A serious challenge in photocatalytic solar fuel production lies in the design of efficient catalysts that are stable, have visible light response and are easy to make. In order to realize this goal, efforts should be focused on designing new photocatalysts that have such properties to drive the field forward towards commercialization. Metal-Organic Frameworks (MOFs) are a class of crystalline and porous materials that offer tunable and diverse structural and electronic properties that can be exploited for enhanced photocatalytic solar fuels production. This thesis focuses on the utilization and characterization of a 3-D MOF photocatalyst with metal-oxo chain and pyrene-based ligand as secondary building units. Specifically, through hydrothermal synthesis technique, we constructed a bimetallic cerium/titanium MOF that exhibits excellent and stable photoactivity for visible-light driven hydrogen generation. The incorporation of two redox active metals of CeIII /CeIV and TiIII/TiIV in an oxo-chain connected by a photosensitizing organic ligand resulted in a strong ligand-tometal charge transfer (LMTC), evident by EPR, for efficient reduction of water. A high hydrogen production rate of 49 μmol h-1 was achieved, which is attributed to energetic LMTC and better charge separation. This work expands on MOFs photocatalysis field and open new direction towards designing redox active heterometallic MOFs for solar fuels production.

Thesis advisor: Jeffery A. Byers / Thesis advisor: Chia-Kuang Tsung / Host-guest chemistry provides a unique platform for catalysis by combining the specificity of homogeneous catalysts with the stability and recyclability of heterogeneous catalysts. Metal-Organic Frameworks (MOFs), such as UiO-66 are ideal hosts for host-guest catalysis. The vast porous network UiO-66 forms is chemically and thermally stable and the individual cages that make up the crystals can be modified by simple organic syntheses. The method developed in our group provides a mild, synthetically simple route for non-covalent organometallic guest encapsulation that decouples host synthesis from guest encapsulation. In this study, the so-called aperture opening encapsulation method is tested using an unstable class of iron-based carbon dioxide hydrogenation catalysts. The study results in launching an extensive investigation into the driving force behind aperture opening encapsulation with the goal of increasing guest loadings. Various methods to achieve this goal are explored including synthesizing novel UiO-66 linkers and taking advantage of factors such as columbic force. In conclusion, the information gained from a bigger picture examination of aperture opening encapsulation directly leads to guest loadings high enough to utilize useful characterization techniques. Accordingly, a standard protocol for characterization of iron catalysts encapsulated in UiO-66 is developed. / Thesis (MS) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

L'énergie, le développement durable et la santé sont au cœur des préoccupations actuelles de la planète. La disparition inéluctable des énergies fossiles, les conséquences graves des émissions de gaz carbonique sur l'environnement et la santé appellent des solutions rapides et efficaces pour suppléer aux premières et minimiser les autres.Parmi les solutions envisagées la catalyse hétérogènes représentés par les matériaux poreux, ces derniers ont prouvé leur efficacité, néanmoins des obstacles sont à corriger ou à contourner tel que le problème d'inaccessibilité des molécules encombrantes dans sites des micropores de ce matériau. Dans cette thèse nous avons essayé de trouver la solution à ce problème en travaillant sur des nanostructures ZSM-5.Dans une première étape, nous avons optimisé ce matériau en l'occurrence ZSM-5, avec une réduction de la taille des particules, d'une échelle microscopique vers une autre nanométrique, ce qui nous a permis d'augmenter la surface externe après une modification de certains paramètres. Dans la deuxième étape, et afin de donner une entité catalytique à notre support (la zéolithe), nous avons activé ce matériau par l'incorporation des cations, choisis en fonction d'une réaction bien spécifique, qui est celle d'oxydation des méthylènes benzéniques. Pour ce fait nous avons élaboré différents catalyseurs pour nos réactions.Nous avons conclu cette thèse par la catalyse avec la M-ZSM-5 (M = Cu, Cr et Fe) et une étude comparative est faite avec les MOFs qui portent les mêmes cations actifs dans leur partie minérale. / Energy, sustainable development, and health are at the heart of contemporary concerns of the planet. The inevitable disappearance of fossil fuels, the severe consequences of carbon emissions on the environment and health require quick and effective solutions to supplement the first and minimize others. Among the solutions proposed, there are porous materials which have proven their effectiveness; however, there are still obstacles to be corrected or circumvented. In this thesis, we focus on the problem of bulky molecules' inaccessibility in micro pores of the materials we wish to study. In the first part, we optimize the material in this case, ZSM-5, with a reduction in particle size to a microscopic scale to another nano, which allows us to increase the external surface after changing certain parameters. In the second step, in order to give a catalytic entity to our support (zeolite), we activate with this material incorporating cations selected according to a specific property of the benzyl methylenes oxidation reaction. For this reason we developed different method of preparation. We conclude this thesis by catalysis with M-ZSM-5 (M = Cu, Cr and Fe) and a comparative study on the method of preparation and the MOFs that bears the same cations as mineral part which constitutes the materials.

