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Synthesis of 2D and 3D Covalent Organic Frameworks for Advanced Applications in Adsorption, Electrochemistry and Catalysis
No full textCovalent Organic Frameworks (COFs) are a class of crystalline porous organic polymers constructed through reticular chemistry, wherein organic linkers are connected by strong covalent bonds. The structural and functional diversity of COFs can be significantly enriched by the strategic design approach. By applying a certain combination of organic building units, it is possible to achieve materials with advanced properties and tailored functionalities. Depending on the structural composition and geometric configuration of the final material, COFs can be applied as sensors, catalysts, and in the fields of adsorption, energy and environmental applications.
In this dissertation work I focused on the development of COFs series with various structural architectures, connectivities and pore interfaces. Through a thorough search of organic building units, COFs with unique properties and advanced functionalities were designed and their structure-property correlations were analyzed: 1) using a nitrogen-rich carbazole-based linker, π-conjugated COFs with donor-acceptor units were synthesized. Resulting materials displayed acidochromism phenomena and unique sensing abilities, as well as enhanced water adsorption properties, which renders them promising for humidity control applications. 2) Introducing donor-acceptor charge transfer moieties within 2D COF structure resulted in suitable band gap energy, allowing for the utilization of COF material as catalyst in photocatalytic H2O2 production reaction. 3) Employing triphenylamine-based linker resulted in COF structure with redox-active functionalities, which demonstrated reversible electrochromic behavior upon application of voltage. 4) Implementing a bipyridine moiety within the COF structure offered a platform for metal ions coordination, making the COF material suitable for application in heterogeneous catalysis. 5) By using a combination of rigid and flexible building units, novel 3D COFs and porous organic polymers were synthesized and characterized. Correlation between topological predesign and crystallinity of final COFs was discussed. 6) Structure and thermal properties of boronate ester-linked 3D COF were analyzed and negative thermal expansion phenomena of boroxine-linked 3D COF was investigated. 7) An 8-topic linker with diol functionalities was synthesized and the synthesis of novel boronate ester-linked 3D COF with hierarchical porosity was attempted.
This work provides new insights into the chemistry, structural design and synthesis of 2D and 3D COFs, as well as in the utilization of COFs in adsorption, catalysis, environmental and energy-related applications.:Acknowledgments .................................................................................................. iv
Abstract .................................................................................................................. vi
Table of contents .................................................................................................. viii
List of abbreviations ................................................................................................ x
1 Motivation ........................................................................................................ 1
2 State of the art ................................................................................................. 4
2.1 Covalent Organic Frameworks .................................................................... 5
2.2 Synthesis and topologic diagrams ............................................................... 6
2.2.1 Two dimensional COFs ............................................................................ 8
2.2.2 Three dimensional COFs ....................................................................... 10
2.2.3 Imine-linked COFs ................................................................................. 12
2.2.4 Boroxine and boronate ester-linked COFs ............................................. 14
2.3 Electronic structure of COFs and band-gap engineering ........................... 16
2.4 Adsorption ................................................................................................. 19
2.4.1 Adsorption isotherms, BET area and pore size distribution ............ 20
2.4.2 Water vapor adsorption ................................................................... 24
2.4.3 Flexibility in COFs .................................................................................. 28
2.5 Negative thermal expansion ................................................................... 31
2.6 Applications ............................................................................................... 34
3 Results and discussion.................................................................................. 38
3.1 Acidochromism and humidity sensing properties of DUT-175 and DUT-
176 ............................................................................................................... 39
3.1.1 Synthesis and characterization .............................................................. 40
3.1.2 Chemical stability and acidochromism ................................................... 44
3.1.3 Water adsorption properties ................................................................... 48
3.1.4 Humidity sensing properties ................................................................... 51
3.1.5 Summary ................................................................................................ 52
3.2 Potential of DUT-175 as photocatalyst in ORR and organic
transformations ................................................................................................... 54
3.2.1 DUT-175 photocatalytic properties ......................................................... 55
3.2.2 Outlook ................................................................................................... 59
3.3 Imine-linked redox active COF DUT-168 for the electrochromic layer in
electrochromic devices ....................................................................................... 60
3.3.1 Synthesis and characterization .............................................................. 61
3.2.2 Electrochemical properties ..................................................................... 64
ix
3.2.3 Electrochromism ...................................................................................... 65
3.2.4 Summary ................................................................................................. 69
3.4 Bipyridine based COF DUT-156 synthesis and its potential in
heterogeneous catalysis ..................................................................................... 70
