Esta tesis doctoral resume nuestros esfuerzos por contribuir al desarrollo de nuevos catalizadores heterogéneos basados en compuestos Metal-Orgánico estructurados (MOFs). Para ello, y con el fin de cubrir un amplio espectro de posibilidades en el diseño de catalizadores basados en MOFs, se han considerado distintos materiales en los que los centros catalíticos se encuentran situados en los nodos metálicos, en los ligandos orgánicos o encapsulados en el interior del sistema poroso del material. En consecuencia, los resultados presentados se organizan en tres bloques, en función de dónde se localizan los centros activos dentro del material. A lo largo de este estudio se ha prestado especial interés en evaluar el verdadero potencial de los MOFs con respecto a otros catalizadores homogéneos y heterogéneos existentes, así como en determinar su estabilidad y reusabilidad, ya que se trata de las dos objeciones más importantes que se plantean al considerar el uso de los MOFs para aplicaciones catalíticas. En el primer bloque de resultados se ha evaluado la actividad catalítica de varios MOF con iones Cu2+ en los nodos metálicos en reacciones que pueden ser catalizadas por otros catalizadores homogéneos y heterogéneos que contienen este mismo tipo de centros. En particular, varios MOFs de cobre han demostrado ser catalizadores heterogéneos activos, selectivos, estables y reusables para la oxidación aeróbica de alquenos activados (Capítulo 1), acoplamiento oxidativo C-O por activación directa de enlaces C-H (Capítulo 2), síntesis regio-selectiva de triazoles por adición “click” de azidas a alquinos (Capítulo 3), así como para la síntesis de propargilaminas y derivados heterocíclicos mediante reacciones de acomplamiento de multicomponentes. (Capítulo 4). Para completar este bloque de resultados, en el capítulo 5 se evalúa el comportamiento de MOFs con oxo-agregados de Zr con propiedades semiconductoras como fotocatalizadores para la generación de H2 por disociación de agua . En el capítulo 6 se describe el desarrollo de un nuevo método de modificación post-síntesis que permite convertir los grupos amino libres en los ligandos de un MOF en especies quelante tipo oxamato, lo que nos permite introducir centros catalíticos metálicos adicionales directamente anclados a las paredes del MOF. El potencial de esta estrategia se demuestra a través de la introducción de iones Cu2+ y el estudio de la actividad catalítica de los materiales resultantes en reacciones típicas catalizadas por los nuevos centros, como las ya descritas en los Capítulos 3 y 4. Como último bloque de esta tesis, en el Capítulo 7 se describe la preparación de nanopartículas de Pd encapsuladas en el interior de MOFs de Zr (UiO-66 y UiO-67) mediante adsorción en fase gas de un precursor de Pd seguida de descomposición/reducción mediante irradiación con luz UV. La localización de las nanopartículas metálicas exclusivamente en el interior de las cavidades estructurales confiere al material propiedades de selectividad de forma, como demostramos para la reducción selectiva de compuestos carbonílicos con diferente impedimento estérico a los correspondientes alcoholes. / Luz Mínguez, I. (2014). Materiales metal orgánicos estructurados como catalizadores heterogéneos [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48489 / TESIS

Gaining control over the assembly of crystalline solid-state materials has been significantly advanced through the field of reticular chemistry and metal organic frameworks (MOFs). MOFs have emerged as a unique modular class of porous materials amenable to a rational design with targeted properties for given applications. Several design approaches have been deployed to construct targeted functional MOFs, where desired structural and geometrical attributes are incorporated in preselected building units prior to the assembly process. This dissertation illustrates the merit of the molecular building block approach (MBB) for the rational construction and discovery of stable and highly porous MOFs, and their exploration as potential gas storage medium for sustainable and clean energy applications. Specifically, emphasis was placed on gaining insights into the structure-property relationships that impact the methane (CH4) storage in MOFs and its subsequent delivery. The foreseen gained understanding is essential for the design of new adsorbent materials or adjusting existing MOF platforms to encompass the desired features that subsequently afford meeting the challenging targets for methane storage in mobile and stationary applications.In this context, we report the successful use of the MBB approach for the design and deliberate construction of a series of novel isoreticular, highly porous and stable, aluminum based MOFs with the square-octahedral (soc) underlying net topology. From this platform, Al-soc-MOF-1, with more than 6000 m2/g apparent Langmuir specific surface area, exhibits outstanding gravimetric CH4 uptake (total and working capacities). It is shown experimentally, for the first time, that the Al-soc-MOF platform can address the U.S. Department of Energy (DOE) challenging gravimetric and volumetric targets for the CH4 working capacity for on-board CH4 storage. Furthermore, Al-soc-MOF-1 exhibits the highest total gravimetric and volumetric uptake for carbon dioxide and the utmost total and deliverable uptake for oxygen at relatively high pressures among all microporous MOFs. Additionally, the research studies presented in this dissertation highlight the latest discoveries on our continuous quest for highly-connected nets. Specifically, we report the discovery of two fascinating and highly-connected minimal edge-transitive nets in MOF chemistry, namely pek and aea topologies, via a systematic exploration of rare earth metal salts in combination with relatively less symmetrical 3-connected tricarboxylate ligands. Adsorption studies revealed that pek-MOF-1 offers excellent volumetric CO2 and CH4 uptakes at high pressures.

