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Structure, organization and dynamics of functional supramolecular materials studied by solid-state NMR [Elektronische Ressource] / Ümit Akbey

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Structure, Organization and Dynamics of Functional Supramolecular Materials Studied by Solid-State NMR Dissertation Zur Erlangung des Grades “Doktor des Naturwissenschaften” im Promotionsfach Chemie am Fachbereich Chemie, Pharmazie und Geowissenschaften der Johannes Gutenberg-Universität Mainz Ümit Akbey Geboren in Çorum, Turkey Mainz, (2008) Dekan: Prof. Dr. Wolfgang Hofmeister 1. Berichterstatter: Prof. Dr. Hans W. Spiess 2. Berichterstatter:. Holger Frey Tag der mündlichen Prüfung: 13.11.2008 Acknowledgements I would like to thank my research supervisor, Prof. Hans Wolfgang Spiess for all of his inspiring advises and discussions. I sincerely thank my advisor Dr. Robert Graf for endless NMR explanation and helpful discussions about the projects. I would like to thank also to Prof. Ayhan Bozkurt, Prof. Bryan Coughlin, Dr. Sergio Granados-Focil, Prof. Virgil Percec and Prof. Peter Chu for supplying the samples and fruitful discussions which clarify many key points. I am grateful to all Spiess group members for supplying the friendly research environment. Also I would like to thank to my friends Mihael Mondeshki, Mustafa Diken, and Hamit Erdemi for their proof reading the text and for their support which I feel always.

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Structure, Organization and Dynamics of
Functional Supramolecular Materials
Studied by Solid-State NMR




Dissertation
Zur Erlangung des Grades
“Doktor des Naturwissenschaften”
im Promotionsfach Chemie

am Fachbereich Chemie, Pharmazie und Geowissenschaften
der Johannes Gutenberg-Universität Mainz



Ümit Akbey
Geboren in Çorum, Turkey



Mainz, (2008)





Dekan: Prof. Dr. Wolfgang Hofmeister



1. Berichterstatter: Prof. Dr. Hans W. Spiess
2. Berichterstatter:. Holger Frey




















Tag der mündlichen Prüfung: 13.11.2008





Acknowledgements




I would like to thank my research supervisor, Prof. Hans Wolfgang Spiess for all of his
inspiring advises and discussions.
I sincerely thank my advisor Dr. Robert Graf for endless NMR explanation and helpful
discussions about the projects.
I would like to thank also to Prof. Ayhan Bozkurt, Prof. Bryan Coughlin, Dr. Sergio
Granados-Focil, Prof. Virgil Percec and Prof. Peter Chu for supplying the samples and
fruitful discussions which clarify many key points.
I am grateful to all Spiess group members for supplying the friendly research environment.
Also I would like to thank to my friends Mihael Mondeshki, Mustafa Diken, and Hamit
Erdemi for their proof reading the text and for their support which I feel always.
Finally, I am forever indebted to my parents Meliha and Duran and my brother Murat for
their endless support and love in my life.


















































Contents


1. Introduction ........................................................................................................... 1
2. NMR Spectroscopy ............................................................................................... 7
2.1. Nuclear Spin Interactions ................................................................................... 9
2.1.1. Zeeman Interaction ................................................................................... 10
2.1.2. Chemical Shift ................................................................................... 11
2.1.3. Dipolar Coupling ................................................................................... 14
2.1.4. Quadrupolar Coupling ....................................................................... 16
2.2. Spherical Representation of Interaction Tensors ............................................... 19
2.3. Density Matrix Representation ....................................................................... 20
2.4. Effect of Radio-Frequency (rf) Pulses ........................................................... 21
2.5. Magic Angle Spinning (MAS) ....................................................................... 23
2.6. Basic NMR Experiments ................................................................................... 28
2.6.1. One-Pulse Experiment ....................................................................... 29
2.6.2. Cross Polarization ................................................................................... 30
2.6.3. Heteronuclear Dipolar Decoupling ........................................................... 31
2.6.4. Echo Experiments ................................................................................... 33
2.6.5. Multidimensional NMR Experiments ............................................... 34
2.7. Advanced NMR Experiments ....................................................................... 35
2.7.1. Recoupling Methods under MAS Condition ............................................... 35
2.7.2. Multiple Quantum Techniques ........................................................... 38
2.7.3. Back-to-Back as a MQ Technique for Homonuclear Dipolar
Recoupling ............................................................................................... 39
2.7.4. Double-Quantum Buildup Curves ........................................................... 41
2.7.5. Two-Dimensional Rotor-Synchronized Double-Quantum MAS Spectra ... 43
2.7.6. Spinning-Sideband Patterns ................................... 45
2.7.7. Heteronuclear Dipolar Recoupling Techniques based on REDOR ........... 48
2.7.7.1.REPT-HSQC ................................................................................... 51 Contents II

