/THF O O O O O O reflux

239a= R = TIPS 240a= R = TIPS R R C H 239b= R = C6H13 240 240b= R = 6 13 239 = = C H 239c= R = C12H25 240c R 12 25

Scheme: 22

3.2.3. Utilization of 2,7-substituted pyrene tetraketones for azaacene synthesis: The obtained tetraketones 240a was used for synthesis of tetraazahexacene 241a and tetraazaoctacene 242a by cyclocondensation with o-phenylenediamine 243 and 2,3- diaminonaphthalene 244 respectively. These reactions were carried out in the mixture of refluxing EtOH/AcOH and purified by filtration and washing with alcohol to give compounds 241a and 242a with 76% and 62% yields respectively (Scheme 23). Following same protocol all the compounds 241b-c and 242b were synthesized. The solubilies of these compounds were depending on the type of substitution and size of the π-core. The TIPS substituted “hexacene” and “octacene” were more soluble as compare to others may be due to the bulky group that avoided the π-π stacking. Also it was observed that the “octacenes” 242a-b were less soluble than their respective “hexacene” analogues 241a-c might be due the increased conjugation which allowed more π-π stacking.

- 100 -

R

NH2

NH2 N N 243

R N N

241a = R = TIPS R O O EtOH/AcOH 241b = R = C6H13 241 241c C H reflux = R = 12 25 O O R

NH2

R NH2 244 N N 240 N N

242a = R = TIPS R 242b = R = C6H13 242

Scheme: 23

3.2.4. Optical properties: The photophysical properties of compounds 241a-c and 242a-b were investigated by steady state UV-Vis and fluorescence spectroscopy (Fig. 73). The spectra were recorded in o-dichlorobenzene solution. As shown in the Fig. 73, in case of tetraazahexacenes 241a-c the absorption was quite similar with major peaks at 340 nm, 397 nm and 420 nm. The peak at 340 nm and the small peak at 320 nm were assigned to pyrene core where as, the peaks at 420 nm, 397 nm and a small peak at 375 nm were assigned to “phenanthrene” and “benzopyrazine” units of the hexacenes. The emission spectra of 241b-c were obtained by excitation with UV or visible light, which showed peak, centered around 460 nm with a shoulder at 428 nm which was reversed in case of 241a in which it showed two distinct emission at 420 and 450 nm.

Fig. 73: Absorption and emission spectra of 241a-c in ODCB.

- 101 - The absorption pattern of tatraazaoctacenes 242a-b was also identical, with major peaks at 332 nm, 347 nm, 424 nm and 450 nm. The peak at 332 nm and the small peak at 315 nm were assigned to pyrene core where as, the peaks at 424 nm, 450 nm and a small peak at 400 nm were assigned to pheanthrene and naphthopyrazine units of the octacenes. In emission spectra it can be seen from Fig. 74, both the octacenes 242a-b gave emission band centered at 560 nm apart from this in 242a peaks at 405 and 425 nm were also observed.

Fig. 74: Normalized absorption and emission spectra of 241a-b in ODCB.

In absorbtion spectra of hexacenes and octacenes considerable red shift was observed for the units absorbing in the range of 400 – 500 nm where as the shift at the pyrene core is not that much. Also in the emission spectra there is red shift of around 100 nm. This might be due to the expansion of the π system along the pyrene core.

3.2.5. Electrochemical properties: The electrochemical properties of all the compounds were investigated by cyclic voltammetry in a degassed solution of o-dichlorobenzene and tetrabutyl ammonium perchlorate (TBAP/ODCB). The electron deficient nature of the pyrene-fused azaacene core is reflected by cyclic voltammetry. Electrochemically reversible reduction waves were observed for “hexacenes” 241a-c (Fig. 75) around –1.3 and –1.5 V. The hexacenes 241a-c displayed similar half-wave potentials (E1⁄2) around –1.3 V. The waves for 241c are broad due to the aggregates formed in the solution. The voltammograms of “octacenes” 242b also revealed strong aggregation displaying multiple and very broad waves. On the contrary, due to the enhanced solubility 242a three reduction processes were observed (Fig. 75) with more anodically shifted half-wave potentials –1.03 V than for the analogous “hexacene” 241a, which is –1.25 V.

- 102 -

Fig. 75: Cyclic voltammograme of 241a-c (left) and 242a (right) in ODCB (E=Fc/Fc+).

The bandgaps for hexacenes were estimated from the absorption onsets of 241a-c in range 2.7-2.9 eV (Table 4). The bandgaps for octacene 242a was found in the range of 3.01 eV that are smaller than their hexacene analogues. This decreasing band gap is due to the extended conjugation of the respective azaacenes. The LUMO levels were estimated from the potential onsets of the first reduction waves. The ELUMO for 241a-c are in the range of –3.18 - –3.2 eV as shown in Table 4. There is very small influence of the substitution on acetylene end. In the octacenes the ELUMO for 242a was around –3.38 eV.

a a c c e Comp E1/2 (V) Eonset ELUMO(eV) λonset λem EHOMO (eV) Egap(opt) 241a -1.25 -1.06 -3.21 430 450 -6.09 2.88

241b -1.30 -1.19 -3.18 435 460 -6.03 2.85

241c -1.38 -1.21 -3.19 440 460 -5.99 2.80

242a -1.03 -0.97 -3.38 510 522 -6.39 3.01

242b ------512 520 --- 2.42 a b Measured from 0.1 M ODCB/TBAP vs. SCE. Estimated from EONSET according to ELUMO = – 4.8 – e c d e (EONSET - E1/2Fe) eV. Measured in ODCB. Measured electrochemically. estimated from absorption onset.

Table: 4. Selected Photophysical and Electrochemical Data.

From the photophysical and electrochemical studies of all the molecules, it can conclude that bulky substituents or long aliphatic chains at the acetylene end doesn’t show any considerable influnce on the pyrene azaacenes. But the properties changes on extending the conjugation of pyrene azaacenes.

- 103 - From the photophysical and electrochemical studies of all the molecules, it can be concluded that, change in the substitution on azaacene core provides pace to tune the electrochemical and photophysical properties of the respective molecule. The substitution with electronegative groups like fluoro, nitro, cyano on the core of azaacenes could be resulted into the drop of the LUMO levels and synthesis of such low LUMO materials is explained below.

3.3. Low LUMO Azaacene material synthesis: At this stage we decided to test if the developed building blocks will be able to react with diamines with electron withdrawing groups as explained in section 3.2.1. Such electron withdrawing groups are necessary to bring down the LUMO levels to prepare more efficient n-type semiconductors. The low LUMO material was synthesized mainly by using tetraketone 240a and different type of diamines possessing electron withdrawing sunstituents like fluoro, nitro, cyano, etc as shown in Scheme 24. Due to the enhanced solubility, compound 240a is used as starting material for the synthesis of “azaacenes” with electron withdrawing groups. Tetraketone 240a was cyclocondensed with commercially available tetrafluoro diaminobenzene 249. At first the reaction was attempted in the mixture of EtOH/AcOH but only monocondensed product was obtained hence it was done successfully in pure AcOH. The crude product was purified by washing with alcohol which, after drying offered the compound 245 as yellow solid with 68% yield. In order to study the influence of electron withdrawing nature of nitro groups on the properties of the tatraazahexacene, compound 246 was synthesized via cyclocondensation of the tetraketone 240a with the dinitrodiaminobenzene 250. The reaction was done by using EtOH/AcOH and product was purified by washing with alcohol which offered the compound 246 as yellow solid with 78% yield. Where as the dicyano substituted tetraazatetraacene 247 and octaazahexacene 248 were synthesized from commercially available diaminomaleonitrile 251 and dicyanopyrazine diamine 252 respectively via cyclocondensation with tetraketone 240a that offered compounds 247 and 248 with 78% and 71% yields respectively.

- 104 - TIPS

F F F N N F

F N N F F F

245 TIPS

F H2N F EtOH/AcOH

reflux, 68% H2N F F 249

TIPS TIPS TIPS

NC N NH2

EtOH/AcOH NC N NH2 O2N N N NO2 reflux, 78% 252 NC N N N N CN O O

O N N N NO AcOH NC N N N N CN 2 2 O2N NH2 O O reflux, 71%

O2N NH2 246 TIPS TIPS TIPS 248 246

H2N CN EtOH/AcOH reflux, 78% H2N CN 251

TIPS

NC N N CN

NC N N CN

TIPS 247

Scheme: 24

3.3.1. Optical properties of low LUMO Azaacenes: The photophysical properties were investigated by steady state UV-Vis and fluorescence spectroscopy. The spectra were recorded in o-dichlorobenzene solution are shown in Fig. 76. The absorption for compound 245 comes at 425 nm which is slightly red shifted than the normal hexacene 241a (λmax = 420 nm) consistent with the presence of eight electron withdrawing fluorine atoms. Where as in compound 246 showed the absorption at λmax = 440 nm that even more shifted towards red than 245 with four electron withdrawing nitro groups on the azaacene core of compound 246. The hexacene 248 showed absorption at λmax = 480 nm which is red shifted than the compounds 245, 246 and 247. The absorption of pyrene core in all the compound was observed in the range of 350 – 380 nm and the absorption of “tetracene” 247 is shifted towards red than that of the fluoro substituted hexacene 245. From all above absorption patterns it can be concluded that, the absoption shifts towards red due to the withdrawing groups but the

- 105 - effect is more with the combination of electron withdrawing group and pyrazine ring as in 247 and 248.

Fig. 76: Normalized absorption and emission spectra of 245-247 in ODCB.

In emission spectra compounds 245 and 247 showed peak centered around 480 nm. The emission of 247 is slightly red shifted than 245 where as the compound 246 showed considerable red shift with peak centered at 530 nm. The hexacene 248 did not show considerable emission.

3.3.2. Electrochemical properties of low LUMO materials: The electrochemical properties of all the compounds were investigated by cyclic voltammetry in a degassed solution of 1,2-dichlorobenzene and tetrabutyl ammonium perchlorate (TBAP/ODCB). The electron deficient nature of the pyrene-fused azaacene core is reflected by cyclic voltammetry. Electrochemically reversible reduction waves were observed for compounds 245-247 (Fig. 77) around –0.59 to 0.87 V. The half wave potentials were calculated from the CVs, which were in the range of 0.72 to 0.96 V, it varied with respect to the electronegativity on the acene core. The 247 showed different behavior with respect to the half wave potential and reduction potential although having same group as 248. It is due to the less number of fused pyrazine rings in principle 11 is “tetracene” where as the 248 is “hexacene”. The voltammogram of 248 showed the nature of forming aggregates and gave very broad curve due to its less solubility in ODCB.

- 106 -

Fig. 77: Cyclic voltammograme of 245-247 in ODCB (E=Fc/Fc+).

The data calculated from photopysical and electrochemical study is tabulated in Table: 5. The ELUMO were calculated from E1/2 of ferrocene and the the Eonset obtained from the voltammograms and band gaps were calculated from λonset obtained from the absoption spectras in ODCB solution of respective compound. From all the ELUMO, 245 shows LUMO leval lying at –3.43 eV which is less than simple hexacene 241a (–3.21 eV), the eight electron withdrawing fluorine substitutions might be the reason. The 247 showed ELUMO even lower i. e. –3.74 eV may be due to the four cyano substitutions and the 246 comes at –3.9 eV. The lowest LUMO of 246 might be be due to the electron withdrawing nitro groups and extentended conjugation compared to 247.

a a b c c e Comp E1/2 (V) Eonset ELUMO(eV) λonset λem EHOMO(eV) Egap(opt) 245 –0.96 –0.87 –3.43 445 484 –6.21 2.78

246 –0.93 –0.8 –3.9 460 525 –6.59 2.69

247 –0.72 –0.59 –3.74 443 490 –6.53 2.79

248 ------545 ------2.27 a b Measured from 0.1 M ODCB/TBAP vs. SCE. Estimated from EONSETaccording to ELUMO = - 4.8 – e c d (EONSET - E1/2Fe) eV. Measured in ODCB. estimated from absorption onset.

Table: 5. Selected Photophysical and Electrochemical Data.

The ELUMO showed trend depending on the nature of the substitution in 245 and 246. as the electronegativity increases the fall in ELUMO occurred, the compound 247 was exception for this due to its “tetracene” nature.

- 107 -

3.3.3. Photocurrent-Voltage Curves (J-V Profile) of 247: The compound 247 was implemented in OPV devices and studied the photocurrent generation properties in the lab of Prof. Emilio Palomares from the blend comprising different ratios of poly(3-hexylthiphene) (P3HT):247. The J-V curve of the P3HT:247 (7:3) (Fig. 78) revealed FF of 26.12 respectively. The Jsc generated by the system was 0.25 mA/cm2 whereas the Voc obtained was 559 mV. The overall efficiency was maximum up to 0.04 % with the system P3HT:247 (3:7).

Fig. 78: Current-voltage profile of 247 in dark (black) and in sunlight (red).

From all the studies done on these molecules it can be concluded that, by using this methodology which is not tedious in the synthesis, it was possible to synthesize stable material with low LUMO competing to that of the LUMO of PCMB (-3.7eV).26

- 108 -

3.4. References:

1) Laurent, A. Ann. Chim. Phys. 1837, 66, 136. 2) Forster, T.; Kasper, K. Z. Elektrochem. 1955, 59, 976. 3) Bevilacqua, P. C.; Kierzek, R.; Johnson, K. A.; Turner, D. H. Science 1992, 258, 1355. 4) Figueira-Duarte, T. M.; Müllen; K. Chem. Rev., 2011, 111, 7260–7314. 5) Wu, K. C.; Ku, P. J.; Lin, C. S.; Shih, H. T.; Wu, F. I.; Huang, M. J.; Lin, J. J.; Chen, I. C.; Cheng, C. H. Adv. Funct. Mater. 2008, 18, 67. 6) Liu, F.; Tang, C.; Chen, Q. Q.; Li, S. Z.; Wu, H. B.; Xie, L. H.; Peng, B.; Wei, W.; Cao, Y.; Huang, W. Org. Electron. 2009, 10, 256. 7) Bernhardt, S.; Kastler, M.; Enkelmann, V.; Baumgarten, M.; Müllen, K. Chem. Eur. J., 2006, 12, 6117. 8) Sotoyama, W.; Sato, H.; Kinoshita, M.; Takahashi, T. SID 03 Dig. 2003, 1294. 9) Marc, G.; Virginie, P.; Jean-Manuel, R.; Bergamini, G.; Ceroni, P.; Balzani, V. Chem. Eur. J., 2008, 14, 10357 – 10363. 10) (a)H. Zhang, Y. Wang, K. Shao, Y. Liu, S. Chen, W. Qiu, X. Sun, T. Qi, Y. Ma, G. Yu, Z. Su and D. Zhu, Chem. Commun., 2006, 755–757; (b) Oyamada, Takahito; Akiyama, Seiji; Yahiro, Masayuki; Saigou, Mari; Shiro, Motoo; Sasabe, Hiroyuki; Adachi, Chihaya, Chemical Physics Letters, 2006, 421, 295- 299. (c) Liu, F.; Lai, W. Y.; Tang, C.; Wu, H. B.; Chen, Q. Q.; Peng, B.; Wei, W.; Huang, W.; Cao, Y. Macromol. Rapid Commun. 2008, 29, 659. 11) Hayer, A.; de Halleux, V.; Kohler, A.; El-Garoughy, A.; Meijer, E. W.; Barbera, J.; Tant, J.; Levin, J.; Lehmann, M.; Gierschner, J.; Cornil, J.; Geerts, Y. H. J. Phys. Chem. B 2006, 110, 7653. 12) Llanes-Pallas, A.; Carlos-Andres, P.; Piot, L.; Belbakra, A.; Listorti, A.; Prato, M.; Samori, P.; Armarol, N.; Bonifazi, D. J. Am. Chem. Soc., 2009, 131, 509– 520. 13) Kulisic, N.; More, S.; Mateo-Alonso, A. Chem. Commun. 2011, 47, 514–516. 14) (a) Stille, J. K.; Mainen, E. L. Macromolecules 1968, 1, 36. (b) Young, E. R. R.; Funk, R. L. J. Org. Chem. 1998, 63, 9995. (c) Cho, H.; Harvey, R. G. Tetrahedron Lett. 1974, 1491. 15) Oberender, F. G.; Dixon, J. A. J. Org. Chem. 1959, 24, 1226. 16) Hu, J.; Zhang, D.; Harris, F. W. J. Org. Chem. 2005, 70, 707. 17) a) Mateo-Alonso, A.; Kulisic, N.; Valenti, G.; Marcaccio, M.; Paolucci, F.; Prato, M. Chem. As. J. 2010, 5, 482-485. b) Stille, J. K.; Mainen, E. L J. Polym. Sci., Part B, 1966, 4, 665–667. c) Xu, Q.; Duong, H. M.; Wudl, F. Appl. Phys. Lett. 2004, 85, 3357. 18) Rodenburg, L.; Brandsma, R.; Tintel, C.; Thuijl, J. van; Lugtenburg, J.; Cornelisse, J.; Recueil des Travaux Chimiques des Pays-Bas 1986, 105, 156 – 161. 19) J. Hu, D. Zhang and F. W. Harris, J. Org. Chem., 2005, 70, 707–708. 20) (a) Ghera, E.; Bendavid, Y. J. Org. Chem. 1988, 53, 2972-2979. (b) Rausch, D.; Lambert, C. Organic Letters, 2006, 8, 5037 – 5040.

- 109 - 21) Qiao, Y.; Zhang, J.; Xua, W.; Zhu, D. Tetrahedron 2011, 67, 3395-3405. 22) Andrew, G. C.; Zhiqiang, L.; Ibraheem, A. I. M.; Marie-Helene T.; Nicolle, S.; Gilles, A.; Steffen, A.; Collings, J. C.; Batsanov, A. S.; Howard, J. A; Marder, T. B. Chem. Eur. J. 2012, 18, 5022 – 5035. 23) Letizia, J. A.; Cronin, s.; Ortiz, R. P.; Facchetti, A.; Ratner, M. A.; Marks, T. J. Chem. Eur. J. 2010, 16, 1911 – 1928. 24) Sonogashira, K. J. Organomet. Chem. 2002, 653 (1-2), 46–49. 25) More, S.; Bhosale, R.; Choudhray, S.; Mateo-Alonso, A.; Org. Lett., 2012, 14, 4170-73. 26) Chu, C. W.; Shrotriya, V.; Li, G.; Yang, Y. App. Phy. Lett. 2006, 88, 153504.

- 110 -

Chapter: 4

Synthesis and properties of “twisted” pyrene fused azaacenes

- 111 -

- 112 -

4.1. Introduction: Synthesis and properties of pyrene fused azaacenes with variety of substituents has been described in the Chapter 2 and 3. All the molecules mentioned before were supposed to be planar as there was no parametere involved which can change the topology of molecule. Acenes, a kind of polycyclic aromatic hydrocarbons (PAHs) are linearly fused benzenoid hydrocarbons and generally flat and rigid. However there are several reports on peri substituted overcrowded acenes in which the aromatic core deviates from planarity. The strategic substitution on acenes came up with a new class of acenes called twistacenes. Such twisted acenes have been extensively synthesized and characterized by Pascal.1 Twistacenes with substantial degree of twist angles are briefly mentioned here, the twists are calculated by the torsion angles of the twisted molecule from start to end i. e. ABCD or BADC as shown in Fig. 79.

A D B C

Fig. 79: Representation of a twisted molecule.

The substitution on periphery of acene does not always leads to twistacene but it is an easy way for the preparation of twistacene as compared to the distortion by streaching or bending of C-C bond. The bulky groups attached to the periphery of acene causes a twist in the tortion angle which results into twistacene. There are ceveral reports on such substitution at the acene periphery but only selected examples are briefly mentioned here. In early 1980’s 254-256 were synthesized with different halide substitutions (Fig. 80).2 These substituted naphthalenes 254-256 showed twisted geometry with torsion angles 31o, 24o and 26o respectively. Apart from the halide substitution, heterocycles like Pyrrole were also used as bulky substituent in order to prepare molecules like 257 that showed twist of 22o.3 The molecules 258-260 also known as eight legged “spider” hosts due to their resemblance with spider, showed twist in the range of 29o to 44o.4

SR SR X X N N RS SR X X N N RS SR X X N N SR SR X X N N 258 = R = Ph 254 = X = Br 255 = X = Cl 259 = R = m-tolyl 256 = X = Me 257 260 = R = 3,4-Me2-phenyl

Fig. 80: Highly substituted naphthalene with twisted geometry.

Pascal and co-workers synthesized decaphenylanthracene 261 as shown in Fig. 81.

- 113 - The anthracene 261 showed end-to-end twist of 63o. As per the report, even with such deformed geometry the anthracene 261 did not show any different optical properties than simple anthracene except the red shift of E2 band, which was assigned to the phenyl substitutions.5

Ph Ph Ph maleimide O Ph Ph 1) NaOH/NaOCl Ph CO2H PhNO2 O NH reflux Ph Ph 2) KOH/PrOH/reflux Ph NH2 Ph Ph O Ph

1) isoamyl nitrile 2) Ph Ph Ph O Ph Ph Ph

Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph Zn / AcOH O Ph Ph reflux Ph Ph Ph Ph Ph Ph Ph Ph 261

Fig. 81: Synthesis of highly substituted anthracene.

Like the substitution of phenyl rings, the fusion of phenyls is another way to introduce twist or distortion in the plane of a molecule. The 262-266 are also known as dibenzonaphthalene (Fig. 82) and showed significant distortion with different substituents. The dimethyl- 262 and tetraphenyl-triphenylene 263 showed twists of 29o and 31o respectively.6 Where as twist of naphthalene in the triphenylenes 264-266 was 40o, 56o and 45o respectively.7 The phenyl groups on benzannulated acenes positioned in such a way that it clashes with benzo hydrogens of the acene core, produced twist in the molecules 267-270 of 66o, 61o, 70o and 60o respectively.8

X X X X X X Y X X Y X X X X X X 262 = X = Me, Y = H X 263 = X = Y = Ph 264 = X = F 265 = X = Cl X 266 = X = O(p-tolyl) Ph Ph 267 = X = H Ph 268 = X = Cl

269 = X = CF3 Ph Ph Ph 270

Fig.82: Synthesis of highly substituted benzannulated acenes.