Synthesis of materials with certain properties for targeted applications is an ongoing challenge in materials science. One of the most interesting classes of solid-state materials that have been recently introduced with the potential to address this is metal-organic frameworks (MOFs). MOFs chemistry offers a higher degree of control over materials to be synthesized utilizing various new design strategies, such as the molecular building blocks (MBBs) and the supermolecular building layers (SBLs) approaches. Depending on using predetermined building blocks, these strategies permit the synthesis of MOFs with targeted topologies and enable fine tuning of their properties. This study examines a number of aspects of the design and synthesis of MOFs while exploring their possible utilization in two diverse fields related to energy and pharmaceutical applications. Concerning MOFs design and synthesis, the work presented here explores the rational design of various MOFs with predicted topologies and tunable cavities constructed by pillaring pre-targeted 2-periodic SBLs using the ligand-to-axial and six-connected axial-to-axial pillaring strategies. The effect of expanding the confined spaces in prepared MOFs or modifying their functionalities, while preserving the underlying network topology, was investigated. Additionally, The MBBs approach was employed to discover new modular polynuclear rare earth (RE)-MBBs in the presence of different angular polytopic ligands containing carboxylate and nitrogen moieties with the aid of a modulator. The goal was to assess the diverse possible coordination modes and construct highly-connected nets for utility in the design of new MOFs and enhance the predictability of structural outcomes. The effect of adjusting ligands’ length-to-width ratio on the prepared MOFs was also evaluated. As a result, the reaction conditions amenable for reliable formation of the unprecedented octadecanuclear, octanuclear and double tetranuclear RE-MBBs were isolated, and their corresponding MOFs were successfully synthesized and characterized. Regarding the applications of MOFs, gas sorption behavior of the novel prepared MOFs was studied to establish structure-property relationships that elucidate the effect of using different metals and/or ligands on tuning various properties of the prepared compounds. Furthermore, the magnetic properties of selected MOFs were investigated. Besides, as a proof-of-concept, known neutral and anionic MOFs were considered as potential drug delivery carriers.

The development and design of efficient catalysts are essential for catalytic energy technologies, accompanied with the fundamental understanding of structure-property relationships of these catalysts. Metal-organic frameworks (MOFs), as the new class of promising catalysts, have been intensively investigated primarily in their fundamental electrochemistry and the broad spectrum of catalytic applications due to their structural flexibility, tailorable crystalline, and multi-functionality. In this work, we combine experiments and mechanism investigation to gain a fundamental understanding of how the surface property and the structure of MOFs affect their catalytic performance. With the aim of material design for MOFs catalysts, we developed two novel superhydrophilic and aerophobic metal-organic frameworks (AlFFIVE-1-Ni MOFs and FeFFIVE-1-Ni MOFs) used as electrocatalysts for the first time during oxygen evolution reactions (OER). Under the facilitation of hydrophilicity and aerophobicity, developed FeFFIVE-1-Ni MOFs electrocatalysts deliver optimal OER performance, better than that of the state-of-art RuO2 and referred NiFe-BDC MOFs electrocatalysts. Most importantly, the practical strategy demonstrated that the hydrophilic and aerophobic structure of MOFs does indeed deliver the optimal electrocatalytic performance. With the aim of investigating the structural transformation process of metal-organic framework, we used a series of advanced characterization techniques to monitor the structure evolution and defects presence for post-heating treated UiO-66 MOFs. The structural and electronic features of UiO-66 MOFs were intensely studied in their hydroxylated, dehydroxylated, defected, and pyrolytic forms. Meanwhile, one concept about the framework situation, quasi-MOF (like a transition state, defined high activation along the structure evolution corresponding to the presence of many defects), was presented and demonstrated. Compared with pristine UiO-66 MOF, the Quasi-MOF with the presence of active defects showed enhanced catalytic activity on the Meerwein-Ponndorf-Verley reduction reaction, which offers an opportunity to understand the structure-property relationship along with the structure evolution process of UiO-66 MOFs.