L’évolution rapide des technologies de stockage d’énergie requiert la mise en point de nouveaux matériaux plus performants afin d’utiliser l’énergie relative à l’adsorption d’un fluide (eau) pour restituer l’énergie solaire préalablement stockée sur une période courte (heures) ou prolongée (inter saisonnière). Ces matériaux sont des sels inorganiques (chimisorption de l’eau), des adsorbants physiques ou des composites (sel inorganique dans une matrice poreuse).Les polymères de coordination poreux (PCPs) ou ’Metal-Organic Frameworks‘ (MOFs) sont des solides poreux hybrides dont la structure cristalline résulte de l’association de ligands organiques polycomplexants et de briques inorganiques interagissant par liaisons fortes. Les MOFs présentent une plus grande diversité chimique et structurale par rapport aux solides poreux inorganiques, ce qui permet de varier ‘à la carte’ leur caractère amphiphile, leur volume poreux, la taille et la forme des pores.Dans le cadre de cette thèse, nous avons étudié en premier lieu une série de MOFs poreux et stables dans l’eau, construits à partir des cations métalliques à haut degré d’oxydation (Fe3+, Al3+, Cr3+, Ti4+, Zr4+) et de ligands polycarboxylates. Nous avons choisi cette série de MOFs en tant qu’adsorbants physiques tout en évaluant dans un second temps leur capacité en tant que matrices d’immobilisation de sels inorganiques.L’étude des propriétés d’adsorption d’eau des MOFs seuls a démontré leurs grandes capacités d’adsorption conduisant ainsi à des densités énergétiques relativement élevées pour des systèmes en physisorption pure. La synthèse du MOF le plus performant de cette série (MIL-160(Al)) a été mise à l’échelle. Ce matériau a ensuite été mis en forme et ses propriétés de stockage de chaleur ont été évaluées dans un prototype de laboratoire (réacteur ouvert).Les applications de stockage inter saisonnier requièrent des matériaux avec une densité énergétique plus élevée par rapport à celle des adsorbants physiques et à ce titre, les composites qui résultent de l’encapsulation de sels inorganiques au sein de matrices poreuses sont intéressants en termes de densité énergétique et de stabilité chimique. De ce fait, le deuxième chapitre porte sur l’exploration d’une série de MOFs en tant que matrices d’encapsulation de sels afin de préparer des composites pour le stockage de l’énergie.Les MOFs sélectionnés permettent d’étudier l’influence de certains paramètres de la matrice (balance amphiphile, volume/taille des pores) sur les propriétés d’adsorption d’eau des composites. Les capacités de stockage énergétique des composites ont été évaluées dans les conditions d’utilisation d’un système de stockage d’énergie.Finalement la capacité de stockage élevée et la bonne stabilité de cyclage (adsorption-désorption) des deux meilleurs composites à base de matrices mésoporeuses (MIL-100(Fe) et MIL-101(Cr)) confirment l’intérêt de ces solides pour ce type d’application. / Nowadays the forceful development of the energy storage technologies requires the design of novel adsorbents. Energy reallocation concept allows storing renewable solar energies at short (hours) and long term (inter seasonal) using adsorption method. Energy storage materials can be divided in chemical storage materials, physical storage materials and composite materials (inorganic salt in porous matrix).Metal-Organic Frameworks (MOFs) are a new class of porous crystalline materials that are built from an inorganic subunits and organic ligands defining an ordered structure with regular accessible porosity. In comparison with other classes of porous solids, MOFs display a higher degree of versatility (chemical composition, topology) and tunable amphiphilic character, pore volume, pore size, shape, etc.In this work, we have studied a series of water stable porous metal carboxylates made from cheap metal cations (Fe3+, Al3+, Cr3+, Ti4+, Zr4+) and polycarboxylate linkers as pure physical adsorbents and as host matrices of salts for the design of composite adsorbents. The study of the adsorption properties of pure MOFs in conditions of thermal