2.7.7.2.REPT-HDOR ................................................................................... 53
2.7.7.3.REREDOR ................................................................................... 54
3. Structure and Dynamics of Anhydrous Proton Conducting Triazole-Functional
Siloxane Polymer ............................................................................................... 57
3.1. General Introduction to Proton Conductors ........................................................... 58
3.2. Results ........................................................................................................... 60
13.2.1. One-dimensional H MAS & DQF MAS NMR: Structure of the System ... 62
13.2.2. Two-dimensional rotor-synchronized H DQ MAS NMR: Proton
Proximities and Order in the System in the Solid-Phase ....................... 63
1 133.2.3. Variable Temperature H & C MAS NMR: Dynamics in the System &
Chemical Exchange ................................................................................... 66
23.2.4. H NMR Results: Acidic Ring NH Dynamics ................................... 69
3.3. Discussion & Interpretation .................................................................................. 70
3.3.1. Chemical exchange of the triazole ring NH protons ................................... 70
3.3.2. The Comparison of Microscopic and Macroscopic Conductivity ........... 74
3.3.3. The activation processes monitored by selective deuteration of acidic NH
2 proton: H NMR ................................................................................... 77
3.3.4. The motional processes at the triazole ring ............................................... 79
3.3.5. Mobility of the Spacer and Backbone of the System ................................... 81
3.4. Conclusions ........................................................................................................... 82
4. Anhydrous Proton Conducting Acid-Base Poly(acrylic acid)-Poly(4-vinyl pyridine)
Polymer Blend System: A Study of Hydrogen Bonding and Proton Conduction .. 83
4.1. Introduction ........................................................................................................... 85
4.2. Materials ........................................................................................................... 86
4.3. Results ........................................................................................................... 86
1 134.3.1. Structure of the PAA-P4VP System via SQ H MAS and C CP-MAS
NMR ........................................................................................................... 86
4.3.2. Formation of the Acid-Base Polymer Complex and the Hydrogen
Bonding ............................................................................................... 89
14.3.3. H MAS DQF Spectra and the Molecular Mobility ................................... 90
14.3.4. H MAS Variable Temperature Studies of the System and Relation to
Conductivity ............................................................................................... 93
14.3.5. 2D H DQ MAS NMR Spectra: Spatial Proximities and Proton
Connectivity in Systems ....................................................................... 98 Contents III
4.3.6. Effect of Hydration to the Systems ........................................................... 103
4.3.7. Deuterium NMR Results: Molecular Level Mobility ....................... 106
24.3.7.1.Static H NMR Results ....................................................................... 107
24.3.7.2.Spinning H NMR Results ........................................................... 108
4.4. Relation of NMR Observations to Proton Conductivity ................................... 110
4.5. Conclusions ........................................................................................................... 111
5. Hydrogen Bonding and Proton Conduction of Anhydrous Poly(2,5-benzimidazole)
-Poly(vinyl-phosphonic acid) Acid-Base Polymer Blends ................................... 113
5.1. Materials ........................................................................................................... 115
5.2. Results ........................................................................................................... 116
15.2.1. One-Dimensional H MAS Spectra: Molecular Structure of the
System ………………………………………………………........... 116
15.2.2. H DQ MAS NMR (one-dimensional DQ-filtered spectra): Mobility of
Hydrogen Bonding Proton Sites .......................................................... 121
15.2.3. H DQ MAS NMR (two-dimensional rotor synchronized spectra): Molecular
Level Proton Proximities ................................................................................... 122
135.2.4. C CPMAS NMR Results ....................................................................... 127
5.2.5. Molecular Dynamics & Proton Mobility in the Systems at Elevated
Temperatures ............................................................................................... 129
315.2.6. P NMR Results: The anhydride formation in the system ....................... 131
5.3. Interpretation and Discussions ....................................................................... 133
5.3.1. Proton Chemical Shifts and Hydrogen Bonding Network ....................... 133
5.3.2. Relation to Proton Conduction ........................................................... 133
5.4. Conclusions ........................................................................................................... 135
6. Anhydrous Proton Conducting Properties of Triazole-Phosphonic Acid Functional
Copolymers ........................................................................................................... 137
6.1. Proton Conductivity Properties of the Materials ............................................... 139
6.2. NMR Results ............................................................................................... 141
13 316.2.1. C and P MAS NMR Results: Structure of the Copolymers &
Coordination Behavior ........................................................... 141
16.2.2. H MAS SQ and DQ NMR: Hydrogen Bonding Network and Proton
Proximities ............................................................................................... 144
16.2.3. H Variable Temperature MAS NMR: Proton Mobility ....................... 148
16.2.4. H DQ Sideband-Patterns ....................................................................... 151
Contents IV

