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Recent studies have demonstrated that metal−organic frameworks (MOFs) can be miniaturized down to the submicroscale and even nanoscale to create small MOFs. Herein, the basic concepts and recent progresses concerning the core question of “MOFs, why make them small?” are briefly introduced from three perspectives: those of size, shape, and processability. Small sizes endow MOFs with large outer surface area/volume ratios, leading to important differences in their characteristics (e.g., outer surface energy, number of defects, etc.) relative to their bulk scale counterparts and thus, opening the door to size-dependent properties such as flexibility or catalytic performance. Downsizing MOFs also enables shaping of them into unusual shapes. Among the most appealing morphologies are 2D nanosheets, whose structure can favor certain porosity-related applications. The controlled miniaturization of MOF particles also favors their integration onto surfaces and into devices as well as their colloidal stability, which in turn translates to the ability to use readily processable MOF-based liquids in countless processes, such as to drive the assembly of sophisticated meso- and macroscopic architectures, gels, monoliths, and porous liquids. It is believed that ongoing research to shrink MOFs via nanotechnology, as has been done with other classes of materials, will continue to yield novel MOF-related materials that exhibit unprecedented structural and functional properties.

We have synthesised and characterised the two possible isomers of heteroleptic trigonal antiprismatic M12L6L′6 MOPs by screening reactions of rhodium acetate with different pairs of complementary dicarboxylate linkers. The resulting 12 new MOPs (eight of isomer A + four of isomer B) are microporous in the solid state, exhibiting Brunauer–Emmett–Teller (BET) surface areas as high as 770 m2 g−1.

Supraparticles are spherical colloidal crystals prepared by confined self-assembly processes. A particularly appealing property of these microscale structures is the structural color arising from interference of light with their building blocks. Here, we assemble supraparticles with high structural order that exhibit coloration from uniform, polyhedral metal–organic framework (MOF) particles. We analyse the structural coloration as a function of the size of these anisotropic building blocks and their internal structure. We attribute the angle-dependent coloration of the MOF supraparticles to the presence of ordered, onion-like layers at the outermost regions. Surprisingly, even though different shapes of the MOF particles have different propensities to form these onion layers, all supraparticle dispersions show well-visible macroscopic coloration, indicating that local ordering is sufficient to generate interference effects.

