Porous covalent organic frameworks (COFs) enable the realisation of bespoke functional materials with molecular precision. Past research has focused on generating rigid frameworks where structural and optoelectronic properties are static. We have developed dynamic two-dimensional COFs that can open and close their pores upon uptake or removal of guests while fully retaining their crystalline long-range order. Constructing dynamic, yet crystalline and robust frameworks requires a well-controlled degree of flexibility. We have achieved this through a “wine rack” design where rigid π-stacked columns of perylene diimides (PDIs) are interconnected by non-stacked, flexible bridges. The resulting COFs show stepwise phase transformations between their respective contracted pore and open pore conformations with up to 40% increase in unit cell volume. Moreover, the variable geometry of dynamic COFs provides a handle for introducing stimuli-responsive optoelectronic properties. We illustrate this by demonstrating switchable optical absorption and emission characteristics, which approximate “null-aggregates” with monomer-like behaviour in the contracted COFs. Our findings reveal a general design strategy for dynamic 2D COFs and could offer a new route for realising stimuli-responsive optical, electronic, and spintronic materials.

Kovalente organische Frameworks (COFs) haben in den letzten Jahren aufgrund ihrer potenziellen Anwendungen in verschiedenen Bereichen großes Interesse hervorgerufen. Obwohl die Eigenschaften der synthetisierten Materialien empfindlich von den Eigenschaften der entsprechenden organischen Liganden abhängen, ist der Beitrag der einzelnen Bausteine zu den Kristalleigenschaften nicht eindeutig definiert. In dieser Arbeit werden die elektronischen und mechanischen Eigenschaften von einschichtigen zweidimensionalen (2D) COFs untersucht, wobei der Schwerpunkt auf den molekularen Bausteinen liegt. Zunächst wurde die Kristallstruktur als Hooke'sches Federnetzwerk angenommen, und analytische Formeln für 2D-COFs mit quadratischer und hexagonaler Gittertopologie wurden abgeleitet, wobei eine Vorhersage des Kompressionsmoduls aus der Berechnung der Monomer-Federkonstante angestrebt wurde. Alle geschätzten Werte für Moleküle und periodische Strukturen wurden mit der DFTB-Methode (Density Functional based Tight-Binding) berechnet. Benchmarking-Berechnungen mit der Dichtefunktionaltheorie (DFT) wurden eingesetzt, um die Anwendbarkeit der semiempirischen Methode zu überprüfen. In einem zweiten Schritt wurden Methoden vorgeschlagen, um die elektronische Bandstruktur und die elektronischen Eigenschaften von COFs zu verändern, wie z.B. die Änderung von Bindungen oder Linkern, Seitengruppen oder Funktionalisierung und die Erhöhung der Massendichte. Die verschiedenen Methoden ergeben unterschiedliche Eigenschaften der resultierenden Strukturen. Darüber hinaus wurden mehrere Polymere durch periodische Fortsetzung in einer oder zwei Dimensionen auf der Grundlage derselben molekularen Bausteine modelliert. Es wurde ein zweistufiges System auf der Grundlage des Tight-Binding-Ansatzes vorgeschlagen, und dessen Parameter wurden mit Hilfe der Bandoberkante des Valenzbandes und der Bundunterkante des Leitungsbandes abgeschätzt. Ein maschinelles Lernverfahren wurde eingesetzt, um die elektronische Bandlücke auf der Grundlage der gleichen Kernmonomere vorherzusagen. Interessanterweise erbt das 2D-COF die elektronische Lücke von der monomeren Einheit mit der niedrigeren elektronischen Energiedifferenz zwischen besetztem und unbesetztem Band. Schließlich wurde die Protonentautomerisierung in zwei sehr häufig verwendeten Kernmonomeren für 2D-COFs, Porphyrin und Phthalocyanin, und ihren Derivaten untersucht. Die Freie-Energie-Oberfläche wurde mit Quanten-Molekulardynamik-Simulationen durch Kombination von DFTB und Metadynamik berechnet. Durch die Analyse der Potenzialporträts werden die strukturellen Symmetrien des Moleküls in Protonentransferreaktionen widergespiegelt. Ich erwarte, dass die Ergebnisse dieser Arbeit Einsichten für die Synthese von 2D COFs geben werden, welche auf optimierte elektronische Eigenschaften mit hoher struktureller Stabilität abzielt.:ABSTRACT ZUSAMMENFASSUNG 1. INTRODUCTION Motivation Nomenclatures Experimental characterization and computational studies Objectives and outline 2. THEORETICAL AND COMPUTATIONAL BACKGROUND Many-body system Density Functional Theory (DFT) Kohn-Sham auxilary approach and the computational application of DFT Exchange-correlation functional Hybrid functionals Basis-set Pseudo-potentials Tight-binding model Density Functional based Tight-binding model (DFTB) Slater-Koster approach Slater-Koster sets in DFTB Molecular Dynamics and Metadynamics Classical Molecular Dynamics (MD) Quantum Molecular Dynamics (QMD) Metadynamics(MTD) 3. PREDICTING THE BULK MODULUS Conceptualization Equivalent spring constant Two dimensional bulk modulus Computational details COFs with square lattice type Models Molecular Spring constant Single layer 2D COFs COFs with hexagonal lattice type Models Single layer 2D COFs Synopsis 4. ENGINEERING THE ELECTRONIC PROPERTIES Computational details COFs with square lattice type Models Benchmarking of different methods π -conjugated COFs COFs with hexagonal topology Models π -conjugated COFs Synopsis PREDICTING THE ELECTRONIC BAND GAP Conceptualization Models Computational protocol 1D- and 2D-polymer Comparing the cores Predicting the gap Synopsis 6 SIMULATING THE PROTON TAUTOMERIZATION Models Collective variables (CVs) Computational protocol FES portraits and energy barriers Synopsis 7 CONCLUSIONS AND OUTLOOK APPENDIX A APPENDIX B APPENDIX C BIBLIOGRAPHY SCIENTIFIC OUTPUT ACKNOWLEDGEMENTS