- 114 -

Similarly, long acenes with multiple phenyl rings were synthesized as shown in Fig. 83 which gave twisted ribbons, the molecule 271 showed end-to-end twist around 105o.9

Ph Ph Ph Ph Ph Ph CO2H Ph isoamyl nitrile Ph + O O NH2 Ph Ph Ph Ph Ph Ph Ph Ph

Ph Ph Ph Zn / AcOH Ph

Ph Ph Ph Ph 271

Fig. 83: Synthesis of highly substituted benzannulated long acenes.

Later in 2003 Wudl and co-workers came up with pyrene-fused acene with strategically substituted phenyls and the molecule 220 (Fig. 84) found to be twisted with torsion angle up to 23o.10 This molecule 220 was successfully implemented in twistacene doped polymer white light emitting diode.11

Ph

O Ph Ph HO TMS TfO TMS Ph Tf2O / pyridine

TMS OH TMS OTf Ph Ph 220

Fig. 84: Synthesis of pyrene fused “twistacene”.

Similar to 220, the molecule 273 was synthesized (Fig. 85) and the torsion angle of 23.8o was determined by X-ray crystallography. This molecule 273 was also incorporated in OLED as an emitter or charge transporting material and the result obtained indicates the bipolar transporting behavior of the material.12

Ph

O Ph

HOOC NO2 Ph COOMe

isoamyl nitrile H2N COOMe NO2 DCE/reflux Ph 273

- 115 - Fig. 85: Synthesis of pyrene fused tetratwistacene.

Wudl and co-workers modified the molecule 273 and reported the synthesis of molecule 274 as shown in Fig. 86 with twisted topology by torsion angle of 23o. This molecule was also successfully implemented in OLEDs as an emitter.13

Ph Ph Ph O Ph Ph Ph Ph COOH Ph

isoamyl nitrile, reflux NH2 Ph Ph Ph Ph 274

Fig. 86: Synthesis of pyrene-fused pentatwistacene.

Using similar building block, Zhang and co-workers reported synthesis pyrene- fused heptatwistacene 275 and hexatwistacene 276 as shown in Fig. 87. Both the molecules 275 and 276 showed twist in the plane with torsion angle of 23.49o and 27.34o respectively. The molecule 276 was also applied in OLEDs as emitter and proved to be promising red light emitter.14

Ph Ph Ph O O Ph Ph N Ph Ph Ph Ph COOH N Ph Ph Ph NH isoamyl nitrile Ph 2 Ph Ph Ph

Ph Ph Ph Ph 320oC

Ph Ph Ph Ph

275

Ph O O Ph N Ph Ph COOH N Ph

NH2 isoamyl nitrile Ph Ph DCE/reflux Ph

Ph Ph 320oC

Ph Ph 276

- 116 - Fig. 87: Synthesis of pyrene-fused heptatwistacene and hexatwistacene.

4.2. Synthesis of Twistazaacene using bulky substituents: 4.2.1.Objective: In this project synthesis of twistacenes has been carried out using easy synthetic protocol. The synthetic scheme was based on cyclocondensation of substituted o- phenylene diamine with 2,7-substituted pyrene tetraketone. The respective substitutions on damine and tetraketone moieties was carried out by Sonogashira coupling that provided rigidity as well as the substitutents were posed away from core that avoided electronic interference with chromophore (Fig. 88). During the preparation of twistacene different types of bulky groups in the form of silanes were used which facilitated the variations in the size of substituent. The final compounds obtained after synthesis were soluble in common organic solvents and easy to crystallize.

Fig. 88: General structure of pyrene-fused base twistacene.

4.2.2. Attempts to synthesize trimethylsillyl acetylene (TMS) substituted tetraazahexacene: The preparation of twistacene was started by Sonogashira coupling of the commercially available smallest silyl acetylene i.e. trimethylsilyl acetylene. Unfortunately unsusceptibility of intermediates to the reaction conditions and lack of solubility did not allow the desired material to be formed.

4.2.2.1. Ist Attempt: In the first attempt, trimethylsilyl (TMS) acetylene was coupled with 1,7- diiodopyrene 238 by Sonogashira coupling reaction using Pd(II), copper iodate in dry THF and diisopropyl ethylamine (Scheme 25). This reaction was stirred first at 55oC for 6 hrs and then 70oC for overnight due to low boiling point of TMS acetylene. The crude obtained was purified by column chromatography in order to get pure compound 277 as white solid with 62% yield. The obtained TMS pyrene 277 was subjected to ketal- deprotection by using 9:1 TFA and water but it did not work. It was observed that the

- 117 - TMS groups were not susceptible to this deprotection condition. At the time of ketal deprotection the TMS was also getting deprotected and 2,7-acetylene pyrene tetraketone 279 was obtained which was insoluble.

Si Si H

I

TMS-acetylene, CuI, O O O O O [Pd(PPh3)2Cl2], DIPEA, FA:H O - 9:1 O O O O O O O T 2 + O O O O THF, 55-80oC, 43% r.t., 48% O O O O O O O O

I

238 Si Si H 279 277 278 not observed

Scheme: 25

4.2.2.2. IInd attempt: In the second attempt the tetrketone 237 was coupled with the TMS substituted phenylene diamine (282)15 as shown in Scheme 26. The obtained diiodohexacene 281 was quite insoluble so the attempts for Sonogashira coupling using different solvent systems and catalysts failed (Table 6). From all the efforts it was clear that TMS substituted pyrene was carrying issues regarding solubility.

Solvent System Temp. Catalyst Result

THF : DIPEA Reflux [Pd(PPh3)2Cl2] No Reaction

THF : DIPEA Reflux [Pd(PPh3)4] No Reaction

THF : TEA Reflux [Pd(PPh3)2Cl2] No Reaction

o DMF : DIPEA 150 C [Pd(PPh3)2Cl2] No Reaction

o DMF : TEA 150 C [Pd(PPh3)2Cl2] No Reaction

Table 6.

- 118 - TMS

Si H2N I H2N Si I Si Si Si Sonogashira TMS coupling O O N N N N 282

O O EtOH/AcOH N N N N reflux

I Si I Si Si Si

237 281 Si

281 Scheme: 26

4.2.3. Synthesis and crystal structure study of tri-isopropylsilyl (TIPS) acetylene substituted tetraazahexacene: The next step towards twistacene was use of more bulky and more stable group like tri-isopropylsilyl (TIPS) acetylene, which was commercially available, used for substitution. The TIPS pyrene tetraketone was prepared as explained in the previous section (Chapter: 3). The amine 284 was prepared in our lab by Sunil Choudhary16 and it was refluxed with the tetraketone 240a in EtOH/AcOH mixture for 24 hrs (Scheme 27). After completion of reaction, the product 283 was obatained pure after washing with methanol.

TIPS Si Si

H2N Si Si H2N

TIPS N N O O 284 EtOH/AcOH O O N N reflux, 78%

Si Si

Si Si

240a 283

Scheme: 27

The strucure of compound 283 was confirmed by crystal structure. The crystals were obtained from CHCl3 / CH3OH mixture (Fig. 89). From the crystal structure, it can be seen that the acetylene groups are slightly bended because of the high steric hinderance between the confronting groups but this strain was not translated into a big twist in the “acene” core. But the small twist can be seen in the side view of crystal (Fig. 90a); the pyrene carbons (C12 and C14) are not in the same plane as pyrazine core with a small twist of 4o. In general acenes gets arranged with π stacking but due to the

- 119 - bulky groups the π stacking was disturbed. The crystal packing was with herringbone style with TIPS groups directed perpendicularly to the pyrene core (Fig. 90b).

Fig. 89: Crystal structures (ORTEP) of 283.

Fig. 90: Crystal structures of 283 a) side view; b) crystal packing

- 120 - 4.2.4. Synthesis and crystal structure study of tri-isobutylsilyl (TIBS) acetylene substituted tetraazahexacene: Since the TIPS groups did not seem to be sufficiently large to induce twist in the molecular plane, larger group triisobutylsillyl (TIBS) acetylene was selected as substituent. The synthetic route started from acetal protected 2,7-diiodopyren 238 as shown in Scheme 28. Sonogashira with TIBS acetylene was carried out using THF and DIPEA in order to get compound 285. The ketal deprotection of compound 285 was done in TFA:H2O (9:1) mixture. The resulted tetraketone 286 was purified by column chromatography. This tetraketone 286 was cyclocondensed with TIBS substituted diamine c that was prepared in our lab by Sunil Choudhary17 to get desired hexacene 287, which was crystallized using CHCl3 / CH3OH mixture.

Si Si

I

H TIBS O O O O [Pd(PPh3)2Cl2] TFA:H O O O O O O O 2 O O CuI,DIPA/THF O O r.t., 80% O O O O O O 80oC, 62%

I

238 Si Si

285 286

TIBS Si

H2N Si Si H2N

N N TIBS 288 N N AcOH, reflux 80oC, 78%

Si Si

Si

287

Scheme: 28

The structure of compound 287 was illustrated by X-ray crystallography in which the bending of acetylene bonds observed (Fig. 91). The bending of TIBS acetylene was more than that of in TIPS compound 283 but here any effect on the pyrene core was not observed. The TIBS group is bulkier than TIPS, due to the longer iso-butyl chains; the

- 121 - rigidity could have been lost. Although technically TIBS is bulkier than TIPS, the higher flexibility of this group did not provide the sufficient strain to induce a twist.

Fig. 91: Crystal structures (ORTEP) of 287

The columnar type of crystal packing of the TIBS molecule 287 was observed (Fig. 92b). The growth of column was with equidistant sets of five molecules in different planes and the distance between two molecules in a column was found to be around 7.02 Ao.

Fig. 92: Crystal structures of 287 a) side view; b) crystal packing

- 122 - From the crystal structure it was clear that the TIBS groups were also not sufficient for twisting the plane of azaacene. This study pointed out the requirement of more bulky substituents than TIPS and TIBS hence tri-phenylsilly (TPS) acetylene was used as a substituent.

4.2.5. Synthesis and crystal structure study of tri-phenylsilyl (TPS) acetylene substituted tetraazahexacene: At this stage TPS was introduced since it is not only a large bulky group but also very rigid. The synthetic route was same as for TIBS substituted pyrene azaacene 287. The 2,7-diidopyrene-4,5,9,10-ketal 238 was subjected to Sonogashira coupling with TPS acetylene following same procedure as shown in Scheme 29. The product 289 was purified by column chromatography and characterized. The ketal deprotection was done o by using TFA:H2O:DCM at 40 C. Here different conditions for deprotection were needed as the compound 289 was not enough soluble in TFA:H2O mixture. The obtained tetraketone 290 was then coupled with TPS substituted phenylenediamine 292, which was prepared in our lab by Sunil Choudhary17 to get the required tetraazahexacene 291.

Si Si

I

H TPS O O O O [Pd(PPh3)2Cl2] TFA:H O:DCM O O O O O O 2 O O CuI,DIPA/THF O O 40oC, 72% O O O O O O 80oC, 20%

I

238 Si Si

289 290

TPS Si H2N

Si Si H2N

TPS N N 292 AcOH, reflux, 51% N N

Si Si

Si

291

Scheme: 29

- 123 - The structure of compound 291 was confirmed by X-ray crystallography of crystals obtained from DCM. From the crystal structure (Fig. 93), clear “twist” in the plane of molecule was observed. The pyrene core was tilted completely out of plane and o the torsion angle of C24-C25-C6-C6 was found to be 20 . It was also observed that, even with such bulky groups there is no bending of acetylenes as in case of TIBS molecule 287. It might be due to the π-π stacking in between the neighboring phenyl rings of TPS acetylene, which stabilizes the whole structure. In the crystal packing herringbone motif was observed (Fig. 94). Due to these large substituents the intermolecular π-π stacking was disturbed and this disturbed π-π stacking have been improved solubility of the compound 291.

Fig. 93: Crystal structures (ORTEP) of 291

- 124 -

Fig. 94: Crystal structures of 291 a) side view; b) crystal packing

4.3. Optical properties: The photophysical studies were carried out in ODCB solvent (Fig. 95). The TIPS (283) and TIBS (287) “hexacenes” showed almost similar absorption at λmax = 435 nm where as the TPS (291) showed slight red shift with absorption at λmax = 439 nm. This slight red shift might be due to the twist in azaacene plane of molecule 291. In the emission spectra there was no considerable change between TIPS and TIBS that showed emission peaks centered at 480 nm whereas for TPS, fluorescence was slightly shifted towards blue with emission peak centered at 470 nm.

Fig. 95: Normalized absorption and emission spectra of 283, 287 and 291 in ODCB.

- 125 - 4.4. Conclusion: In this chapter, the synthesis of TIPS, TIBS and TPS acetylene substituted azaacenes was carried out in order to prepare azaacenes with twisted plane. From the crystal structures of molecules 283, 287 and 291, it was found that, the substituent like TIPS and TIBS were not enough to carry out twist in the plane of molecule but the bulkier substituent, TPS successfully “twisted” the plane of azaacene by torsion angle of 20o.

- 126 - 4.5. References:

1) (a) Smyth, N.; Engen, V. D.; Pascal, R. A., Jr. J. Org. Chem. 1990, 55, 1937. (b) Pascal, R. A., Jr.; McMillan, W. D.; Engen, V. D.; Eason, R. G. J. Am. Chem. Soc. 1987, 109, 4660. (c) Schuster, I. I.; Cracium, L.; Ho, D. M.; Pascal, R. A., Jr. Tetrahedron 2002, 58, 8875. (d) Zhang, J.; Ho, D. M.; Pascal, R. A., Jr. Tetrahedron Lett. 1999, 40, 3859. (e) Qiao, X.; Ho, D. M.; Pascal, R. A., Jr. Angew. Chem., Int. Ed. Engl. 1997, 36, 1531. 2) (a) Brady, J. H.; Redhouse, A. D.; Wakefield, B. J. J. Chem. Res. 1982, 137, 1541. (b) Herbstein, F. H. Acta Crystallogr., Sect. B 1979, 35, 1661. (c) Sim, G. A. Acta Crystallogr., Sect. B 1982, 38, 623. 3) Biemans, H. A. M.; Zhang, C.; Smith, P.; Kooijman, H.; Smeets, W. J. J.; Spek, A. L.; Meijer, E. W. J. Org. Chem. 1996, 61, 9012. 4) (a) Barbour, R. H.; Freer, A. A.; MacNicol, D. D. J. Chem. Soc., Chem.Commun. 1983, 362. (b) MacNicol, D. D.; McGregor, W. M.; Mallinson, P. R.; Robertson, C. D. J. Chem. Soc., Perkin Trans. 1 1991, 3380. (c) Downing, G. A.; Frampton, C. S.; Gall, J. H.; MacNicol, D. D.Angew. Chem., Int. Ed. Engl. 1996, 35, 1547. (d) Suenaga, Y.; Ueda, A.; Kuroda-Sowa, T.; Maekawa, M.; Munakata,M. Thermochim. Acta 2003, 400, 87. 5) Qiao, X.; Padula, M. A.; Ho, D. M.; Vogelaar, N. J.; Schutt, C. E.;Pascal, R. A., Jr. J. Am. Chem. Soc. 1996, 118, 741. 6) (a) Plater, M. J.; Howie, R. A.; Schmidt, D. M. J. Chem. Crystallogr. 1998, 28, 317. (b) Pascal, R. A., Jr.; Van Engen, D.; Kahr, B.; McMillan, W. D. J. Org. Chem. 1988, 53, 1687. 7) (a) Hursthouse, M. B.; Smith, V. B.; Massey, A. G. J. Fluorine Chem. 1977, 10, 145. (b) Weck, M.; Dunn, A. R.; Matsumoto, K.; Coates, G. W.; Lobkovsky, E. B.; Grubbs, R. H. Angew. Chem., Int. Ed. 1999, 38, 2741. (c) Shibata, K.; Kulkarni, A. A.; Ho, D. M.; Pascal, R. A., Jr. J. Am.Chem. Soc. 1994, 116, 5983. (d) Shibata, K.; Kulkarni, A. A.; Ho, D. M.; Pascal, R. A., Jr. J. Org.Chem. 1995, 60, 428. (e) Frampton, C. S.; MacNicol, D. D.; Rowan, S. J. J. Mol. Struct. 1997,405, 169. 8) (a) Pascal, R. A., Jr.; McMillan, W. D.; Van Engen, D. J. Am. Chem.Soc. 1986, 108, 5652. (b) Pascal, R. A., Jr.; McMillan, W. D.; Van Engen, D.; Eason, R. G. J. Am. Chem. Soc. 1987, 109, 4660. (c) Smyth, N.; Van Engen, D.; Pascal, R. A., Jr. J. Org. Chem. 1990, 55, 1937. 9) Qiao, X.; Ho, D. M.; Pascal, R. A., Jr. Angew. Chem. Int. Ed. Engl. 1997, 36, 1531. 10) Duong, H. M.; Bendikov, M.; Steiger, D.; Zhang, Q.; Sonmez, G.; Yamada, J.; Wudl, f. Org. Lett., 2003, 5, 4433–4436. 11) Xu, Q.; Duong, H. M.; Wudl, F. Appl. Phys. Lett. 2004, 85, 3357. 12) Zhang, Q.; Divayana, Y.; Xiao, J.; Wang, Z.; Tiekink, E. R. T.; Doung, H. M.; Zhang, H.; Boey, F.; Wei Sun, X.; Wudl, F. Chem. Eur. J. 2010, 16, 7422 – 7426. 13) Zhang, Q.; Divayana, Y.; Xiao, J.; Wang, Z.; Tiekink, E. R. T.; Doung, H. M.; Zhang, H.; Boey, F.; Wei Sun, X.; Wudl, F. J. Mater. Chem., 2010, 20, 8167- 8170.

- 127 - 14) (a) Xiao, J.; Malliakas, C. D.; Liu, Y.; Zhou, F.; Li, G; Su, H.; Kanatzidis, M. G.; Wudl, F.; Zhang, Q. Chem. Asian J., 2012, 7, 672–675. (b) Xiao, J.; Liu, S.; Liu, Y.; Ji, L.; Liu, X.; Zhang, H.; Sun, X.; Zhang, Q. Chem. An Asian Journal, 2012, 7, 561-564. 15) Bryant, J. J.; Lindner, B. D.; Bunz, U. H. F.; Zhang, Y.; Davey, E. A.; Appleton, A. L.; Qian, X. J. Org. Chem., 2012 , 77, 7479 – 7486. 16) Lindner, B. D.; Engelhart, J. U.; Maerken, M.; Tverskoy, O.; Rominger, F.; Bunz, U. H. F.; Appleton, A. L.; Hardcastle, K. I.; Enders, M. Chem. Eur. J., 2012, 18, 4627 – 4633. 17) Sunil Choudhary, Ph.D. dissertation, 2013, Albert-Ludwigs University, Freiburg (Germany).

- 128 -

Chapter: 5

Self-assembling properties of 2,7-substituted pyrene fused azaacenes

- 129 -

- 130 - 5.1. Introduction:- It is widely recognized that the properties of materials depend not only on the molecular properties but also on the supramolecular organization. Therefore the self- assemblies of these π conjugated materials can also be used to prepare nanostructures having high level of supramolecular organization. There are certain supramolecular properties like self agreegation, liquid crystals, etc which has potential application in devices like OFET,1 OPVs2 and OLEDs,3 etc. In case of acenes such types of self-assemblies showed the novel properties and proved to be advantageous than their respective microcrystalline counterparts. Nitrogen atoms in azaacenes helps aggregation through increased polarity and probability of hydrogen bonding as well as formation of molecular dipoles. Azaacenes, which are amphiphilic in nature and with the appropriate hydrophobic groups it should show better results. Some examples of aggregated azaacenes which showed excellent self assembling properties are mentioned here. Azaacenes 293-295 were prepared and studied the effect of halogen substitutions on self-assembly (Fig. 96).4 Different self assemblies can be obtained depending on intermolecular forces like, hydrogen bonding between hydrogens and nitrogens, halogen-halogen bonding in some cases as well the Van der Wall’s forces. Ariga and co-workers reported pyrazine fused azaacenes 296 and 297 and studied the self assemblies.5 Azaacene 296 in dichloromethane or chloroform forms sheets with tendency to roll up and in tetrahydrofuran and water fibrous structures with average dimeter of around 50 nm obtained. On the other hand the extended azaacene 297 self assembled into fibrous structures in both type of solvents i. e. chlorinated or tetrahydrofuran. Pyrazine derivative 2986 with dodecyl substitution showed self assembly in non-polar solvent (toluene) and pyrazinacene nanotubes were obtained. These derivatives found in liquid crystalline form and potential material for OFETs.7 Phenanthrene derivatives 299-303 were obtained via simple coupling of phenanthrene diketone and variety of diamines with different halogen substitutents. The condensation offered disc shaped molecules, some of them with columnar phases.8

X N OC10H21 C12H25 C12H25 N N N N N N N X N OC10H21 293 = X = H N N N N N N N 294 = X = F C12H25 C12H25 297 295 = X = Br 296

C6H13O OC6H13 N N C12H25

N N N C6H13O OC6H13

N N N 299 = X = H, Y = F N N N N C12H25 300 = X = H, Y = Cl 301 = X = H, Y = CN 298 302 = X = H, Y = NO2 Y X 303 = X = Y = Cl 304

Fig. 96: Azaacenes showing self assembling properties.