[EN] The aim of the present PhD Thesis has been the exploration of Metal-Organic Frameworks (MOFs) as a potential source of polyhedral for the assembly of a new generation of materials. The discovery of thousands of MOFs over the past 25 years has created a huge pool of highly porous, crystalline particles that encompass most known polyhedral shapes. The research presented in this Thesis hopes to dip in this pool, opening up new avenues to synthesize new porous self-assembled materials with original structures that will give access to new photonic properties The Thesis is organized into two parts. Chapter 1 constitutes the first part where the reader will find an introduction of the self-assembly field, with a brief description of the different interactions that are involved in self-assembly processes, and of different self-assembled systems and synthetic strategies. This Chapter continues with a brief introduction to MOFs, from an historical perspective to their representative applications. We have also pay attention on the few examples in which MOF particles have already been used to generate self-assembled superstructures. The second part of this Thesis contains a description of the general and specific objectives. Then, in Chapter 3, we will briefly describe and discuss the different results obtained during this Thesis. The detailed results will be found in the three publications reproduced in Chapters 5, 6 and Appendix. The publication in Chapter 5 focuses on the use of the polyhedral shape of MOF particles to direct the assembly of colloidal clusters through colloidal fusion. Thanks to the geometry of colloidal MOF particles, colloidal clusters with well-defined geometries can be prepared by controlling the attachment of a single polystyrene particle on each face of the polyhedral MOF particle. Following this approach, we show the synthesis of six-coordinated (6-c) octahedral, 8-c cubic, and 12-c cuboctahedral clusters using cubic ZIF-8, octahedral UiO-66, and, [CA] La present Tesi Doctoral ha tingut com a objectiu investigar el potencial dels Metall-Organic Frameworks (MOFs) com a font de partícules polièdriques per ser acoblades i donar lloc a una nova generació de materials autoassemblats. Des del seu descobriment fa uns 25 anys, el descobriment de milers de MOF ha generat un ampli catàleg de partícules cristal·lines altament poroses que engloben la majoria de les formes polièdriques. La investigació presentada en aquesta Tesi té com a propòsit aprofitar aquest ampli catàleg de partícules polièdriques per fabricar nous materials autoassemblats porosos amb estructures originals i que presentin noves propietats fotòniques. La Tesi s'estructura en dues parts. El Capítol 1 compon la primera part, en la qual el lector trobarà una introducció al camp de l'autoassemblat, amb una breu descripció de les interaccions involucrades, els diferents tipus d'autoassemblat i les diferents estratègies sintètiques. El capítol continua amb una breu introducció als MOFs des dels seus orígens fins a les aplicacions potencials. En aquesta secció, s'ha fet especial èmfasi en els pocs exemples de la literatura en els quals partícules de MOFs han estat usades per generar estructures autoassemblades. La segona part de la Tesi comença amb el Capítol 2, on es defineixen els objectius generals i específics. A continuació, al Capítol 3, es descriuen de manera concisa els diferents resultats obtinguts durant aquesta Tesi. Els resultats detallats es podran trobar a les tres publicacions reproduïdes als Capítols 5, 6 i Apèndix. La publicació del Capítol 5 descriu l'ús de la forma polièdrica de les partícules de MOF per dirigir l'acoblament de clústers col·loïdals a través de la fusió col·loïdal. S'ha estudiat com, gràcies a aquesta forma polièdrica, es poden construir clústers amb diferents geometries controlant la interacció d'una sola partícula esfèrica de poliestirè a cadascuna de cares dels políedres de MOF. Amb aquesta estratègia, s'han pogut obten, [ES] La presente Tesis Doctoral ha tenido como objetivo investigar el potencial de los Metal-Organic Frameworks (MOFs) como fuente de partículas poliédricas para ser ensambladas y dar lugar a una nueva generación de materiales auto-ensamblados. Desde su descubrimiento hace unos 25 años, el descubrimiento de miles de MOFs ha generado un amplio catálogo de partículas cristalinas altamente porosas que engloban la mayoría de las formas poliédricas. La investigación presentada en esta Tesis tiene como propósito aprovechar este amplio catálogo de partículas poliédricas para fabricar nuevos materiales auto-ensamblados porosos con estructuras originales y que presenten nuevas propiedades fotónicas. La Tesis se estructura en dos partes. El Capítulo 1 compone la primera parte, en la cual el lector encontrará una introducción al campo del auto-ensamblado, con una breve descripción de las interacciones involucradas, los diferentes tipos de auto-ensamblado y las diferentes estrategias sintéticas. El capítulo continua con una breve introducción a los MOFs desde sus orígenes hasta sus aplicaciones potenciales. En esta sección, se ha hecho especial énfasis en los pocos ejemplos de la literatura en los cuales partículas de MOFs han sido usadas para generar estructuras auto-ensambladas. La segunda parte de la Tesis se inicia con el Capítulo 2, donde se definen los objetivos generales y específicos. A continuación, en el Capítulo 3, se describen de una manera concisa los diferentes resultados obtenidos durante esta Tesis. Los resultados detallados se podrán encontrar en las tres publicaciones reproducidas en los Capítulos 5, 6 y Apéndice. La publicación del Capítulo 5 describe el uso de la forma poliédrica de las partículas de MOF para dirigir el ensamblaje de clústeres coloidales a través de la fusión coloidal. Se ha estudiado como, gracias a esta forma poliédrica, se pueden construir clústeres con diferentes geometrías controlando la interacción de una sola partícula esférica de pol

