Metal-organic frameworks (MOFs) have attracted much attention in the past few decades due to their ordered, crystalline nature, synthetic tunability, and porosity. MOFs represent a class of hybrid inorganic-organic materials that have been investigated for their applications in areas such as gas sorption and separation, catalysis, drug delivery, and electron or proton conduction. It has been the goal of my graduate research to investigate MOFs for their ability to transport electrons and store and separate gases for ultimate catalytic applications in alternative energy generation. I aim to provide new insight into the design and development of stable MOFs for such applications. We first investigated a cobalt(III) porphyrin based MOF comprised of Co(II)-carboxylate nodes, designated as CoPIZA, for its electron transport capabilities. Thin films of CoPIZA were formed solvothermally on conductive fluorine-doped tin oxide (FTO) substrates and used for electrochemical characterization. Electrochemistry coupled with spectroscopic analysis of the CoPIZA film revealed reversible reduction of the cobalt centers of the porphyrin linkers with maintenance of the overall framework structure. The mechanism of charge transport throughout the film was facilitated by redox hopping of electrons between the metal centers of the nodes and linkers. The ability to incorporate desired properties, such as pore functionalities or open metal centers, into frameworks makes them attractive for applications in separation of gaseous mixtures, such as CO2/N2 from combustion power plants. To investigate the selective adsorption properties, we performed gas sorption measurements on bulk MOF materials to determine their affinity toward CO2. Two Zn-based MOFs containing 2,5-pyridine dicarboxylate linkers were prepared in our laboratory and contained unsaturated Zn(II) metal centers, which possess a binding site on the metal without an activation procedure to remove bound solvent molecules. These MOFs were compared to the well-known Zn-based MOF-69C containing 1,4-benzene dicarboxylate linkers. Thermodynamic analysis of the gas sorption data revealed that the mechanism of CO2 binding involved the coordinatively unsaturated Zn(II) center. The microporous MOF also demonstrated selectivity for CO2 over N2 under the same conditions. As these materials were able to uptake CO2, their ability to transport electrons was also investigated for ultimate applications in catalysis. Electrochemical impedance spectroscopy was performed on the bulk MOF powders and was coupled with solid-state nuclear magnetic resonance spectroscopy. These results determined that the conduction mechanism proceeded via solvent molecules within the pores of the framework. The catalytic ability toward water oxidation of two MOFs was investigated electrochemically. Initial studies focused on a cobalt-based MOF comprised of 2-pyrimidinolate (pymo) linkers, designated as Co(pymo)2, which was prepared on FTO via drop-casting and used for electrochemical experiments. At applied anodic potentials, the CoII centers of Co(pymo)2 became oxidized to form a Co-oxide species on the electrode surface, which was found to be the active catalysis for water oxidation. Further investigations utilized a notably more stable Zr-based MOF with nickel(II) porphyrin linkers, designated as PCN-224-Ni. PCN-224-Ni was prepared solvothermally on FTO and used directly for electrochemical water oxidation. The mechanism of water oxidation at PCN-224-Ni proceeds via oxidation of the porphyrin macrocycle followed by binding of water to the Ni(II) center. Cooperative proton transfer to the Zr-oxo node facilitated water oxidation with the eventual release of O2. Thorough characterization revealed that PCN-224-Ni retained its structural integrity over the course of electrochemical catalysis. These results have allowed us a deeper understanding of the mechanisms of electron transport and conduction throughout frameworks. Specifically, the incorporation of metalloporphyrin molecules with redox active metal centers coupled with the presence of redox active metal nodes resulted in redox hopping charge transport throughout the MOF. In addition, the presence of solvent molecules in the pores of the framework provided an extended network for charge transport. We have gained insight into the structure-function relationship of MOFs for applications in selective gas sorption, where an unsaturated metal center serves as the binding site for gas molecules. Finally, through selection of the components that comprise the framework, a stable metalloporphyrin MOF was found to be capable of electrochemically facilitating the water oxidation reaction. As a result, we have gained valuable insight into the properties of frameworks necessary for charge transport and stability, which will allow for further improvements in the smart design of MOFs for catalytic applications. / Ph. D.