- 131 - Phenanthroline derivaive 304 self organizes in the mixture of THF and water gave rise to small and large nanowires as shown in Fig. 97. Such wires have been used as scaffolds exploiting the ability of phenanthrolines to bind metals. The self assembling scaffolds of 304 were used to arrange collidal nanoparticles. This nanoscale hybrid is a tool to tune the collective properties of nano-particle ensembles.9

Fig. 97: TEM micrographs of small and large nanowires (Image was taken from ref. 30 with permission)

In 2009 Lee and co-workers synthesized pyrene fused azaacene 305-307 and presented the morphological control of this T-shaped structure depending on the peripheral substituents (Fig. 98).10 The methoxy groups in 305 rotates freely and the compound could not show self assembly which might be due the free rotation of methoxy group that interferes the molecular packing. In a follow-up work the azaacenes 308-312 were reported.11 These self assembled molecules with different substituents and conjugation lengths were found to behave as n-type semiconductor. The self- assembled properties of these materials are depend on the alkyl side chain length, peripheral substituents and self assembly conditions by using SEM and XRD. The fibers obtained from 308 were homogeneous and upto 600 nm in width. The compounds 309 and 312 were recrystallized from dichloromethane, which produced nanobelt of nano and micrometer size. The 312 produced narrower nanobelts than 309 may be due to more solubility in dichloromethane. The compound 310 showed flexible and flat nanofibers which were endless and the bundles were of varied size ranging from 300 nm to 2 µm. The fibers obtained out of 311 were with varied thickness, which was supposed due to the interaction between the halogens and imine nitrogen of neighboring molecules that interfered the π-π interaction. Recently Cheng and co-workers reported the molecules 313-316 to study the phase transition with the length of alkyl chains for OPV.

- 132 -

R R

N N R N N R'

R N N R'

305 = R = OMe N N 306 = R = H 308 = R = F, R' = OC16H33 311 = R = I, R' = OC16H33 307 = R = CN 309 = R = NO2, R' = OC16H33 312 = R = NO2, R' = OC12H25 C H O OC H 16 33 16 33 310 = R = H, R' = OC16H33

RS N N SR H

N N OC16H33 RS N N SR

N N OC16H33 H 313 = R = C6H13 315 = R = C10H21 317 314 = R = C8H17 316 = R = C12H22

Fig. 98: Azaacenes showing self assembling properties.

From all above examples it is clear that, the pyrene provides large π core that increases the intermolecular π-orbital overlap. This intermolecular π-orbital overlap acts as a driving force for self-assembly. Functionalization of pyrene provides an additional parameter for controlling molecular packing, which results into change in the morphology of the nanostructure obtained from the respective molecules.12

5.2. Supramolecular self-assemblies of 2,7-substituted pyrene azaacenes: It is known that, each and every compound has its own way to form assemblies in solution or in solid state. From the molecules 241a and 241b synthesized in the previous sections, the study of their behavior in solution was carried out. The hexacenes were choosed for this study as the extended aromaticity of pyrene to both the ends improves its amphiphilic character. Also to check the effect of different substitutions at 2,7-positions of pyrene on the π- π stacking of pyrene-fused azacenes. These experiments were performed in the mixture of solvents with same concentration of the compound. The TIPS substituted tetraazapyren hexacene 241a was studied first.

- 133 - 5.2.1. Self assemblies of compound 241a:

N N

Si Si

N N

241a

The experiment was carried out by using THF and H2O mixture with variable ratio but the concentration was kept constant in all the samples. Samples were prepared with the increasing ratio of water by 10% with fixed concentration of 7a (50 µM). Preparation of stock solution:- Compound 241a (3.8 mg 0.5mM) was dissolved in 20 ml of THF and sonicated for sometime in order to make it completely soluble. After preparation of stock solution, 10 sample solutions were prepared with varying stochiometry as shown in Table 7. Then the Uv-vis spectra were recorded and compared for each sample.

n No. Stock Sol THF H2O % of H2O 1 1 ml 9 ml 0 ml 0 % 2 1 ml 8 ml 1 ml 10 % 3 1 ml 7 ml 2 ml 20 % 4 1 ml 6 ml 3 ml 30 % 5 1 ml 5 ml 4 ml 40 % 6 1 ml 4 ml 5 ml 50 % 7 1 ml 3 ml 6 ml 60 % 8 1 ml 2 ml 7 ml 70 % 9 1 ml 1 ml 8 ml 80 % 10 1 ml 0 ml 9 ml 90 %

Table 7. Preparation of samples for UV-Vis spectroscopy.

In the spectra initially the absorption bands at around 285, 338, 375, 395 and 420 nm were observed (Fig. 99) which on addition of water showed change in intensity. From the sample with 50% of water onwards a new band formation took place at 440 nm. The disappearance of the “original” absorption bands of hexacene and formation of new band around 440 nm suggests the formation of aggregation. From all these samples 8 and 10 were chosen as they have shown drastic change in the absorption. The

- 134 - morphology of the self organized structure was characterized by using Transmission Electron Microscopy (TEM) technique.

Fig. 99: UV-Vis of 241a with different H2O/THF ratio.

The sample 8 70 % water was selected for TEM due to the drastic change in its absorption spectra. The TEM images of the compound 241a were recorded in the different areas of the grid carrying drop-casted sample 8 that showed nanorod like structures with length ranging from 300 nm to 500 nm and width or diameter 60 nm to 80 nm were observed all over the grid (Fig. 100). It can be seen that, there are no polar functional groups like –OH, -COOH, -CONH2, etc in the molecule 241a which may help in organization through hydrogen bonding. By taking into consideration the lack of polar functional groups it can be concluded that, the rod like structures might have been appeared due to the intermolecular π-π stacking. The sample 8 was subjected to selected area electron diffraction (SAED) studies and showed well defined diffraction pattern with lattices matching the rings (Fig. 100d), which represents the polycrystalline nature of rods.

- 135 -

Fig. 100: TEM of 8 fresh sample.

The same sample 8 of compound 241a was kept for 10 days at room temperature then measured the changes in assembly formation by using TEM and found increase in the size of the rod like structures from nano to micro scale as shown in Fig. 101. The crystals of length 2 µm to 8 µm with thickness of 600 nm to 1 µm were observed. The SAED studies also showed clear difference than the previous pattern. In the previous recording circles representing the presence of multiple crystals at the specific area were detected which underlined the polycrystalline nature. But after 10 days well-defined lattice structure with lines was observed that represents single crystal diffraction.

Fig. 101: TEM for 8 after 10 days.

- 136 - For next measurement the quantity of water was increased in the solvent ratio from 70% to 90% and nanorods with much smaller size than that of with 70% of water were detected. This sample was studied with fresh sample and also after 10 days but there was no difference found in the morphology. With this sample 10, rods with length 100 to 500 nm and width in the range of 30 nm to 60 nm were observed. The difference was in the size of rods and also found that in previous sample 8 the structures were spread all over the grid where as in sample 10 structures were in the form of clusters. The SAED studies also shown presence of multiple structures or crystals with well defined circles as shown in Fig. 102.

Fig. 102: TEM for 10.

The TEM investigation showed that the substantial changes in the absorption spectrum could be associated to the formation of different microstructures as well. The sample with 70 % of water showed formation of microcrystals as well as nano structures depending on time. Where as in the sample with 90% of the structures were in the form of nano rods and the morphology didn’t change after keeping it for long time. It can be concluded that, the in THF the molecule tends to crystallize so the size was grown after keeping the sample for long time. In case of 90% water containing sample the reason might be the hydrophobic nature of molecule which prevented the formation of large structure even after long time.

- 137 - 5.2.2. Self assemblies of compound 241b:

N N

N N

241b

Tetraazahexacene 241b with octyne chains on 2,7-positions of pyrene was selected for the TEM studies. It can be seen that the core of the molecule 241b is pyreneazaacene with the long alkyl chains so the expected morphology was quite different than the 241a. The long chains on pyrene affected the morphology of compound 241b and clear difference was observed in the TEM studies (Fig. 103).

Fig. 103: TEM for 241b with 40% water.

Compound 241b was dissolved in THF to prepare the stock solution. For the study three samples were prepared out of the stock solution. The ratio of THF and water was

- 138 - as, 4:6, 7:3 and 9:1 respectively. In the 40% water containing sample flakes like structures with length about 400 nm to 700 nm and width about 200 nm to 300 nm were detected. These flakes were spread all over the grid and not in the form of clusters as shown in Fig. 104.

Fig. 104 : TEM for 241b with different amount of water 70% (a,b)& 90% (c,d).

The samples with 70% and 90% of water also showed same morphology but there was difference in size of the flakes. In 70% water sample large as well small flakes were detected. The small flakes were of length 300 nm and width 120 nm where as the large ones were of length 1 µm and 400 nm by width. The nature was perfectly polycrystalline, which was proved by SAED experiment as we can see in the Fig. 104b that shows the bright circles. In case of the sample with 90% water, flakes with length 800 nm and width 350 nm were abserved. As there was no active site in the molecule 241b for perfect hydrogen bondings so may be the molecule 241b organises by π stack along the pyrene core and the alkyl chains directed outwards and by combination of these both arrangement the molecule results into the flake like morphology.

5.3. Conclusion: From all the experiments it was clear that the subsstituion on 2,7-positions of pyrene plays an important role in the formation of supramolecular assemblies. This phenomenon can be used to prepare desirable assemblies by tuning the properties of azaacene core with different types of substituents.

- 139 - 5.4. References:

1) (a) Xiao, S.; Tang, J.; Beetz, T.; Guo, X.; Tremblay, N.; Siegrist, T.; Zhu, Y.; Steigerwald, M.; Nuckolls, C. J. Am. Chem. Soc. 2006, 128, 10700–10701. (b) Briseno, A. L.; Roberts, M.; Ling, M. M.; Moon, H.; Nemanick, E. J.; Bao, Z. J. Am. Chem. Soc. 2006, 128, 3880– 3881. (c) Briseno, A. L.; Mannsfeld, S. C. B.; Lu, X.; Xiong, Y.; Jenekhe, S. A.; Bao, Z.; Xia, Y. Nano Lett. 2007, 7, 668–675. (d) Briseno, A. L.; Mannsfeld, S. C. B.; Reese, C.; Hancock, J. M.; Xiong, Y.; Jenekhe, S. A.; Bao, Z.; Xia, Y. Nano Lett. 2007, 7, 2847–2853. 2) (a) Schmidt-Mende, L.; Fechtenko Utter, A.; Müllen, K.; Moons, E.; Friend, R. H.; MacKenzie, J. D. Science 2001, 293, 1119–1122. (b) Yang, X.; Loos, J.; Veenstra, S. C.; Verhees, W. J. H.; Wienk, M. M.; Kroon, J. M.; Michels, M. A. J.; Janssen, R. A. J. Nano Lett. 2005, 5, 579–583. (c) Berson, S.; De Bettignies, R.; Bailly, S.; Guillerez, S. AdV. Funct. Mater. 2007, 17, 1377–1384. (d) Xin, H.; Kim, F. S.; Jenekhe, S. A. J. Am. Chem. Soc. 2008, 130, 5424–5425. (e) Wienk, M. M.; Turbiez, M.; Gilot, J.; Janssen, R. A. J. AdV. Mater. 2008, 20, 2556– 2560. 3) (a) A. E. A. Contoret, S. R. Farrar, P. O. Jackson, S. M. Khan, L. May, M. O’Neill, J. E. Nicholls, S. M. Kelly and G. J. Richards, Adv. Mater., 2000, 12, 971; (b) K. L. Woon, M. O’Neill, G. J. Richards, M. P. Aldred, S. M. Kelly and A. M. Fox, Adv. Mater., 2003, 15, 1555; (c) S. R. Farrar, A. E. A. Contoret, M. O’Neill, J. E. Nicholls, G. J. Richards and S. M. Kelly, Phys. Rev. B, 2002, 66, 125107. (d) A. E. A. Contoret, S. R. Farrar, S. M. Khan, M. O’Neill, G. J. Richards, M. P. Aldred and S. M. Kelly, J. Appl. Phys., 2003, 93, 1465. (e) A. E. A. Contoret, S. R.Farrar, M. O’Neill, J. E. Nicholls, G. J. Richards, S. M. Kelly and A. W. Hall, Chem. Mater., 2002, 14, 1477. (f) M. Grelf, D. D. C. Bradley, M. Inhasekarun and E. P. Woo, Adv. Mater., 1997, 9, 798. (g) T. Hiroaki, E. Masanao and T. Tetsuo, Appl. Phys. Lett., 1998, 72, 2639. 4) Lee, D. C.; Cao, B.; Jang, K.; Forster, P. M. J. Mater. Chem., 2010, 20, 867. 5) Richards, G. J.; Hill, J. P.; Okamoto, K.; Shundo, A.; Akada, M.; Elsegood, M. R. J.; Mori, T.; Ariga, K. Langmuir, 2009, 25, 8408. 6) Richards, G. J.; Hill, J. P.; Subbaiyan, N. K.; D’Souza, F.; Karr, P. A.; Elsegood, M. R. J.; Teat, S. J.; Mori, T.; Ariga, K. J. Org. Chem., 2009, 74, 8914. 7) Richards, G. J.; Hill, J. P.; Labuta, J.; Wakayama, Y.; Akada, M.; Ariga, K. Phys. Chem. Chem. Phys., 2011, 13, 4868. 8) Foster, E. J.; Jones, R. B.; Lavigueur, C.; Williams, V. E. J. Am. Chem. Soc., 2006, 128, 8569. 9) Grzelczak, M.; Kulisic, N.; Prato, M.; Mateo-Alonso, A. Chem. Commun., 2010, 46, 9122-9124. 10) Lee, D. C.; Jang, K.; McGrath, K. K.; Uy, R.; Robins, K. A.; Hatchett, D. Chem. Mater., 2008, 20, 3688. 11) McGrath, K. K.; Jang, K.; Robins, K. A.; Lee, D. C. Chem. Eur. J., 2009, 15, 4070. 12) (a) An, B. K.; Lee, D. S.; Lee, J. S.; Park, Y. S.; Song, H. S.; Park, S. Y. J. Am. Chem. Soc. 2004, 126, 10232–10233. (b) Balakrishnan, K.; Datar, A.; Naddo, T.;

- 140 - Huang, J.; Oitker, R.; Yen, M.; Zhao, J.; Zang, L. J. Am. Chem. Soc. 2006, 128, 7390–7398. (c) Li, Y.; Li, F.; Zhang, H.; Xie, Z.; Xie, W.; Xu, H.; Li, B.; Shen, F.; Ye, L.; Hanif, M.; Mab, D.; Ma, Y. Chem. Commun. 2007, 231–233. (d) Zhang, X.; Zou, K.; Lee, C. S.; Lee, S. T. J. Am. Chem. Soc. 2007, 129, 3527 – 3532.

- 141 -

- 142 -

Experimental procedures

- 143 -

- 144 - Reagents, Solvents and Equipment Reagents for synthesis were, if not otherwise specified, purchased from Aldrich, Fluka or Acros. Triethyamine, trifluroacetic acidwere from Fluka or Aldrich. All reactions were carried out under argon, with magnetic stirring. Commercial chemicals and solvents were used as received. Petrol ether refers to the fraction that distills between 40-60 °C. Anhydrous solvents were dried using a MB SPS Solvent Purification System. In the case of dry THF the first and second column is charged with molecular sieves (2Å) type II.

Chromatographic Methods Column chromatography was carried out using silica gel 60 (40-63 µm) from Fluka. Analytical thin layer chromatography (TLC) was done using aluminum sheets (20x20 cm) pre-coated with silica gel RP-18W 60 F254 from Merck, aluminum foils (20x20 cm) covered with nano-silica gel from Fluka. Column chromatography was carried out by using Merck silica gel with particle size 40-63 µm. UV-active compounds were detected with a UV-lamp from CAMAG at wavelength λ = 254 or 366 nm. Amines were stained with ninhydrin (0.2% ninhydrin in ethanol) and poorly UV-active substances were detected using a cesium- molybdenum staining reagent made of Ce(SO4)2 (2 g), H3PMo12O40 (4 g) and H2SO4 (40 g) in 160 mL of water.

Mass Spectroscopy: Electrospray Ionization (ESI) and Atmosphere Pressure Chemical Ionization (APCI) were performed on a Thermo LCQ Advantage while the Electron Impact (EI) was performed on a Thermo TSQ700, at the Organische Chemie MS service (Universität Freiburg).

UV-Vis-NIR and Emission: Spectra were recorded on a Perkin-Elmer Lambda 950 spectrometer, and a LS55 Perkin-Elmer Fluorescence spectrometer, respectively.

Cyclic Voltammetry : Studies were made on a Princeton Applied Research Parstat 2273 in a 3-electrode single compartment cell with Pt disk (Ø = 0.5 mm) working electrode, a platinum wire counter electrode and a silver wire reference electrode. The cell and the electrodes were custom made.

- 145 -

- 146 - 1,2-bis-(N-4--toluenesulphonamino)benzene:

NHTos

NHTos

The o-phenylenediamine (4 g, 0.037mol) was dissolved in pyridine (100ml) and added solution of p-toluenesulphonyl chloride (14.08gm, 0.073 mol) in it at 0oC. The reaction mixture allowed to stir for 2h and add again the remaing p-toluenesulphonyl chloride. Allowed to stir the reaction mixture for 2-3 h more and reaction was moderated by TLC. After completion the reaction mixture was poured on ice and washed with DCM. The organic layer was washed with 2M HCl, saturated NaHCO3 and brine. Organic layer was dried over sodium sulphate and solvent was removed under reduced pressure. The crude product was recrystalised from ethanol to give pure 1,2-bis-(N-4-toluenesulphonamino)benzene (7 gm, 52% yield). The analytical data correspond to the literature.1

1H NMR (400 MHz, DMSO): δ ppm = 2.33 (s, 6H), 6.87–6.93 (m, 2H), 6.93–6.99 (m, 2H), 7.30 (d, 4H, J = 8.0 Hz), 7.56 (d, 4H, J = 8.0 Hz), 9.23 (br s, 2H).

13C NMR (100 MHz, DMSO): δ ppm = 143.3, 136.5, 130.2, 126.9, 129.6, 125.1, 122.6, 21.0

MS: Found: 439.0762 [M+Na]+ Calculated Mass: 416.51

1,2-dinitro-4,5-bis-(p-toluenesulphonamido)benzene:

O2N NHTos

O2N NHTos

About one-third of a solution of fuming nitric acid (6.4 ml, 0.15mol) in glacial acetic acid (8 ml) was added to a stirred suspension of 1,2-bis-(N-4- toluenesulphonamino)benzene (31.2 gm, 0.075mol) in acetic acid (250ml) at 60oC. After initial reaction, addition was completed so that the temperature was kept below 70oC. The mixture was heated at 70oC for a further 30 min., then cooled and filtered. Crystallization of the precipitate from glacial acetic acid (1 lt.) gave the dinitro compound as yellowish needles (20 gm, 54% yield). The analytical data correspond to the literature.2

1H NMR (400 MHz, DMSO): δ ppm = 7.75 (s, 2H), 7.68 (d, 4H), 7.36 (d, 4H), 2.37 (s, 6H).

13C NMR (100 MHz, DMSO): δ ppm =137.6, 136.7, 135.8, 135.6, 129.3, 128.3, 110.9, 21.3.

- 147 -

MS: Found: 507.21 (M + H) Calculated Mass: 506. 51

1,2-diamino-4,5-bis-(p-toluenesulphonamido)benzene (171):

H2N NHTos

H2N NHTos

To a suspension of 1,2-dinitro-4,5-bis-(p-toluenesulphonamido)benzene (2.23 g, 4.40 mmol) in ethanol (20 mL) and conc. HCl (4 mL) was added tin powder (2.37 g, 20.0 mmol, 150 mesh). The mixture was stirred for 1.5 h and occasionally cooled with ice to maintain the internal temperature below 50oC. The resulting golden solution was poured into ethyl acetate (300ml) and satd NaHCO3 (40 mL) was carefully added follwed by 0.5 M Na2S solution (40 mL). The mixture was stirred for 20 min and then filtered. The filtrate was separated and organic layer was washed with aqueous Na2S (15 mL, 2x), satd NaHCO3 (20 mL), brine and dried over Na2SO4. Filtration and removal of solvent followed by washing with ethyl acetate (15 mL) and diethyl ether (15 mL) gave 171 (1.45gm, 76% yield) as a yellow solid. The analytical data corresponds to literature.3

1 H NMR (300 MHz, CDCl3): δ ppm = 7.92 (s, 2H), 7.54 (d, J = 8.3 Hz, 4H), 7.28 (d, J = 8.0 Hz, 4H), 6.32 (s, 2H), 4.16 (s, 4H), 2.37 (s, 6H).

