Materials moleculars nanoporosos magnètics

Consultable des del TDXTítol obtingut de la portada digitalitzadaAquesta Tesi Doctoral s'ha basat en el disseny de materials moleculars nanoporosos i magnètics. En aquest sentit, s'ha dissenyat una nova estratègia sintètica enfocada a l'obtenció de materials híbrids metal·lorgànics que combinin canals de grans dimensions i propietats magnètiques interessants. Fins aleshores, el disseny d'un material d'aquestes característiques presentava certes contradiccions sintètiques, fet que provocava que la seva síntesi resultés molt complicada. No obstant, la introducció, per part del nostre grup, d'una variació consistent en l'ús de lligands amb caràcter paramagnètic ha permès obtenir diversos materials amb ambdues característiques. Un primer material molecular nanoporós i amb ordenament magnètic (designat com a MOROF-1, metal-organic radical open-framework) s'ha sintetitzat utilitzant un ió metàl·lic com el coure(II) i un radical perclorotrifenilmetílic trifuncionalitzat amb tres grups carboxílics (D. MASPOCH, NATURE MATERIALS, 2002, 2, 190). Aquest compost presenta unes característiques nanoporoses realment interessants. Les dimensions dels seus canals són d'aproximadament 3 nm. A més, la desorpció i absorció de molècules de dissolvent (etanol o metanol) provoca uns canvis estructurals sorprenents: el materials té un comportament semblant al d'una esponja molecular; conferint-li unes bones característiques per poder actuar com a sensor de dissolvents com el metanol i etanol. A més, aquesta estructura altament porosa s'ordena ferromagnèticament a baixes temperatures. Aquest material també ha vingut acompanyat de dos nous materials, tots ells amb interessants propietats poroses i magnètiques. El material MOROF-2 (D. MASPOCH ET AL., CHEM COMMUN., 2004, 1164) es defineix com un sòlid paramagnètic amb una topologia arquitectònica inèdita fins ara i amb uns canals helicoidals. Altrament, el material MOROF-3 novament s'ordena magnèticament i també presenta una porositat important. Per altra banda, l'ús d'aquest radicals com a blocs moleculars paramagnètics enllaçats per ponts d'hidrogen també ha permès l'obtenció dels primers materials moleculars purament orgànics porosos i magnètics, els quals són estables en absència de dissolvent pressenten una estabilitat tèrmica elevada (275º©). Aicí, l'empaquetament del radical PTMDC forma un material molecular paramagnètic (POROF-1) amb una estructura composta d'uns nanocontenidors moleculars hidrofòbics de fins a 1 nm de diàmetre connectats a través de finestres hidrofíliques de 5 Å (D. MASPOCH ET AL., J. AM. CHEM. SOC., 2004, 126, 730) . D'altra banda, el radical PTMTC forma un segon material purament orgànic porós (POROF-2), el qual s'ordena magnèticament (D. MASPOCH, ANGEW. CHEM. INT. ED., 2004, 43, 1828). S'ha demostrat doncs la viabilitat de l'ús d'aquests nous materials moleculars porosos i magnètics com a materials de partida per la formació de materials moleculars multifuncionals. Aplicant aquesta aproximació, s'ha aconseguit sintetitzar un materials molecular porós que combina canals formats per parets amb diversos grups quirals i propietats magnètiques d'interès.This thesis has mainly focused on the design of nanoporous and magnetic molecular materials. In this way, in our group, we have designed a new synthetic strategy for the obtaining of hybrid metal-organic materials that could combine large nanopores and interesting magnetic properties. Up to now, the design of this kind of materials shows some synthetic contradictions. However, the recently introduction of paramagnetic ligands in our group has allowed the obtaining several materials that show both characteristics. A first nanoporous molecular ferromagnet (referred as MOROF-1, Metal-Organic Radical Open-Framework) has been synthesized by the use of a paramagnetic metal ion such as Cu(II) and a perclorotrifenilmethyl radical trifucntionalized with three carboxylic functions (D. MASPOCH, NATURE MATERIALS, 2002, 2, 190). This material shows a really interesting nanoporous characteristics. The dimensions of their channels are around 3 nm. Furthermore, the desorption and absorption of solvent molecules (ethanol or methanol) produces surprising structural changes: this material shows a similar behavior of that a molecular sponge; giving an excellent characteristics to behave as a sensor for solvents such as ethanol or methanol. Furthermore, this highly porous structure shows a magnetic ordering at low temperatures. This material has been accompanied by two new materials, both with interesting porosity and magnetic properties. MOROF-2 (D. MASPOCH ET AL., CHEM COMMUN., 2004, 1164) is a paramagnetic solid with a new topology and helicoidal channels. Moreover, MOROF-3 also shows a magnetic ordering and a highly porosity characteristic. On the other hand, the use of this radicals as paramagnetic organic building-blocks linked by hydrogen-bonds has allowed the design of the first purely organic nanoporous and magnetic materials, which are stable in absence of solvent molecules and are stable at high temperatures (275 ºC). Thus, the proper packing of PTMDC radical forms a paramagnetic molecular material (POROF-1) with a structure composed by hydrophobic nanocontainers of 1 nm connected by narrow hydrophilic windows of 5 Å (D. MASPOCH ET AL., J. AM. CHEM. SOC., 2004, 126, 730). Furthermore, PTMTC radical forms a second purely organic material (POROF-2), which are magnetically ordered (D. MASPOCH, ANGEW. CHEM. INT. ED., 2004, 43, 1828). It has been also showed the possible use of this new nanoporous and magnetic molecular materials for the formation of new multifunctional molecular materials. With this aim, a new porous materials that combines channels covered by chiral groups and interesting magnetic properties has been obtained

Programmable self-assembling 3D architectures generated by patterning of swellable MOF-based composite films

The integration of swellable metal-organic frameworks (MOFs) into polymeric composite films is a straightforward strategy to develop soft materials that undergo reversible shape transformations derived from the intrinsic flexibility of MOF crystals. However, a crucial step toward their practical application relies on the ability to attain specific and programmable actuation, which enables the design of self-shaping objects on demand. Herein, a chemical etching method is demonstrated for the fabrication of patterned composite films showing tunable self-folding response, predictable and reversible 2D-to-3D shape transformations triggered by water adsorption/desorption. These films are fabricated by selective removal of swellable MOF crystals allowing control over their spatial distribution within the polymeric film. Upon exposure to moisture, various programmable 3D architectures, which include a mechanical gripper, a lift, and a unidirectional walking device, are generated. Remarkably, these 2D-to-3D shape transformations can be reversed by light-induced desorption. The reported strategy offers a platform for fabricating flexible MOF-based autonomous soft mechanical devices with functionalities for micromanipulation, automation, and robotics

Millimeter-shaped metal-organic framework/inorganic nanoparticle composite as a new adsorbent for home water-purification filters

Altres ajuts: this work was also funded by the CERCA Program/Generalitat de Catalunya.Heavy-metal contamination of water is a global problem with an especially severe impact in countries with old or poorly maintained infrastructure for potable water. An increasingly popular solution for ensuring clean and safe drinking water in homes is the use of adsorption-based water filters, given their affordability, efficacy, and simplicity. Herein, we report the preparation and functional validation of a new adsorbent for home water filters, based on our metal-organic framework (MOF) composite containing UiO-66 and cerium(IV) oxide (CeO2) nanoparticles. We began by preparing CeO2@UiO-66 microbeads and then encapsulating them in porous polyethersulfone (PES) granules to obtain millimeter-scale CeO2@UiO-66@PES granules. Next, we validated these granules as an adsorbent for the removal of metals from water by substituting them for the standard adsorbent (ion-exchange resin spheres) inside a commercially available water pitcher from Brita. We assessed their performance according to the American National Standards Institute (ANSI) guideline 53-2019, "Drinking Water Treatment Units - Health Effects Standard". Remarkably, a pitcher loaded with a combination of our CeO2@UiO-66@PES granules and activated carbon at standard ratios met the target reduction thresholds set by NSF/ANSI 53-2019 for all the metals tested: As(III), As(V), Cd(II), Cr(III), Cr(VI), Cu(II), Hg(II), and Pb(II). Throughout the test, the modified pitcher proved to be robust and stable. We are confident that our findings will bring MOF-based adsorbents one step closer to real-world use