Zeolitic imidazolate frameworks (ZIFs) is a new class of metal-organic frameworks (MOFs) with zeolite-like properties such as permanent porosity, uniform pore size, and exceptional thermal and chemical stability. Until recently, ZIF materials have been mostly synthesized by solvothermal method. In this thesis, further analysis to tune the size and morphology of ZIF-8 is done upon our group’s recent success in preparing ZIF-8 crystals in pure aqueous solutions. Compositional parameters (molar ratio of 2-methylimidazole/Zn2+, type of zinc salt reagents, reagent concentrations, addition of surfactants) as well as process parameters (temperature and time) were systematically investigated. Upon characterizations of as-synthesized samples by X-ray powder diffraction, thermal gravimetric analysis, N2 adsorption, and field-emission scanning electron microscope, the results show that the particle size and morphology of ZIF-8 crystals are extremely sensitive to the compotional parameters of reagent concentration and addition of surfactants. The particle size and morphology of hydrothermally synthesized ZIF-8 crystals can be finely tuned; with the size ranging from 90 nm to 4 μm and the shape from truncated cubic to rhombic dodecahedron.

Copper-based materials are one of the most promising catalysts for performing transformations of important organic compounds in both academic and industrial operations. However, it is challenging to consistently synthesize highly active and stable copper species as heterogeneous catalysts due to their relatively high surface energy. As a result, agglomeration usually occurs, which limits the catalytic activities of the copper species. The work presented in this dissertation shows different synthetic strategies for obtaining active and stable copper-based materials by modifying chemical/physical properties of copper nanoparticles (NPs). Emphasis is placed on discussing specific catalytic systems, including carbon-supported catalysts (monometallic and bimetallic copper-based heterogeneous catalysts) and titania-supported catalysts, and their advantages in terms of catalytic performance. In recent years, there has been increasing interest in using metal-organic frameworks (MOFs) as a sacrificial template to obtain carbon-supported NPs via a thermolysis process. The advantages of using MOFs to prepare carbon supported nanomaterials are a fine distribution of active particles on carbon matrix without post-synthesis treatments and corresponding increased catalytic activity and stability in many reaction conditions. To better understand the potential of this synthetic approach, MOF pyrolyzed products have been characterized. Then, they were applied as heterogeneous catalysts for several chemical reactions. In particular, the high energy copper-based MOF, CuNbO-1, was decomposed to obtain an amorphous copper species supported on carbon (a-Cu@C). This catalyst was found to be highly active for reduction, oxidation, and N-arylation reactions without further tuning or optimization. Higher catalyst turnover numbers for each of these transformations were obtained when comparing a-Cu@C activity to that of similar Cu-based materials. To improve catalyst performance, a secondary metal can be introduced to create synergistic effects with the parent copper species. In order to gain insights into the role of the second metal, a well-known Cu-MOF, HKUST-1, was doped with nickel, cobalt, and silver solutions, followed by a decomposition process with 2,4,6-trinitrotoluene (TNT) as additive. This additive was used to enhance the rapid thermolysis of the bimetallic MOFs. In these bimetallic systems, the addition of a second metal was found to help in dispersing both metals over the carbon composite support and in influencing the particle size and oxidation state of the metals. Catalytic performance showed that even <1% of a secondary metal increased the rate for nitrophenol reduction. Optimal catalytic performance was achieved using a Ni-CuO@C bimetallic catalyst. Another synthetic strategy for Cu-catalyst preparation involves using the deposition-precipitation method, in which a copper catalyst anchored on a titania support was synthesized at low weight % in order to obtain a single atom catalyst (1-Cu/TiO2). The higher copper loading catalyst, 5-Cu/TiO2, was synthesized as a benchmark catalyst for comparison. The copper structure in the synthesized catalysts was investigated by powder X-ray diffraction (PXRD), Raman, scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDX), X-ray photoelectron spectroscopy (XPS), N2 physisorption and inductively coupled plasma mass spectrometry (ICP-MS) in order to characterize physical and chemical properties. STEM-EDX observations showed single atom copper species less than 0.75 nm in size, as well as nanoparticles with an average diameter of ~1.31 nm. This catalyst was highly active in the reduction of nitro-aromatic compounds with NaBH4 at room temperature. The small to atomic level sizes of the Cu species and multiple oxidation states of Ti species were found to play a crucial role in the catalytic activity.