[EN] The present PhD thesis has been dedicated to the study, development and implementation of composite materials made of Metal-Organic Frameworks (MOFs) and Inorganic Nanoparticles (INPs) with enhanced functionalities not achievable by the constituent materials alone. In Chapter 1, a brief review of the state of the art in the field of porous crystalline materials is presented, from their conception to actual successful application in the industrial field. This Chapter offers a quick look to the most relevant concepts for the design and synthesis of this class of materials, as well as their most promising exploitable functionalities. Especial emphasis has been given in presenting works that successfully combine MOFs with other functional materials in order to compensate shortcomings of the individual constituents, or complement their strengths. The aim of this chapter is to contextualize the reader to the work presented in this thesis. In Chapter 2, the general and specific objectives of this Thesis are described. In Chapter 3, a composite material synthetized through spray drying for water remediation applications is presented. This material, shaped in the form of microbeads, combines a MOF from the UiO-66 family and CeO2 INPs. Both materials are known for their capabilities for the removal of various heavy metals from water. The synthetized composite microbeads are tested to assess their adsorptive capabilities in several experiments including ones simulating real water samples from polluted rivers. Furthermore, the material is incorporated into a continuous-flow fixed bed filtration system prototype where breakthrough and regeneration experiments are performed Finally, to prove the versatility of the synthetic method utilized for the formation of the beads an additional magnetic composite is developed by simultaneously incorporating CeO2 and Fe3O4 INPs into UiO-66-(SH)2. In Chapter 4, one of the materials presented in the previous chapter, UiO-66 microbeads wit, [CA] La present tesi doctoral ha estat dedicada a l'estudi, desenvolupament i implementació de materials compòsits fets d'estructures organometàl·liques (MOFs) i nanopartícules inorgàniques (INPs) amb funcionalitats augmentades que no són possibles d'obtenir pels materials constituents sols. En el Capítol 1 es presenta un breu resum de l'estat actual del camp dels materials porosos cristal·lins. Des de la seva concepció, a casos on són aplicats exitosament en el camp de la indústria. Aquest capítol ofereix un cop d'ull als conceptes més importants per la síntesi i disseny d'aquesta classe de materials, així com les seves funcionalitats més útils. S'ha posat especial èmfasi en presentar treballs que combinen de forma exitosa MOFs amb altres materials funcionals per tal de compensar els desavantatges dels constituents individuals, o potenciar els seus punts forts. L'objectiu d'aquest capítol es el de contextualitzar el lector en el treball presentat en aquesta tesi. En el Capítol 2 es descriuen els objectius específics i generals d'aquesta tesi. En el Capítol 3 es presenta un material compòsit sintetitzat a través d'assecat per esprai aplicat a la purificació d'aigua. Aquest material, estructurat en forma de microperles, combina un MOF de la família del UiO-66 i INPs de CeO2. Tots dos materials són coneguts per la seva capacitat d'extraure diferents metalls pesants de l'aigua. Les microperles compòsit sintetitzades han estat provades per avaluar les seves capacitats absortives en multitud d'experiments incloent uns que simulaven mostres reals de rius contaminats. A més a més, el material estudiat és incorporat a un sistema de flux continuo en un prototip de columna de filtració de llit empacat fix per efectuar experiments de corbes d'esgotat i regeneració del material. Finalment, i per tal de demostrar la versatilitat de la síntesi d'assecat per esprai, vam desenvolupar microperles magnètiques mitjançant la incorporació simultània de INPs de CeO2 i Fe3O4 dintre de UiO, [ES] La presente tesis doctoral ha estado dedicada al estudio, desarrollo e implementación de materiales compuestos hechos de estructuras organometálicas (MOFs) y nanopartículas inorgánicas (INPs) con funcionalidades aumentadas que no son posibles de obtener por los materiales constituyentes solos. En el Capítulo 1 se presenta un breve resumen del estado actual del campo de los materiales porosos cristalinos. Desde su concepción, a casos donde son aplicados exitosamente en el campo de la industria. Este capítulo ofrece un vistazo a los conceptos más importantes para la síntesis y diseño de esta clase de materiales, así como sus funcionalidades más útiles. Se ha prestado especial atención en presentar trabajos que combinen de forma exitosa MOFs con otros materiales funcionales con tal de compensar las desventajas de los constituyentes individuales, o potenciar sus puntos fuertes. El objetivo de este capítulo es el de contextualizar el lector en el trabajo presentado en esta tesis. En el Capítulo 2 se describen los objetivos específicos y generales de esta tesis. En el Capítulo 3 se presenta un material compuesto sintetizado a través de secado por espray aplicado a la purificación de agua. Este material, estructurado en forma de microperlas, combina un MOF de la familia del UiO-66 y INPs de CeO2. Los dos materiales son conocidos por su capacidad de extraer diferentes metales pesados del agua. Las microperlas compuestas sintetizadas han estado probadas para evaluar sus capacidades adsorbentes en multitud de experimentos incluyendo unos en que simulaban muestras reales de ríos contaminados. Además, el material estudiado es incorporado a un sistema de flujo continuo en un prototipo de columna de filtración de lecho fijo empaquetado para efectuar experimentos de corvas de agotamiento y regeneración del material. Finalmente, y para demostrar la versatilidad de la síntesis de secado por espray, desarrollamos microperlas magnéticas mediante la incorporación simultánea de INP