Nanoestructures metal·lobiomoleculars

La miniaturització de materials metal·lorgànics a escala nanomètrica és una estratègia emergent per al desenvolupament de noves nanoestructures d'una gran diversitat composicional, estructural i morfològica. Aquests nous nanomaterials, molts d'ells porosos, poden presentar un ventall variat de propietats i, en conseqüència, poden ser utilitzats en diverses àrees tecnològiques, sigui en l'emmagatzematge o la separació de gasos i catàlisis, sigui per formar nous sensors, nanotransportadors de fàrmacs i agents de contrast. Immersos en el desenvolupament d'aquestes nanoestructures, el nostre grup de recerca està actualment desenvolupant una nova aproximació basada en l'ús de biomolècules com a lligands orgànics que, coordinades amb ions metàl·lics, permetin la creació de nanoarquitectures metal·lobiomoleculars. Aquestes nanoestructures combinaran les propietats dels nanomaterials metal·lorgànics (per exemple, la porositat) amb les propietats intrínseques de les biomolècules, com ara la biocompatibilitat, el reconeixement selectiu o la quiralitat. En aquesta comunicació s'exposaran els últims avanços efectuats en el desenvolupament de noves metodologies sintètiques i el seu ús per sintetitzar les primeres nanoestructures metal·lobiomoleculars formades per aminoàcids com l'àcid aspàrtic (Asp) i la cisteïna (Cys).The miniaturization of metal-organic materials to the nanoscale is an emerging strategy for the development of new nanostructures with tailored compositions, structures and morphologies. These new nanomaterials, many of which are porous, may have a wide range of properties and consequently show promise for many practical applications, such as gas storage or separation, catalysis, sensors, drug-delivery and contrast agents. With this aim, our research group is currently developing a new approach using biomolecules to coordinate metal ions and create metal-biomolecule nanoarchitectures. These new bioinspired nanostructures will combine the properties of more conventional metal-organic nanomaterials (e. g. porosity) with the intrinsic characteristics of the biomolecules, such as biocompatibility, chirality and selective recognition capabilities. This paper presents the latest advances in the development of new synthesis methodologies and their use in producing the first metal-biomolecule nanostructures based on amino acids, such as aspartic acid (Asp) and cysteine (Cys)

Assembly of colloidal clusters driven by the polyhedral shape of metal-organic framework particles

Altres ajuts: This work was supported by the CERCA Program/Generalitat de Catalunya.Control of the assembly of colloidal particles into discrete or higher-dimensional architectures is important for the design of myriad materials, including plasmonic sensing systems and photonic crystals. Here, we report a new approach that uses the polyhedral shape of metal-organic-framework (MOF) particles to direct the assembly of colloidal clusters. This approach is based on controlling the attachment of a single spherical polystyrene particle on each face of a polyhedral particle via colloidal fusion synthesis, so that the polyhedral shape defines the final coordination number, which is equal to the number of faces, and geometry of the assembled colloidal cluster. As a proof of concept, we assembled six-coordinated (6-c) octahedral and 8-c cubic clusters using cubic ZIF-8 and octahedral UiO-66 core particles. Moreover, we extended this approach to synthesize a highly coordinated 12-c cuboctahedral cluster from a rhombic dodecahedral ZIF-8 particle. We anticipate that the synthesized colloidal clusters could be further evolved into spherical core-shell MOF@polystyrene particles under conditions that promote a higher fusion degree, thus expanding the methods available for the synthesis of MOF-polymer composites

The Imine-Based COF TpPa-1 as an Efficient Cooling Adsorbent That Can Be Regenerated by Heat or Light

Adsorption-based cooling systems, which can be driven by waste heat and solar energy, are promising alternatives to conventional, compression-based cooling systems, as they demand less energy and emit less CO. The performance of adsorption-based cooling systems relates directly to the performance of the working pairs (sorbent-water). Accordingly, improvement of these systems relies on the continual discovery of new sorbents that enable greater mass exchange while requiring less energy for regeneration. Here, it is proposed that covalent-organic frameworks (COFs) can replace traditional sorbents for adsorption-based cooling. In tests mimicking standard operating conditions for industry, the imine-based COF TpPa-1 exhibits a regeneration temperature below 65 °C and a cooling coefficient of performance of 0.77 - values which are comparable to those reported for the best metal-organic framework sorbents described to date. Moreover, TpPa-1 exhibits a photothermal effect and can be regenerated by visible light, thereby opening the possibility for its use in solar-driven cooling