energy storage system has shown high water adsorption capacity and high energy storage densities.The most promising MOF from this series namely MIL-160(Al) has been prepared at large scale, processed as pellets and then evaluated in open-reactor prototype.The second chapter has been focused on the first exploitation of a series of Metal Organic Framework (MOFs) as host matrices of salts for the preparation of composite sorbents for heat storage application.Indeed, inter seasonal energy storage requires materials with higher energy densities (composite and chemical storage materials), than physical sorption materials can offer. We have selected a series of MOFs differing by their amphiphilic balance and pore volume in order to investigate the impact of such physico-chemical properties on the water sorption properties of composites. The energy storage capacity of salt-MOFs composites has been evaluated in representative conditions of thermal storage devices. The high energy storage capacity and good stability under numerous adsorption-desorption cycles for two composites based on mesoporous MIL-100(Fe) and MIL-101(Cr) confirm the potentiality of such composites for this application.

La tesis Doctoral está dividida en dos grandes bloques: el primero relacionado con el estudio estructural y de flexibilidad de distintos "Zeolític imidazolate fremewroks (ZIFs) utilizando distintas técnicas de caracterización de alta resolución y, además, simulación molecular; así como el efecto en la adsorción de distintas moléculas en fase gas. El segundo bloque hace referencia al estudio de MOFs en aplicaciones biomédicas, en específico en el estudio de adsorción y liberación en fase líquida de fármacos para el tratamiento del glaucoma.

[ES] Se ha desarrollado un método de síntesis "verde" de compuestos metal orgánicos en medio acuoso, a temperatura y presión ambientes, fácilmente escalable y con tiempos de cristalización muy cortos (10 min). El método se ha aplicado con éxito a la síntesis de trimesatos de metales divalentes isoreticulares y con fórmula general M3(BTC)2·12 H2O (M = Ni2+, Co2+, Cu2+ y Zn2+; BTC = trimesato). La estructura de estos materiales presenta dos tipos de centros metálicos ("puente" y "ter-minales") en proporción 2 a 1, ambos con coordinación octaédrica y unidos a 4 moléculas de H2O y a dos oxígenos carboxilato del ligando. Usando este método de síntesis, se han preparado también series de compuestos bimetálicos isoreticulares de Co-Ni y Co-Zn en todo el rango de concentraciones, así como compues-tos de Mn-Ni con una concentración máxima de Mn2+ del 50%. Mediante la combinación de difracción de rayos X (en polvo y de monocristal) y microscopía EDX/SEM se ha demostrado que los compuestos bimetálicos forman verdaderas disoluciones sólidas (no meras mezclas de fases) y que los iones metálicos se dis-tribuyen homogéneamente en todo el cristal. Además, el análisis detallado de la variación de los parámetros de celda con la composición en compuestos Co-Ni y Co-Zn aporta fuertes evidencias de que los iones Co2+ ocupan preferentemente las posiciones "terminales". Se ha evaluado la actividad de los compuestos preparados como catalizadores para la oxidación aeróbica de cumeno (CM) a cumeno hidroperóxido (CHP). El com-puesto monometálico de Co2+, Co-BTC, presentó una elevada actividad, aunque la selectividad a CHP obtenida fue relativamente baja (69%), ya que los iones Co2+ catalizan también la descomposición del CHP formado. Una buena estrategia para optimizar esta selectividad consistió en aislar los iones Co2+ en una matriz de Ni-BTC (que es inerte tanto para la oxidación de CM como para la descomposición de CHP). Así, al disminuir la concentración de iones Co2+ en compuestos bimetálicos Co-Ni se observó un aumento de la selectividad a CHP de hasta el 91% para el material con un 5% de Co. Se ha calculado que estadísticamente el 73% de los iones Co2+ en este material se encuentran aislados, por lo que la des-composición/sobreoxidación del CHP se ve muy limitada. Usando una variación del método de síntesis, se han obtenido también compuestos isoreticulares de Co2+ en los que los ligandos trimesato se han reemplazado parcialmente por ligandos isoftálico o 5-aminoisoftálico. Al utilizar estos com-puestos como catalizadores para la oxidación aeróbica de CM, se ha observado que la introducción de este segundo ligando (y en particular del 5-aminoisoftálico) en la red metal-orgánica facilita la descomposición del CHP formado y aumenta la selectividad final a 2-fenil-2-propanol (PP). Esto se ha atribuido a la creación de defectos puntuales en la red del material, que presentan una mayor actividad para la descomposición de CHP. Siguiendo con la oxidación de CM como reacción modelo, se ha evaluado la actividad catalítica de compuestos isoreticulares de cobalto con ligandos bispirazolato funcionalizados con distintos grupos (CoBPZ, CoBPZ-NO2 y CoBPZ-NH2). En este caso se ha observado una clara influencia del ligando utilizado sobre la acti-vidad catalítica y la selectividad a CHP o PP del material. Mientras que el Co-BPZ presenta una baja conversión de CM y una elevada selectividad a CHP, Co-BPZ-NH2 presenta las características opuestas: una elevada velocidad de reacción pero una baja selectividad a CHP. En este último caso, el producto mayoritario forma-do es el PP. Por último, el estudio de MOFs de cationes divalentes como catalizadores de oxidación se ha completado con una reacción de síntesis de quinazolina mediante acoplamiento oxidativo de bencilamina y 2-aminoacetofenona usando TBHP co-mo oxidante. Como catalizadores para esta reacción se ha utilizado el trimesato de / [CA] S'ha desenvolupat un mètode de síntesi "verda" de compostos metall orgànics en medi aquós, a temperatura i pressió ambients, fàcilment escalable i amb temps de cristal·lització molt curts (10 min). El mètode s'ha aplicat amb èxit a la síntesi de trimesats de metalls divalents isoreticular i amb fórmula general M3(BTC)2·12 H2O (M = Ni2+, Co2+, Cu2+ y Zn2+; BTC = trimesat). L'estructura d'aquests materials presenta dos tipus de centres metàl·lics ("pon" i "terminals") en una proporció de 2 a 1, ambdós amb coordinació octaèdrica i units a 4 molècules d'aigua i a 2 oxígens carboxilat del lligand. Emprant aquest mètode de síntesi, s'han preparat també sèries de compostos bimetàl·lics isoreticular de Co-Ni i Co-Zn en tot el rang de concentracions, així com compostos de Mn-Ni amb una concentració màxima de Mn2+ del 50%. Mitjançant l'ús combinat de difracció de raigs X (en pols i de monocristall) i microscòpia EDX/SEM s'ha demostrat que els compostos bimetàl·lics formen vertaderes dissolucions sòlides (no simples mescles de fase) i que els ions metàl·lics es distribueixen homogèniament en tot el cristall. A més, l'anàlisi detallat de la variació dels paràmetres de cel·la amb la composició de compostos Co-Ni i Co-Zn aporta fortes evidències de que els ions Co2+ ocupen preferentment les posicions "terminals". S'ha avaluat l'activitat dels compostos preparats com a catalitzador per a l'oxidació aeròbica de cumè (CM) a cumè hidroperòxid (CHP). El compost monometàl·lic de Co2+, Co-BTC, presenta una elevada activitat, encara que la selectivitat a CHP obtinguda és relativament baixa (69%), ja que els ions Co2+ catalitzen també la descomposició del CHP format. Una bona estratègia per optimitzar aquesta selectivitat consisteix en aïllar els ions Co2+ en una matriu de Ni-BTC (que és inert tant per a l'oxidació de CM com per a la descomposició de CHP). Així, a mesura que disminueix la concentració d'ions Co2+ en compostos bimetàl·lics Co-Ni s'observa un augment de la selectivitat a CHP de fins el 91% per al material amb un 5% de cobalt. S'ha calculat que estadísticament el 73% dels ions Co2+ d'aquest material es troben aïllats, de manera que la descomposició/sobreoxidació del CHP es veu molt limitada. Emprant una variació del mètode de síntesi, s'han obtingut també compostosisoreticulars de Co2+ en els que els lligands trimesat s'han reemplaçat parcialment per lligands isoftàlic o 5-aminoisoftàlic. Quan aquest compostos s'usen com a catalitzadors per a l'oxidació aeròbica de CM, sobserva que la introducció d'aquest segon lligand (i en particular del 5-aminoisoftàlic) en la xarxa metallorgànica es facilita la descomposició del CHP format i augmenta la selectivitat final a 2-fenil-2-propanol (PP). Això s'ha atribuït a la creació de defectes puntuals en la xarxa del material, que presenten una major activitat per a la descomposició del CHP. Seguint amb l'oxidació de CM com a reacció model, s'ha avaluat l'activitat catalítica de compostosisoreticulars de cobalt amb lligands bispirazolat funcionalitzats amb distints grups (CoBPZ, CoBPZ-NO2 i CoBPZ-NH2). En aquest cas s'ha observat una clara influència del lligand utilitzat sobre l'activitat catalítica i la selectivitat a CHP o PP del material. Mentre que el CoBPZ presenta una baixa conversió de CM i una elevada selectivitat a CHP, CoBPZ-NH2 presenta les característiques oposades: una elevada velocitat de reacció però una baixa selectivitat a CHP. En aquest últim cas, el producte majoritari format és el PP. Per últim, l'estudi de MOFs amb cations divalent como a catalitzadors d'oxidació s'ha completat amb una reacció de síntesi de quinazolina mitjançant acoblament oxidatiu de benzilamina i 2-aminoacetofenona emprant TBHP como a oxidant. Com a catalitzadors per aquesta reacció s'ha utilitzat el trimesat de coure, HKUST-1, així com materials isoreticular amb lligands mixtes obtinguts reemplaçant pa / [EN] A "green" synthesis method has been developed for the preparation of metal organic frameworks in aqueous media, which is easily scalable, at room tempera-ture, ambient pressure and very short crystallization times (10 min). This method has been successfully applied to the synthesis of isoreticular divalent metal trimesates of general formula M3(BTC)2·12 H2O (M = Ni2+, Co2+, Cu2+ y Zn2+; BTC = trimesate). The structure of these compounds features two types of metal centers ("bridging" and "terminal") in a 2 to 1 ratio, both with octahedral coordina-tion and linked to 4 water molecules and 2 carboxylate oxygens of the ligand. Using this method, two series of bimetallic isoreticular compounds of Co-Ni and Co-Zn have also been prepared in all range of compositions, as well as bimetallic Mn-Ni compounds up to a maximum concentration of 50% of Mn2+. A combined X-ray diffraction (powder and single crystal) and EDX/SEM has shown that these bimetallic compounds form true solid solutions (not simple mixture of phases) and that both ions distribute homogeneously throughout the crystal. A detailed analysis of the variation of cell parameters with the composition strongly sug-gests that Co2+ ions occupy preferentially the "terminal" positions of the frame-work. The materials obtained with the above method have been evaluated as catalysts for the aerobic oxidation of cumene (CM) to cumene hydroperoxide (CHO). The monometallic Co2+ compound, Co-BTC, showed a high catalytic activity, but a relatively low selectivity to CHP 69%), since the Co2+ ions can also catalyze the decomposition of the formed CHP. A good strategy to optimize the CHP selectivity consisted in isolating the Co2+ ions into a Ni-BTC (which is inert for both CM oxidation and CHP decomposition). In this way, as the concentration of Co2+ ions in the bimetallic Co-Ni compound decreases, a parallel increase of the CHP selec-tivity was observed, up to 91% for the material with 5% of Co. In this compound, 73% of the total Co2+ ions are statistically isolated, so that decomposi-tion/overoxidation of CHP is unlikely to occur. By using a variation of the above synthesis method, additional isoreticular Co2+ compounds have been prepared in which the trimesate ligands have been partially replaced by either isophthalic or 5-aminoisophthalic. When these compounds were used as catalysts for the aerobic oxidation of cumene, we observed that the introduction of this second ligand (in particular in the case of 5-aminoisophthalic) into the framework facilitates decomposition of CHP and in-creases the final selectivity to 2-phenyl-2-propanol (PP). This has been attributed to the progressive creation of point defects in the framework, having a higher activity for CHP decomposition. Following with the