13 C NMR (125 MHz, - d6) δ ppm = 143.1, 136.7, 134.3, 129.7, 127.5, 120.7, 111.1, 21.2.

MS: Found: 446.10 [M+] Calculated Mass: 446.10

4,5-Dinitro-o-phenylenediamine (172):4

O2N NH2

O2N NH2

The preceding 1,2-dinitro-4,5-bis-(p-toluenesulphonamido)benzene (3 g, 5.92 mmol) was heated in concentrated sulphuric acid (3ml) and water (0.34 ml) on the steam bathfor 4hr., then poured into ice water. The mixture was diluted to 300 ml and gently warmed until the yellow salt had disappeared. The precipitate of 4,5-Dinitro-o- phenylenediamine was filtered off. The filtrate was neutralised in order to get next crop of 4,5-Dinitro-o-phenylenediamine. The solid obtained was crystallized from ethanol and water as dark red crystals of 172 (500mg, 45% yield). The analytical data corresponds to the literature.5

1H NMR (300 MHz, DMSO): δ ppm = 7.07 (s, 2H), 6.11 (S, 4H)

- 148 -

13C NMR (100 MHz, DMSO): δ ppm = 143.1, 134.6, 110.9

MS: Found 198.13 [M+] Calculated Mass: 198.13

Pyrene-4,5-dione (148):

O

O

To a solution of the pyrene (2.04 g, 10 mmol) in CH2Cl2 (40.0 mL) and CH3CN (40.0 mL) were added NaIO4 (8.75 g, 40.5 mmol), H2O (50.0 mL), and RuCl3‚ xH2O (0.175 g, 0.6 mmol). The dark brown suspension was stirred at room temperature overnight. The reaction mixture was poured into 200 mL of H2O, and organic phase was separated. The aqueous phase was extracted with CH2Cl2 (3 × 50 mL). The CH2Cl2 extracts were combined with the organic phase and washed with H2O (3 × 200 mL). The organic layer was dried over Na2SO4 and safter filtration solvent was removed by rotatory evaporation. Column chromatography (CH2Cl2) gave pure product as dark orange solid (900 mg, 40% yield). The analytical data corresponds to literature.6

1 H NMR (500 MHz, CDCl3): δ ppm = 8.40 (dd, 2H, J = 7.3, 1.0 Hz), 8.10 (dd, 2H, J = 7.9, 1.0 Hz), 7.76 (s, 2H), 7.69 (t, 2H, J = 7.8 Hz)

13 C NMR (125 MHz, CDCl3) δ ppm = 135.6, 131.9, 130.1, 130.0, 128.3, 127.9, 127.2

MS: Found: 232.05 [M] Calculated Mass: 232.05

Pyrene-4,5,9,10-tetraone (149):

O O

O O

To a solution of the pyrene (147) (2.04 g, 10 mmol) in CH2Cl2 (40.0 mL) and CH3CN (40.0 mL) were added NaIO4 (17.5 g, 81.8 mmol), H2O (50.0 mL), and RuCl3‚ xH2O (0.25 g, 1.2 mmol). The dark brown suspension was heated at 30-40°C overnight. The reaction mixture was poured into 200 mL of H2O, and the solid was removed by filtration. After the dark green product was washed with 500 mL of H2O, the organic phase was separated. The aqueous phase was extracted with CH2Cl2 (3 × 50 mL). The CH2Cl2 extracts were combined with the organic phase and washed with H2O (3 × 200

- 149 - mL) to give a dark green solution. The solvent was removed under reduced pressure to afford a dark green solid that was combined with the dark green product. Column chromatography (CH2Cl2) offered 149 as yellow solid (1 g, 43% yield). The analytical data corresponds to literature.6

1H NMR (300 MHz, DMSO): δ ppm = 8.32 (d, 4H), 7.71 (t, 2H)

13C NMR δ ppm = Not sufficiently soluble.

MS: Found: 262.03 [M+] Calculated Mass: 262.03

2,7-ditert-butyl pyrene (184):

To a solution of pyrene (8.0 g, 40.0mmol) of pyrene (147) and 200 ml of tert-butyl chloride was added 8.0 g (60.0 mmol) of powdered AlCl3, at 0°C. After the reaction mixture had been stirred at room temperature for 3 h, it was poured into a large amount of ice/water and extracted with CH2Cl2(2 x 250 ml). The combined CH2Cl2 extracts were washed with water (2 x 200 ml), dried with Na2S04 and the solvent was evaporated and the solid residue was purified by column chromatography (pet ether) to give a colorless solid. Recrystallization from ethanol afforded 184 as colorless crystals (10.0 g, 86% yield). The analytical data corresponds to literature.7

1 H NMR (500 MHz, CDCl3): δ ppm = 8.37 (s, 4H), 8.16 (s, 4H), 1.70 (s, 18H)

13 C NMR (125 MHz, CDCl3) δ ppm = 147.9, 130.51, 126.9, 122.4, 34.8, 31.3

MS: Found: 314.46 [M+] Calculated Mass: 314.39

- 150 - 2,7-ditert.-butyl-pyrene-4,5-dione (185):

O

O

To a solution of the pyrene (3.14 g, 10 mmol) in CH2Cl2 (40.0 mL) and CH3CN (40.0 mL) were added NaIO4 (8.75 g, 40.5 mmol), H2O (50.0 mL), and RuCl3‚ xH2O (0.175 g, 0.6 mmol). The dark brown suspension was stirred at room temperature overnight. The reaction mixture was poured into 200 mL of H2O, and organic phase was separated. The aqueous phase was extracted with CH2Cl2 (3 × 50 mL). The CH2Cl2 extracts were combined with the organic phase and washed with H2O (3 × 200 mL). The organic layer was dried over Na2SO4 and safter filtration solvent was removed by rotatory evaporation. Column chromatography (CH2Cl2) offered 185 as dark orange solid (1.4 g, 41% yield). The analytical data corresponds to literature.6

1 H NMR (500 MHz, CDCl3): δ ppm = 8.54 (dd, 2H), 8.12 (dd, 2H), 7.79 (s, 2H), 1.49 (s, 18H)

13 C NMR (125 MHz, CDCl3): δ ppm = 181.2, 51.3, 132.1, 132.0, 130.0, 128.5, 127.5, 126.7, 35.4, 31.4

MS: Found: 344.18 [M+] Calculated Mass: 344.18

2,7-ditert.-butyl-pyrene-4,5,9,10-tetraone (188):

O O

O O

To a solution of the pyrene (147) (3.14 g, 10 mmol) in CH2Cl2 (40.0 mL) and CH3CN (40.0 mL) were added NaIO4 (17.5 g, 81.8 mmol), H2O (50.0 mL), and RuCl3‚ xH2O (0.25 g, 1.2 mmol). The dark brown suspension was heated at 30-40 °C overnight. The reaction mixture was poured into 200 mL of H2O, and the solid was removed by

- 151 - filtration. After the dark green product was washed with 500 mL of H2O, the organic phase was separated. The aqueous phase was extracted with CH2Cl2 (3 × 50 mL). The CH2Cl2 extracts were combined with the organic phase and washed with H2O (3 × 200 mL) to give a dark green solution. The solvent was removed under reduced pressure to afford a dark green solid that was combined with the dark green product. Column chromatography (CH2Cl2) offered 188 as yellow solid (1.2 g, 32% yield). The analytical data corresponds to literature.6

1 H NMR (500 MHz, CDCl3): δ ppm = 8.47(s, 4H), 1.42 (s, 18H)

13 C NMR (125 MHz, CDCl3): δ ppm = 178.4, 155.1, 134.05 132.4, 130.8, 35.6, 30.9

MS: Found: 374.15 [M] Calculated Mass: 374.15

Pyrene-4,5-di(ethyleneglycol)ketal (175) :

O O O O

To the solution of 148 (250 mg , 1.07 mmol) in toluene (50 ml) was added ethylene glycol (0.66 ml, 10.77 mmol ) and p-tolulenesulphonic acid (5mg, 20% w/w). The reaction mixture was refluxed for 48 hrs by using Dean-Stark aparatus. The solution was allowed to cool at room temperature. After washing with aq NaHSO3 the solution was dried over Na2SO4 and filtered. The solution was removed on rota evaporator. After column chromatography (PE : DCM ; 30:70) offered 175 as pale yellow solid (140 mg, 43.75 % yield).

1 H NMR (500 MHz, CDCl3): δ ppm = 7.98 (d, 2H, J=15Hz); 7.92 (d, 2H, J=15Hz); 7.77 (s, 2H); 7.72 (t, 2H, J=20Hz); 4.32 (br s, 4H); 3.79 (br s, 4H).

13 C NMR: (100 MHz, CDCl3): δ ppm = 132.91; 131.75; 127.36; 126.61; 124.12; 93.78; 62.05.

MS: Found 344.3 [M+Na]+ Calculated Mass: 320.3.

- 152 - Pyrene-4,5-dione-9,10-di(ethyleneglycol)ketal (176) :

O O O

O O O

To a solution of the 175 (600 mg, 1.875 mmol) in CH2Cl2 (15.0 mL), H2O (17.0 mL) and CH3CN (15.0 mL) were added NaIO4 (3 gm, 14.084 mmol) and RuCl3‚ xH2O (100 mg, 0.483 mmol). The dark brown suspension was stirred at room temperature overnight. The reaction mixture was poured into 200 mL of H2O and the organic phase was separated. The aqueous phase was extracted with CH2Cl2 (3 × 50 mL). The CH2Cl2 extracts were combined with the organic phase and washed with H2O (3 × 200 mL). The organic layer was dried over Na2SO4 and after filtration solvent was removed on rota evaporator. Obtained product was purified by column chromatography (PE : EA, 7:3) offered 176 (145 mg; 20%) as orange solid.

1 H NMR (500 MHz, CDCl3): δ ppm = 8.21 (d, 2H, J=15Hz); 8.02 (d, 2H, J=10Hz); 7.57 (t, 2H, J=20Hz); 4.26 (br s, 4H); 3.70 (br s, 4H).

13 C NMR: (100 MHz, CDCl3): δ ppm = 179.46; 134.62; 133.46; 132.29; 131.33; 130.78; 130.42; 127.08; 92.08; 61.50.

MS: Found 351.1 [M+1]+ Calculated Mass: 350.3.

Compound 177:

O N NO O 2 O N NO O 2

A mixture of compound 176 (500 mg, 1.428 mmol) and 172 (282.85 mg, 1.428 mmol) in ethanol (150 ml) and acetic acid (50 ml) was refluxed for 15 hrs. and the reaction was monitored by TLC. After completion of reaction, the mixture was cooled to room temperature and filtered. Further washing with ethanol offered 177 (450 mg) as a solid.

1 H NMR (500 MHz, CDCl3): δ ppm = 9.24 (d, 2H, J=10Hz); 8.82 (s, 2H); 8.23 (d, 2H, J=10Hz); 7.83 (t, 2H, J=20Hz); 4.35 (br s, 4H); 3.80 (br s, 4H).

- 153 - 13 C NMR: (100 MHz, CDCl3): δ ppm = 145.80; 142.57; 141.74; 133.92; 130.09; 129.54; 129.51; 128.69; 128.10; 127.69; 92.89; 61.91.

MS: Found 550.4 [M+K]+ Calculated Mass: 512.2

Compound 178:

O N O NH2 O N NH O 2

To a suspension of 177 (200 mg, 0.390 mmol) and Pd/C (35 mg) in EtOH (40 ml) was added NH2NH2.H2O (1ml) prior to heating at reflux for 10 h. After cooling to room temperature, the reaction mixture was filtered through celite to remove Pd/C. The solvent was evaporated and the obtained crude was purified by column chromatography (DCM:MeOH, 9:1) which gave 178 (160 mg; 90% yield) as dark red solid .

1 H NMR (500 MHz, CDCl3): δ ppm = 9.3 (d, 2H, J=10Hz); 8.82 (s, 2H); 8.05 (d, 2H, J=10Hz); 7.79 (t, 2H, J=20Hz); 4.32 (br, s, 4H); 3.82 (br, s, 4H).

13 C NMR: (125 MHz, CDCl3): δ ppm = 141.11; 140.26; 132.87; 130.99; 128.43; 128.28; 127.51; 127.11; 126.40; 126.35; 93.45; 61.96.

MS: Found 453.3 [M+1]+ Calculated Mass: 452.2

Compound 179 :

O N N O O N N O

A mixture of 178 (30mg, 0.066 mmol) and 148 (15mg, 0.066 mmol) in EtOH (10 ml) was refluxed for 24 hrs and reaction was monitored by TLC. After 24hrs the reaction mixture was cooled at room temperature and poured in ice-cold water then filtered and washed with ethanol. The crude was further purified by column chromatography (DCM : PE - 8:2) which gave 179 (25 mg, 58% yield) as orange solid.

- 154 - 1H NMR (500 MHz, TFA): δ ppm = 9.95 (s, 2H); 9.67 (d, 2H, J=10Hz); 9.49 (d, 2H, J=10Hz); 8.65 (d, 2H, J=5Hz); 8.53 (d, 2H, J=5Hz); 8.26 (t, 2H, J=20Hz); 8.18 (s, 2H); 8.14 (t, 2H, J=15Hz); 4.53 (br, s, 4H); 3.96 (br, s, 4H).

13C NMR: (100 MHz, TFA): δ ppm = Not sufficiently soluble.

MS: Found 649.2 [M-1]+ Calculated Mass: 650.6

Compound 191 :

O HN S CH O N 3 O O O N HN S CH3 O

A mixture of compound 188 (228 mg, 0.603 mmol) and 171 (250 mg, 0.603 mmol) in ethanol (10 ml) and acetic acid (4 ml) was refluxed overnight. The mixture was cooled to room temperature and filtered. Further washing with ethanol and removal of solvent on rota evaporator offered 191 (260 mg, 55% yield) as a solid.

1 H NMR (500 MHz, DMSO-d6): δ ppm = 9.51 (s, 2H); 8.62 (s, 2H); 8.01 (s, 2H); 7.74 (d, 4H, J=10Hz); 7.27 (d, 4H, J=10Hz); 4.57 (s, 6H); 1.56 (s, 18H).

13 C NMR: (125 MHz, DMSO-d6): Not soluble enough.

MS: Found 785.4 [M+1]+ Calculated Mass: 784.94.

- 155 - Compound 196 :

O O O O

To the solution of 185 (2 gm, 5.76 mmol) in toluene (200 ml) was added 15 ml of ethylene glycol and p-tolulenesulphonic acid (400 mg, 20% w/w). The reaction mixture was refluxed for 48 hrs by using Dean-Stark aparatus. After completion of reaction, the solution was allowed to cool at room temperature. The work-up was carried out in CHCl3 by washing organic phase with aq. NaHCO3 and dried over Na2SO4. The solvent was removed on rota evaporator and product was purified by column chromatography (PE : DCM - 20:80) that offered 196 as white solid (1.1 gm, 45 % yield)

1 H NMR (250 MHz, DMSO-d6): δ ppm = 8.03 (s, 2H); 7.86 (s, 2H); 7.72 (s, 2H); 4.32 (br s, 4H), 3.80 (br s, 4H); 1.48 (s, 18H).

MS: Found 471 [M+K]+ Calculated Mass: 432.5.

Compound 197 :

O O O O O O

To a solution of the 196 (400 mg, 0.925 mmol) in CH2Cl2 (20 mmol) and CH3CN (20 mL) were added NaIO4 (1.5 gm, 7.042 mmol), H2O (25 mL), and RuCl3 (50 mg, 0.24 mmol). The dark brown suspension was stirred at room temperature overnight. The reaction mixture was poured into 200 mL of H2O, and organic phase was separated. The aqueous phase was extracted with CH2Cl2 (3 × 50 mL). The CH2Cl2 extracts were combined with the organic phase and washed with H2O (3 × 200 mL). The organic layer was dried over Na2SO4 and after filtration solvent was removed on rota evaporator. Column chromatography (DCM) gave pure 197 (150 mg, 35%) as yellow solid.

1 H NMR (500 MHz, CDCl3): δ ppm = 8.19 (s, 2H); 8.00 (s, 2H); 4.24 (br s, 4H); 3.67 (br s, 4H), 1.38 (s, 18H).

- 156 -

13 C NMR: (100 MHz, DMSO-d6): δ ppm = 180.03; 153.82; 133.78; 130.45; 130.34; 129.95; 128.07; 92.56; 61.49; 35.36; 31.09.

MS: Found 463.1 [M+1]+ Calculated Mass: 462.5.

Compound 198 :

O N NO O 2 O O N NO2

A suspension of compound 197 (66.85 mg, 0.33 mmol) and 172 (130 mg, 0.28 mmol) in ethanol (15 ml) and acetic acid (5 ml) was refluxed overnight. The mixture was cooled to room temperature and filtered. Further washing with ethanol and removal of solvent on rota evaporator offered compound 198 (150 mg, 85%) as a yellow solid.

1 H NMR (500 MHz, CDCl3): δ ppm = 9.34 (s, 2H); 8.94 (s, 2H); 8.25 (s, 2H); 4.34 (br s, 4H); 3.79 (br s, 4H), 1.55 (s, 18H).

13 C NMR: (125 MHz, CDCl3): δ ppm = 152.73; 146.47; 141.62; 141.54; 128.23; 127.74; 127.37; 125.91; 124.34; 123.88; 93.37; 61.87; 35.70; 31.54.

MS: Found 625.2 [M+1]+ Calculated Mass: 624.6.

Compound 199 :

O N NH2 O O O N NH2

To a suspension of 198 (50 mg, 0.08 mmol) and Pd/C (5 mg) in EtOH (10 ml) was added NH2NH2.H2O (0.5ml) prior to heating at reflux for 10 h. After cooling to room temperature, the reaction mixture was filtered over celite to remove catalyst. The

- 157 - solvent was evaporated and the obtained compound 199 as red solid, which was directly used for next reaction.

MS: Found 565.4 [M+1]+ Calculated Mass: 564.6

Compound 187 :

N NH2

N NH2

The compound 158 (100 mg, 0.22 mmol) was dissolved in degassed conc. H2SO4 and the solution was heated at 60oC for 12 hrs after completion the reaction mixure was cooled to room temperature and pouried on ice. The mixture was diluted by 300 ml of water and neutralized by adding solid NaHCO3. After neutralization red precipitate was formed which was filtered and washed with water several times and dried under vacuum to obtain 187 as red solid that was used as such for next reaction.

1 H NMR (300 MHz, CDCl3): δ ppm = 9.57 (s, 2H ); 8.21 (s, 2H); 7.98 (s, 2H); 7.53 (s, 2H); 1.66 (s, 9H).

MS: Found 447.2 [M+1]+ Calculated Mass: 446.5

Compound 189 :

N N O

N N O

A mixture of 187 (100mg, 0.22 mmol) and 188 (100.62 mg, 0.26 mmol) in AcOH (20 ml) was refluxed for 3 days and reaction was monitored by TLC. After completion, the reaction mixture was cooled at room temperature and solvent was removed by rotatory evaporation. The crude was purified by washing with methanol, which gave 189 (120 mg; 68% yield) as bright orange solid.

- 158 - 1 H NMR (500 MHz, CDCl3+TFA): δ ppm = 9.80 (s, 2H); 9.70 (s, 2H); 9.66 (s, 2H); 8.74 (s, 2H); 8.55 (s, 2H); 8.11 (s, 2H); 1.67 (s, 18H); 1.62 (s, 18H).

13 C NMR: (125 MHz, CDCl3+TFA): δ ppm = Not soluble enough.

MS: Found 785.4 [M+1]+ Calculated Mass: 784.9.

2,7- diidopyrene-4,5,9,10-tetra(ethyleneglycol)ketal (238).

I

O O O O O O O O

I

A 100 ml round bottom flask was charged with 237 (100 mg, 0.194 mmol) in 1,2-dichlorobenzene (50 ml). Then added ethylene glycol (3ml, 48.332 mmol) and p-toluenesulphonic acid (30mg, 0.174 mmol). The resulting reaction mixture was refluxed for 18 hrs, allowed to cool down to room temperature. The solvent was removed on by evaporation. The obtained crude was washed with water in order to remove excess ethylene glycol. The crude product purified by column chromatography (petrol ether : CH2Cl2 = 1:4) gave 238 as white solid (68.62 mg, 51.20% yield).

1 H NMR (500 MHz, CDCl3): δ ppm = 8.08 (s, 4H); 4.21 (br s, 8H); 3.66 (br s, 8H).

13 C NMR: (100 MHz, CDCl3): δ ppm = 136.36, 134.88, 132.25, 91.89.

MS: Found 690.8 [M]+ Calculated Mass: 690.22

- 159 - 2,7-di(triisopropylsilylethynyl)pyrene-4,5,9,10-tetra(ethyleneglycol) ketal (239a).

Si

O O O O O O O O

Si

Compound 238 (150 mg, 0.217 mmol) was added to a degassed solution of i-Pr2NH (20 mL) and dry THF (20 mL) and the solution was degassed. Subsequently CuI (2.061 mg, 0.0108 mmol) and [Pd(PPh3)2Cl2] (7.70 mg, 0.0108 mmol) were added and degassed. TIPS acetylene (0.205 mL, 13.5 mmol) was added, the solution was once again degassed and heated at 80 °C under Argon overnight. The resulting mixture was filtered over celite and washed with 200 mL of CH2Cl2. Removal of the solvent under vacuum and purification of the crude product by column chromatography (pet ether : ethyl acetate = 20 : 1) yielded 239a as white solid (140 mg, 80.92 %yield).

1 H NMR (500 MHz, CDCl3): δ ppm = 7.84 (s, 4H); 4.22 (br s, 8H); 3.69 (br s, 8H); 1.13 (m, 42H).

13 C NMR (125 MHz, CDCl3): δ ppm = 133.38, 130.61, 128.55, 125.26, 106.51, 92.84, 92.31, 61.59, 18.80, 11.45

MS:Found 799.0 [M]+ Calculated Mass: 799.151

- 160 - 2,7-di(triisopropylsilylethenyl)pyrene-4,5,9,10-tetraketone (240a).

Si

O O

O O

Si

A solution of 239a (100 mg, 0.125 mmol) in a mixture of TFA-H2O (9:1, 10 ml) was stirred at room temperature for 8 hrs and reaction was monitored on TLC. After completion, the reaction mixture was poured in ice cold water and the precipitate was filtered which after drying offered 240a as dark orange solid (64 mg, 80% yield).

1 H NMR (500 MHz, CDCl3): δ ppm = 8.49 (s, 4H); 1.16 (m, 42H).

13 C NMR (125 MHz, CDCl3): δ ppm = 177.23, 139.63, 132.92, 130.87, 127.45, 103.04, 99.17, 18.77, 11.35.

MS: Found 622.3 [M]+ Calculated Mass: 622.94

Compound (241a).

Si

N N

N N

Si

- 161 -

In a dry argon flushed Schlenk flask compound 240a (100 mg, 0.16 mmol) was dissolved in a mixture of acetic acid (6 ml) and ethanol (20 ml). Then o-phenylenediamine (67.5 mg; 0.64 mmol) was added. The reaction mixture was heated at 800C for overnight. After completion the reaction, mixture was allowed to cool down to room temperature. The solution was filtered; solid was washed with ethanol and dried under vacuum that gave compound 241a (94 mg, 76%) as yellow solid.