6.3. Conclusions ........................................................................................................... 153
7. Structure and Dynamics of Self-Organization Supramolecular Conductors:
Perylenebisimide Derivatives ................................................................................... 155
7.1. Introduction to Perylene Bisimide Derivatives ............................................... 155
7.2. PBI derivatives with High Phase Transition Temperatures: Structural
Investigation ............................................................................................... 159
17.2.1. H SQ-DQ MAS NMR results ........................................................... 159
137.2.2. C MAS NMR results ....................................................................... 163
7.3. Peryleneimide derivatives with Low Phase Transition Temperatures: Structural
Investigation ........................................................................................................... 167
17.3.1. H SQ-DQ MAS NMR Results ........................................................... 167
137.3.2. C MAS NMR Results ....................................................................... 169
7.4. Molecular Dynamics of Peryleneimide Derivatives ............................................... 172
7.4.1. Qualitative investigation of local molecular dynamics: Comparison of
1 1H MAS and H DQF MAS and 1D Rept Experiments ....................... 172
17.4.2. Mobility changes due to the elevation of temperature: H VT MAS and
DQF-MAS NMR ................................................................................... 175
7.5. Structure of Packing: Revealed by combination of NMR Results with Quantum
Chemical Calculations, and X-Ray Results ........................................................... 180
7.5.1. Proposed X-Ray Structures for n=2 (EM266) PBI Derivative ........... 180
7.5.2. NICS Maps ............................................................................................... 181
7.5.3. CPMD Calculation ................................................................................... 183
7.6. Conclusions ........................................................................................................... 186
8. Conclusions ........................................................................................................... 189
Bibliography ........................................................................................................... 193






Abstract:
Functional materials have great importance due to their many important applications. The
characterization of supramolecular architectures which are held together by non-covalent
interactions is of most importance to understand their properties. Solid-state NMR methods
have recently been proven to be able to unravel such structure-property relations with the
help of fast magic-angle spinning and advanced pulse sequences.
The aim of the current work is to understand the structure and dynamics of functional
supramolecular materials which are potentially important for fuel-cell (proton conducting
membrane materials) and solar-cell or plastic-electronic applications (photo-reactive aromatic
materials). In particular, hydrogen-bonding networks, local proton mobility, molecular
packing arrangements, and local dynamics will be studied by the use of advanced solid-state
NMR methods.
The first class of materials studied in this work is proton conducting polymers which
1also form hydrogen-bonding network. Different materials, which are prepared for high H
conduction by different approaches are studied: PAA-P4VP, PVPA-ABPBI, Tz5Si, and
Triazole-functional systems. The materials are examples of the following major groups;
- Homopolymers with specific functional groups (Triazole functional polysiloxanes).
- Acid-base polymer blends approach (PAA-P4VP, PVPA-ABPBI).
- Acid-base copolymer approach (Triazole-PVPA).
- Acid doped polymers (Triazole functional polymer doped with H PO ). 3 4
Perylenebisimide (PBI) derivatives, a second type of important functional
supramolecular materials with potent applications in plastic electronics, were also
investigated by means of solid-state NMR. The preparation of conducting nanoscopic fibers
based on the self-assembling functional units is an appealing aim as they may be incorporated
in molecular electronic devices. In this category, perylene derivatives have attracted great
attention due to their high charge carrier mobility. A detailed knowledge about their
supramolecular structure and molecular dynamics is crucial for the understanding of their
electronic properties. The aim is to understand the structure, dynamics and packing
arrangements which lead to high electron conductivity in PBI derivatives.