aerobic oxidation of CM as model reaction, we evaluated the catalytic activity of isoreticular cobalt compounds having bispyrazolate ligands bearing differnent functional groups (CoBPZ, CoBPZ-NO2 and CoBPZ-NH2). In this case, there is a clear influence of the ligand used on the catalytic activity of the material and the obtained selectivity to CHP or PP. While CoBPZ showed a low CM conversion and high CHP selectivity, the opposite properties are obtained for the Co-BPZ-NH2: i.e., a high reaction rate but a low CHP selectivity. In this latter case, the major product of the reaction was PP. Finally, the evaluation of divalent MOFs as oxidation catalysts has been complet-ed by addressing the synthesis of quinazoline through the oxidative coupling reaction of benzylamine and 2-aminoacetophenone using TBHP as oxidant. As catalysts for this reaction we have used a copper trimesate, HKUST-1, as well as isoreticular mixed-ligand compounds obtained by partially replacing trimesate ligands by 5-hydroxyisophthalic (OH-isophthalic). / Nowacka, AE. (2019). Divalent Metal Organic Frameworks as Heterogeneous Oxidation Catalysts [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/129872

In this dissertation a novel ZLC setup has been developed as part of a DOE-funded grant in collaboration with UOP, to provide rapid screening of novel adsorbent materials for carbon capture (CC). The key features of the new apparatus that was developed are: the use of 5-15 mg of sample and a dual detector system – a thermal conductivity detector (TCD) for single component measurements and a mass spectrometer for studying the influence of water and other impurities. Improvements over previous ZLC apparatuses include: 1. Extension to lower flowrates, i.e. < 3 cc/min, thereby reducing consumption of gases and allowing to run the system under equilibrium control conditions; 2. A new gas dosing system that allows the use of vapours without a chilled bath and bubbler system; 3. A new switching valve system, which prevents leakages; 4. Automated series of experiments, which are implemented using Labview. The new ZLC technique was first applied to provide rapid screening capacity ranking of more than 15 MOF materials from the open literature and three typical zeolites for carbon capture. At the point of interest for flue gas application (38°C, 0.1 bar CO2 partial pressure), Mg/DOBDC was found to outperform significantly all other MOFs and benchmark zeolites at the point of interest in low pressure physisorption of CO2. The ZLC was also used to investigate steaming on Ni/DOBDC as well as see the effect of forming powders into pellets. The new ZLC system also enables one to measure micropore and macropore diffusivity. Experiments were carried out on both powders and pellets of typical MOFs and zeolites. For Co/DOBDC crystals, since the system is close to equilibrium control even at the highest flow rate, a low limit of diffusivity can be estimated. For all the formed samples of Ni/DOBDC and 13X pellets, the results indicate that mass transfer is controlled by macropore diffusion. The ZLC technique can also estimate realistic void fraction and tortuosity values for the pellets. The new ZLC technique was applied to study the stability on the MOF M/DOBDC series. The preliminary water tests showed that all M/DOBDC samples are highly hydrophilic. Therefore in a process design using these MOFs, we conclude that there is a needs to use a guard bed layer to adsorb water or use a gas drying unit before the CO2 capture section of the plant. The ZLC system appears to be extremely useful to accelerate the deactivation of samples due to SOX and NOX impurities. The key advantages are based on the fact that the treatment can be repeated in situ, in a relatively simple way using a very small sample. The results show that in the presence of impurities and water the candidate MOFs undergo significant deactivation. The Ni based material shows the best resistance to degradation. This result indicates further that there would be a need for a drying unit prior to the carbon capture adsorption process.