1 H NMR (500 MHz, CDCl3): δ ppm = 9.68 (s, 4H); 8.45 (d, 4H, J=5Hz); 7.96 (d, 4H, J=10Hz); 1.30 (m, 42H).

13 C NMR (125 MHz, CDCl3): δ ppm = 142.69, 141.86, 130.73, 130.59, 130.05, 129.77, 126.68, 123.75, 106.92, 93.38, 18.98, 11.63.

MS: Found 767.3 [M + H]+ Calculated Mass: 767.162

Compound (242a).

Si

N N

N N

Si

In a dry argon flushed Schlenk flask compound 240a (30 mg, 0.048 mmol) and 2,3-diaminonaphthalene (30.46 mg 0.192 mmol) were dissolved in a mixture of acetic acid (3 ml) and ethanol (7 ml). The reaction mixture was refluxed for 24 hrs, after completion reaction mixture was allowed to cool down to room temperature, filtered and the solid was washed with ethanol that gave compound 242a (26 mg, 62%) as orange solid.

1 H NMR (500 MHz, CDCl3+ TFA): δ ppm = 9.96 (s, 4H); 9.37 (s, 4H); 8.42 (d, 4H, J=10Hz); 7.96 (d, 4H, J=5Hz); 1.28 (m, 42H).

13 C NMR (125 MHz, CDCl3+ TFA): δ ppm = 138.61, 137.64, 136.11, 135.12, 132.99, 131.55, 129.30, 127.52, 125.57, 125.11, 106.06, 100.23, 18.58, 11.52.

- 162 -

MS: Found 867.3 [M]+ Calculated Mass: 867.279

Compound (239b). C6H13

O O O O O O O O

C6H13

Compound 238 (200 mg, 0.289 mmol) was added to a degassed solution of i-Pr2NH (10 mL) and dry THF (10 mL) and the solution was degassed. Subsequently CuI (11.02 mg, 0.057 mmol) and [Pd(PPh3)2Cl2] (41.15 mg, 0.057 mmol) were added and degassed. Then 1-octyne (127.53 mg, 1.15 mmol) was added and degassed once again. The reaction mixture was heated at 80oC for 18 hrs. After completion of the reaction, obtained crude was purified by column chromatography (pet ether : CH2Cl2 = 10 : 3) yielded 239b as white solid (150 mg, 72 %yield).

1 H NMR (500 MHz, CDCl3): δ ppm = 7.76 (s, 4H); 4.19 (br s, 8H); 3.69 (br s, 8H); 2.41 (t, 4H, J=15Hz); 1.59 (m, 4H); 1.45 (m, 4H); 1.33 (m, 8H); 0.91 (t, 6H, J=20Hz).

13 C NMR (125 MHz, CDCl3): δ ppm = 133.16, 130.17, 127.91, 125.66, 92.42, 92.40, 80.52, 61.7, 31.50, 28.80, 28.73, 22.68, 19.64, 14.20.

MS: Found 655.0 [M + H]+ Calculated Mass: 654.788

Compound (240b).

C6H13

O O

O O

C6H13

- 163 -

A solution of 239b (70 mg, 0.107 mmol) in a mixture of TFA-H2O (9:1, 10 ml) was stirred at room temperature for 8 hrs and reaction was monitored on TLC. After completion the reaction mixture was poured in ice cold water. The precipitate was filtered and the solid was washed with water, which after drying offered 240b as orange solid (45 mg, 88% yield).

1 H NMR (500 MHz, CDCl3): δ ppm = 8.41 (s, 4H); 2.47 (t, 4H, J=15 Hz); 1.64 (m, 4H); 1.47 (m, 4H); 1.33 (m, 8H); 0.92 (t, 6H, J=20Hz).

13 C NMR (125 MHz, CDCl3): δ ppm = 177.43, 139.25, 132.50, 130.76, 128.12, 97.80, 78.01, 31.43, 28.77, 28.42, 22.65, 19.70, 14.18.

MS: Found 478.3 [M]+ Calculated Mass: 478.57

Compound (241b).

C6H13

N N

N N

C6H13

In a dry argon flushed Schlenk flask the compound 240b (70 mg, 0.146 mmol) was dissolved it in a mixture of acetic acid (5 ml) and ethanol (10 ml). Then o-phenylenediamine (61.5 mg 0.585 mmol) was added and reaction mixture was refluxed for overnight, after completion reaction mixture was allowed to cool down to room temperature, filtered and the solid was washed with ethanol, which after drying gave compound 241b (65 mg, 71.36%) as yellow solid.

1 H NMR (300 MHz, CDCl3+TFA): δ ppm = 9.70 (s, 4H); 8.64 (d, 4H); 8.23 (d, 4H); 2.56 (t, 4H); 1.75 (m, 4H); 1.55 (m, 4H); 1.41 (m, 8H); 0.97 (t, 6H, J=20Hz).

13 C NMR (125 MHz, CDCl3): δ ppm = 140.28, 139.37, 132.56, 127.46, 127.21, 126.36, 126.08, 31.55, 29.01, 28.7, 22.7, 19.79, 14.07.

MS: Found 623.3 [M + H]+ Calculated Mass: 622.79

- 164 -

Compound (242b). C6H13

N N

N N

C6H13

In a dry argon flushed Schlenk flask the compound 240b (30 mg, 0.062 mmol) and 2,3-diaminonaphthalene (39.66 mg 0.257 mmol) was dissolved it in a mixture of acetic acid (6 ml) and ethanol (20 ml). The reaction mixture was refluxed for 36 hrs, after completion reaction mixture was allowed to cool down to room temperature, filtered and the solid was washed with ethanol that gave compound 242b (29 mg, 64%) as reddish brown solid.

1 H NMR (500 MHz, CDCl3+TFA): δ ppm = 9.53 (s, 4H); 9.06 (s, 4H); 8.22 (m, 4H); 7.77 (m, 4H); 2.58 (t, 4H, J=20Hz); 1.76 (m, 4H); 1.58 (m, 4H); 1.44 (m, 8H); 1.00 (m, 6H).

13 C NMR (125 MHz, CDCl3+TFA): δ ppm = 138.54, 136.78, 133.20, 130.71, 129.00, 127.74, 126.38, 125,33, 125.05, 98.59, 31.54, 29.06, 28.60, 22.72, 19.78, 14.09.

MS: Found 723.3 [M + H]+ Calculated Mass: 722.91

Compound (239c). C12H25

O O O O O O O O

C12H25

- 165 - Compound 238 (200 mg, 0.289 mmol) was added to a degassed solution of i-Pr2NH (10 mL) and dry THF (10 mL) and the solution was degassed. Subsequently CuI (11.02 mg, 0.057 mmol) and [Pd(PPh3)2Cl2] (41.15 mg, 0.057 mmol) were added and degassed. Then 1-tetradecyne (224.92 mg, 1.15 mmol) was added and degassed again. The reaction mixture was heated at 80oC for 18 hrs. After completion of the reaction, obtained crude was purified by column chromatography (pet ether : CH2Cl2 = 9 : 1) yielded 239c as white solid (142 mg, 59 % yield).

1 H NMR: (500 MHz, CDCl3): δ ppm = 7.76 (s, 4H); 4.19 (br s, 8H); 3.66 (br s, 8H); 2.41 (t, 4H, J=15Hz); 1.60 (m, 4H); 1.27 (m, 32H); 0.88 (t, 6H, J=20Hz).

13 C NMR: (100 MHz, CDCl3): δ ppm = 133.17, 130.18, 127.92, 125.67, 92.42, 80.52, 32.05, 29.82, 29.63, 29.34, 28.86, 22.82, 19.65, 14.24.

MS: Found 823.3 [M]+ Calculated Mass: 823.107

Compound (240c). C12H25

O O

O O

C12H25 A solution of 239c (100 mg, 0.121 mmol) in a mixture of TFA-H2O (9:1, 10 ml) was stirred at room temperature for 32 hrs and reaction was monitored on TLC. After completion the reaction mixture was poured in ice cold water. The precipitate was filtered which was purified by column (pet ether : CH2Cl2 = 7 : 3) offered 240c as orange solid (34 mg, 44% yield).

1 H NMR: (300 MHz, CDCl3) δ ppm = 8.42 (s, 4H); 2.47 (t, 4H, J=15Hz); 1.65 (m, 4H); 1.44 (m, 4H); 1.27 (m, 32H); 0.88 (t, 6H, J=20Hz).

13 C NMR: (100 MHz, CDCl3): δ ppm = 177.45, 134.27, 130.77, 130.79, 125.47, 97.81, 29.63, 29.48, 29.26, 29.10, 28.46, 22.81, 18.64, 14.24.

MS: Found 646.6 [M]+ Calculated Mass: 646.89

- 166 - Compound (241c).

C12H25

N N

N N

C12H25

In a dry argon flushed Schlenk flask the compound 240c (20 mg, 0.03 mmol) was suspended in the mixture of acetic acid (5 ml) and ethanol (10 ml). Then o-phenylenediamine (30 mg 0.285 mmol) was added and reaction mixture was refluxed for 30 hrs and monitored by TLC, after completion reaction mixture was allowed to cool down to room temperature. Then filtered and the solid was washed with ethanol which gave compound 241c (12 mg, 49%) as yellow solid.

1 H NMR: (300 MHz, CDCl3+TFA) δ ppm = 19.54 (s, 4H); 8.56 (d, 4H); 8.17 (d, 4H); 2.52 (t, 4H); 1.75 (t, 4H); 1.58 (m, 4H); 1.36 (m, 32H); 0.99 (t, 6H).

13C NMR: Not soluble enough.

MS: Found 791.6 [M]+ Calculated Mass: 791.118

Compound (245).

Si

F F F N N F

F N N F F F

Si

- 167 -

In a dry argon flushed Schlenk flask the compound 240a (50 mg, 0.08 mmol) and amine 249 (57 mg, 0.32 mmol) was suspended it in a mixture of acetic acid (5 ml) and ethanol (5 ml). The reaction mixture was heated at 80oC for overnight. After completion the reaction, mixture was allowed to cool down to room temperature. Then filtered and the solid was washed with ethanol, which after drying under vacuum offered compound 245 (50 mg, 68%) as yellow solid.

1 H NMR: (300 MHz, CDCl3) δ ppm = 9.63 (s, 4H); 1.22 (m, 42H).

13C NMR: Not soluble enough.

MS: Found 907.5 [M-4]+ Calculated Mass: 911.08.

Compound (246).

Si

O2N N N NO2

O2N N N NO2

Si

In a dry argon flushed Schlenk flask the compound 240a (50 mg, 0.08 mmol) and amine 250 (47 mg, 0.24 mmol)was suspended it in a mixture of acetic acid (10 ml) and ethanol (10 ml). The reaction mixture was heated at 80oC for overnight. After completion the reaction, mixture was allowed to cool down to room temperature. Then filtered and the solid was washed with ethanol, which after drying under vacuum offered compound 246 (60 mg, 78%) as yellow solid.

1 H NMR: (300 MHz, CDCl3) δ ppm = 9.8 (s, 4H); 9.07 (s, 4H); 1.29 (m, 42H).

13C NMR: Not soluble enough.

- 168 - MS: Found 948.5 [M-4]+ Calculated Mass: 947.15.

Compound (247).

Si

NC N N CN

NC N N CN

Si

In a dry argon flushed Schlenk flask the compound 240a (30 mg, 0.04 mmol) and amine 251 (26.04 mg, 0.24 mmol) were suspended in a mixture of acetic acid (5 ml) and ethanol (5 ml). The reaction mixture was heated at 80oC for overnight. After completion the reaction, mixture was allowed to cool down to room temperature. Then filtered and the solid was washed with ethanol, which after drying under vacuum offered compound 247 (56 mg, 78%) as yellow solid.

1 H NMR: (400 MHz, CDCl3) δ ppm = 9.64 (s, 4H); 1.26 (m, 42H).

13 C NMR: (100 MHz, CDCl3): δ ppm = 142.42; 133.76; 131.72; 127.65; 127.28; 125.94; 113.38; 104.52; 97.65; 18.91; 11.49.

MS: Found 767.5 [M]+ Calculated Mass: 767.08

- 169 - Compound (248).

Si

NC N N N N CN

NC N N N N CN

Si

In a dry argon flushed Schlenk flask the compound 240a (30 mg, 0.04 mmol) and amine 252 (30.84 mg, 0.19 mmol) were suspended in acetic acid (10 ml). The reaction mixture was heated at 120oC for 60 hrs. After completion the reaction, mixture was allowed to cool down to room temperature. Then filtered and the solid was washed with ethanol, which after drying under vacuum offered compound 248 (30 mg, 71%) as red solid.

1 H NMR: (300 MHz, CDCl3) δ ppm = 9.94 (s, 4H); 1.24 (m, 42H).

13C NMR: Not soluble enough.

MS: Found 871.3 [M]+ Calculated Mass: 871.15

Compound (277):

Me Me Me Si

O O O O O O O O

Si Me Me Me

Compound 238 (100 mg, 0.14 mmol) was added to a degassed solution of i-Pr2NH (10 mL) and dry THF (10 mL) and the solution was degassed.

- 170 - Subsequently CuI (2.061 mg, 0.0108 mmol) and [Pd(PPh3)2Cl2] (7.70 mg, 0.0108 mmol) were added and degassed. TMS acetylene (56.8 mg, 0.57 mmol) was added, the solution was once again degassed and heated at 80 °C under Argon overnight. The resulting mixture was filtered over celite and washed with 200 mL of CH2Cl2. Removal of the solvent under vacuum and purification of the crude product by column chromatography using chloroform yielded 277 as white solid (40 mg, 43 %).

1 H NMR (500 MHz, CDCl3): δ ppm = 7.84 (s, 4H); 4.20 (br s, 8H); 3.67 (br s, 8H); 0.25 (s, 18H).

13 C NMR (125 MHz, CDCl3): δ ppm = 133.44, 131.06, 128.59, 124.73, 104.59, 96.24, 92.22, 29.77, 22.76.

MS: Found 653.6 [M+Na]+ Calculated Mass: 630.83

Compound (279).

H

O O

O O

H

A solution of 277 (50 mg, 0.079 mmol) in a mixture of TFA-H2O (9:1, 10 ml) was stirred at room temperature for 8 hrs and reaction was monitored on TLC. After completion, the reaction mixture was poured in ice cold water and the precipitate was filtered and the solid was washed with water, which after drying offered 279 as dark orange solid (12 mg, 48% yield).

1 H NMR (500 MHz, CDCl3+TFA): δ ppm = 8.58 (s, 4H); 3.46 (s, 2H).

13C NMR: Not soluble enough.

MS: Found 332.8 [M+Na]+ Calculated Mass: 310.25

- 171 - Compound (283).

Si

Si Si

N N

N N

Si Si

Si

In a dry argon flushed Schlenk flask the compound 240a (30 mg, 0.04 mmol) and amine 284 (90.28 mg, 0.19 mmol) were suspended in the mixture of acetic acid (3 ml) and ethanol (7 ml). The reaction mixture was heated at 80oC for overnight. After completion the reaction, mixture was allowed to cool down to room temperature. Then filtered and solid was washed with ethanol and dried under vacuum which gave compound 283 (56 mg, 78%) as yellow solid.

1 H NMR: (500 MHz, CDCl3) δ ppm = 9.76 (s, 4H); 8.03 (s, 4H); 1.29 (m, 84H); 1.24 (m, 42H).

13 C NMR: (125 MHz, CDCl3): δ ppm = 142.48, 142.35, 135.06, 130.07, 127.44, 124.22, 124.05, 106.52, 104.03, 100.66, 93.63, 19.07, 18.97, 12.13, 11.52

MS: Found 1488.8 [M]+ Calculated Mass: 1488.06

- 172 -

2,7-di(triisobutylsilylethynyl)pyrene-4,5,9,10-tetra(ethyleneglycol)ketal (285).

Si

O O O O O O O O

Si

Compound 238 (100 mg, 0.14 mmol) was added to a degassed solution of i-Pr2NH (10 mL) and dry THF (10 mL) and the solution was degassed. Subsequently CuI (2.061 mg, 0.0108 mmol) and [Pd(PPh3)2Cl2] (7.70 mg, 0.0108 mmol) were added and degassed. Then triisobutylsilyl acetylene (0.129 mL, 0.57 mmol) was added, the solution was once again degassed and heated at 80 °C under Argon overnight. The resulting mixture was filtered over celite and washed with 200 mL of CH2Cl2. Removal of the solvent under vacuum and purification of the crude product by column chromatography (pet ether : ethyl acetate = 20 : 1) yielded 285 as white solid (80 mg, 62 %).

1 H NMR (500 MHz, CDCl3): δ ppm = 7.78 (s, 4H); 4.18 (br s, 8H); 3.65 (br s, 8H); 1.90 (m, 6H); 1.01 (d, 36H, J=10Hz); 0.68 (d, 12H, J=10Hz).

13 C NMR (125 MHz, CDCl3): δ ppm = 133.33, 130.40, 128.56, 125.27, 106.27, 96.09, 92.30, 61.51, 29.82, 26.45, 25.21.

MS: Found 883.3 [M]+ Calculated Mass: 883.31

- 173 -

2,7-di(triisobutylsilylethenyl)pyrene-4,5,9,10-tetraketone (286).

Si

O O

O O

Si

A solution of 285 (100 mg, 0.125 mmol) in a mixture of TFA-H2O (9:1, 10 ml) was stirred at room temperature for 8 hrs and reaction was monitored by TLC. After completion, the reaction mixture was poured in ice cold water and the precipitate was filtered then the solid was washed with water, which after drying offered 286 as dark orange solid (64 mg, 80% yield).

1 H NMR (500 MHz, CDCl3): δ ppm = 8.37 (s, 4H); 1.85 (m, 6H); 0.95 (d, 36H, J=15Hz); 0.70 (d, 12H, J=15Hz).

MS: Found 707.6 [M]+ Calculated Mass: 707.10

Compound (287).

Si

Si Si

N N

N N

Si Si

Si

- 174 -

In a dry argon flushed Schlenk flask the compound 286 (50 mg, 0.07 mmol) and amine 288 (156.43 mg, 0.28 mmol) were suspended in the mixture of acetic acid (3 ml) and ethanol (10 ml). The reaction mixture was heated at 80oC for overnight. After completion the reaction, mixture was allowed to cool down to room temperature. Then filtered and the solid was washed with ethanol, which after drying under vacuum offered compound 287 (56 mg, 78%) as yellow solid.

1 H NMR: (300 MHz, CDCl3) δ ppm = 9.72 (s, 4H); 7.97 (s, 4H); 2.08 (m, 18H); 1.14(d, 108H); 0.90 (d, 36H)

MS: Found 1740.9 [M]+ Calculated Mass: 1741.08

Compound 289 :

Si

O O O O O O O O

Si

The compound 238 (100 mg, 0.144 mmol) was added to a degassed solution of i-Pr2NH (10 mL) and dry THF (10 mL) and the solution was degassed. Subsequently CuI (1.37 mg, 0.007 mmol) and [Pd(PPh3)2Cl2] (5.14 mg, 0.007 mmol) were added and degassed. Triphenylsily acetylene (164 mg, 0.57 mmol) was added, the solution was once again degassed and heated at 80 °C under Argon overnight. The resulting mixture was filtered over celite and washed with 200 mL of CH2Cl2. Removal of the solvent under vacuum and purification of the crude product by column chromatography (CHCl3 : MeOH = 20 : 1) yielded 289 as white solid (30 mg, 20 %).

- 175 - 1 H NMR (300 MHz, CDCl3): δ ppm = 7.96 (s, 4H); 7.7 (m, 6H); 7.43 (m, 24H); 4.22 (br s, 8H); 3.68 (br s, 8H).

13 C NMR (125 MHz, CDCl3): δ ppm = 135.76, 133.75, 133.42, 130.95, 130.14, 128.21, 128.16, 124.50, 101.36, 92.23.

MS: Found 1002.9 [M-1]+ Calculated Mass: 1003.24

Compound 290 :

Si

O O

O O

Si

A solution of 289 (20 mg, 0.009 mmol) in a mixture of TFA-H2O- DCM (5:1:4, 10 ml) was stirred at 40oC for 24 hrs and reaction was monitored on TLC. After completion, the reaction mixture was poured in ice cold water and extracted with CH2Cl2 (10 ml) 2-3 times the organic layer was dried over Na2SO4. After removal of solvent under reduced pressure offered 290 as orange solid (12 mg, 72% yield).

1 H NMR (500 MHz, CDCl3): δ ppm = 8.61 (s, 4H); 7.69 (m, 6H); 7.46 (m, 24H).

13 C NMR (125 MHz, CDCl3): δ ppm = 176.94, 139.77, 135.72, 132.39, 131.00, 130.5, 128.35, 128.28, 126.84, 104.79, 97.28.

+ MS: Found 897.1 [M + 2NH4OH] Calculated Mass: 827.03

- 176 -

Compound (291) :

Si

Si Si

N N

N N

Si Si

Si

In a dry argon flushed Schlenk flask, compound 290 (40 mg, 0.04 mmol) and amine 292 (92.4 mg, 0.13 mmol) were dissolved in the mixture of acetic acid (3 ml) and ethanol (10 ml). The reaction mixture was heated at 80oC for overnight. After completion the reaction, mixture was allowed to cool down to room temperature. Then filtered and the solid was washed with ethanol. The obtained product was purified by column chromatogryphy (DCM : PE = 4 : 1) which gave compound 291 (52 mg, 51%) as yellow solid.

1 H NMR: (500 MHz, CDCl3) δ ppm = 10.06 (s, 4H); 8.19 (s, 4H); 7.91 (m, 24H); 7.26 (m, 48H); 7.14 (m, 6H); 6.98 (m, 12H).

13 C NMR (125 MHz, CDCl3): δ ppm = 142.54, 135.89, 135.78, 135.65, 135.34, 133.37, 133.04, 132.42, 130.34, 130.19, 129.74, 128.35, 128.32, 128.00, 124.19, 108.24, 106.30, 99.68, 93.45.

MS: Calculated Mass: 2098.64

- 177 - References:

1) Kato, T.; Masu, H.; Takayanagi, H.; Kaji, E.; Katagiri, K.; Tominaga, M.; Azumaya, I. Tetrahydron, 2006, 62, 8458-8462. 2) Shang, X. F.; Lin, H.; Lin, H. K. Journal of Fluorine Chemistry 2007, 128, 530– 534. 3) Bhosale, S. V.; Bhosale, S. V.; Kalyankar M. B.; Langford, S. J. Org. Lett., 2009, 11, 5418. 4) Cheeseman G. W. H.; Journal of the Chemical Society, 1962, 1170-1176. 5) (a)Ming, Y. Journal of Molecular Recognition 2007, 20, 69-73. (b) Ming, Y. Supramolecular Chemistry 2008, 20, 309-315. 6) Hu, J.; Zhang, D.; Harris, F. W. Journal of Organic Chemistry, 2005, 70, 707 – 708. 7) Minsky, A. J. Am. Chem. Soc. 1982, 104, 2475-2482.

- 178 -

- 179 -

Appendix

- 180 -

- 181 - NMR:

1 Fig. 105: H NMR of compound 175 in CDCl3

13 Fig. 106: C NMR of compound 175 in CDCl3

- 182 -

1 Fig. 107: H NMR of compound 176 in CDCl3

13 Fig. 108: C NMR of compound 176 in CDCl3

- 183 -

1 Fig. 109: H NMR of compound 177 in CDCl3

13 Fig. 110: C NMR of compound 177 in CDCl3

- 184 -

1 Fig. 111: H NMR of compound 178 in CDCl3

13 Fig. 112: C NMR of compound 178 in CDCl3

- 185 -

1 Fig. 113: H NMR of compound 179 in CDCl3

1 Fig. 114: H NMR of compound 191 in CDCl3

- 186 -

13 Fig. 115: C NMR of compound 191 in CDCl3

1 Fig. 116: H NMR of compound 196 in CDCl3

- 187 -

1 Fig. 117: H NMR of compound 197 in CDCl3

13 Fig. 118: C NMR of compound 197 in CDCl3

- 188 -

1 Fig. 119: H NMR of compound 198 in CDCl3

13 Fig. 120: C NMR of compound 198 in CDCl3

- 189 -

1 Fig. 121: H NMR of compound 199 in CDCl3

1 Fig. 122: H NMR of compound 189 in CDCl3+TFA.

- 190 -

13 Fig. 123: C NMR of compound 189 in CDCl3+TFA.

1 Fig. 124: H NMR of compound 238 in CDCl3

- 191 -

13 Fig. 125: C NMR of compound 238 in CDCl3

1 Fig. 126: H NMR of compound 239a in CDCl3

- 192 -

13 Fig. 127: C NMR of compound 239a in CDCl3

1 Fig. 128: H NMR of compound 240a in CDCl3

- 193 -

13 Fig. 129: C NMR of compound 240a in CDCl3

1 Fig. 130: H NMR of compound 241a in CDCl3

- 194 -

13 Fig. 131: C NMR of compound 241a in CDCl3

1 Fig. 132: H NMR of compound 242a in CDCl3+TFA

- 195 -

13 Fig. 133: C NMR of compound 242a in CDCl3+TFA.

1 Fig. 134: H NMR of compound 239b in CDCl3

- 196 -

13 Fig. 135: C NMR of compound 239b in CDCl3

1 Fig.136: H NMR of compound 240b in CDCl3

- 197 -

13 Fig. 137: C NMR of compound 240b in CDCl3

1 Fig. 138: H NMR of compound 241b in CDCl3+TFA

- 198 -

13 Fig. 139: C NMR of compound 241b in CDCl3+TFA.

1 Fig. 140: H NMR of compound 242b in CDCl3+TFA

- 199 -

13 Fig. 141: C NMR of compound 242b in CDCl3+TFA.

1 Fig. 142: H NMR of compound 239c in CDCl3

- 200 -

13 Fig. 143: C NMR of compound 239c in CDCl3

1 Fig. 144: H NMR of compound 240c in CDCl3

- 201 -

13 Fig. 145: C NMR of compound 240c in CDCl3

1 Fig. 146: H NMR of compound 241c in CDCl3+TFA

- 202 -

1 Fig. 147: H NMR of compound 245 in CDCl3

1 Fig. 148: H NMR of compound 247 in CDCl3

- 203 -

13 Fig. 149: C NMR of compound 247 in CDCl3

1 Fig. 150: H NMR of compound 246 in CDCl3

- 204 -

13 Fig. 151: C NMR of compound 246 in CDCl3

1 Fig. 152: H NMR of compound 248 in CDCl3

- 205 -

1 Fig. 153: H NMR of compound 277 in CDCl3

13 Fig. 154: C NMR of compound 277 in CDCl3

- 206 -

1 Fig. 155: H NMR of compound 239 in CDCl3+TFA.

1 Fig. 156: H NMR of compound 283 in CDCl3

- 207 -

13 Fig. 157: C NMR of compound 283 in CDCl3

1 Fig. 158: H NMR of compound 285 in CDCl3

- 208 -

13 Fig. 159: C NMR of compound 285 in CDCl3

1 Fig. 160: H NMR of compound 286 in CDCl3

- 209 -

1 Fig. 161: H NMR of compound 287 in CDCl3

1 Fig. 162: H NMR of compound 289 in CDCl3

- 210 -

13 Fig. 163: C NMR of compound 289 in CDCl3

1 Fig. 164: H NMR of compound 290 in CDCl3

- 211 -

13 Fig. 165: C NMR of compound 290 in CDCl3

1 Fig. 166: H NMR of compound 291 in CDCl3

- 212 -

13 Fig. 167: C NMR of compound 291 in CDCl3

- 213 - Single crystal structures:

Compound 175:

O O O O

TITL x in P2(1)2(1)2 CELL 0.71073 9.6653 7.8109 9.5422 90.000 90.000 90.000 ZERR 2.00 0.0003 0.0003 0.0004 0.000 0.000 0.000 LATT -1 SYMM -X, -Y, Z SYMM 0.5-X, 0.5+Y, -Z SYMM 0.5+X, 0.5-Y, -Z SFAC C H O UNIT 40 32 8

L.S. 8 MERG 4 ACTA BOND $H CONF SIZE 0.22 0.15 0.12 TEMP -143 FMAP 2 PLAN 20

WGHT 0.053300 0.109100 EXTI 0.052278 FVAR 0.88096 O1 3 0.851470 0.029869 0.065608 11.00000 0.01925 0.01889 = 0.01654 0.00000 -0.00386 -0.00077 O2 3 0.982761 0.233893 0.169484 11.00000 0.02040 0.01646 = 0.01766 0.00071 0.00246 -0.00133 C1 1 0.937288 0.062197 0.183729 11.00000 0.01638 0.01636 = 0.01559 -0.00008 -0.00050 -0.00011 C2 1 0.857461 0.058845 0.320692 11.00000 0.01898 0.01481 = 0.01791 -0.00092 0.00226 -0.00079 C3 1 0.719681 0.104810 0.322849 11.00000 0.02125 0.01926 = 0.02285 0.00017 0.00057 0.00003 AFIX 43 H3 2 0.672814 0.127146 0.237270 11.00000 -1.20000 AFIX 0 C4 1 0.648154 0.118875 0.450165 11.00000 0.02176 0.02131 =

- 214 - 0.03181 -0.00255 0.00735 0.00053 AFIX 43 H4 2 0.552729 0.148018 0.450546 11.00000 -1.20000 AFIX 0 C5 1 0.716112 0.090518 0.574044 11.00000 0.03061 0.02245 = 0.02427 -0.00176 0.01188 -0.00163 AFIX 43 H5 2 0.667414 0.101450 0.660059 11.00000 -1.20000 AFIX 0 C6 1 0.857065 0.045421 0.575559 11.00000 0.03112 0.01690 = 0.01808 -0.00150 0.00376 -0.00296 C7 1 0.931951 0.020222 0.704101 11.00000 0.04037 0.02465 = 0.01527 -0.00070 0.00484 -0.00501 AFIX 43 H7 2 0.884838 0.032234 0.790921 11.00000 -1.20000 AFIX 0 C8 1 0.928093 0.025700 0.446795 11.00000 0.02231 0.01428 = 0.01690 -0.00138 0.00226 -0.00236 C9 1 0.805125 -0.144810 0.057796 11.00000 0.02040 0.02021 = 0.02017 -0.00193 -0.00297 -0.00364 AFIX 23 H9A 2 0.746564 -0.160674 -0.026329 11.00000 -1.20000 H9B 2 0.749010 -0.172869 0.141496 11.00000 -1.20000 AFIX 0 C10 1 1.070970 0.262078 0.050233 11.00000 0.02131 0.01938 = 0.01996 0.00342 0.00426 -0.00187 AFIX 23 H10A 2 1.102158 0.382793 0.048805 11.00000 -1.20000 H10B 2 1.018788 0.239643 -0.037134 11.00000 -1.20000 HKLF 4

REM x in P2(1)2(1)2 REM R1 = 0.0311 for 919 Fo > 4sig(Fo) and 0.0337 for all 983 data REM 110 parameters refined using 0 restraints

END

WGHT 0.0533 0.1091 REM Highest difference peak 0.293, deepest hole -0.177, 1-sigma level 0.042 Q1 1 1.0000 0.0000 0.1839 10.50000 0.05 0.29 Q2 1 0.8986 0.0535 0.2559 11.00000 0.05 0.23 Q3 1 1.0000 0.0000 0.4446 10.50000 0.05 0.22 Q4 1 0.9614 0.0448 -0.0589 11.00000 0.05 0.20 Q5 1 0.8962 0.0414 0.6323 11.00000 0.05 0.20 Q6 1 0.8910 0.0509 0.5110 11.00000 0.05 0.20 Q7 1 0.8839 0.0035 0.3800 11.00000 0.05 0.19

- 215 - Q8 1 0.8424 0.0447 0.8081 11.00000 0.05 0.16 Q9 1 0.8081 0.0654 0.5767 11.00000 0.05 0.16 Q10 1 0.9946 0.0240 0.6970 11.00000 0.05 0.14 Q11 1 0.5000 0.0000 0.4417 10.50000 0.05 0.13 Q12 1 1.0595 0.1192 -0.0785 11.00000 0.05 0.12 Q13 1 0.6813 0.0604 0.3850 11.00000 0.05 0.12 Q14 1 0.8989 0.0757 0.8695 11.00000 0.05 0.12 Q15 1 0.7221 0.1170 0.8233 11.00000 0.05 0.11 Q16 1 0.6340 0.1202 0.2019 11.00000 0.05 0.11 Q17 1 0.8644 -0.2022 0.0619 11.00000 0.05 0.11 Q18 1 0.6819 0.0499 0.5047 11.00000 0.05 0.11 Q19 1 0.6610 -0.1365 -0.1721 11.00000 0.05 0.10 Q20 1 0.7198 0.0882 0.0627 11.00000 0.05 0.10

Compound 283:

Si

Si Si

N N

N N

Si Si

Si

TITL SPM-269 CELL 0.71073 17.7982 14.7823 19.3641 90 105.335 90 ZERR 4 0.0012 0.0010 0.0014 0.00 0.004 0.00 LATT 1 SYMM 1/2-x,1/2+y,1/2-z SFAC C H N Si Cl UNIT 192 272 8 12 12 FVAR 1.00 Si1 4 0.186430 0.659020 0.249030 1.000000 0.0203 0.0247 = 0.0273 0.0002 0.0074 0.0026 Si2 4 0.088830 0.757700 -0.110020 1.000000 0.0166 0.0323 = 0.0241 0.004 0.0039 0.0122 Si3 4 0.730210 0.182130 0.353550 1.000000 0.0272 0.0251 = 0.0279 0.006 -0.0009 0.0069 N1 3 0.551010 0.410170 0.195830 1.000000 0.0161 0.0151 = 0.0289 0.001 -0.0019 0.0002 N2 3 0.414950 0.516780 0.164810 1.000000 0.0143 0.0158 = 0.0253 -0.0008 -0.0017 -0.0006 C10 1 0.464150 0.526140 -0.008230 1.000000 0.0138 0.0112 = 0.0289 -0.0045 -0.0035 0.0001 C8 1 0.522990 0.447800 0.131700 1.000000 0.0125 0.0125 = 0.0291 -0.001 -0.0029 -0.0005

- 216 - C7 1 0.453100 0.500840 0.115820 1.000000 0.013 0.0121 = 0.0295 -0.0012 -0.0025 -0.0004 C9 1 0.422790 0.538820 0.043990 1.000000 0.0138 0.0118 = 0.0277 -0.0028 -0.0013 0 C3 1 0.405510 0.498070 0.285570 1.000000 0.0163 0.018 = 0.0304 0.0009 0.0009 -0.0026 C28 1 0.608820 0.323800 0.330980 1.000000 0.0357 0.0139 = 0.0188 0.0105 -0.0099 -0.0031 C14 1 0.352960 0.587630 0.026840 1.000000 0.013 0.0154 = 0.0289 -0.0025 0.0006 0.003 H14 2 0.325500 0.596600 0.062200 1.000000 0.024 C15 1 0.248830 0.668500 -0.060300 1.000000 0.0199 0.0242 = 0.0273 0.0018 0.0032 0.0052 C4 1 0.511990 0.425070 0.245930 1.000000 0.0159 0.0168 = 0.0287 0.0016 -0.0016 -0.0006 C6 1 0.539180 0.384700 0.315670 1.000000 0.0194 0.0187 = 0.0322 0.0035 -0.0035 -0.0005 C12 1 0.365180 0.613030 -0.092860 1.000000 0.0149 0.0156 = 0.028 0.0001 -0.0026 0.0032 H12 2 0.345800 0.639200 -0.139000 1.000000 0.025 C37 1 0.337100 0.554900 0.272250 1.000000 0.0248 0.0206 = 0.024 -0.0014 0.0066 -0.0064 C2 1 0.434940 0.459600 0.352130 1.000000 0.0203 0.0251 = 0.0322 0.0029 0.0049 -0.0046 H2 2 0.410200 0.471800 0.389000 1.000000 0.032 C5 1 0.443920 0.480430 0.230730 1.000000 0.017 0.0141 = 0.0298 -0.0002 -0.0002 -0.0037 C11 1 0.434940 0.564970 -0.077120 1.000000 0.0138 0.0128 = 0.0267 -0.0031 -0.0035 -0.0007 C17 1 0.118330 0.591700 0.176090 1.000000 0.0218 0.0356 = 0.0355 -0.0028 0.0062 -0.0009 H17 2 0.108200 0.533700 0.198700 1.000000 0.037 C13 1 0.323320 0.623220 -0.041650 1.000000 0.0144 0.0137 = 0.032 -0.001 -0.0016 0.003 C1 1 0.500280 0.403000 0.366780 1.000000 0.0243 0.0241 = 0.0291 0.006 -0.0003 -0.0033 H1 2 0.518200 0.376700 0.413000 1.000000 0.033 C24 1 0.026340 0.722900 -0.049790 1.000000 0.0238 0.0396 = 0.025 0.0011 0.0058 0.0051 H24 2 0.059100 0.730100 0.000500 1.000000 0.035 C23 1 0.051200 0.722300 -0.206610 1.000000 0.0251 0.048 = 0.0273 0.0015 0.0052 0.0157 H23 2 0.088400 0.748500 -0.231900 1.000000 0.041 C27 1 0.656000 0.272200 0.348100 1.000000 0.0311 0.037 = 0.037 -0.0022 0.0032 -0.0065 C18 1 0.153100 0.565000 0.114080 1.000000 0.0311 0.046 = 0.0328 -0.0095 0.003 0.0039 H18A 2 0.159800 0.619300 0.087300 1.000000 0.057 H18B 2 0.117800 0.522800 0.082100 1.000000 0.057 H18C 2 0.203800 0.535900 0.133400 1.000000 0.057 C26 1 -0.045940 0.782700 -0.057100 1.000000 0.0242 0.062 = 0.033 -0.0051 0.0111 0.0072 H26A 2 -0.029700 0.845900 -0.047600 1.000000 0.059 H26B 2 -0.074100 0.763000 -0.022600 1.000000 0.059

- 217 - H26C 2 -0.080000 0.777500 -0.105800 1.000000 0.059 C21 1 0.105640 0.883300 -0.103230 1.000000 0.0223 0.0328 = 0.0376 0.0068 0.007 0.0111 H21 2 0.053800 0.913400 -0.121500 1.000000 0.037 C16 1 0.185550 0.703600 -0.077350 1.000000 0.0221 0.0304 = 0.0255 0.0036 0.0044 0.0078 C29 1 0.749670 0.118700 0.440190 1.000000 0.0217 0.029 = 0.0327 0.0091 0.0045 0.0047 H29 2 0.788900 0.070900 0.438500 1.000000 0.034 C36 1 0.280720 0.599500 0.265750 1.000000 0.0263 0.0265 = 0.0258 0 0.0025 -0.0017 C46 1 0.893200 0.176200 0.365300 1.000000 0.036 0.05 = 0.048 0.0165 0.0144 0.0131 H46A 2 0.903000 0.162300 0.416400 1.000000 0.067 H46B 2 0.938600 0.207200 0.356800 1.000000 0.067 H46C 2 0.884000 0.119900 0.337700 1.000000 0.067 C34 1 -0.028000 0.764800 -0.242180 1.000000 0.0282 0.059 = 0.0315 0.0032 0.0001 0.017 H34A 2 -0.067600 0.739500 -0.220900 1.000000 0.061 H34B 2 -0.042100 0.751700 -0.293600 1.000000 0.061 H34C 2 -0.025000 0.830500 -0.234800 1.000000 0.061 C25 1 0.002000 0.623400 -0.058700 1.000000 0.039 0.047 = 0.044 0.0024 0.0107 -0.001 H25A 2 -0.032300 0.613700 -0.106800 1.000000 0.065 H25B 2 -0.025800 0.607400 -0.022900 1.000000 0.065 H25C 2 0.048400 0.585300 -0.052000 1.000000 0.065 C38 1 0.154600 0.656800 0.334000 1.000000 0.052 0.047 = 0.035 -0.004 0.019 -0.0003 H38 2 0.200500 0.676200 0.373400 1.000000 0.052 C35 1 0.255900 0.829900 0.287800 1.000000 0.038 0.0326 = 0.059 -0.0056 0.0061 -0.004 H35A 2 0.233600 0.828900 0.329000 1.000000 0.067 H35B 2 0.261900 0.892700 0.274000 1.000000 0.067 H35C 2 0.307000 0.800300 0.300800 1.000000 0.067 C19 1 0.038900 0.636900 0.147200 1.000000 0.0218 0.074 = 0.041 -0.014 0.0026 0.0085 H19A 2 0.015100 0.647600 0.186700 1.000000 0.07 H19B 2 0.005100 0.597400 0.111600 1.000000 0.07 H19C 2 0.045700 0.694800 0.124900 1.000000 0.07 C22 1 0.157600 0.915600 -0.149700 1.000000 0.034 0.045 = 0.053 0.0147 0.0149 0.0079 H22A 2 0.206900 0.882100 -0.136800 1.000000 0.065 H22B 2 0.168100 0.980400 -0.141800 1.000000 0.065 H22C 2 0.131200 0.905000 -0.200200 1.000000 0.065 C30 1 0.820900 0.237900 0.341800 1.000000 0.0345 0.043 = 0.047 0.0253 0.0166 0.0136 H30 2 0.812200 0.248700 0.289300 1.000000 0.049 C32 1 0.784500 0.176500 0.505900 1.000000 0.056 0.056 = 0.0297 0.0018 0.006 0 H32A 2 0.834600 0.201200 0.502800 1.000000 0.072 H32B 2 0.792500 0.139200 0.549100 1.000000 0.072 H32C 2 0.748800 0.226200 0.508200 1.000000 0.072 C33 1 0.677300 0.070300 0.449200 1.000000 0.0315 0.048 = 0.063 0.017 0.0183 0.0013