Zigzag Ligands for Transversal Design in Reticular Chemistry: Unveiling New Structural Opportunities for Metal–Organic Frameworks

International audienc

Self-assembly of colloidal metal-organic framework (MOF) particles

Self-assembly of colloidal particles into ordered superstructures enables the development of novel advanced materials for diverse applications such as photonics, electronics, sensing, energy conversion, energy storage, diagnosis, drug or gene delivery, and catalysis. Recently, polyhedral metal-organic framework (MOF) particles have been proposed as promising colloidal particles to form ordered superstructures, based on their colloidal stability, size-tunability, rich polyhedral shapes, porosity and multifunctionality. In this review, we present a comprehensive overview of strategies for the self-assembly of colloidal MOF particles into ordered superstructures of different dimensionalities, highlighting some of their properties and applications, and sharing thoughts on the self-assembly of MOF particles

Surface chemistry of metal-organic polyhedra

This work was funded by the CERCA Programme/Gen-eralitat de Catalunya and through a fellowship (LCF/BQ/PR20/ 11770011) from the "La Caixa" Foundation (ID 100010434).Metal-organic polyhedra (MOPs) are discrete, intrinsically-porous architectures that operate at the molecular regime and, owing to peripheral reactive sites, exhibit rich surface chemistry. Researchers have recently exploited this reactivity through post-synthetic modification (PSM) to generate specialised molecular platforms that may overcome certain limitations of extended porous materials. Indeed, the combination of modular solubility, orthogonal reactive sites, and accessible cavities yields a highly versatile molecular platform for solution to solid-state applications. In this feature article, we discuss representative examples of the PSM chemistry of MOPs, from proof-of-concept studies to practical applications, and highlight future directions for the MOP field

Use of autoantigen-loaded phosphatidylserine-liposomes to arrest autoimmunity in type 1 diabetes

This is an open access article distributed under the terms of the Creative Commons Attribution License.-- et al.[Introduction]: The development of new therapies to induce self-tolerance has been an important medical health challenge in type 1 diabetes. An ideal immunotherapy should inhibit the autoimmune attack, avoid systemic side effects and allow β-cell regeneration. Based on the immunomodulatory effects of apoptosis, we hypothesized that apoptotic mimicry can help to restore tolerance lost in autoimmune diabetes.[Objective]: To generate a synthetic antigen-specific immunotherapy based on apoptosis features to specifically reestablish tolerance to β-cells in type 1 diabetes.[Methods]: A central event on the surface of apoptotic cells is the exposure of phosphatidylserine, which provides the main signal for efferocytosis. Therefore, phosphatidylserine-liposomes loaded with insulin peptides were generated to simulate apoptotic cells recognition by antigen presenting cells. The effect of antigen-specific phosphatidylserine-liposomes in the reestablishment of peripheral tolerance was assessed in NOD mice, the spontaneous model of autoimmune diabetes. MHC class II-peptide tetramers were used to analyze the T cell specific response after treatment with phosphatidylserine-liposomes loaded with peptides.[Results]: We have shown that phosphatidylserine-liposomes loaded with insulin peptides induce tolerogenic dendritic cells and impair autoreactive T cell proliferation. When administered to NOD mice, liposome signal was detected in the pancreas and draining lymph nodes. This immunotherapy arrests the autoimmune aggression, reduces the severity of insulitis and prevents type 1 diabetes by apoptotic mimicry. MHC class II tetramer analysis showed that peptide-loaded phosphatidylserine-liposomes expand antigen-specific CD4+ T cells in vivo. The administration of phosphatidylserine-free liposomes emphasizes the importance of phosphatidylserine in the modulation of antigen-specific CD4+ T cell expansion.[Conclusions]: We conclude that this innovative immunotherapy based on the use of liposomes constitutes a promising strategy for autoimmune diseases.This work was supported by a grant from Spanish Government (FIS PI12/00195). IPA was supported by AGAUR, Generalitat de Catalunya. MVP and RA are supported by the Health Dept. of the Catalan Government, Generalitat de Catalunya.Peer reviewe