The development of the new cathode and anode materials of Lithium-Ion Batteries (LIBs) with high energy density and outstanding electrochemical performance is of substantial technological importance due to the ever-increasing demand for economic and efficient energy storage system. Because of the abundance of element sulfur and high theoretical energy density, Lithium-Sulfur (Li-S) batteries have become one of the most promising candidates for the next-generation energy storage system. However, the shuttling effect of electrolyte-soluble polysulfides severely impedes the cell performance and commercialization of Li-S batteries, and significant progress have been made to mitigate this shuttle effect in the past two decades. Coordination polymers (CPs) or Metal-organic Frameworks (MOFs) have been attracted much attention by virtue of their controllable porosity, nanometer cavity sizes and high surface areas, which supposed to be an available material in suppressing polysulfide migration. In this thesis, we investigate different mechanisms of mitigating polysulfide diffusion by applying a layer of MOFs (including Y-FTZB, ZIF-7, ZIF-8, and HKUST-1) on a separator. We also fabricate a new free-standing 2D coordination polymer Zn2(Benzimidazolate)2(OH)2 with rich hydroxyl (OH-) groups by using a simple, scalable and low cost method at air/water surface. Our results suggest that the chemical stability, the cluster morphology and the surface function groups of MOFs shows a greater impact on minimizing the shuttling effect in Li-S batteries, other than the internal cavity size in MOFs. Meanwhile, the new design of 2D coordination polymer efficiently mitigate the shuttling effect in Li-S battery resulting in a largely promotion of the battery capacity to 1407 mAh g-1 at 0.1 C and excellent cycling performance (capacity retention of 98% after 200 cycles at 0.25C). Such excellent cell performance is mainly owing to the fancying physical and chemical structure controllability of MOFs or CPs, which has substantial potential for future commercial utilizations.

The controlled assembly of molecular building blocks is an emerging strategy that allows for the preparation of materials with tailor-made properties. This involves the precise combination of molecular subunits that interact with one another via specifically designed reactive sites. Such a strategy has produced materials exhibiting remarkable properties, including those based on metal-organic frameworks and single-molecule magnets. The present Thesis aims to highlight how such metal-organic assemblies can be engineered at the molecular level to promote certain desired functionalities. Specifically, Chapter 2 will focus on the confinement effects of a crystalline sponge on a ferrocene-based guest molecule that is nanostructured within the porous cavities of a host material. In doing so, we evaluate how one can exert some level of control over the binding sites of the guest molecule, through the addition of electron-withdrawing groups, as well as tuning the physical properties of the guest itself through molecular encapsulation. Notably, we demonstrate a distinct change in the dynamic rotational motion of the ferrocene molecules once confined within the crystalline sponge. In Chapter 3, we investigate the generation of slow relaxation of the magnetization from a Co(II)-based metal-organic framework. We compare this to a closely related 2D Co(II) sheet network, and how slight changes in the crystal field, probed through computational methods, can impact the magnetic behaviour. This type of study may be particularly beneficial in the optimization of single-ion magnets, by sequestering metal centres in select chemical environments, and minimizing molecular vibrations that may offer alternative magnetic relaxation pathways. We extend these principles in Chapter 4, through the use of a nitrogen-rich ligand that acts as a scaffold for Ln(III) ions, thereby yielding 0D and 1D architectures. The coordination chemistry of Ln(III) ions with N-donor ligands remains scarce, especially when evaluated from a magnetic perspective, and therefore, we sought to determine the magnetic behaviour of such compounds. The monomeric unit displays clear single-molecule magnet behaviour with an energetic barrier for the reversal of the magnetization, while the 1D chain displays weaker magnetic characteristics. Nevertheless, such compounds incorporating nitrogen-rich ligands offer much promise in the design of environmentally-friendly energetic materials. In Chapter 5, we take a look at different two different systems that involve the formation of radical species. On one hand, we can promote enhanced magnetic communication between Ln(III) ions, which is typically quite challenging to achieve given the buried nature of the 4f orbitals, and on the other hand, we rely on a redox-active ligand to design stimuli-responsive metal-organic assemblies. The latter case provides access to “smart” molecular materials that can respond to changes in their environment. Here, a multi-stimuli responsive nanobarrel was studied, which displayed sensitivity to ultraviolet radiation, heat and chemical reduction. Lastly, Chapter 6 provides a new method for the systematic generation of cationic frameworks, termed Asymmetric Ligand Exchange (ALE). This strategy focuses on the replacement of linear dicarboxylates with asymmetric linkers that features one less negative charge, in order to tune the ionicity of porous frameworks. This allows for the retention of the structural topology and chemical reactivity of the original framework, representing distinct advantages over other similar strategies. Methods to retain permanent porosity in such cationic frameworks are also proposed. Altogether, these studies highlight how the directed assembly of ordered networks can generate varied properties of high scientific interest.