3.4.1 Synthesis and characterization .............................................................. 71
3.4.2 Metal incorporation in COF .................................................................... 74
3.4.3 Potential of Ni@DUT-156 in photocatalytic cross-coupling reactions .... 78
3.4.4 Summary ................................................................................................ 79
3.5 COF-102 and COF-108-int adsorption properties and negative thermal
expansion investigation ...................................................................................... 81
3.5.1 Synthesis and characterization .............................................................. 82
3.5.2 Adsorption properties ............................................................................. 85
3.5.3 Thermal properties ................................................................................. 87
3.5.4 Summary ................................................................................................ 90
3.6 3D COF and porous organic polymers based on carbazole ligand ........ 91
3.6.1 Synthesis and characterization .............................................................. 92
3.6.2 Outlook ................................................................................................... 97
3.7 3D phenazine based boronate ester linked COF design and synthesis . 99
3.7.1 COF and linker design ......................................................................... 100
3.7.2 Linker synthesis and characterization .................................................. 102
3.7.3 COF synthesis and characterization .................................................... 106
3.7.4 Outlook ................................................................................................. 107
4 Conclusion and outlook ............................................................................... 108
5 Experimental section ................................................................................... 113
5.1 Instruments .......................................................................................... 114
5.2 List of chemicals................................................................................... 117
5.3 List of solvents ..................................................................................... 118
5.4 Synthesis and characterization of organic ligands ............................... 118
5.5 Synthesis of COFs and organic polymers ............................................ 123
6 References .................................................................................................. 127
7 Appendix ..................................................................................................... 165
7.1 Supplementary data ................................................................................ 166
7.2 List of publications ................................................................................... 190
7.3 Conferences contribution ......................................................................... 191
8 Erklärung gemäß §5 Abs. 1 Punkt 5 ..........................................................19
Influence of electronic structure and band topology on nonlinear optical responses
No full textOver the past few decades, advancements in optical technologies, particularly in laser technologies, have significantly deepened our understanding of light-matter interactions. When light illuminates a quantum system, it can drive electrons away from their ground states within one or a few optical cycles, resulting in both linear and nonlinear optical responses (NLORs). In recent years, explosive progress in the study of solid-state materials, especially topological materials, has motivated efforts to manipulate their response to light fields using their symmetry, electronic structure, and topological properties. Against this backdrop, the investigation of NLORs in materials forms the main focus of this dissertation. Several aspects of light-matter interaction in topological insulators, Weyl semimetals, and graphene nanoribbons are explored. In particular, using density functional theory and Wannier models, we examine how electronic structure, band topology, and crystal symmetries influence NLORs.
Starting with a detailed analysis of the topological properties of the van der Waals material TaRhTe in different dimensions, the first part of the dissertation investigates the second-order optical response --- specifically, the photogalvanic effect (PGE) --- in monolayer TaRhTe and a family of transition metal dichalcogenides, all of which are two-dimensional topological insulators. We demonstrate that the PGE can, in principle, serve as a probe for topological phase transitions through changes in quantum geometric quantities.
The latter part of the dissertation concentrates on high-order NLORs, particularly high-harmonic generation (HHG). We systematically elucidate the relationship between crystal symmetries and harmonic selection rules, developing a Jones matrix formalism for this purpose. In the Weyl semimetal TaAs, we analyze the feasibility of using HHG to probe topological phase transitions, finding that due to the sensitivity of HHG to crystal symmetries and laser parameters, it is less feasible to detect the topological features of the Weyl nodes. Finally, we utilize the subband structure in graphene nanoribbons to modulate HHG. Our study shows that cascaded resonances between subbands can significantly enhance the harmonic yield, surpassing the HHG spectrum as compared to extended systems. Our results reveal the intricate interplay between electronic structure, band topology, crystal symmetry, and NLORs, offering potential pathways for experimentally probing and controlling the nonlinear optical properties of topological and quantum-confined materials
Ein kurzer Beitrag über einen kurzen Beitrag zu einem rätselhaften Liederheft: Nebel von Boris Blacher: Variable Schwaden im Kleinformat
No full textImmer auf dem Sprung: Das Finale von Regers Klavierkonzert aus der Sicht eines Leidtragenden
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Beiträge zum 5. Kongress der Fachgruppe Verkehrspsychologie an der TU München:
No full textDiese Veröffentlichung enthält alle Beiträge (Abstracts) des 5. Kongresses der Fachgruppe Verkehrspsychologie der Deutschen Gesellschaft für Psychologie (DPGs), die am 19./20. März 2025, von der TU München ausgerichtet, in Garching b. München stattfand.This publication contains all contributions (abstracts) of the 5th Congress of the Traffic & Transport Psychology Section of the German Society for Psychology (DPGs), which took place on March 19/20, 2025, organized by the Technical University of Munich, in Garching near Munich