Designing new materials for CO₂ capture and utilization is one of the most challenging research topics. Metal-organic frameworks (MOFs) are one of the most efficient CO₂ adsorbents, as well as an emerging class of heterogeneous catalysts for CO₂ chemical transformations. Highlighted by their high content of active centers, large internal surface areas, tunable pore size, and versatile chemical functionalities, MOFs can serve as highly stable and reusable heterogeneous catalysts and provide a great platform to explore the structure-function relationships for transforming CO₂ into useful chemicals. In this dissertation, we aim to develop a new class of metal-cyclam based robust MOFs as porous materials for CO₂ uptake as well as efficient catalysts for CO₂ chemical transformations, including CO₂ chemical fixation, CO₂ photo- and electroreduction. Chapter 1 introduces the concept and main challenges of CO₂ capture and conversion. The potential of metal-cyclam complexes as molecular catalysts for CO₂ conversion is also mentioned. The current state of the art in designing stable MOFs and azamacrocyclic-based MOFs is briefly discussed. Finally, the strategies, challenges and future outlook of using MOF as catalysts in CO₂ chemical transformation are summarized. Metal-organic frameworks (MOFs) as highly ordered, tunable hybrid materials have shown great promise in photon collection, energy transfer and photocatalytic reactions. In Chapter 2, the fundamental principles of energy transfer in the condensed phase are summarized, and a series of studies in light-harvesting, excited state quenching and photo-excited reactivity occurring within ruthenium-polypyridyl-doped zirconium MOFs are reviewed. The application of MOFs in energy conversion devices such as dye-sensitized solar cells (DSSC) is also discussed. Chapter 3 reports two new robust 3D porous metal-cyclam based Zr-MOFs, VPI-100 (Cu) and VPI-100 (Ni) with potential as heterogeneous catalysts for CO2 chemical fixation. The frameworks are prepared by a modulated synthetic strategy and the structure highlighted by eight-connected Zr₆ clusters and metallocyclams as organic linkers. The VPI-100 MOFs exhibit excellent chemical stability in various organic and aqueous solvents over a wide pH range and show high CO₂ uptake capacity (up to ∼9.83 wt% adsorption at 273 K under 1 atm). Moreover, VPI-100 MOFs demonstrate some of the highest reported catalytic activity values (turnover frequency and conversion efficiency) among Zr-based MOFs for the chemical fixation of CO₂ with epoxides. The MOFs, which bear dual catalytic sites (Zr and Cu/Ni), enable chemistry not possible with the cyclam ligand under the same conditions and can be used as recoverable stable heterogeneous catalysts without losing performance. A follow-up study of CO₂ chemical fixation using Hf analogs of VPI-100 is presented in Chapter 4. Structural characterization and catalytic performance of Hf-VPI-100 are summarized. Moreover, a detailed comparison of VPI-100 and Hf-VPI-100 is made. In situ powder X-ray diffraction (PXRD), quartz crystal microbalance (QCM) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) have been used to probe the interaction between the guest molecules (CO₂/epoxide) and Hf-VPI-100. For CO₂, no specific chemical binding sites in MOFs has been observed and the uptake of CO₂ does not change the crystal structure of Hf-VPI-100. Both QCM and DRIFTs revealed the irreversible binding between the framework and 1,2-epoxybutane. The epoxide uptake per unit cell of VPI-100 MOFs and diffusion coefficients have been calculated by QCM analysis. Transition metal complexes capable of visible light-triggered cytotoxicity are appealing potential candidates for photodynamic therapy (PDT) of cancer. In Chapter 5, two monometallic polyazine complexes, [(Ph₂phen)₂Ru(dpp)]²⁺ and [(Ph₂phen)₂Os(dpp)]⁺ (Ph₂phen = 4,7-diphenyl-1,10-phenanthroline; dpp =2,3-bis(2-pyridyl)pyrazine), were synthesized, characterized and studied as light activated drugs to kill rat malignant glioma F98 cells. Both compounds display strong absorption in visible spectrum, oxygen-mediated DNA and BSA photocleavage and significant photocytotoxicity under blue light irradiation along with negligible activity in the dark. The compounds show approximately five-fold higher cytotoxicity compared the traditional chemotherapeutic drug, cisplatin. Furthermore, [(Ph₂phen)₂Os(dpp)]⁺ shows promising photocytotoxicity in F98 rat malignant glioma cells within the phototherapeutic window with an IC50 value of (86.07±8.48) µM under red light (625 