Multidrug-resistant bacteria have become a global health problem for which new prophylactic strategies are now needed, including surface-coatings for hospital spaces and medical equipment. This work reports the preparation and functional validation of a metal-organic framework (MOF) based composite for the triggered controlled release of iodine, an antimicrobial element that does not generate resistance. It comprises beads of the iodophilic MOF UiO-66 containing encapsulated gold nanorods (AuNRs) coated with a silica shell. Irradiation of the AuNRs with near-infrared light (NIR) provokes a photothermal effect and the resultant heat actively liberates the iodine. After validating the performance of this composite, it is integrated into a polymer for the development of antibacterial films. This work assesses the adsorption of iodine into these composite films, as well as its passive long-term release and active light-triggered. Finally, this work validates the antibacterial activity of the composite films in vitro against gram-positive and gram-negative bacteria. The findings will surely inform the development of new prophylactic treatments.

The functionalization of an imine-based layered covalent organic framework (COF), containing phenanthroline units as ligands, has allowed the obtention of a heterobimetallated material. Photoactive Ir and Ni fragments were immobilized within the porous structure of the COF, enabling heterogeneous light-mediated Csp 3 -Csp 2 cross-couplings. As radical precursors, potassium benzyl- and alkoxy-trifluoroborates, organic silicates, and proline derivatives were employed, which brings out the good versatility of Ir,Ni@Phen-COF. Moreover, in all the studied cases, an enhanced activity and stability have been observed in comparison with analogous homogenous systems.

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 functionalization of an imine-based layered covalent organic framework (COF), containing phenanthroline units as ligands, has allowed the obtention of a heterobimetallated material. Photoactive Ir and Ni fragments were immobilized within the porous structure of the COF, enabling heterogeneous light-mediated Csp-Cspcross-couplings. As radical precursors, potassium benzyl- and alkoxy-trifluoroborates, organic silicates, and proline derivatives were employed, which brings out the good versatility ofIr,Ni@Phen-COF. Moreover, in all the studied cases, an enhanced activity and stability have been observed in comparison with analogous homogenous systems.

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.

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 use of covalent organic frameworks (COFs) in practical applications demands shaping them into macroscopic objects, which remains challenging. Herein, we report a simple three-step method to produce COF aerogels, based on sol-gel transition, solvent-exchange, and supercritical CO drying, in which 2D imine-based COF sheets link together to form hierarchical porous structures. The resultant COF aerogel monoliths have extremely low densities (ca. 0.02 g cm), high porosity (total porosity values of ca. 99 %), and mechanically behave as elastic materials under a moderate strain (<25–35 %) but become plastic under greater strain. Moreover, these COF aerogels maintain the micro- and meso-porosity of their constituent COFs, and show excellent absorption capacity (e.g. toluene uptake: 32 g g), with high removal efficiency (ca. 99 %). The same three-step method can be used to create functional composites of these COF aerogels with nanomaterials.