Nitrogen-rich porous organic frameworks show great promise for use as acid-doped proton conducting membranes, due to their high porosity, excellent chemical and thermal stability, ease of synthesis, and high nitrogen content. Aided by very high surface area and pore volume, the material has the ability to adsorb high amounts of H3PO4 into its network, which creates a proton rich environment, capable of facile proton conduction. The morphology and chemical environment, doping behavior, and proton conduction of these materials were investigated. With such high acid-doping, ex-situ studies revealed that under anhydrous conditions, PA@BILP-16 (AC) produced a proton conductivity value of 5.8 x 10-2 S cm-1 at 60 °C and PA@ALP-6 showed a slightly higher value of 5.91 x 10-2 S cm-1 at 60 °C. With such promising results, in-situ experiments with various analogues are scheduled to be conducted in the near future.

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Linear conjugated polymers have attracted significant attention in organic electronics in recent decades. However, despite intrachain π-delocalization, interchain hopping is their transport bottleneck. In contrast, two-dimensional (2D) conjugated polymers, as represented by 2D π-conjugated covalent organic frameworks (2D c-COFs), can provide multiple conjugated strands to enhance the delocalization of charge carriers in space. Herein, we demonstrate the first example of thiophene-based 2D poly(arylene vinylene)s (PAVs, 2DPAV-BDT-BT and 2DPAV-BDT-BP, BDT=benzodithiophene, BT=bithiophene, BP=biphenyl) via Knoevenagel polycondensation. Compared with 2DPAV-BDT-BP, the fully thiophene-based 2DPAV-BDT-BT exhibits enhanced planarity and π-delocalization with a small band gap (1.62 eV) and large electronic band dispersion, as revealed by the optical absorption and density functional calculations. Remarkably, temperature-dependent terahertz spectroscopy discloses a unique band-like transport and outstanding room-temperature charge mobility for 2DPAV-BDT-BT (65 cm2 V−1 s−1), which far exceeds that of the linear PAVs, 2DPAV-BDT-BP, and the reported 2D c-COFs in the powder form. This work highlights the great potential of thiophene-based 2D PAVs as candidates for high-performance opto-electronics.

The interest in two-dimensional conjugated polymers (2D CPs) has increased significantly in recent years. In particular, vinylene-linked 2D CPs with fully in-plane sp2-carbon-conjugated structures, high thermal and chemical stability, have become the focus of attention. Although the Horner-Wadsworth-Emmons (HWE) reaction has been recently demonstrated in synthesizing vinylene-linked 2D CPs, it remains largely unexplored due to the challenge in synthesis. In this work, we reveal the control of crystallinity of 2D CPs during the solvothermal synthesis of 2D-poly(phenylene-quinoxaline-vinylene)s (2D-PPQVs) and 2D-poly(phenylene-vinylene)s through the HWE polycondensation. The employment of fluorinated phosphonates and rigid aldehyde building blocks is demonstrated as crucial factors in enhancing the crystallinity of the obtained 2D CPs. Density functional theory (DFT) calculations reveal the critical role of the fluorinated phosphonate in enhancing the reversibility of the (semi)reversible C−C single bond formation.

