Heteroepitaxial MOF-on-MOF Photocatalyst for Solar-Driven Water Splitting.

Assembly of different metal-organic frameworks (MOFs) into hybrid MOF-on-MOF heterostructures has been established as a promising approach to develop synergistic performances for a variety of applications. Here, we explore the performance of a MOF-on-MOF heterostructure by epitaxial growth of MIL-88B(Fe) onto UiO-66(Zr)-NH nanoparticles. The face-selective design and appropriate energy band structure alignment of the selected MOF constituents have permitted its application as an active heterogeneous photocatalyst for solar-driven water splitting.

A zero-valent palladium cluster-organic framework.

Acquiring spatial control of nanoscopic metal clusters is central to their function as efficient multi-electron catalysts. However, dispersing metal clusters on surfaces or in porous hosts is accompanied by an intrinsic heterogeneity that hampers detailed understanding of the chemical structure and its relation to reactivities. Tethering pre-assembled molecular metal clusters into polymeric, crystalline 2D or 3D networks constitutes an unproven approach to realizing ordered arrays of chemically well-defined metal clusters.

Alternative protein encapsulation with MOFs: overcoming the elusive mineralization of HKUST-1 in water.

Protein encapsulation by formation of MOFs is a valuable strategy to immobilise and protect these bioentities. However the required biocompatible conditions limits the scope of MOFs under investigation, particularly in the case of hydrolytically unstable MOFs such as HKUST-1. We report alternative synthetic procedures to obtain protein@HKUST-1 biocomposites from related Cu-BTC dense biocomposites.

ZIF-8 encapsulation improves the antifungal activity of benzaldehyde and methyl anthranilate in films.

In this work, two ZIF-8-based biocomposites were obtained by entrapping the biomolecules benzaldehyde and methyl anthranilate direct impregnation with fast encapsulation kinetics and high molecule payloads were achieved. The obtained biocomposites exhibit an enhanced antifungal activity against after integration in biopolymeric zein films in comparison with the action of free molecules, making these biomaterials promising candidates for food preservation and packaging applications.

Hierarchical mesoporous NanoMUV-2 for the selective delivery of macromolecular drugs.

Although Metal-organic frameworks (MOFs) have received attention as drug delivery systems, their application in the delivery of macromolecules is limited by their pore size and opening. Herein, we present the synthesis of nanostructured MUV-2, a hierarchical mesoporous iron-based MOF that can store high payloads of the macromolecular drug paclitaxel ( 23% w/w), increasing its selectivity towards HeLa cancer cells over HEK non-cancerous cells. Moreover, this NanoMUV-2 permits full degradation under simulated physiological conditions while maintaining biocompatibility, and is amenable to specific surface modifications that increase its cell permeation, efficient cytosol delivery and cancer-targeting effect, further intensifying the cancer selectivity of paclitaxel.

Imparting structural robustness of metal-organic cages based on oxo-dimolybdenum clusters.

A family of robust and stable molybdenum-based metal-organic cages have been obtained based on the [MoO(μ-O)] secondary building unit. The resulting cages are decorated with different pyrdine derivatives that impart structural stability, resulting in the structural elucidation of the activated cage with single-crystal diffraction. The chemical robustness of the cage is also demonstrated by the post-synthetic modification of the cage, which allows the exchange of the pyridine derivatives without rupture of the cage.

Ultramicroporous iron-isonicotinate MOFs combining size-exclusion kinetics and thermodynamics for efficient CO/N gas separation.

Two ultramicroporous 2D and 3D iron-based Metal-Organic Frameworks (MOFs) have been obtained by solvothermal synthesis using different ratios and concentrations of precursors. Their reduced pore space decorated with pendant pyridine from tangling isonicotinic ligands enables the combination of size-exclusion kinetic gas separation, due to their small pores, with thermodynamic separation, resulting from the interaction of the linker with CO molecules. This combined separation results in efficient materials for dynamic breakthrough gas separation with virtually infinite CO/N selectivity in a wide operando range and with complete renewability at room temperature and ambient pressure.

