Sur la mise en oeuvre de composés de coordination tétraédriques pour l'élaboration d'architecturess supramoléculaires nanoporeuses : synthèse, caractérisation et propriétés zéolitiques d'édifices hétérométalliques ou hybrides

Cette thèse est dédiée à la synthèse et à la caractérisation d'une famille inédite d'édifices métallo-organiques micro-poreux. La voie de synthèse explorée se fonde sur des briques moléculaires tétrahédriques préformées dont un exemple type est {M(oxalate)4}4- (où M = UIV, ZrIV, etc...). Les complexes tétraédriques {Zr(dihydrobenzoquinolate)4}4- et {Zr(chloranilate)4}4- sont également décrits. Les structures de plusieurs architectures supramoléculaires 2-D et 3-D parcourues par des canaux dont la section peut atteindre 8 Å x 12 Å, sont décrites. Des polymères de coordination hétérométalliques {U-Mn}, {U-Cd}, {Zr- Mn} ou encore {U-Gd} sont obtenus par association d'une brique avec un ion de métal de transition ou de terre-rare. Mais ces briques permettent aussi la formation de réseaux hybrides par assemblage avec des cations organiques au travers de liaisons-Hydrogène robustes. La diffraction des rayons X sur poudre et mono-cristal a mis en évidence la stabilité de ces édifices vis à vis d'un cycle désorption-adsorption mais aussi, pour certains, leur flexibilité. La déformation réversible de l'édifice est illustrée au travers des structures hydratées et déshydratées du réseau [K4{Zr(dhbq)4}] (dhbq = dihydrobenzoquinolate).Des mesures de sorption (BET, Langmuir) montrent que ces structures sont ouvertes. Un des édifices décrit adsorbeH2et permet d'envisager cette famille de matériaux supramoléculaires pour le stockage de l'hydrogène.The preparation of micro-porous metal-organic frameworks has been envisaged by assemblage of pre-formed tetrahedral coordination compounds involved as primary building units. A typical example of such a building block is {M(oxalate)4}4- (with M = UIV, ZrIV, etc...) but the tetrahedral {Zr(chloranilate)4}4- and {Zr(dihydrobenzoquinolate)4}4- complexes have been envisaged as well. Their assemblage with either metal ions by the means of coordination bonds or organic cations through charge-assisted H-bond lead to a series of structurally characterized 2-D and 3-D supramolecular nano-porous architectures. This approach permitted the synthesis of rare examples of heterometallic open frameworks. These structures display channels with apertures up to 12 Å x 8 Å which are emptied from solvates at mild temperatures without affecting the chemical scaffolds which integrity is maintained up to 250-300°C. A certain degree of flexibility of the coordination polymers upon guest release is suggested by the temperature dependence of the powder X-ray patterns and N2 sorption experiments, but reversible and selective sorption of small molecules has been observed suggesting these open-frameworks to behave like sponges. The flexibility of the framework upon guest release is illustrated by the crystal structures of the hydrated and dehydrated phases of [K4{Zr(dhbq)4}] (dhbq = dihydrobenzoquinolate). Finally, the different sorption measurements (BET, Langmuir) show that these supramolecular porous materials are promising adsorbents; preliminary results show that they might be envisaged for hydrogen storage

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

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

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

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

International audienc

Introducing asymmetric functionality into MOFs via the generation of metallic Janus MOF particles

Herein we report a versatile methodology for engineering metallic Janus MOF particles based on desymmetrization at interfaces, whereby each MOF particle is partially coated with a desired metal. We demonstrate that it enables the fabrication of homogeneous Janus MOF particles according to the MOF (ZIF-8, UiO-66 or UiO-66-SH), the metal (Au, Co or Pt), the MOF particle size (from the micrometer to the submicrometer regime) and the metal-film thickness (from 5 nm to 50 nm) employed. We anticipate that our strategy could be applied to impart new functionalities to MOFs, including asymmetric functionalization, magnetic-guidance and motorization

Towards nanowire sensors on a microfluidic platform: In-situ formation, positioning and sizing of nanowire bundles

Funding from the European Research Council under the 7th Framework Programme (ERC Strating Grant no. 203428 nµLIPIDS) is gratefully acknowledgedPeer Reviewe

Metal-organic frameworks : from molecules/metal ions to crystals to superstructures

Altres ajuts: I.I. thanks MINECO for a Ramón y Cajal grant.Metal-organic frameworks (MOFs) are among the most attractive porous materials known today, exhibiting very high surface areas, tuneable pore sizes and shapes, adjustable surface functionality, and flexible structures. Advances in the formation of MOF crystals, and in their subsequent assembly into more complex and/or composite superstructures, should expand the scope of these materials in many applications (e.g., drug delivery, chemical sensors, selective reactors and removal devices, etc.) and facilitate their integration onto surfaces and into devices. This Concept article aims to showcase recently developed synthetic strategies to control the one-, two- and three-dimensional (1-, 2- and 3D) organisation of MOF crystals. Superstructures: Recent developments are described for the construction of the first-ever MOF superstructures, all of which entail control over MOF crystallisation and/or the subsequent spatial layout of the resulting crystals. These methods are characterised as 1) spontaneous higher-order assembly, 2) self-assembly using hard templates, 3) self-assembly using soft templates and 4) self-templated synthesis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim