Porphyrin-related MOFs: structural design towards environmental challengues

418 p.Development and improvement of multifunctional and environmentally friendly materials is a constant challenge for Materials Science and Technology. In this sense, MOF (Metal-Organic Framework) materials are of great interest, due to the fact that these porous solid coordination networks exhibit attractive properties, with potential applications in fields in which society manifests an increasing demand of knowledge as, for example, energy storage and transport, drug delivery, capture of pollutants and greenhouse effect gases, and heterogeneous catalysis, among others. In this context, the work herein presented was designed with the aim of developing new porphyrin-based MOF materials. Thus, our goal is to mimic the functions that porphyrins play in biological systems, as catalysis, in order to reproduce them in the solid state, as well as applications with environmental interest, as gas sorption and separation. With this aim, TCPP porphyrin (meso-tetra-4-carboxyphenylporphyrin) and protoporphyrin IX have been combined with first transition metals, such as manganese, nickel and copper. In this way, we explored the different coordination modes that these ligands offer with different metals. In addition, carboxylic secondary ligands (1,2,4,5-benzenetetracarboxylic acid and isophthalic acid) have been occasionally used as modulating agents. The synthesis design has been focused on suitable combinations of metals and ligands and the selection of the proper conditions. In this way, even if quite a high amount of compounds were obtained, just five of them are presented in this thesis, synthesized under mild solvothermal conditions. Preliminary characterization has been carried out using quantitative elemental analysis, infrared spectroscopy, X-ray diffraction and fluorescence and density measurements. The structural study was performed using single-crystal X-ray diffractometry and the thermal study was carried out by means of thermogravimetry and thermodifractometry. In compounds with the appropriate structural features, heterogeneous catalytic experiments and gas and pollutants adsorption experiments have been performed, according to the aim of this thesis. In addition, in cases where it was considered appropriate, compounds have also been characterized by ultraviolet-visible (UV-Vis) and electron paramagnetic resonance (EPR) spectroscopy and by means of magnetic susceptibility measurements. Besides, occasionally, quantum-mechanical calculations based on the functional density theory (DFT) have been carried out. The first compound, with formula [Cu24(m-BDC)24(DMF)20(H2O)4]·24DMF·40H2O, (DMF = N,N-dimethylformamide) consists of cuboctahedral clusters of 24 CuII ions linked by isophthalic acid (m-BDC), where protoporphyrin IX plays an important role in the production of high quality crystals. By means of a crystallochemical study including other similar compounds existing in the literature, in this thesis two mother structures, of greater symmetry, have been identified, the rest of them deriving from them. On the other hand, structural features of this compound, able to host a large number of solvent molecules, correspond to its adsorption capability, confirmed by the study of pollutants adsorption in aqueous solution, with adsorption kinetics are among the most rapid in literature. Faced with the difficulty of obtaining new materials with protoporphyrin IX, the inclusion of porphyrin TCPP as the main ligand has allowed to obtain the 2D compound [Mn3(TCPP)(H2O)4]·nD (D=solvent), with a layered crystalline structure, which consists of MnTCPP units linked by dimers of pentacoordinated MnII. This arrangement gives rise to large structural voids. The use of diverse characterization techniques allowed to determine its high thermal stability and its solid state transformation to the 0D compound [Mn(H4TCPP)(H2O)2]·nD. This transformation takes place by means of a cationic exchange Mn2+↔2H+ of the non-dissolved compounds in the mother liquor. These solid state transformations are unusual in this type of compounds where common processes are induced by the solvent exchange. By adding the first transition metals Ni and Cu, combined with the porphyrinic ligand TCPP, two new compounds have been obtained with different dimensionality: the 3D compound [Ni5(H2TCPP)2O(H2O)4]·nS (S=solvent) and the 0D compound [Cu(H4TCPP)]·6DMF. The first one has a three-dimensional crystalline structure formed by TCPP units and NiII ions, joined by ferromagnetic NiII trinuclear complexes and it exhibits a large accessible pore volume. The crystal structure of the second one is based on TCPP and CuII monomers. Both have high thermal stability and high catalytic activity. The structural features of compound [Ni5(H2TCPP)2O(H2O)4]·nS provide significant robustness that makes its crystal lattice stable after several catalysis cycles, confirming its properties as heterogeneous and recyclable catalyst. In addition, due to its large surface area, this compound rises as a good adsorbent for pollutants in solution and in gaseous state, with some selectivity towards certain gases in mixtures with industrial interest. Therefore, the work gathered in this report is an approach of three different topics: porphyrins of biological systems in the solid state, crystallography (and structural analysis), and the scientific vocation to contribute to the improvement of our society. All of them come together in this thesis in order to coexist with beautiful purposes: to face the environmental challenges demanded by our society and to expand the knowledge in the field of advanced materials as a paradigm of the evolution of our species.Tesis realizada a partir de una investigación subvencionada por la UPV/EHU (beca predoctoral) , el Gobierno Vasco (IT-630-13) y el Ministerio de Economía y Competitividad (MAT2013-42092-R y MAT2016-76739-R

Intrusion and extrusion of liquids in highly confining media: bridging fundamental research to applications

Wetting and drying of pores or cavities, made by walls that attract or repel the liquid, is a ubiquitous process in nature and has many technological applications including, for example, liquid separation, chromatography, energy damping, conversion, and storage. Understanding under which conditions intrusion/extrusion takes place and how to control/tune them by chemical or physical means are currently among the main questions in the field. Historically, the theory to model intrusion/extrusion was based on the mechanics of fluids. However, the discovery of the existence of metastable states, where systems are kinetically trapped in the intruded or extruded configuration, fostered the research based on modern statistical mechanics concepts and more accurate models of the liquid, vapor, and gas phases beyond the simplest sharp interface representation. In parallel, inspired by the growing number of technological applications of intrusion/extrusion, experimental research blossomed considering systems with complex chemistry and pore topology, possessing flexible frameworks, and presenting unusual properties, such as negative volumetric compressibility. In this article, we review recent theoretical and experimental progresses, presenting it in the context of unifying framework. We illustrate also emerging technological applications of intrusion/extrusion and discuss challenges ahead

Coordination and crystallisation molecules: Their interactions affecting the dimensionality of metalloporphyrinic SCFs

Synthetic metalloporphyrin complexes are often used as analogues of natural systems, and they can be used for the preparation of new Solid Coordination Frameworks (SCFs). In this work, a series of six metalloporphyrinic compounds constructed from different meso substituted metalloporphyrins (phenyl, carboxyphenyl and sulfonatophenyl) have been structurally characterized by means of single crystal X-ray diffraction, IR spectroscopy and elemental analysis. The compounds were classified considering the dimensionality of the crystal array, referred just to coordination bonds, into 0D, 1D and 2D compounds. This way, the structural features and relationships of those crystal structures were analyzed, in order to extract conclusions not only about the dimensionality of the networks but also about possible applications of the as-obtained compounds, focusing the interest on the interactions of coordination and crystallization molecules. These interactions provide the coordination bonds and the cohesion forces which produce SCFs with different dimensionalities.Ministerio de Economia y Competitividad (MAT2013-42092-R), Gobierno Vasco (Basque University System Research Groups, IT-630-13) and UPV/EHU (UFI 11/15

Highly thermally stable heterogeneous catalysts: study of 0D and 3D porphyrinic MOFs

Heterogeneous catalysts are a great bet for green chemistry in many industrial processes and, in the past decade, promising results have been achieved in order to improve the catalytic activity of Metal Organic Frameworks (MOFs). Accordingly, porphyrins make possible to design new coordination polymers with better properties, taking into account the important functions they develop in nature. In this sense, porphyrin-based MOFs are becoming very relevant in heterogeneous catalysis. Thus, the aim of this work was obtaining metalloporphyrinic MOFs exhibiting catalytic activity. Studying the effect of dimensionality on the MOF properties (including thermal stability and catalytic activity), in this work we study two catalysts with different dimensionalities, 3D [Ni5(H2TCPP)2O(H2O)4]•nS (1) and 0D [Cu(H4TCPP)]•6DMF (2) (where H6TCPP is meso-tetra(4-carboxyphenyl)porphyrin, DMF is N,N-dimethylformamide and S is the solvent). The structural features of both compounds, combined with their high thermal stability and accessible networks, are responsible for the excellent behaviour as heterogeneous catalysts. It is worth mentioning that significant reduction in reaction time compared to other reported catalysts has been observed. The recyclability of one of the herein studied porphyrin-based MOFs is outstanding. Further structural and thermal characterization has been carried out by means of single crystal X-ray diffraction, IR spectroscopy, thermogravimetry (TG), powder X-ray diffraction (XRD) and transmission electron microscopy (TEM).Ministerio de Economia, Industria y Competitividad (MAT2016-76739-R) Gobierno Vasco’’ (Basque University System Research Groups, IT-630-13

Cationic Mn2+/H+ exchange leading a slow solid-state transformation of a 2D porphyrinic network at ambient conditions

Metalloporphyrins exhibit outstanding chemical, physical and biological properties in dissolution, however, it is a challenge to synthesize them as stable solid frameworks. Long-time stability is crucial for future applications of these materials, and we have detected a slow, solid-state transformation of a 2D MnII-porphyrin at RT. The remarkable point is that this transformation showed up as a result of Electronic Paramagnetic Resonance measurements. Otherwise, the evolution of the system could have remained undetected. Thus, 2D [Mn3(TCPP)(H2O)4]•nD (1) (where TCPP is meso-tetra(4-carboxyphenyl)porphyrin and D is the sovent) has been synthesized hydrothermally, and characterised by means of X-ray diffraction (XRD), Thermogravimetry and X-ray thermodiffractometry (XRTD). This compound slowly transforms into [Mn(H4TCPP)(H2O)2]•nD (2) according to the equilibrium [Mn3(TCPP)]+4H+ ↔ [Mn(H4TCPP)]+2Mn2+. The evolution of the system has been studied through analysis of the distortion (both of the coordination sphere and the tetrapyrrolic macrocycle) and Density Functional Theory (DFT) quantum mechanical calculations.Ministerio de Economia y Competitividad (MAT2013-42092-R), Gobierno Vasco (Basque University System Research Groups, IT-630-13) and UPV/EHU (UFI11/15

Mechanism of Water Intrusion into Flexible ZIF-8: Liquid Is Not Vapor

Zeolitic Imidazolate Frameworks (ZIF) find application in storage and dissipation of mechanical energy. Their distinctive properties linked to their (sub)nanometer size and hydrophobicity allow for water intrusion only under high hydrostatic pressure. Here we focus on the popular ZIF-8 material investigating the intrusion mechanism in its nanoscale cages, which is the key to its rational exploitation in target applications. In this work, we used a joint experimental/theoretical approach combining in operando synchrotron experiments during high- pressure intrusion experiments, molecular dynamics simulations, and stochastic models to reveal that water intrusion into ZIF-8 occurs by a cascade filling of connected cages rather than a condensation process as previously assumed. The reported results allowed us to establish structure/function relations in this prototypical microporous material, representing an important step to devise design rules to synthesize porous media

Optimization of the wetting-drying characteristics of hydrophobic metal organic frameworks via crystallite size: The role of hydrogen bonding between intruded and bulk liquid

Hypothesis: The behavior of Heterogeneous Lyophobic Systems (HLSs) comprised of a lyophobic porous material and a corresponding non-wetting liquid is affected by a variety of different structural parameters of the porous material. Dependence on exogenic properties such as crystallite size is desirable for system tuning as they are much more facilely modified. We explore the dependence of intrusion pressure and intruded volume on crystallite size, testing the hypothesis that the connection between internal cavities and bulk water facilitates intrusion via hydrogen bonding, a phenomenon that is magnified in smaller crystallites with a larger surface/volume ratio. Experiments: Water intrusion/extrusion pressures and intrusion volume were experimentally measured for ZIF-8 samples of various crystallite sizes and compared to previously reported values. Alongside the practical research, molecular dynamics simulations and stochastic modeling were performed to illustrate the effect of crystallite size on the properties of the HLSs and uncover the important role of hydrogen bonding within this phenomenon. Findings: A reduction in crystallite size led to a significant decrease of intrusion and extrusion pressures below 100 nm. Simulations indicate that this behavior is due to a greater number of cages being in proximity to bulk water for smaller crystallites, allowing cross-cage hydrogen bonds to stabilize the intruded state and lower the threshold pressure of intrusion and extrusion. This is accompanied by a reduction in the overall intruded volume. Simulations demonstrate that this phenomenon is linked to ZIF-8 surface half-cages exposed to water being occupied by water due to non-trivial termination of the crystallites, even at atmospheric pressure

MOFS metaloporfirínicos 1D y 2D: Estudio cristaloquímico

Comunicación a congreso (póster): XXIV Simposio del Grupo Especializado de Cristalografía y Crecimiento Cristalino, GE3C. 23-26 de junio de 2014, BilbaoLos sistemas metaloporfirínicos son piezas clave en el engranaje de la vida, debido a las propiedades bioquímicas, enzimáticas y fotoquímicas que desempeña el macrociclo tetrapirrólico presente en las porfirinas. Las distorsiones que presentan estos macrociclos porfirínicos son biológicamente relevantes, y tienen influencia en diferentes propiedades químicas y físicas en este tipo de compuestos. En este sentido, se ha utilizado el programa NSD para analizar la distorsión que presentan los anillos tetrapirrólicos fuera del plano y relacionarla con diferentes parámetros estructurales, característicos en este tipo de compuestos. En el trabajo que aquí se muestra se han analizado MOFs metaloporfirínicos tanto monodimensionales (1D) como bidimensionales (2D) que se han obtenido mediante síntesis hidrotermal. De esta manera, los compuestos estudiados presentan las fórmulas: [CoTPP(bipy)]•([CoTPP])0.22•(TPP)0.78, [CoTPPS0.5(bipy)(H2O)2]•6H2O, [Mn3TCPP(H2O)4]•EtOH•2DMF y [MnTCPP]•nDMF donde TPP: meso-tetra-4-fenilporfirina, TPPS: meso-tetra-4-sulfonatofenilporfirina, TCPP: meso-tetra-4-carboxifenilporfirina, bipy: 4,4´-bipiridina y DMF: N,N-dimetilformamida, para los que se ha podido establecer una relación entre la distorsión que presenta el macrociclo tetrapirrólico y diferentes ángulos, distancias y otros parámetros estructurales.Ministerio de Ciencia e Innovación (MAT2010-15375), el Gobierno Vasco (Grupos de Investigación del Sistema Universitario Vasco IT-630-13) y la UPV/EHU (UFI 11/15

Materiales de tipo MOF orientados a la adsorción de contaminantes y catálisis heterogénea. Nuevas perspectivas.

Comunicación oral al Workshop H2BioCatO2 (Complejos metálicos biomiméticos: Utilización de oxígeno, hidrógeno y dióxido de carbono) celebrado en Castellón, 22 - 24 Noviembre 2017Nuestro grupo de investigación cuenta con una amplia experiencia en la síntesis y caracterización de materiales multifuncionales basados en redes de coordinación porosas de tipo MOF (metal-organic framework). La estrategia de preparación de estos materiales pasa por el uso de métodos de síntesis solvotermal y por microondas con metales de la 1ª serie de transición y ligandos orgánicos policarboxílicos, dipiridínicos y porfirínicos. Los nuevos materiales obtenidos se enfocan a su aplicación como adsorbentes de gases contaminantes, como adsorbentes de colorantes en aguas contaminadas o como catalizadores heterogéneos, entre otros. Dentro de la red H2BioCatO2 se ha estudiado la foto- y electroreducción de CO2 y la reducción y oxidación de H2O con catalizadores metaloporfirínicos. Recientemente, y profundizando aún más en la aplicabilidad de nuestros MOFs se ha estudiado la toxicidad de los mismos en cultivos de células mamíferas y su capacidad antioxidante en levaduras. En este sentido, vamos a apostar por establecer una novedosa vía de investigación basada en bioMOFs de CaII que permitan difundir moléculas activas para la regeneración del tejido óseo.Ministerio de Economía y Competitividad (MAT2016-76739-R y CTQ2015-71470-REDT, AEI/FEDER, UE) Gobierno Vasco (Grupos de Investigación del Sistema Universitario Vasco, IT‐630‐13

Conductividad superprotónica en MOFs metaloporfirínicos bioinspirados

Comunicacion oral a la X Reunión Científica de Bioinorgánica, BioBilbao 2017. Bilbao 9-12 de julio de 2017 - Bizkaia Aretoa - Paraninfo de la UPV/EHULos materiales de tipo MOF muestran un gran potencial para una amplia gama de aplicaciones debido a su elevada porosidad, baja densidad y facilidad en la modificación estructural. En particular, los MOF basados en metaloporfirinas están adquiriendo gran importancia en muchos campos. Estos materiales se inspiran en las funciones biológicas de estos macrociclos naturales coordinados a metales. Por otro lado, durante los últimos años, los materiales conductores de protones han despertado mucho interés, y aquellos que presentan altos valores de conductividad son potenciales candidatos a desempeñar un papel clave en algunos dispositivos electroquímicos de estado sólido, tales como baterías y pilas de combustible. De esta manera, empleando metaloporfirinas hemos obtenido un nuevo material cristalino con fórmula [H(bipy)2][MnTPPS)(H2O)2]·2bipy·14H2O, donde bipy es la 4,4'-bipiridina y TPPS la meso-tetra (4-sulfonatofenil) porfirina. La estructura cristalina se determinó mediante difracción de rayos X en monocristal y la caracterización térmica se llevó a cabo mediante medidas termogravimétricas (TG/DSC) y de termodifracción de rayos X (TDX). El compuesto muestra una cadena de agua en zigzag a lo largo de la dirección [100] localizada entre los grupos sulfonato de la porfirina. Teniendo en cuenta esas características estructurales, se testeó el compuesto para conducción protónica obteniendo muy buenos resultados (1x10-2 S·cm-1) a 40 °C y 98% de humedad relativa.Ministerio de Economía, Industria y Competitividad (MAT2016-76739-R, AEI/FEDER, UE) Gobierno Vasco (Grupos de Investigación del Sistema Universitario Vasco, IT-630-13