Philosophiae Doctor - PhD / The application of porous materials into industrial hydrogen (H2) storage systems is based on their use in combination with high-pressure cylinders. The processing of metal-organic frameworks (MOF) powders into shaped forms is therefore imperative in order to counteract the adverse effects of poor packing of powders in cylinders. The fabrication of shaped MOFs has, however, been shown to be accompanied by compromised properties such as surface areas, gravimetric and volumetric H2 capacities, and also the working/deliverable H2 capacities in comparison to MOF powders.

Les réseaux métallo-organiques (MOF) sont une nouvelle classe de matériaux poreux hybrides. Néanmoins leurs propriétés uniques introduisent également des difficultés significatives dans la caractérisation par adsorption de gaz. Dans cette thèse, la création d'un code source libre est détaillé, pour standardiser le traitement des isothermes. En utilisant ce code, un traitement à haut débit de plus de 18 000 isothermes est utilisé pour explorer l'échelle d'incertitude présente dans les données publiées sur l'adsorption dans les matériaux poreux. De plus, la mesure directe de l'enthalpie différentielle de l'adsorption en utilisant la microcalorimétrie s'avère être un excellent moyen d'obtenir la contribution des interactions particulières sur l'énergie d'adsorption. Ensemble, ces méthodes peuvent être utilisées pour étudier les sources d'incertitude des MOF. On étudie d’abord l’impact des défauts structurels au moyen d’une méthode post-synthétique alternative de génération de linker/cluster manquants dans l'UiO-66(Zr). Le traitement des matériaux pour leurs utilisations dans un environnement industriel par façonnage est étudié ici sous l’effet de la granulation par voie humide sur trois MOF topiques (UiO-66(Zr), MIL-100(Fe) et MIL-127(Fe)). Enfin, les comportements contre-intuitifs intrinsèques aux cristaux poreux «souples» sont étudiés, où la structure elle-même est responsable de la fluctuation dans les isothermes d'adsorption. Ici, une étude fondamentale sur un matériau flexible DUT-49 (Cu), apporte des informations sur la source de flexibilité induite par adsorption et sa changeabilité par modification structurelle / Metal organic frameworks (MOF) are novel adsorption materials with unique and desirable properties. However, structural defects, processing and structural compliance can lead to irreproducibility in adorption measurements. In this thesis, the creation of an open-source codebase is detailed, which is intended to standardize the processing of isotherms. Using this framework, high throughput processing of over 18 000 isotherms is used to explore the scale of uncertainty present in published adsorption data. Then, direct measurement of the differential enthalpy of adsorption using microcalorimetry is shown to be an excellent avenue of obtaining further insight into the contribution of guest-host and host-host interactions to the overall energetics of adsorption. Together, these methods are used to study some of the sources of the variability of MOFs, and quantify their effect. First, the impact of structural defects is investigated, through an alternative post-synthetic method of missing linker/cluster generation in the prototypical UiO-66(Zr) MOF. The processing of materials for their use in an industrial environment through shaping is another potential source of performance modification, which is here studied as the effect of wet granulation on three topical MOFs (UiO-66(Zr), MIL-100(Fe) and MIL-127(Fe)). Finally, counterintuitive behaviours intrinsic to ``soft'' porous crystals are investigated, where the structure itself is responsible for fluctuation in adsorption isotherms. A fundamental study on a copper paddlewheel based material, DUT-49(Cu) yields know-how on the source of adsorption induced compliance and its tunability through structural modification