La conception de nouveaux matériaux fonctionnels a une longue histoire. Durant les deux dernières décennies, le domaine des polymères organiques et inorganiques a attiré l'attention des chercheurs. Plus important encore, les matériaux poreux tels que les Metal Organic Frameworks (MOFs), en anglais, Covalent Organic Frameworks (COFs), en anglais, ainsi que des polymères de coordination poreux sont maintenant étudiés de manière intensive en raison de leurs applications potentielles, comprenant le stockage de gaz, la séparation de gaz, la catalyse et la détection. D'un autre côté, les polymères contenant du Pt ont montré l'application potentielle dans les cellules solaires et les diodes électroluminescentes. Le mémoire est divisé en trois sections principales présentant des résultats nouveaux. Dans la première section, le chapitre 2 traite essentiellement de la formation de polymères de coordination (CP) avec des sels CuX (X = Cl, Br, I) et trans-[p-MeSC6H4C≡C-Pt(PMe3)2-C≡CC6H4SMe] (L1), soit dans le PrCN ou PhCN. Les polymères résultants sont soit 2D (bidimensionel) ou 1D (unidimensionel). Cependant, en presence de PrCN ou de PhCN, le CP 2D obtenu avec le CuBr n'a pas incorporé de solvant dans ses espaces vides. D'autre part, le CP 2D et le reste des CP 1D obtenus avaient soit des molécules de solvant de cristallisation dans leurs cavités ou coordonnés au cuivre sur la chaîne. Les unités cuivre-halogénures étaient soit des rhomboïdes Cu2X2 ou le cubane Cu4I4. Leurs mesures photophysiques en présence et en l'absence de molécules de solvant de cristallisation ont été effectuées. En outre, la porosité du CP a été évaluée par BET (N2 à 77 K). Le vapochromisme du CP 2D sans solvant et des CP 1D ont été étudiés, ainsi que les mesures de sorption du CO2 ont été effectuées. De plus, nous avons utilisé CuCN et L1 dans MeCN pour former de nouveaux CP’s. Ceci est rapporté dans la deuxième section, le chapitre 3. Le CP obtenu était inattendu : L1 s’est rompu et du cyanure CN‾ s’est coordonné sur le Pt. Ceci a conduit à la formation d’un CP 1D zigzag. Généralement, les CP sont formés avec L1 via des liens Cu-S ou/et Cu([éta]2-C≡C), mais pas dans le cas du CuCN qui lui forme une chaîne 1D (CuCN)n où le L1 rompu se lie avec cette chaîne via un lien Cu-N. Les propriétés photophysiques et de stabilité thermique ont été étudiées. La troisième section (Chapitre 4) traite d'une exploration des CP formés par la reaction des sels CuX (X = Cl, Br, I) et le trans-[p-MeSC6H4C≡C-Pt(PMe3)2-C≡CC6H4SMe] (L1) ou le trans-[p-MeSC6H4C≡C-Pt(PEt3)2-C≡CC6H4SMe] (L2) dans du MeCN afin de trouver des tendances. L'utilisation de L1 a donné lieu à un CP 2D ou 1D CPs avec le MeCN piégé à l'intérieur des cavités, il y a de l’espace vide. L2 a conduit uniquement à des CP 1D sans molecules de solvant de cristallisation. Des analyses thermogravimétriques, photophysique et des mesures d’adsorption de gaz (uniquement pour ceux avec du solvant) ont été étudiées. / Abstract: The design of new functional materials has a long history. For the past two decades, the field of organic and inorganic polymers has attracted attention of researchers. More importantly, porous materials such as Metal Organic Frameworks (MOFs), Covalent Organic Frameworks (COFs) as well as porous coordination polymers are now being intensively studied due to their potential applications including gas storage, gas separations, catalyst and sensing. On another hand, Pt-containing polymers have shown potential applications in solar cells and light emitting diodes. The masters’ thesis is mainly divided into three main sections presenting new results. In the first section; Chapter 2 mainly discusses the formation of coordination polymers with CuX salts (X= Cl, Br, I) and trans-[p-MeSC6H4C≡C-Pt(PMe3)2-C≡CC6H4SMe] (L1), in either PrCN or PhCN. The resulting polymers obtained were 2D (bidimensional) CPs or 1D (unidimensional) CPs in all cases. However, 2D CPs obtained when CuBr salt is used by either using PrCN or PhCN did not incorporate the solvents in their cavities. On the other hand, the 2D CP and the rest of 1D CPs obtained had either the crystallization molecules in the cavities or coordinated to the copper cluster. The copper-halide clusters were either the rhomboids Cu2X2 fragments or the step cubane Cu4I4. The photophysical measurements in the presence and absence of solvent crystallization molecules were performed. In addition, the porosity of the CPs was evaluated by adsorption isotherms. The vapochromism of the solvent-free 2D and 1D CPs were investigated as well as CO2 sorption measurements were perfomed. Furthermore, we then attempted to use CuCN and L1 in MeCN which is reported in the second section as Chapter 3. The obtained CP was unexpected as L1 broke and a cyanide (CN‾) ion coordinated to the Pt atom leading to the formation of zigzag 1D CP. The coordination bonds Cu-S or/and Cu([eta]2-C≡C) were generally observed with L1, but not in the CuCN case. Instead a 1D chain of (CuCN)n was made and the broken L1 now binds the chain via a Cu-N bond. The photophysical and thermal stability properties were studied. Lastly, the third section, Chapter 4 deals with a potential predictability of CP formation by using CuX salts (X= Cl, Br, I) and either trans-[p-MeSC6H4C≡C-Pt(PMe3)2-C≡CC6H4SMe] (L1) or trans-[p-MeSC6H4C≡C-Pt(PEt3)2-C≡CC6H4SMe] (L2) in MeCN as the solvent. The use of L1 resulted in either 2D or 1D CPs with the MeCN trapped inside of the cavities while L2 resulted in 1D CPs without MeCN being present in their cavities. The thermogravimetric, photophysical as well as gas sorption measurements (only for those with crystalisation molecules) were perfomed.