No description available.

There is a pressing need for advanced solid-state materials that can be implemented in industrial gas separation processes to achieve separations with a significantly reduced energy input compared to what is typically required from current technologies. Although certain porous materials like zeolites bear some commercial significance for gas separation; their inherent lack of tunability limits the extent to which these materials may be exploited in industry. Zeolite-like Metal-Organic Frameworks (ZMOFs) are a sub-class of Metal-Organic Framework materials (MOFs) that show a structural semblance to zeolites while possessing the tunability advantages of MOF materials. ZMOFs which are topologically similar to certain zeolites can be functionalised and tuned in numerous ways to improve their gas separation properties. In this work, indium-based sod-ZMOF was tuned by cation-exchange and then characterised by different experimental tools such as single-crystal x-ray diffraction, elemental analysis and gas adsorption. It was found that various parameters like the choice of cation, the concentration of salt solution and the choice of solvent had a significant bearing on the cation-exchange of sod-ZMOF and its subsequent adsorption properties.

A growing field of research has evolved around the design and synthesis of a variety of porous metal-organic framework (MOF) materials. Some of the most promising areas for which these materials are potentially useful candidates include gas-separation, heterogeneous catalysis, and gas-storage, and all of these applications involve placing the MOF under pressure. There is clearly a need to understand the structural response of MOFs to applied pressure. Nevertheless, hitherto there are very few published investigations dedicated to determining the behaviour of porous hybrid materials under pressure. Through the use of high-pressure single-crystal X-ray diffraction studies, a series of MOF materials have been studied. Here we present the effect of pressure on a series of MOFs. In chapter 2, the effect of pressure on the prototypical MOF called MOF-5 was studied experimentally from ambient pressure to 3.2 GPa. Here, application of pressure was driven by the hydrostatic medium being forced into the pores of the MOF, which altered the mechanical properties of MOF-5, in particular, medium inclusion delayed the onset of amorphization. Complementary computational analysis was also performed to elucidate further the effect of medium inclusion on compressive behaviour. Detailed structural data was also collected as a function of pressure on the MOF Cu-btc. Application of pressure caused solvent to be squeezed into the pores (like MOF-5) until a phase transition occurred, driven by the sudden compression and expansion of equatorial and axial Cu–O bonds. High-pressure post-synthetic modification of a MOF is reported for the first time. On application of pressure of 0.2 GPa to the Cu-based MOF called STAM-1, a ligand exchange reaction takes place resulting in a change in pore size, shape, and hydrophilicity of the resulting pores. Here, we also demonstrate the ability to force hydrophilic molecules into hydrophobic pores using pressure, counteracting the hydrophobic effect. A high-pressure combined experimental and computational study has been carried to probe the effect of pressure on ‘breathing’ mechanisms in a zeolitic imidazolate framework (or ZIF) called ZIF-8. The penetration of guest molecules and the accommodation of pressure are shown to be inextricably linked to the rotation of methylimidazolate groups in the structure. Finally, the application of pressure to the MOF Sc₂BDC₃ and the nitro functionalized derivative Sc₂(NO₂-BDC)₃ was also studied. Here, the effect of chemical modification of the organic ligand, whilst maintaining framework topology, has been investigated as it pertains to compressibility. Directionality of compression is observed and this is rationalized with respect to the framework topology and medium inclusion/exclusion.