With their strong confining porosity and versatile surface chemistry, zeolitic imidazolate frameworks—including the prototypical ZIF-8—display exceptional properties for various applications. In particular, the forced intrusion of water at high pressure (∼25 MPa) into ZIF-8 nanopores is of interest for energy storage. Such a system reveals also ideal to study experimentally water dynamics and thermodynamics in an ultrahydrophobic confinement. Here, we report on neutron scattering experiments to probe the molecular dynamics of water within ZIF-8 nanopores under high pressure up to 38 MPa. In addition to an overall confinement-induced slowing down, we provide evidence for strong dynamical heterogeneities with different underlying molecular dynamics. Using complementary molecular simulations, these heterogeneities are found to correspond to different microscopic mechanisms inherent to vicinal molecules located in strongly adsorbing sites (ligands) and other molecules nanoconfined in the cavity center. These findings unveil a complex microscopic dynamics, which results from the combination of surface residence times and exchanges between the cavity surface and center.

Mixtures of triphenylamine (TPA) and phenyl phenothiazine (PTH) fragments have been incorporated into a series of extended polyimine structures that have been applied in the photodegradation of pollutants of different nature under visible light irradiation. Results obtained revealed that materials containing PTH as the sole photoactive unit resulted in the most active photocatalytic material in the degradation of polybrominated diphenyl ether-1 and Sudan Red III. In contrast, the covalent organic framework containing only TPA acted as the best photocatalyst for the degradation of Methylene Blue. These different trends are related to the versatility of PTH moiety to trigger both photoredox and energy transfer processes, while TPA is only an effective energy transfer catalyst.

Use of preformed metal-organic polyhedra (MOPs) as supermolecular building blocks (SBBs) for the synthesis of metal-organic frameworks (MOFs) remains underexplored due to lack of robust functionalized MOPs. Herein we report the use of polycarboxylate cuboctahedral RhII-MOPs for constructing highly-connected MOFs. Cuboctahedral MOPs were functionalized with carboxylic acid groups on their 12 vertices or 24 edges through coordinative or covalent post-synthetic routes, respectively. We then used each isolated polycarboxylate RhII-MOP as 12-c cuboctahedral or 24-c rhombicuboctahedral SBBs that, upon linkage with metallic secondary building units (SBUs), afford bimetallic highly-connected MOFs. The assembly of a pre-synthesized 12-c SBB with a 4-c paddle-wheel SBU, and a 24-c SBB with a 3-c triangular CuII SBU gave rise to bimetallic MOFs having ftw (4,12)-c or rht (3,24)-c topologies, respectively.

Molecular Russian dolls (matryoshkas) have proven useful for testing the limits of preparative supramolecular chemistry but applications of these architectures to problems in other fields are elusive. Here we report a three-shell, matryoshka-like complex—in which C60 sits inside a cycloparaphenylene nanohoop, which in turn is encapsulated inside a self-assembled nanocapsule—that can be used to address a long-standing challenge in fullerene chemistry, namely the selective formation of a particular fullerene bis-adduct. Spectroscopic evidence indicates that the ternary complex is sufficiently stable in solution for the two outer shells to affect the addition chemistry of the fullerene guest. When the complex is subjected to Bingel cyclopropanation conditions, the exclusive formation of a single trans-3 fullerene bis-adduct was observed in a reaction that typically yields more than a dozen products. The selectivity facilitated by this matryoshka-like approach appears to be a general phenomenon and could be useful for applications where regioisomerically pure C60 bis-adducts have been shown to have superior properties compared with isomer mixtures.