nm) irradiation. In Chapter 6, the mixed-metal supramolecular complex, [(Ph₂phen)₂Ru-(dpp)PtCl₂]²⁺, was found to display significant DNA modification, cell growth inhibition, and toxicity towards F98 malignant glioma cells following visible light irradiation. The design of this complex has a significantly higher potential for membrane permeability than three other FDA-approved anti-cancer agents, including cisplatin, and exhibited a dramatic ten-fold higher uptake by F98 cells than cisplatin in a two-hour window. Based on studies with a rat glioma cell line, the compound has very low cytotoxicity in the dark, but results in substantial cell death upon light treatment. The complex is thus among the first to exhibit all the hallmarks of a very promising new class of PDT agents. / Ph. D. / Increased carbon dioxide (CO₂) emissions have triggered a series of environmental effects, including global warming and ocean acidification. Scientists are trying to develop new materials to capture and convert CO₂ into useful chemical products. However, the main challenge is that CO₂, the gas generated upon burning fossil fuels, has strong C=O bonds that are hard to break. In other words, it is too stable to be easily changed into other compounds. A class of highly porous materials known as metal-organic frameworks (MOFs) possess significant potential for CO₂ adsorption uptake and chemical fixation. MOFs are metal ions or clusters held together by organic linkers to make highly ordered, crystalline 3D structures with tunable porosity and functionality. The design and synthesis of MOFs is similar to playing with Legos at the molecular level; you need to pick the right pieces (metal nodes and linkers) to get your desired structure. In this dissertation, we aim to develop a new class of macrocycle complexes based stable MOFs as porous materials for CO₂ uptake as well as efficient catalysts for CO₂ chemical transformations. We have developed two new stable three dimensional porous frameworks, VPI-100 (Cu) and VPI-100 (Ni) as catalysts for CO₂ chemical fixation. The new 3D robust MOFs named VPI-100 (VPI = Virginia Polytechnic Institute) are assembled by the reaction of zirconium oxo clusters and linkers bearing metal complexes. Using the metal complexes as the linker provides additional metal active sites in the framework that can act as accessible catalytic centers for CO₂ conversion. The VPI-100 MOFs are not only able to convert CO₂ to cyclic carbonates (important industrial chemicals) in high efficiency (~ 98%), but also can be reused for multiple cycles. The heterogeneous catalyst can be easily recovered from the reaction mixture by centrifugation and the active metal centers are earth-abundant transition metals (Cu and Ni), which are cost effective. Additionally, VPI-100 MOFs also show high CO₂ uptake capacity (up to ~10 wt%) at ambient pressure. Since the MOFs can enhance the local concentration of CO₂ around the active catalytic centers located inside the pores of the framework, these materials could be used as catalysts for flow chemistry, which is widely used in industry. We further investigated the CO₂ chemical fixation using Hf analogs of VPI-100. Structural characterization and catalytic performance of Hf-VPI-100 are summarized. Moreover, a detailed comparison of VPI-100 and Hf-VPI-100 is made. Different analytical techniques have been used to further understand the reaction mechanism as well as the interaction between the CO₂/epoxide and the frameworks. These insights would help us to design new MOFs as better catalysts for practical applications.

L'objectif de cette thèse était d'évaluer quelques Metal-Organic Frameworks (MOFs), choisis en fonction de leur taille de pores, de leur volume poreux et de leur stabilité thermique, en adsorption et séparation des hydrocarbures. Pour étudier le comportement général des MOFs nous avons choisi des MOFs avec des centres métalliques insaturés, des MOFs à charpente anionique et des ZIFs neutres et avons étudié leur sélectivité en séparation de trois familles d'hydrocarbures, à savoir alcanes, alcènes, aromatiques. Les MOFs à centre métallique insaturé se comportent généralement comme des zéolithes polaires, les ZIFs comme des zéolithes apolaires et/ou comme des tamis moléculaires. Les adsorbants les plus prometteurs sont testés sur des séparations d'intérêt industriel telles que la séparation des isomères de xylène, la séparation des paraffines linéaires, monobranchées et di-branchées et l'adsorption sélective du thiophène en vu de l'évaluation de ces adsorbants en désulfuration des essences.

A modular approach for the synthesis of highly ordered porous and chiral auxiliary (Evans auxiliary) decorated metal–organic frameworks is developed. Our synthesis strategy, which uses known porous structures as model materials for incorporation of chirality via linker modification, can provide access to a wide range of porous materials suitable for enantioselective separation and catalysis. Chiral analogues of UMCM-1 have been synthesized and investigated for the enantioseparation of chiral compounds in the liquid phase and first promising results are reported. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Ce travail de thèse s’inscrit dans un contexte d’explosion des nanoparticules et de leur très grand potentiel pour des applications en cancérologie. Ainsi, deux classes de nanoparticules ont été étudiées afin de valider et de caractériser biologiquement ce potentiel. Premièrement les Nanodiamants hydrogénés (H-NDs) dont l’interaction avec les photons de l’irradiation comme générateur de stress oxidatif était au cœur du postulat physico-chimique. Nous avons non seulement validé cette hypothèse dans plusieurs lignées cellulaires de cancer du rein et du sein notamment, insensibles aux doses d’irradiation étudiées ; mais également identifié la sénescence comme étant la voie activée par le double traitement H-NDs et irradiation. Les Solides hybrides poreux sont également des matériaux prometteurs grâce à leur haut pouvoir d’encapsulation de molécules actives. Nous avons ainsi démontré l’absence de toxicité de ces composés seuls dans quatre lignées de cancer du poumon et du foie, élément essentiel avant d’envisager leur utilisation, chargés avec des principes actifs. Enfin, à l’heure où la réglementation internationale encourage le développement et l’utilisation de modèles alternatifs à l’expérimentation animale, nous avons mis au point un modèle de culture tridimensionnelle d’adénocarcinome mucosécrétant de poumon. Il est utilisé pour l’étude de la progression tumorale ainsi que pour la découverte de nouvelles molécules de chimiothérapie. / The present work focuses on nanoparticles and their great skills for oncology therapies. Two kinds of nanoparticles have been studied in order to biologically validate and characterize their features. The use of hydrogenated Nanodiamonds (H-NDs) as radio sensitizer is based on a physic-chemical postulate where they act as oxidative stress generator through interaction with irradiation. Thus we validated this hypothesis in radio resistant kidney and breast cancer cell lines and identify senescence as the main pathway after co-treatment with H-NDs and irradiation. Metal organic frameworks are also of particular interest for drug delivery because of their very important loading capacities. Here we demonstrate the biocompatibility of the empty compounds in four lung and hepatic cancer cell lines, a main point before their involvement in drug delivery strategies. Finally, following international guidelines encouraging to make animal testing more ethic, we developed a new 3D cell culture mimicking mucinous lung adenocarcinoma. This well characterized model will be used for the study of cancer development and drug screening.

L'objectif de cette thèse était d’évaluer quelques Metal-Organic Frameworks (MOFs), choisis en fonction de leur taille de pores, de leur volume poreux et de leur stabilité thermique, en adsorption et séparation des hydrocarbures. Pour étudier le comportement général des MOFs nous avons choisi des MOFs avec des centres métalliques insaturés, des MOFs à charpente anionique et des ZIFs neutres et avons étudié leur sélectivité en séparation de trois familles d'hydrocarbures, à savoir alcanes, alcènes, aromatiques. Les MOFs à centre métallique insaturé se comportent généralement comme des zéolithes polaires, les ZIFs comme des zéolithes apolaires et/ou comme des tamis moléculaires. Les adsorbants les plus prometteurs sont testés sur des séparations d’intérêt industriel telles que la séparation des isomères de xylène, la séparation des paraffines linéaires, monobranchées et di-branchées et l’adsorption sélective du thiophène en vu de l’évaluation de ces adsorbants en désulfuration des essences. / The aim of this thesis was to evaluate several Metal Organic Frameworks (MOFs), selected based on criteria of pore size, pore volume and thermal stability, in adsorption and separation of hydrocarbons. For studying the general behavior of MOFs in hydrocarbon adsorption, we have chosen MOFs with open metal sites, MOFs with anionic frameworks and neutral ZIFs. The MOFs with open metal sites behave similar to polar zeolites, the ZIFs behave like apolar zeolites and/or like molecular sieves. Finally we selected the most interesting MOFs and tested them in several separations with industrial interest: xylene isomers, paraffin isomers and selective adsorption of thiophene for the purpose of fuel desulfuration.