- 218 - H33A 2 0.638200 0.115100 0.453500 1.000000 0.07 H33B 2 0.691200 0.032900 0.492400 1.000000 0.07 H33C 2 0.655900 0.031900 0.407400 1.000000 0.07 C41 1 0.201300 0.779300 0.224430 1.000000 0.0251 0.0278 = 0.045 0.0053 0.0017 0.002 H41 2 0.149400 0.809900 0.213800 1.000000 0.041 C43 1 0.139100 0.913800 -0.025500 1.000000 0.045 0.038 = 0.046 -0.0054 0.0102 0.0023 H43A 2 0.103300 0.896500 0.002900 1.000000 0.065 H43B 2 0.145700 0.979600 -0.024000 1.000000 0.065 H43C 2 0.189700 0.884700 -0.005700 1.000000 0.065 C47 1 0.729800 0.018500 0.274900 1.000000 0.075 0.036 = 0.037 -0.0044 0.003 0.003 H47A 2 0.781900 0.035100 0.271200 1.000000 0.078 H47B 2 0.703500 -0.017900 0.233200 1.000000 0.078 H47C 2 0.734400 -0.016800 0.318700 1.000000 0.078 C48 1 0.682200 0.105000 0.277400 1.000000 0.08 0.04 = 0.046 -0.0077 -0.029 0.016 H48 2 0.635400 0.082100 0.291400 1.000000 0.077 C45 1 0.837100 0.330100 0.378100 1.000000 0.035 0.031 = 0.111 0.026 0.018 0.0023 H45A 2 0.792000 0.369700 0.360300 1.000000 0.089 H45B 2 0.883000 0.357100 0.367300 1.000000 0.089 H45C 2 0.846900 0.322700 0.430000 1.000000 0.089 C42 1 0.231100 0.788700 0.158700 1.000000 0.064 0.049 = 0.046 0.016 0.004 -0.018 H42A 2 0.278400 0.752300 0.164600 1.000000 0.083 H42B 2 0.243100 0.852400 0.152200 1.000000 0.083 H42C 2 0.191200 0.767600 0.116600 1.000000 0.083 C40 1 0.088000 0.723800 0.333800 1.000000 0.038 0.082 = 0.051 -0.021 0.0217 0.001 H40A 2 0.104200 0.785200 0.325300 1.000000 0.083 H40B 2 0.075700 0.721500 0.380200 1.000000 0.083 H40C 2 0.041700 0.707100 0.295800 1.000000 0.083 C44 1 0.049900 0.620600 -0.221100 1.000000 0.076 0.063 = 0.041 -0.011 -0.001 0.033 H44A 2 0.101900 0.595300 -0.200400 1.000000 0.094 H44B 2 0.034500 0.609900 -0.272900 1.000000 0.094 H44C 2 0.012500 0.591400 -0.199200 1.000000 0.094 C49 1 0.649300 0.149300 0.209800 1.000000 0.119 0.115 = 0.056 -0.031 -0.024 0.065 H49A 2 0.616500 0.199900 0.216900 1.000000 0.159 H49B 2 0.617700 0.106000 0.176000 1.000000 0.159 H49C 2 0.691400 0.172200 0.190600 1.000000 0.159 C39 1 0.132800 0.562400 0.352700 1.000000 0.178 0.062 = 0.073 0.015 0.086 -0.007 H39A 2 0.089300 0.539800 0.314200 1.000000 0.142 H39B 2 0.117200 0.564500 0.397600 1.000000 0.142 H39C 2 0.177700 0.522100 0.358300 1.000000 0.142 Cl1 5 0.121970 0.334780 0.430780 1.000000 0.1462 0.054 = 0.0499 -0.0041 0.0389 -0.0013 Cl3 5 0.024100 0.311150 0.525460 1.000000 0.0505 0.0702 = 0.1279 0.0212 0.0277 0.0062 Cl2 5 0.120940 0.470110 0.536530 1.000000 0.1501 0.0386 =

- 219 - 0.0584 -0.0017 0.0378 -0.0039 C20 1 0.111300 0.354600 0.515100 1.000000 0.069 0.042 = 0.051 -0.0008 0.014 0.002 H20 2 0.154500 0.322200 0.549800 1.000000 0.065 END

Compound 287:

Si

Si Si

N N

N N

Si Si

Si

TITL p21c in P2(1)/c CELL 0.71073 8.6899 22.2297 27.9903 90.000 98.732 90.000 ZERR 2.00 0.0024 0.0075 0.0081 0.000 0.016 0.000 LATT 1 SYMM -X, 0.5+Y, 0.5-Z SFAC C H N SI UNIT 224 340 8 12 TEMP -173.180

L.S. 4 BOND FMAP 2 PLAN 20 shel 999 0.92 ACTA

SADI Si3 c311 si3 c611 si3 c321 si3 c621 Si1 c121 si1 c421 = SI1 C111 SI1 C411

EADP c111 c411 EADP c112 c412 EADP c113 c413 EADP c114 c414 EADP c121 c421 EADP c122 c422 EADP c123 c423 EADP c124 c424 EADP c311 c611 EADP c312 c612 EADP c313 c613

- 220 - EADP c314 c614 EADP c321 c621 EADP c322 c622 EADP c323 c623 EADP c324 c624

WGHT 0.116800 FVAR 0.08928 0.64691 0.96328 0.71588 0.95711 SI1 4 0.334256 0.501651 0.259185 11.00000 0.01446 0.02725 = 0.04942 -0.00535 0.00871 0.00084 SI2 4 -0.458868 0.733035 0.645757 11.00000 0.01604 0.02663 = 0.04118 -0.00574 0.00662 0.00288 SI3 4 -0.421639 0.810767 0.457589 11.00000 0.02064 0.02983 = 0.04733 -0.00146 0.00899 0.00089 N1 3 -0.090390 0.651068 0.432712 11.00000 0.00924 0.01214 = 0.03390 -0.00003 -0.00123 0.00005 N2 3 0.079165 0.573556 0.380755 11.00000 0.00765 0.01940 = 0.03109 -0.00484 0.00442 -0.00210 C1 1 -0.275223 0.788331 0.420521 11.00000 0.02857 0.02687 = 0.06494 -0.00784 0.01256 0.00213 C2 1 -0.357833 0.677382 0.612513 11.00000 0.02086 0.02651 = 0.03520 0.00271 0.00437 -0.00338 C3 1 0.232778 0.569245 0.275891 11.00000 0.01614 0.02916 = 0.04110 -0.00018 0.00177 -0.00208 C4 1 0.078401 0.648675 0.319358 11.00000 0.01210 0.02528 = 0.03109 -0.00647 0.00307 -0.00193 C5 1 0.036653 0.705372 0.303604 11.00000 0.02347 0.02140 = 0.03356 -0.00145 0.00682 -0.00065 AFIX 43 H5 2 0.066516 0.719420 0.274295 11.00000 -1.20000 AFIX 0 C6 1 -0.093836 0.726663 0.372686 11.00000 0.01841 0.01782 = 0.03900 0.00717 0.00722 0.00002 C7 1 0.165539 0.607526 0.294167 11.00000 0.01810 0.02768 = 0.02767 0.01556 -0.00288 -0.00606 C8 1 0.034596 0.629288 0.364744 11.00000 0.01409 0.01830 = 0.02139 0.00654 -0.00107 -0.00180 C9 1 -0.049660 0.743521 0.329792 11.00000 0.02446 0.01884 = 0.03488 0.00961 0.00007 0.00323 AFIX 43

- 221 - H9 2 -0.078147 0.782309 0.317199 11.00000 -1.20000 AFIX 0 C10 1 -0.212475 0.598369 0.565496 11.00000 0.00665 0.02017 = 0.03249 0.00252 0.00659 -0.00212 C11 1 -0.167497 0.541224 0.583216 11.00000 0.01528 0.02545 = 0.02520 0.00274 -0.00066 -0.00356 AFIX 43 H11 2 -0.194882 0.528729 0.613276 11.00000 -1.20000 AFIX 0 C12 1 -0.049906 0.668187 0.390130 11.00000 0.01080 0.02210 = 0.02801 0.00456 0.00723 -0.00371 C13 1 -0.084511 0.502477 0.558303 11.00000 0.00953 0.01602 = 0.02831 0.00063 0.00450 0.00216 C14 1 -0.292417 0.640169 0.591856 11.00000 0.01473 0.02371 = 0.04084 0.00603 0.00855 0.00151 C15 1 -0.171749 0.615215 0.520969 11.00000 0.00474 0.01829 = 0.03985 0.00672 -0.00628 -0.00058 AFIX 43 H15 2 -0.201981 0.653661 0.507985 11.00000 -1.20000 AFIX 0 C16 1 -0.047892 0.596558 0.449127 11.00000 0.00566 0.02444 = 0.03286 -0.00485 0.00466 0.00118 C17 1 -0.190399 0.762942 0.398215 11.00000 0.02113 0.02229 = 0.04021 0.00879 0.00525 0.00216 C18 1 0.038624 0.557780 0.422865 11.00000 0.00518 0.02205 = 0.03021 -0.00508 -0.00035 -0.00660 C19 1 -0.042933 0.519837 0.512913 11.00000 0.00760 0.01879 = 0.02710 -0.00572 0.00051 -0.00013 C20 1 -0.089134 0.577449 0.495645 11.00000 0.00714 0.02377 = 0.02397 -0.00315 0.00414 0.00609 PART 1 SAME C231 > c234 C111 1 0.446775 0.517526 0.208927 51.00000 0.01532 0.02744 = 0.05325 -0.00587 0.00601 -0.00461 AFIX 23 H11A 2 0.499322 0.556806 0.215622 51.00000 -1.20000 H11B 2 0.529383 0.486654 0.210129 51.00000 -1.20000 AFIX 0 C112 1 0.359361 0.519376 0.157150 51.00000 0.02822 0.03703 = 0.04714 -0.00467 0.01217 -0.00670 AFIX 13

- 222 - H112 2 0.306413 0.479687 0.150314 51.00000 -1.20000 AFIX 0 C113 1 0.471213 0.527984 0.120824 51.00000 0.05218 0.04295 = 0.06052 -0.01108 0.03087 -0.00953 AFIX 33 H11C 2 0.412825 0.527650 0.087993 51.00000 -1.50000 H11D 2 0.547676 0.495264 0.124265 51.00000 -1.50000 H11E 2 0.525177 0.566583 0.126817 51.00000 -1.50000 AFIX 0 C114 1 0.233964 0.568177 0.150989 51.00000 0.04548 0.06791 = 0.05582 0.00670 0.01773 0.01532 AFIX 33 H11F 2 0.177260 0.566885 0.117952 51.00000 -1.50000 H11G 2 0.282949 0.607707 0.157080 51.00000 -1.50000 H11H 2 0.161297 0.561224 0.173986 51.00000 -1.50000 AFIX 0 PART 2 SAME C231 > c234 C411 1 0.393707 0.509012 0.197866 -51.00000 0.01532 0.02744 = 0.05325 -0.00587 0.00601 -0.00461 AFIX 23 H41A 2 0.497321 0.528521 0.202650 -51.00000 -1.20000 H41B 2 0.409206 0.467641 0.186396 -51.00000 -1.20000 AFIX 0 C412 1 0.294651 0.542169 0.155904 -51.00000 0.02822 0.03703 = 0.04714 -0.00467 0.01217 -0.00670 AFIX 13 H412 2 0.205990 0.515185 0.142954 -51.00000 -1.20000 AFIX 0 C413 1 0.384023 0.556086 0.114593 -51.00000 0.05218 0.04295 = 0.06052 -0.01108 0.03087 -0.00953 AFIX 33 H41C 2 0.423420 0.518577 0.102583 -51.00000 -1.50000 H41D 2 0.471619 0.582746 0.126139 -51.00000 -1.50000 H41E 2 0.314673 0.575913 0.088410 -51.00000 -1.50000 AFIX 0 C414 1 0.225587 0.599790 0.173459 -51.00000 0.04548 0.06791 = 0.05582 0.00670 0.01773 0.01532 AFIX 33 H41F 2 0.168909 0.590310 0.200227 -51.00000 -1.50000 H41G 2 0.153970 0.617783 0.146874 -51.00000 -1.50000 H41H 2 0.309561 0.628255 0.184542 -51.00000 -1.50000 AFIX 0 PART 1 SAME C231 > c234 C121 1 0.189366 0.439352 0.241701 41.00000 0.01558 0.02754 = 0.04558 0.00002 0.00943 0.00895

- 223 - AFIX 23 H12A 2 0.119357 0.452627 0.212356 41.00000 -1.20000 H12B 2 0.247994 0.404198 0.232303 41.00000 -1.20000 AFIX 0 C122 1 0.086086 0.417156 0.278105 41.00000 0.01915 0.02155 = 0.03502 -0.00019 0.00009 -0.00374 AFIX 13 H122 2 0.153861 0.411561 0.310007 41.00000 -1.20000 AFIX 0 C123 1 -0.042038 0.461966 0.285141 41.00000 0.01850 0.02934 = 0.07445 -0.00531 0.01587 0.00356 AFIX 33 H12C 2 0.004040 0.501743 0.292599 41.00000 -1.50000 H12D 2 -0.094521 0.448599 0.311887 41.00000 -1.50000 H12E 2 -0.117764 0.464280 0.255447 41.00000 -1.50000 AFIX 0 C124 1 0.011788 0.356916 0.262934 41.00000 0.02244 0.03237 = 0.06335 -0.00294 0.01120 -0.00150 AFIX 33 H12F 2 -0.047734 0.342713 0.287787 41.00000 -1.50000 H12G 2 0.093243 0.327630 0.259021 41.00000 -1.50000 H12H 2 -0.058082 0.361539 0.232206 41.00000 -1.50000 AFIX 0 PART 2 SAME C231 > c234 C421 1 0.187178 0.441843 0.237833 -41.00000 0.01558 0.02754 = 0.04558 0.00002 0.00943 0.00895 AFIX 23 H42A 2 0.134020 0.453539 0.205351 -41.00000 -1.20000 H42B 2 0.244371 0.404062 0.233999 -41.00000 -1.20000 AFIX 0 C422 1 0.061293 0.428108 0.269407 -41.00000 0.01915 0.02155 = 0.03502 -0.00019 0.00009 -0.00374 AFIX 13 H422 2 0.107340 0.436981 0.303626 -41.00000 -1.20000 AFIX 0 C423 1 -0.081639 0.467960 0.257160 -41.00000 0.01850 0.02934 = 0.07445 -0.00531 0.01587 0.00356 AFIX 33 H42C 2 -0.161166 0.455692 0.276550 -41.00000 -1.50000 H42D 2 -0.123125 0.463874 0.222751 -41.00000 -1.50000 H42E 2 -0.052671 0.509978 0.264293 -41.00000 -1.50000 AFIX 0 C424 1 0.016142 0.361992 0.267064 -41.00000 0.02244 0.03237 = 0.06335 -0.00294 0.01120 -0.00150 AFIX 33 H42F 2 -0.065780 0.355024 0.286936 -41.00000 -1.50000

- 224 - H42G 2 0.107373 0.337452 0.279256 -41.00000 -1.50000 H42H 2 -0.022275 0.350875 0.233490 -41.00000 -1.50000 AFIX 0 PART 0 SAME C231 > c234 C131 1 0.468377 0.478496 0.314545 11.00000 0.01405 0.02916 = 0.04939 -0.01332 0.00842 0.00281 AFIX 23 H13A 2 0.415832 0.446693 0.330858 11.00000 -1.20000 H13B 2 0.561617 0.460071 0.304167 11.00000 -1.20000 AFIX 0 C132 1 0.524043 0.527297 0.352207 11.00000 0.01445 0.03882 = 0.04526 0.00076 -0.00028 0.00158 AFIX 13 H132 2 0.429260 0.547428 0.360963 11.00000 -1.20000 AFIX 0 C133 1 0.622106 0.575833 0.332297 11.00000 0.02181 0.03261 = 0.07151 -0.00290 0.01032 -0.00675 AFIX 33 H13C 2 0.563374 0.592964 0.302772 11.00000 -1.50000 H13D 2 0.718836 0.557937 0.324907 11.00000 -1.50000 H13E 2 0.646864 0.607658 0.356470 11.00000 -1.50000 AFIX 0 C134 1 0.613103 0.500217 0.398495 11.00000 0.02708 0.02688 = 0.05291 -0.00904 -0.00823 -0.00048 AFIX 33 H13F 2 0.548550 0.469616 0.411035 11.00000 -1.50000 H13G 2 0.638383 0.531992 0.422683 11.00000 -1.50000 H13H 2 0.709486 0.481678 0.391450 11.00000 -1.50000 AFIX 0 SAME C231 > c234 C211 1 -0.352148 0.805913 0.652198 11.00000 0.01251 0.02474 = 0.03154 -0.00364 0.00846 0.00436 AFIX 23 H21A 2 -0.335751 0.818366 0.619387 11.00000 -1.20000 H21B 2 -0.422901 0.835943 0.663382 11.00000 -1.20000 AFIX 0 C212 1 -0.195527 0.811669 0.684973 11.00000 0.01691 0.02693 = 0.04727 -0.00320 0.01195 0.00331 AFIX 13 H212 2 -0.201158 0.789125 0.715575 11.00000 -1.20000 AFIX 0 C213 1 -0.064476 0.785437 0.661398 11.00000 0.02526 0.04409 = 0.06397 -0.00947 0.00568 0.00524 AFIX 33 H21C 2 0.033434 0.788148 0.683860 11.00000 -1.50000 H21D 2 -0.055066 0.808037 0.631919 11.00000 -1.50000

- 225 - H21E 2 -0.087121 0.743176 0.653184 11.00000 -1.50000 AFIX 0 C214 1 -0.160901 0.878081 0.697607 11.00000 0.02017 0.04343 = 0.04813 -0.00807 -0.00655 -0.00758 AFIX 33 H21F 2 -0.244199 0.894612 0.713683 11.00000 -1.50000 H21G 2 -0.155010 0.900791 0.667929 11.00000 -1.50000 H21H 2 -0.061418 0.881182 0.719261 11.00000 -1.50000 AFIX 0 SAME C231 > c234 C221 1 -0.472094 0.695842 0.704306 11.00000 0.01724 0.02743 = 0.03018 -0.01034 0.00245 -0.00019 AFIX 23 H22A 2 -0.502716 0.653489 0.697271 11.00000 -1.20000 H22B 2 -0.365983 0.695145 0.723108 11.00000 -1.20000 AFIX 0 C222 1 -0.582737 0.721606 0.737645 11.00000 0.01785 0.03795 = 0.03923 -0.00020 0.00904 -0.00194 AFIX 13 H222 2 -0.689206 0.724180 0.718316 11.00000 -1.20000 AFIX 0 C223 1 -0.536501 0.784458 0.755658 11.00000 0.06169 0.03219 = 0.05695 -0.01384 0.03472 0.00161 AFIX 33 H22C 2 -0.534038 0.811259 0.727985 11.00000 -1.50000 H22D 2 -0.433130 0.783173 0.775315 11.00000 -1.50000 H22E 2 -0.612499 0.799502 0.775298 11.00000 -1.50000 AFIX 0 C224 1 -0.591206 0.678752 0.779397 11.00000 0.03199 0.04543 = 0.04080 0.00346 0.01598 -0.00086 AFIX 33 H22F 2 -0.621872 0.638716 0.766715 11.00000 -1.50000 H22G 2 -0.668244 0.693500 0.798783 11.00000 -1.50000 H22H 2 -0.488969 0.676377 0.799644 11.00000 -1.50000 AFIX 0 C231 1 -0.651331 0.752970 0.608504 11.00000 0.02343 0.03006 = 0.03874 -0.00334 0.00649 -0.00674 AFIX 23 H23A 2 -0.718711 0.769884 0.630686 11.00000 -1.20000 H23B 2 -0.632077 0.785582 0.586061 11.00000 -1.20000 AFIX 0 C232 1 -0.744229 0.703685 0.578548 11.00000 0.01696 0.03460 = 0.03349 -0.01028 0.00608 -0.00081 AFIX 13 H232 2 -0.673500 0.684316 0.558034 11.00000 -1.20000 AFIX 0

- 226 - C233 1 -0.802104 0.655066 0.609084 11.00000 0.02479 0.03690 = 0.06360 0.00236 0.00151 -0.00224 AFIX 33 H23C 2 -0.857366 0.624305 0.588002 11.00000 -1.50000 H23D 2 -0.873048 0.672704 0.629313 11.00000 -1.50000 H23E 2 -0.713442 0.636650 0.629746 11.00000 -1.50000 AFIX 0 C234 1 -0.880777 0.731778 0.544530 11.00000 0.02336 0.04149 = 0.04243 -0.01107 0.00705 -0.00796 AFIX 33 H23F 2 -0.841217 0.762682 0.524576 11.00000 -1.50000 H23G 2 -0.953872 0.750091 0.563695 11.00000 -1.50000 H23H 2 -0.934321 0.700474 0.523627 11.00000 -1.50000 AFIX 0 PART 1 SAME C231 > c234 C311 1 -0.319825 0.851485 0.511061 21.00000 0.01851 0.03819 = 0.04324 -0.00684 -0.00368 -0.00751 AFIX 23 H31A 2 -0.388482 0.850285 0.536219 21.00000 -1.20000 H31B 2 -0.225546 0.827969 0.523580 21.00000 -1.20000 AFIX 0 C312 1 -0.268604 0.917135 0.506674 21.00000 0.02689 0.02734 = 0.05158 -0.00009 0.00853 -0.00631 AFIX 13 H312 2 -0.365074 0.942242 0.500553 21.00000 -1.20000 AFIX 0 C313 1 -0.174345 0.938898 0.553667 21.00000 0.04634 0.03660 = 0.04891 -0.00107 -0.01135 -0.00875 AFIX 33 H31C 2 -0.233604 0.932126 0.580306 21.00000 -1.50000 H31D 2 -0.152662 0.981951 0.551164 21.00000 -1.50000 H31E 2 -0.075965 0.916653 0.559845 21.00000 -1.50000 AFIX 0 C314 1 -0.179028 0.927291 0.464637 21.00000 0.03548 0.03780 = 0.06770 0.00521 0.01523 -0.00044 AFIX 33 H31F 2 -0.242168 0.913768 0.434548 21.00000 -1.50000 H31G 2 -0.081527 0.904421 0.470117 21.00000 -1.50000 H31H 2 -0.155749 0.970218 0.462196 21.00000 -1.50000 AFIX 0 PART 2 SAME C231 > c234 C611 1 -0.323094 0.851619 0.511844 -21.00000 0.01851 0.03819 = 0.04324 -0.00684 -0.00368 -0.00751 AFIX 23 H61A 2 -0.400882 0.878278 0.523439 -21.00000 -1.20000