A well-established strategy to synthesize heterogeneous, metal-organic framework (MOF) catalysts that exhibit nanoconfinement effects, and specific pores with highly-localized catalytic sites, is to use organic linkers containing organocatalytic centers. Here, we report that by combining this linker approach with reticular chemistry, and exploiting three-dimensioanl (3D) MOF-structural data from the Cambridge Structural Database, we have designed four heterogeneous MOF-based catalysts for standard organic transformations. These programmable MOFs are isoreticular versions of pcu IRMOF-16, fcu UiO-68 and pillared-pcu SNU-8X, the three most common topologies of MOFs built from the organic linker p,p’-terphenyldicarboxylic acid (tpdc). To synthesize the four squaramide-based MOFs, we designed and synthesized a linker, 4,4’-((3,4‐dioxocyclobut‐1‐ene‐1,2‐diyl)bis(azanedyil))dibenzoic acid (Sq_tpdc), which is identical in directionality and length to tpdc but which contains organocatalytic squaramide centers. Squaramides were chosen because their immobilization into a framework enhances its reactivity and stability while avoiding any self-quenching phenomena. Therefore, the four MOFs share the same organocatalytic squaramide moiety, but confine it within distinct pore environments. We then evaluated these MOFs as heterogeneous H-bonding catalysts in organic transformations: a Friedel-Crafts alkylation and an epoxide ring-opening. Some of them exhibited good performance in both reactions but all showed distinct catalytic profiles that reflect their structural differences.

Herein we describe the topological influence of zigzag ligands in the assembly of Zr(IV) metal–organic frameworks (MOFs). Through a transversal design strategy using reticular chemistry, we were able to synthesize a family of isoreticular Zr(IV)-based MOFs exhibiting the bcu—rather than the fcu—topology. Our findings underscore the value of the transversal parameter in organic ligands for dictating MOF architectures.

Here, we report the synthesis of (multi)-layered zeolitic imidazolate framework (ZIF-8/-67) composite particles via a sequential deconstruction–reconstruction process. We show that this process can be applied to construct ZIF-8-on-ZIF-67 composite particles whose cores are the initially etched particles. In addition, we demonstrate that introduction of functional inorganic nanoparticles (INPs) onto the crystal surface of etched particles does not disrupt ZIF particle reconstruction, opening new avenues for designing (multi)-layered ZIF-on-INP-on-ZIF composite particles comprising more than one class of inorganic nanoparticles. In these latter composites, the location of the inorganic nanoparticles inside each single metal–organic framework particle as well as of their separation at the nanoscale (20 nm) is controlled. Preliminary results show that (multi)-layered ZIF-on-INP-on-ZIF composite particles comprising a good sequence of inorganic nanoparticles can potentially catalyze cascade reactions.

Here, we report the covalent post-synthetic modification (CPSM) of MOFs using the photothermal effect. Specifically, we subjected mixtures of a photothermally active MOF and another reagent to irradiation with a UV-Vis lamp. This caused the MOF to heat up, which in turn caused the other reagent to melt and subsequently react with the functional groups on the walls of the MOF pores. We have exploited this dual function of MOFs as both heater and host for CPSMs to achieve rapid formation of amides from the reaction of representative MOFs (UiO-66-NH2 or MIL-101-NH2-(Al)) with anhydrides under solvent-free conditions. In addition, this approach enables more complex CPSMs in MOFs such as the formation of amides in UiO-66-NH2 by using an aldehyde through a cascade reaction.

Porous metal–organic frameworks (MOFs) are attracting great attention from industry, thanks to their myriad potential applications in areas such as catalysis and gas storage. Zr-MOFs (also known as UiO-type MOFs) are especially promising, owing to their large surface areas, high chemical versatility and remarkable hydrothermal, chemical and thermal stabilities. However, among the challenges currently precluding the industrial exploitation of MOFs is the lack of green methods for their synthesis. Herein we describe a continuous-flow spray-drying method for the simultaneous synthesis and shaping of spherical MOF microbeads in a mixture of water and acetic acid. We used this approach to build two archetypical Zr-MOFs: UiO-66-NH2 and Zr-fumarate. By tuning the concentration of acetic acid in water, we were able to produce, by a scalable process, UiO-66-NH2 and Zr-fumarate beads with SBET and water-sorption values comparable to the literature values obtained with other methods.

The structural deterioration of archetypical, well‐faceted metal–organic frameworks (MOFs) has been evaluated upon exposure to an acidic environment (H2S). Experimental results show that the structural damage highly depends on the nature of the hybrid network (e.g., softness of the metal ions, hydrophilic properties, among others) and the crystallographic orientation of the exposed facets. Microscopy images show that HKUST‐1 with well‐defined octahedral (111) facets is completely deteriorated, ZIF‐8 with preferentially exposed (110) facets exhibits a large external deterioration with the development of holes or cavities in the mesoporous range, whereas UiO‐66‐NH2 with (111) exposed facets, and PCN‐250 with (100) facets does not reflect any sign of surface damage. Despite the selectivity in the external deterioration, X‐ray diffraction and gas adsorption measurements confirm that indeed all MOFs suffer an important internal deterioration, these effects being more severe for MOFs based on softer cations (e.g., Cu‐based HKUST‐1 and Fe‐based PCN‐250). These structural changes have inevitable important effects in the final adsorption performance for CO2 and CH4 at low and high pressures.

The structural deterioration of archetypical, well‐faceted metal–organic frameworks (MOFs) has been evaluated upon exposure to an acidic environment (H2S). Experimental results show that the structural damage highly depends on the nature of the hybrid network (e.g., softness of the metal ions, hydrophilic properties, among others) and the crystallographic orientation of the exposed facets. Microscopy images show that HKUST‐1 with well‐defined octahedral (111) facets is completely deteriorated, ZIF‐8 with preferentially exposed (110) facets exhibits a large external deterioration with the development of holes or cavities in the mesoporous range, whereas UiO‐66‐NH2 with (111) exposed facets, and PCN‐250 with (100) facets does not reflect any sign of surface damage. Despite the selectivity in the external deterioration, X‐ray diffraction and gas adsorption measurements confirm that indeed all MOFs suffer an important internal deterioration, these effects being more severe for MOFs based on softer cations (e.g., Cu‐based HKUST‐1 and Fe‐based PCN‐250). These structural changes have inevitable important effects in the final adsorption performance for CO2 and CH4 at low and high pressures.

Here, we report the design, synthesis, and functional testing of enzyme-powered porous micromotors built from a metal–organic framework (MOF). We began by subjecting a presynthesized microporous UiO-type MOF to ozonolysis, to confer it with mesopores sufficiently large to adsorb and host the enzyme catalase (size: 6–10 nm). We then encapsulated catalase inside the mesopores, observing that they are hosted in those mesopores located at the subsurface of the MOF crystals. In the presence of H2O2 fuel, MOF motors (or MOFtors) exhibit jet-like propulsion enabled by enzymatic generation of oxygen bubbles. Moreover, thanks to their hierarchical pore system, the MOFtors retain sufficient free space for adsorption of additional targeted species, which we validated by testing a MOFtor for removal of rhodamine B during self-propulsion.

Herein we report the design, synthesis, structural characterisation and functional testing of a series of Cu(II) coordination polymers containing flexible 4,4′-dithiodibenzoate ligand (4,4′-DTBA), with or without auxiliary N-donor ligands. Reaction of Cu(II) with 4,4′-DTBA yielded a 1D coordination polymer (1) based on Cu(II) paddlewheel units connected by 4,4′-DTBA, to form cyclic loop chains with intramolecular voids that exhibit reversible structural transformations upon subsequent solvent exchange in methanol to afford a new, crystalline, permanently-porous structure (1′). However, when the same reaction was run with pyridine, it formed a porous 2D coordination polymer (2). We have attributed the difference in dimensionality seen in the two products to the coordination of pyridine on the axial site of the Cu(II) paddle-wheel, which forces flexible 4,4′-DTBA to adopt a different conformation. Reactions in the presence of 4,4′-bipyridine (4,4′-bpy) afforded two new, flexible, 2D coordination polymers (3 & 4). Lower concentrations of 4,4′-bpy afforded a structure (3) built from 1D chains analogous to those in 1 and connected through 4,4′-bpy linkers coordinated to the axial positions. Interestingly, 3 showed reversible structural transformations triggered by either solvent exchange or thermal treatment, each of which yielded a new crystalline and permanently porous phase (3′). Finally, use of higher concentrations of 4,4′-bpy led to a coordination polymer (4) based on a distorted CuO3N2 trigonal bipyramid, rather than on the Cu(II) paddlewheel. The connection of these motifs by 4,4′-DTBA resulted in a zig-zag 1D chain connected through 4,4′-bpy ligands to form a porous 2D network. Interestingly, 4 also underwent reversible thermal transformation to yield a microporous coordination polymer (4′).

Herein we propose a new approach for deducing the topology of metal–organic frameworks (MOFs) assembled from organic ligands of low symmetry, which we call net-clipping. It is based on the construction of nets by rational deconstruction of edge-transitive nets comprising higher-connected molecular building blocks (MBBs). We have applied net-clipping to predict the topologies of MOFs containing zigzag ligands. To this end, we derived 2-connected (2-c) zigzag ligands from 4-c square-like MBBs by first splitting the 4-c nodes into two 3-c nodes and then clipping their two diagonally connecting groups. We demonstrate that, when this approach is applied to the 17 edge-transitive nets containing square-like 4-c MBBs, net-clipping leads to generation of 10 nets with different underlying topologies. Moreover, we report that literature and experimental research corroborate successful implementation of our approach. As proof-of-concept, we employed net-clipping to form three new MOFs built with zigzag ligands, each of which exhibits the deduced topology.

Metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) are among the most attractive porous materials today. They exhibit outstanding porosity for countless applications such as gas storage, CO2 capture, gas separation, sensing, drug delivery, and catalysis. Moreover, researchers have recently begun to combine MOFs or COFs with other functional materials to obtain composites that boast the respective strengths, and mitigate the respective weaknesses, of each component, enabling enhanced performance in many of the aforementioned applications. Accordingly, development of methods for fabrication of MOFs, COFs, and related composites is important for facilitating adoption of these materials in industry. One promising synthetic technique is spray-drying, which is already well-integrated in manufacturing processes for diverse sectors. It enables rapid, continuous and scalable production of dry microspherical powders in a single step, leading to lower fabrication costs and shorter production times compared to traditional methods.

Controlling interfacial interactions in magnetic/topological insulator heterostructures is a major challenge for the emergence of novel spin-dependent electronic phenomena. As for any rational design of heterostructures that rely on proximity effects, one should ideally retain the overall properties of each component while tuning interactions at the interface. However, in most inorganic interfaces, interactions are too strong, consequently perturbing, and even quenching, both the magnetic moment and the topological surface states at each side of the interface. Here, we show that these properties can be preserved using ligand chemistry to tune the interaction of magnetic ions with the surface states. By depositing Co-based porphyrin and phthalocyanine monolayers on the surface of Bi2Te3 thin films, robust interfaces are formed that preserve undoped topological surface states as well as the pristine magnetic moment of the divalent Co ions. The selected ligands allow us to tune the interfacial hybridization within this weak interaction regime. These results, which are in stark contrast with the observed suppression of the surface state at the first quintuple layer of Bi2Se3 induced by the interaction with Co phthalocyanines, demonstrate the capability of planar metal–organic molecules to span interactions from the strong to the weak limit.

Dynamic covalent bonds have been advantageously used to direct the synthesis of crystalline porous covalent organic frameworks (COFs). Unlike the standard synthetic protocols that involve harsh conditions, this work provides a high-yield “one-pot” green synthesis of imine-based COFs in water. Additionally, this aqueous synthesis can be performed under microwave conditions, considerably reducing the reaction time.