Wasserstoff ist der ideale Energieträger, da er völlig schadstofffrei verbrennt und einen potentiell hohen Energiegehalt pro Masse besitzt. Die größte Herausforderung für den Gebrauch von Wasserstoff als Kraftstoff ist die Wasserstoffspeicherung in sicheren und kostengünstigen Systemen. Die Ziele und Aufgaben der vorliegenden Doktorarbeit sind, poröse Materialien, die unterschiedliche Struktur und Zusammensetzung besitzen, für die Physisorption von Wasserstoff mittels einer neuartigen volumetrischen Apparatur zu untersuchen. Das Erreichen maximaler Speicherdaten stand nicht im Vordergrund dieser Arbeit. Viel wichtiger war es, einen Struktur – Eigenschafts – (Sorptions) – Zusammenhang zu verstehen, auf deren Basis eine systematische Entwicklung von Wasserstoffspeichermaterialien erfolgen könnte. Zwei Klassen von potentiellen Wasserstoffspeichern wurden erforscht: expandierte Graphitmaterialien und Metallorganische Netzwerke. Neue experimentelle Methoden zur Untersuchung der Wasserstoffspeicherkapazität an modifizierter volumetrischer Apparatur wurden erfolgreich entwickelt und geprüft. Das Verwenden einer der Kammern als Referenzkammer ermöglicht das Ausschließen der experimentellen Artefakte aus der Auswertung der gespeicherten Wasserstoffmenge. Es wurde keine Gaszustandgleichung bei tiefen Temperaturen verwendet, was sehr wichtig bei den Experimenten mit Wasserstoff ist.

Pour faire face à l'augmentation des émissions de CO2 dans l'atmosphère à cause de la production électrique dans des centrales à charbon, le captage en post-combustion au moyen d'un procédé VSA est une solution envisageable. Les adsorbants utilisés dans notre étude sont la TEPA imprégnée sur SiO2, les oxydes de terre rare et le MOF (Metal Organic Frameworks) SIM-1. Pour chaque adsorbant, une étude du perçage puis de la régénération a été effectuée à partir d'une alimentation composée de 15%vol de CO2 et de N2. De ces essais, les conditions opératoires des cycles VSA ont été établies (durées des phases courtes, pas de circulation de purge). En cycle, les performances sont comparées à celle du procédé d'absorption avec la monoéthénolamine. La pureté du désorbat varie de 89,2%vol à 97,2%vol selon les adsorbants et les conditions opératoires. Elle est inférieure à celle du procédé d'absorption (99%vol) mais est correcte pour le transport et le stockage. Le taux de captage évolue de 87,2% à 94,9% (absorption : 98%). La consommation énergétique est inférieure à celle du procédé avec la MEA (de 1,53 à 3,45 MJ.kgCO2 1 pour notre procédé et 3,7 MJ.kgCO2¬1 pour l'absorption) Enfin la productivité est du même ordre de grandeur que celle d'autres procédés VSA de la littérature. Avec le modèle numérique, une étude locale de l'adsorbeur a été menée. Puis grâce à une étude paramétrique, des conditions optimales en cycle ont été déterminées. Les résultats obtenus ont permis de mettre en évidence des performances comparables avec les autres procédés VSA de la littérature. De plus, notre procédé est beaucoup moins énergivore que le procédé d'absorption mais la pureté du désorbat et le taux de captage en CO2 restent inférieurs.

