New discotic liquid crystals based on large polycyclic aromatic hydrocarbons as materials for molecular electronics [Elektronische Ressource] / vorgelegt von Željko Tomović
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New discotic liquid crystals based on large polycyclic aromatic hydrocarbons as materials for molecular electronics [Elektronische Ressource] / vorgelegt von Željko Tomović

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NEW DISCOTIC LIQUID CRYSTALS BASED ON LARGE POLYCYCLIC AROMATIC HYDROCARBONS AS MATERIALS FOR MOLECULAR ELECTRONICS Dissertation zur Erlangung des Grades ’’Doktor der Naturwissenschaften’’ dem Fachbereich Chemie und Pharmazie der Johannes Gutenberg-Universität Mainz vorgelegt von Željko Tomovi ć geboren in Kragujevac, Serbien Mainz 2004 Tag der mündlichen Prüfung: 02.03.2005 Dedicated to my wife, brother and parents Contents 1. Introduction....................................................................................1 1.1 Polycyclic Aromatic Hydrocarbons…………….……………….......……..………1 1.2 ”All-Benzenoid” PAHs and the Clar rule of the aromatic sextet…...…….……..2 1.3 Synthesis of PAHs………………………………….…………...………………….5 1.3.1 Synthesis of PAHs via intramolecular Diels-Alder reaction…..….....….…......7 1.3.2 Synthesis of PAHs via cyclotrimerization of diphenylacetylenes…......…........9 1.3.3 Synthesis of PAHs via intermolecular Diels-Alder reaction…..…………....

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Publié par
Publié le 01 janvier 2005
Nombre de lectures 29
Poids de l'ouvrage 9 Mo

Extrait



NEW DISCOTIC LIQUID CRYSTALS BASED ON
LARGE POLYCYCLIC AROMATIC HYDROCARBONS
AS MATERIALS FOR MOLECULAR ELECTRONICS

Dissertation

zur Erlangung des Grades
’’Doktor der Naturwissenschaften’’

dem Fachbereich Chemie und Pharmazie der
Johannes Gutenberg-Universität Mainz
vorgelegt von

Željko Tomovi ć
geboren in Kragujevac, Serbien




Mainz 2004
















































Tag der mündlichen Prüfung: 02.03.2005














































































































Dedicated to my wife, brother and parents













































































Contents



1. Introduction....................................................................................1
1.1 Polycyclic Aromatic Hydrocarbons…………….……………….......……..………1
1.2 ”All-Benzenoid” PAHs and the Clar rule of the aromatic sextet…...…….……..2
1.3 Synthesis of PAHs………………………………….…………...………………….5
1.3.1 Synthesis of PAHs via intramolecular Diels-Alder reaction…..….....….…......7
1.3.2 Synthesis of PAHs via cyclotrimerization of diphenylacetylenes…......…........9
1.3.3 Synthesis of PAHs via intermolecular Diels-Alder reaction…..………….......10
1.4 ”Superbenzene” chemistry ……………...……….…………..…………..……...14
1.5 Discotic liquid crystals…………….……....……...….……….……..……………...16
1.5.1 Mesophase characterization……………………………….....…………......23
1.5.2 Charge carrier mobility……..………………....…………...….…………......25
1.6 Discotic liquid crystals as semiconductors in electronic and optoelectronic
devices....……………………………………….…………………...….…….………27
1.6.1 Field effect transistors (FETs)…….…….……...……………….…………...27
1.6.2 Photovoltaic devices…………...…..….……...………………….…………..28
1.6.3 Light emitting diodes (LEDs)………………...…..……...……….…………...29
1.7 Motivation and objectives………………………….……………..……………...30
1.8 Literature……………………………………………………….…..……………...34

2. Superphenalene-Based Columnar Liquid Crystals..................39
2.1 Synthesis of hexa-substituted ”Superphenalenes”……………......……..……39
2.2 Supramolecular characterization……………………………..….………………52
2.3 Charge carrier mobility………………….……..…………………….……………61
2.4 Uniaxial alignment of C96-C by solution processing……..…….……………66 12
I Contents
2.5 Self-assembly and electrical properties of supramolecular architectures of
C96-C studied by Scanning Force Microscopy (SFM) and Kelvin Probe 12
Force Microscopy (KPFM)….……...………….…………………….……………72
2.5.1 C96-C at the interface with Au electrodes………….…….….……......75 12
2.5.2 Electrical properties………………………………………….…….….……......78
2.6 Superphenalene derivatives with lower symmetry….………….……………...86
2.6.1 Synthesis……………………….…………………………….....…………......88
2.6.2 Phase characterization……..………………....…………...….…………......92
2.6.3 Charge carrier mobility.……..………………....…………...….…………......93
2.7 Study of the oxidative cyclodehydrogenation reaction..……….……………...95
2.8 Literature…………………………………………….….………….……………..101

3. Control of the Homeotropic Order of Discotic Columnar
Systems………………………..……………………………………106
3.1 Introduction…………………..………………………..……………......……..…106
3.2 Synthesis of hexa-alkylether substituted HBC and C96 discs...…...………..108
3.3 Phase characterization of hexa-alkylether substituted HBCs..……….……..114
3.3.1 Thermal phase characterization……….……………….…….….…...….....114
3.3.2 Structure investigation by X-ray scattering……………….…….….……......117
3.3.3 Homeotropic arrangement………..…...…….………………….….……......120
3.4 Literature………………………………………….....….………….……………..125

4. Synthesis and Properties of Dendronized
Superphenalenes…………………………………………...……...128
4.1 Introduction…………………..………………………..……………......……..…128
4.2 Synthesis and structural characterization.…………………………...………..131
4.2.1 Synthesis of hexa(4-iodophenyl)-C96……………….….…….….…...….....131
4.2.2 Functionalization of hexa(4-iodophenyl)-C96 by Hagihara-Sonogashira
coupling reaction towards dendronized superphenalenes…….…….……..133
IIContents
4.3 UV/Vis absorption and fluorescence measurements………………...….…..138
4.4 Literature…………………………………………....….………….……………..144

5. Graphitic Molecules with Partial ”Zig-Zag” Periphery….…...147
5.1 Introduction…………………..………………………..……………......……..…147
5.2 Synthesis …………………….……………..…………………………...………..149
5.3 UV/Vis and fluorescence characterization…………..………………...….…..154
5.4 Synthesis and characterization of soluble ”zig-zag” superphenalene….…..156
5.5 Literature…………………………………………....….………….……………..163

6. Summary………………………………………………………..…...166

7. Experimental Section……………………………………..….…...173
7.1 General methods……..……..……………...………...……………......……..…173
7.2 Materials. ……………………………………..………………………...………..174
7.3 Syntheses.……………………………...……..………………………...………..175

Acknowledgements……...…………………...…………………………………..234
List of publications……...…………………...……………………………………236
Curriculum Vitae………..…………….……...…………………………...……….238
III

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