- 227 - H61B 2 -0.291210 0.821569 0.537548 -21.00000 -1.20000 AFIX 0 C612 1 -0.179307 0.890019 0.506163 -21.00000 0.02689 0.02734 = 0.05158 -0.00009 0.00853 -0.00631 AFIX 13 H612 2 -0.101579 0.863735 0.493342 -21.00000 -1.20000 AFIX 0 C613 1 -0.104523 0.915209 0.554804 -21.00000 0.04634 0.03660 = 0.04891 -0.00107 -0.01135 -0.00875 AFIX 33 H61C 2 -0.075968 0.882017 0.577461 -21.00000 -1.50000 H61D 2 -0.178523 0.941785 0.567587 -21.00000 -1.50000 H61E 2 -0.010972 0.938030 0.550654 -21.00000 -1.50000 AFIX 0 C614 1 -0.224693 0.940908 0.470055 -21.00000 0.03548 0.03780 = 0.06770 0.00521 0.01523 -0.00044 AFIX 33 H61F 2 -0.274713 0.923988 0.439242 -21.00000 -1.50000 H61G 2 -0.131199 0.963186 0.464990 -21.00000 -1.50000 H61H 2 -0.297271 0.968183 0.482778 -21.00000 -1.50000 AFIX 0 PART 1 SAME C231 > c234 C321 1 -0.570385 0.857221 0.417937 31.00000 0.02791 0.03073 = 0.03865 -0.00188 0.00613 -0.00090 AFIX 23 H32A 2 -0.529570 0.898712 0.416979 31.00000 -1.20000 H32B 2 -0.580808 0.840930 0.384683 31.00000 -1.20000 AFIX 0 C322 1 -0.733857 0.860603 0.432502 31.00000 0.02414 0.05052 = 0.06457 -0.00320 0.00673 0.01539 AFIX 13 H322 2 -0.772487 0.818609 0.435534 31.00000 -1.20000 AFIX 0 C323 1 -0.727190 0.891530 0.481385 31.00000 0.03208 0.07100 = 0.06337 -0.02161 0.01209 0.02160 AFIX 33 H32C 2 -0.654158 0.870023 0.505609 31.00000 -1.50000 H32D 2 -0.830999 0.891282 0.491021 31.00000 -1.50000 H32E 2 -0.692129 0.933165 0.478951 31.00000 -1.50000 AFIX 0 C324 1 -0.845978 0.892778 0.393711 31.00000 0.02716 0.05202 = 0.06993 -0.00933 -0.00285 0.00287 AFIX 33 H32F 2 -0.849457 0.871591 0.362862 31.00000 -1.50000 H32G 2 -0.810393 0.934171 0.390297 31.00000 -1.50000 H32H 2 -0.950246 0.893281 0.403007 31.00000 -1.50000

- 228 - AFIX 0 PART 2 SAME C231 > c234 C621 1 -0.614134 0.844614 0.432297 -31.00000 0.02791 0.03073 = 0.03865 -0.00188 0.00613 -0.00090 AFIX 23 H62A 2 -0.575268 0.867913 0.406446 -31.00000 -1.20000 H62B 2 -0.657526 0.807829 0.415412 -31.00000 -1.20000 AFIX 0 C622 1 -0.770317 0.877971 0.429171 -31.00000 0.02414 0.05052 = 0.06457 -0.00320 0.00673 0.01539 AFIX 13 H622 2 -0.855034 0.847131 0.426014 -31.00000 -1.20000 AFIX 0 C623 1 -0.780081 0.914513 0.474588 -31.00000 0.03208 0.07100 = 0.06337 -0.02161 0.01209 0.02160 AFIX 33 H62C 2 -0.758654 0.888352 0.503002 -31.00000 -1.50000 H62D 2 -0.884699 0.931663 0.472776 -31.00000 -1.50000 H62E 2 -0.703179 0.947056 0.477235 -31.00000 -1.50000 AFIX 0 C624 1 -0.798490 0.918336 0.384552 -31.00000 0.02716 0.05202 = 0.06993 -0.00933 -0.00285 0.00287 AFIX 33 H62F 2 -0.780199 0.895353 0.356069 -31.00000 -1.50000 H62G 2 -0.727135 0.952707 0.389049 -31.00000 -1.50000 H62H 2 -0.906214 0.932852 0.379906 -31.00000 -1.50000 AFIX 0 PART 0 SAME C231 > c234 C331 1 -0.502945 0.739506 0.478757 11.00000 0.01859 0.03115 = 0.02703 -0.00356 0.00809 0.00140 AFIX 23 H33A 2 -0.437191 0.727722 0.509357 11.00000 -1.20000 H33B 2 -0.607866 0.748585 0.486554 11.00000 -1.20000 AFIX 0 C332 1 -0.517841 0.684380 0.445123 11.00000 0.01229 0.03356 = 0.03815 -0.00813 0.00401 0.00227 AFIX 13 H332 2 -0.410062 0.672220 0.440753 11.00000 -1.20000 AFIX 0 C333 1 -0.605716 0.698950 0.395498 11.00000 0.02202 0.02524 = 0.04301 -0.00262 -0.00095 0.00280 AFIX 33 H33C 2 -0.610589 0.663043 0.375010 11.00000 -1.50000 H33D 2 -0.551848 0.731251 0.380874 11.00000 -1.50000 H33E 2 -0.711551 0.711982 0.398508 11.00000 -1.50000

- 229 - AFIX 0 C334 1 -0.591692 0.630622 0.467406 11.00000 0.01317 0.03264 = 0.05430 -0.01234 0.00429 -0.00425 AFIX 33 H33F 2 -0.532601 0.621773 0.499306 11.00000 -1.50000 H33G 2 -0.590126 0.595429 0.446399 11.00000 -1.50000 H33H 2 -0.699557 0.640302 0.470758 11.00000 -1.50000

HKLF 4

REM p21c in P2(1)/c REM R1 = 0.0803 for 3584 Fo > 4sig(Fo) and 0.1797 for all 7167 data REM 602 parameters refined using 496 restraints

END

WGHT 0.1189 0.0000 REM Highest difference peak 0.401, deepest hole -0.593, 1-sigma level 0.099 Q1 1 -0.2842 0.8182 0.4596 11.00000 0.05 0.40 Q2 1 0.5050 0.5000 0.1799 11.00000 0.05 0.37 Q3 1 0.4239 0.5758 0.0824 11.00000 0.05 0.37 Q4 1 -0.3559 0.7376 0.6006 11.00000 0.05 0.35 Q5 1 -0.5267 0.8155 0.4321 11.00000 0.05 0.33 Q6 1 -0.3337 0.7780 0.5200 11.00000 0.05 0.32 Q7 1 -0.6827 0.7226 0.6395 11.00000 0.05 0.32 Q8 1 -0.5623 0.7470 0.6103 11.00000 0.05 0.32 Q9 1 -0.3808 0.8424 0.5966 11.00000 0.05 0.31 Q10 1 -0.4016 0.7679 0.5565 11.00000 0.05 0.31 Q11 1 -0.3865 0.9571 0.4734 11.00000 0.05 0.31 Q12 1 -0.5373 0.7605 0.5296 11.00000 0.05 0.30 Q13 1 -0.6904 0.7648 0.6197 11.00000 0.05 0.30 Q14 1 -0.2681 0.7587 0.5680 11.00000 0.05 0.30 Q15 1 -0.4127 0.7773 0.5116 11.00000 0.05 0.30 Q16 1 -0.4613 0.7063 0.7758 11.00000 0.05 0.30 Q17 1 0.0547 0.5194 0.1688 11.00000 0.05 0.30 Q18 1 -0.0659 0.8564 0.5440 11.00000 0.05 0.30 Q19 1 -0.6442 0.9233 0.4613 11.00000 0.05 0.30 Q20 1 -0.4324 0.8371 0.5087 11.00000 0.05 0.29

- 230 - Compound 291:

Si

Si Si

N N

N N

Si Si

Si

TITL gast_spm369_0m CELL 0.71073 17.4521 19.5717 20.2714 90 101.544 90 ZERR 4 0.0004 0.0005 0.0005 0.00 0.0016 0.00 LATT 1 SYMM 1/2-x,1/2+y,-z SFAC C H N Si UNIT 296 196 8 12 FVAR 1.00 Si1 4 0.861140 0.735920 0.407710 1.000000 0.0201 0.0272 = 0.0334 -0.0072 0.0012 -0.0044 Si2 4 0.687690 0.844700 0.672920 1.000000 0.0276 0.0204 = 0.0343 -0.0116 -0.0017 -0.0059 Si3 4 0.354360 0.421230 0.074810 1.000000 0.0293 0.048 = 0.0197 -0.001 -0.0059 -0.0057 N1 3 0.510000 0.499380 0.310780 1.000000 0.0183 0.0187 = 0.0175 -0.0006 -0.0012 -0.0004 N2 3 0.613370 0.596750 0.382920 1.000000 0.0175 0.0195 = 0.0167 -0.0003 -0.0016 -0.0007 C3 1 0.553360 0.540680 0.279220 1.000000 0.0183 0.0197 = 0.0198 0.0002 -0.0008 0.0003 C4 1 0.566290 0.559170 0.412490 1.000000 0.0139 0.013 = 0.0194 0.0012 -0.004 0.0026 C5 1 0.609710 0.585890 0.316630 1.000000 0.0208 0.0168 = 0.0203 0.0018 -0.0005 0.0007 C6 1 0.520470 0.528790 0.517110 1.000000 0.015 0.013 = 0.0165 -0.0009 -0.0043 0.0014 C7 1 0.519660 0.506250 0.377240 1.000000 0.0154 0.0153 = 0.0195 -0.0005 -0.002 0.0017 C8 1 0.598840 0.631010 0.515120 1.000000 0.0158 0.0167 = 0.0219 -0.0003 -0.0028 -0.0027 H8 2 0.626900 0.660900 0.491600 1.000000 0.023 C9 1 0.594770 0.645810 0.581570 1.000000 0.018 0.0153 = 0.0205 -0.003 -0.002 0.0004 C10 1 0.562940 0.573650 0.482470 1.000000 0.0176 0.0145 = 0.0185 -0.0023 -0.0016 0.0008

- 231 - C11 1 0.520640 0.541520 0.585760 1.000000 0.0153 0.0156 = 0.0175 0.0003 -0.0028 0.001 C12 1 0.724780 0.661230 0.321310 1.000000 0.0262 0.0295 = 0.0218 0.0001 0.0074 -0.0023 C13 1 0.557570 0.599500 0.617250 1.000000 0.0203 0.0165 = 0.0175 -0.0045 -0.0037 -0.0001 H13 2 0.557400 0.607600 0.663400 1.000000 0.023 C14 1 0.627750 0.708430 0.612460 1.000000 0.0187 0.0251 = 0.0188 0.0015 -0.0005 0.0022 C15 1 0.654830 0.761720 0.635910 1.000000 0.0212 0.0215 = 0.0286 -0.0088 0.0002 -0.0034 C16 1 0.662760 0.621640 0.283080 1.000000 0.0213 0.0284 = 0.022 0.0013 -0.0007 -0.0059 C17 1 0.542640 0.538670 0.207520 1.000000 0.0258 0.0265 = 0.0198 -0.001 -0.0033 -0.0054 C18 1 0.791940 0.841630 0.715530 1.000000 0.0315 0.0234 = 0.0394 -0.0098 -0.0003 -0.0051 C19 1 0.778020 0.692710 0.354300 1.000000 0.0259 0.0278 = 0.0298 -0.0021 0.0063 -0.0063 C20 1 0.950730 0.707600 0.378690 1.000000 0.0266 0.027 = 0.0373 -0.0048 0.0031 -0.0031 C21 1 0.479610 0.500500 0.168220 1.000000 0.0282 0.0336 = 0.0151 0.0031 -0.0014 -0.002 C22 1 0.866160 0.706000 0.495820 1.000000 0.023 0.0356 = 0.0347 -0.0076 0.0021 0.0001 C23 1 0.427560 0.471360 0.132290 1.000000 0.0316 0.0417 = 0.0246 0.0005 -0.005 -0.0013 C24 1 0.654130 0.614470 0.214570 1.000000 0.0343 0.0523 = 0.0236 -0.0013 0.0069 -0.0148 H24 2 0.690000 0.636700 0.192100 1.000000 0.044 C25 1 0.593510 0.575070 0.177180 1.000000 0.0375 0.0511 = 0.0175 -0.0016 0.0035 -0.0133 H25 2 0.587400 0.573500 0.129600 1.000000 0.043 C26 1 0.286290 0.381020 0.123700 1.000000 0.0314 0.0414 = 0.0324 0.0028 -0.0013 -0.0007 C27 1 0.849640 0.817450 0.681490 1.000000 0.0346 0.035 = 0.0378 -0.0011 0.0019 -0.007 H27 2 0.834700 0.802100 0.636300 1.000000 0.044 C28 1 0.621790 0.864590 0.732830 1.000000 0.0312 0.0349 = 0.0334 -0.0157 -0.004 -0.0088 C29 1 0.671110 0.910020 0.604920 1.000000 0.0304 0.0225 = 0.0423 -0.0077 0.0033 -0.0033 C30 1 0.299440 0.384590 0.193740 1.000000 0.0318 0.047 = 0.0317 0.0055 -0.004 0.0015 H30 2 0.343800 0.408600 0.217400 1.000000 0.046 C31 1 0.927500 0.815840 0.713050 1.000000 0.0374 0.0411 = 0.059 -0.0015 0.0064 -0.0096 H31 2 0.965700 0.798700 0.689800 1.000000 0.056 C32 1 0.801240 0.679540 0.517690 1.000000 0.0205 0.0464 = 0.036 -0.0017 0 0.0045 H32 2 0.751700 0.679600 0.487900 1.000000 0.042 C33 1 0.302470 0.479540 0.007970 1.000000 0.0309 0.054 = 0.0273 0.0087 -0.0014 -0.0017 C34 1 1.016630 0.748460 0.386150 1.000000 0.0284 0.0318 =

- 232 - 0.044 -0.0048 0.0075 -0.0041 H34 2 1.014200 0.794000 0.401800 1.000000 0.042 C35 1 0.712740 0.971060 0.611960 1.000000 0.0372 0.0274 = 0.0459 -0.0066 -0.0041 -0.0049 H35 2 0.755300 0.976500 0.648900 1.000000 0.046 C36 1 0.844220 0.829670 0.400590 1.000000 0.0199 0.0307 = 0.0531 -0.0124 -0.0055 -0.0066 C37 1 0.949450 0.838810 0.777310 1.000000 0.0345 0.047 = 0.061 -0.0106 -0.0024 -0.0145 H37 2 1.003100 0.837700 0.798600 1.000000 0.059 C38 1 0.407540 0.353540 0.036950 1.000000 0.0452 0.054 = 0.021 -0.0057 -0.0049 -0.0036 C39 1 0.693560 1.024190 0.566320 1.000000 0.045 0.0253 = 0.064 -0.002 -0.0012 -0.0048 H39 2 0.722900 1.065400 0.572100 1.000000 0.056 C40 1 0.943320 0.679040 0.605840 1.000000 0.0317 0.066 = 0.0397 -0.005 -0.0049 0.0085 H40 2 0.992400 0.678800 0.636200 1.000000 0.057 C41 1 0.817070 0.864700 0.780610 1.000000 0.0392 0.051 = 0.0451 -0.0148 0.0013 -0.0085 H41 2 0.779700 0.881800 0.804700 1.000000 0.055 C42 1 0.807630 0.653290 0.581630 1.000000 0.0296 0.057 = 0.0394 0.0026 0.006 0.0056 H42 2 0.762700 0.635700 0.595500 1.000000 0.051 C43 1 0.895700 0.863540 0.811920 1.000000 0.046 0.067 = 0.046 -0.0179 -0.01 -0.015 H43 2 0.911800 0.879700 0.856700 1.000000 0.067 C44 1 0.599700 0.814220 0.773220 1.000000 0.054 0.0434 = 0.0445 -0.0186 0.0148 -0.0137 H44 2 0.621300 0.769700 0.773300 1.000000 0.056 C45 1 0.936830 0.706120 0.541860 1.000000 0.0242 0.053 = 0.0423 -0.0078 -0.0011 -0.0024 H45 2 0.981800 0.725200 0.529100 1.000000 0.049 C46 1 0.878520 0.652530 0.625190 1.000000 0.041 0.069 = 0.0344 0.001 0.0026 0.0109 H46 2 0.882800 0.633600 0.668900 1.000000 0.058 C47 1 0.611520 0.903390 0.548720 1.000000 0.044 0.047 = 0.053 0.0015 -0.007 -0.0222 H47 2 0.583900 0.861400 0.541200 1.000000 0.061 C48 1 0.184400 0.318700 0.196490 1.000000 0.044 0.055 = 0.064 0.0219 0.0168 0.0008 H48 2 0.150200 0.297600 0.221400 1.000000 0.064 C49 1 0.249080 0.353860 0.229210 1.000000 0.041 0.077 = 0.0365 0.0153 0.0084 0.0095 H49 2 0.259300 0.357100 0.276900 1.000000 0.062 C50 1 1.090650 0.659240 0.348760 1.000000 0.0333 0.06 = 0.08 -0.0089 0.0258 0.0062 H50 2 1.138300 0.642600 0.339000 1.000000 0.067 C51 1 1.086340 0.724640 0.371360 1.000000 0.0299 0.047 = 0.059 0.0005 0.0118 -0.0089 H51 2 1.130800 0.753700 0.376900 1.000000 0.054 C52 1 0.588980 0.929240 0.735050 1.000000 0.048 0.054 = 0.0385 -0.0133 0.0011 0.013 H52 2 0.603200 0.964500 0.707600 1.000000 0.058

- 233 - C53 1 0.850390 0.865300 0.343320 1.000000 0.045 0.0367 = 0.071 -0.0017 0.0023 -0.0048 H53 2 0.870300 0.843100 0.308600 1.000000 0.062 C54 1 0.591300 0.956100 0.503590 1.000000 0.046 0.061 = 0.064 0.0178 -0.0196 -0.0165 H54 2 0.549400 0.950500 0.466100 1.000000 0.073 C55 1 0.515500 0.892500 0.814660 1.000000 0.041 0.094 = 0.057 -0.036 0.0119 -0.008 H55 2 0.479200 0.901700 0.842700 1.000000 0.077 C56 1 0.546200 0.828300 0.813680 1.000000 0.061 0.076 = 0.05 -0.0191 0.0198 -0.03 H56 2 0.530800 0.793300 0.840700 1.000000 0.074 C57 1 0.295400 0.546700 0.018900 1.000000 0.08 0.079 = 0.044 0.0091 -0.017 0.007 H57 2 0.321000 0.565500 0.060700 1.000000 0.086 C58 1 0.631950 1.016930 0.512680 1.000000 0.0414 0.0382 = 0.068 0.0103 -0.003 -0.0005 H58 2 0.617400 1.053600 0.482000 1.000000 0.061 C59 1 1.025500 0.617070 0.340000 1.000000 0.052 0.041 = 0.108 -0.026 0.031 -0.0047 H59 2 1.028300 0.571800 0.323700 1.000000 0.078 C60 1 0.956660 0.640950 0.355090 1.000000 0.0336 0.038 = 0.088 -0.0185 0.0221 -0.0091 H60 2 0.912400 0.611600 0.349300 1.000000 0.062 C61 1 0.169500 0.314200 0.127260 1.000000 0.055 0.068 = 0.066 -0.0018 0.008 -0.0279 H61 2 0.125000 0.290000 0.104200 1.000000 0.076 C62 1 0.219830 0.345210 0.091500 1.000000 0.047 0.076 = 0.0372 -0.0007 -0.0001 -0.0224 H62 2 0.208900 0.342100 0.043800 1.000000 0.066 C63 1 0.827600 0.934000 0.335600 1.000000 0.047 0.041 = 0.119 0.014 -0.009 -0.0076 H63 2 0.831400 0.958100 0.295700 1.000000 0.087 C64 1 0.216000 0.565000 -0.089750 1.000000 0.058 0.1 = 0.045 0.031 0.0029 0.019 H64 2 0.186200 0.594100 -0.122800 1.000000 0.082 C65 1 0.472800 0.370500 0.011010 1.000000 0.057 0.075 = 0.045 -0.0056 0.0089 0.0044 H65 2 0.488800 0.416900 0.011900 1.000000 0.071 C66 1 0.430000 0.235300 0.009200 1.000000 0.133 0.076 = 0.1 -0.029 0.051 0.007 H66 2 0.415100 0.188600 0.009000 1.000000 0.119 C67 1 0.816210 0.864760 0.451000 1.000000 0.047 0.042 = 0.084 -0.0262 0.0167 -0.0026 H67 2 0.812200 0.841300 0.491200 1.000000 0.069 C68 1 0.794500 0.931700 0.444200 1.000000 0.06 0.048 = 0.137 -0.041 0.023 -0.006 H68 2 0.775800 0.954300 0.479300 1.000000 0.097 C69 1 0.266600 0.454000 -0.054730 1.000000 0.072 0.074 = 0.0341 0.005 -0.0099 0.003 H69 2 0.271800 0.407000 -0.064600 1.000000 0.075 C70 1 0.251100 0.590400 -0.030000 1.000000 0.106 0.069 = 0.076 0.017 -0.003 0.02 H70 2 0.246300 0.637600 -0.020500 1.000000 0.104

- 234 - C71 1 0.536600 0.943800 0.775710 1.000000 0.06 0.078 = 0.05 -0.016 0.0072 0.02 H71 2 0.515400 0.988400 0.776800 1.000000 0.076 C72 1 0.493600 0.254900 -0.017600 1.000000 0.108 0.098 = 0.062 -0.018 0.019 0.034 H72 2 0.522000 0.221600 -0.037100 1.000000 0.107 C73 1 0.799700 0.966000 0.386500 1.000000 0.033 0.028 = 0.174 -0.031 -0.001 0.0012 H73 2 0.783900 1.012500 0.381500 1.000000 0.098 C74 1 0.388600 0.283900 0.036200 1.000000 0.095 0.064 = 0.08 -0.021 0.036 -0.009 H74 2 0.345600 0.269900 0.055100 1.000000 0.092 C75 1 0.515400 0.321800 -0.016200 1.000000 0.076 0.1 = 0.056 -0.01 0.02 0.016 H75 2 0.559800 0.335100 -0.033700 1.000000 0.092 C76 1 0.223100 0.496700 -0.103220 1.000000 0.076 0.11 = 0.038 0.01 -0.0104 0.013 H76 2 0.198300 0.478500 -0.145600 1.000000 0.093 END

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