Five new coordination polymers, namely, [Zn2(H2O)2(BBC)](NO3)(DEF)6 (DUT-40), [Zn3(H2O)3(BBC)2] (DUT-41), [(C2H5)2NH2][Zn2(BBC)(TDC)](DEF)6(H2O)7 (DUT-42), [Zn10(BBC)5(BPDC)2(H2O)10](NO3)(DEF)28(H2O)8 (DUT-43), and [Co2(BBC)(NO3)(DEF)2(H2O)](DEF)6(H2O) (DUT-44), where BBC – 4,4′,4′′-(benzene-1,3,5-triyl-tris(benzene-4,1-diyl))tribenzoate, TDC – 2,5-thiophenedicarboxylate, BPDC – 4,4′-biphenyldicarboxylate, DEF – N,N-diethylformamide, were obtained under solvothermal conditions and structurally characterized. It has been shown that compounds DUT-40, DUT-41 and DUT-44 exhibit 2D layered structures with large hexagonal channels. Utilization of additional angular dicarboxylic TDC linker led to the formation of the DUT-42 compound with the structure consisting of three interpenetrated 3D networks. Using the linear co-linker dicarboxylic BPDC, DUT-43 was obtained which forms a complicated 3D architecture arising from the polycatenation of triple-layered 2D building units and 2D single layer units. The pore accessibility of the synthesized compounds in the liquid phase was proved by the adsorption of dye molecules. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Im Hinblick auf eine spätere Anwendung als Katalysatorträger in Hydrierungsreaktionen wurden in dieser Arbeit Adsorptionseigenschaften von Metall-Organischen Gerüstverbindungen (MOFs) in der Flüssigphasenadsorption untersucht. In den Experimenten wurden Materialien gegenübergestellt, bei denen entweder freie Koordinationsstellen am Metallatom (MIL 101, DUT 9, HKUST 1) oder eine abgeschlossene Koordinationssphäre (MOF 5, Zn4O(btb)2, Zn2(bdc)2dabco, ZIF 8, DUT 4, DUT 6) in der Struktur vorlagen. Die Substrate und Lösungsmittel wurden hinsichtlich auf die spätere Verwendung als Edukte in der Hydrierungsreaktion ausgewählt. Neben dem polaren Zimtsäureethylester kamen unpolare Substrate wie Styrol, cis-Cyccloocten und Diphenylacetylen zum Einsatz. Die Materialien wurden desweiteren auf ihre Eignung und Stabilität in der Flüssigphasenhydrierung getestet. Da die untersuchten Metall-Organischen Gerüstverbindungen selbst nicht hydrieraktiv sind, wurden sie als Matrix für die Synthese von Palladium-Nanopartikeln (mittels Incipient Wetness Infiltration) verwendet. Als Referenzkatalysatoren kamen kommerziell erhältliche Pd-Trägerkatalysatoren (Pd@C, Pd@NoritA) und Pd@MOF 5 zum Einsatz. Bei den Experimenten erwies sich Pd@MIL 101 als besonders stabil gegenüber den Reduktions- und Reaktionsbedingungen, sowohl in Gasphasen- als auch Flüssigphasenhydrierungen. Die erzielten Ergebnisse zeigen den starken Einfluss des spezifischen Porenvolumens, der Form der Pore bzw. des Poreneingangs, der Polarität des Substrates und des verwendeten Lösungsmittels auf die adsorbierte Substratmenge. Sie verdeutlichen die Relevanz von Adsorptionsuntersuchungen an neuen Materialien. Das Verständnis der Wechselwirkungen zwischen den verwendeten Lösungsmitteln, Substraten und Adsorbentien ist ein entscheidender Faktor bei der Optimierung von Adsorptionsprozessen und bei der Verwendung von MOFs in heterogen katalysierten Reaktionen. Diese Arbeit zeigt das hohe Potential von Metall-Organischen Materialien im Bereich der heterogenen Katalyse. Unter Verwendung dieser Verbindungen als Trägermaterialien für Palladium können sehr hohe Aktivitäten in Hydrierungsreaktionen erreicht werden, welche z.T. auch industriell genutzte, Aktivkohle basierte Pd-Trägerkatalysatoren übertreffen.