Boosting Protein Encapsulation through Lewis-Acid-Mediated Metal-Organic Framework Mineralization: Toward Effective Intracellular Delivery.

Encapsulation of biomolecules using metal-organic frameworks (MOFs) to form stable biocomposites has been demonstrated to be a valuable strategy for their preservation and controlled release, which has been however restricted to specific electrostatic surface conditions. We present a Lewis-acid-mediated general strategy that promotes the spontaneous MOF growth on a broad variety of proteins, for the first time, regardless of their surface nature. We demonstrate that MOFs based on cations exhibiting considerable inherent acidity such as MIL-100(Fe) enable efficient biomolecule encapsulation, including elusive alkaline proteins previously inaccessible by the well-developed azolate-based MOF encapsulation.

Plasmon-assisted spin transition in gold nanostar@spin crossover heterostructures.

Herein we report the design of core@shell nanoparticles formed by a metallic Au nanostar core and a spin-crossover shell based on the coordination polymer [Fe(Htrz)(trz)](BF). This procedure is general and has been extended to other metallic morphologies (nanorods, nanotriangles). Thanks to the photothermal effect arising from the plasmonic properties of the Au nanostar, 60% of iron centers undergo a thermal spin transition inside the thermal hysteresis triggered by a 808 nm laser low intensity irradiation.

Exploiting the Redox Activity of MIL-100(Fe) Carrier Enables Prolonged Carvacrol Antimicrobial Activity.

The design of efficient food contact materials that maintain optimal levels of food safety is of paramount relevance to reduce the increasing number of foodborne illnesses. In this work, we develop a smart composite metal-organic framework (MOF)-based material that fosters a unique prolonged antibacterial activity. The composite is obtained by entrapping a natural food preserving molecule, carvacrol, into a mesoporous MIL-100(Fe) material following a direct and biocompatible impregnation method, and obtaining particularly high payloads.

A tris-oxovanadium pyrogallate complex: synthesis, structure, and magnetic and electronic properties.

With the aim of identifying new cation-phenolate complexes, we herein investigated the reactivity of pyrogallol (Hpgal) with vanadium salts. A trimetallic anionic complex was identified, and found to be formed under a broad set of reaction conditions. This complex, with the formula VO(pgal), consists of three oxovanadium(IV) units connected together by three pyrogallate ligands to afford a bowl-shaped species presenting a pseudo 3-fold symmetry axis.

Fast Polymeric Functionalization Approach for the Covalent Coating of MoS Layers.

We present the covalent coating of chemically exfoliated molybdenum disulfide (MoS) based on the polymerization of functional acryl molecules. The method relies on the efficient diazonium anchoring reaction to provoke the in situ radical polymerization and covalent adhesion of functional coatings. In particular, we successfully implement hydrophobicity on the exfoliated MoS in a direct, fast, and quantitative synthetic approach.

Selective CO Sorption Using Compartmentalized Coordination Polymers with Discrete Voids*.

Carbon capture and storage with porous materials is one of the most promising technologies to minimize CO release into the atmosphere. Here, we report a family of compartmentalized coordination polymers (CCPs) capable of capturing gas molecules in a selective manner based on two novel tetrazole-based ligands. Crystal structures have been modelled theoretically under the Density Functional Theory (DFT) revealing the presence of discrete voids of 380 Å .

MOF-Mediated Synthesis of Supported Fe-Doped Pd Nanoparticles under Mild Conditions for Magnetically Recoverable Catalysis*.

Metal-organic framework (MOF)-driven synthesis is considered as a promising alternative for the development of new catalytic materials with well-designed active sites. This synthetic approach is used here to gradually transform a new bimetallic MOF, with Pd and Fe as the metal components, by the in situ generation of aniline under mild conditions. This methodology results in a compositionally homogeneous nanocomposite formed by Fe-doped Pd nanoparticles that, in turn, are supported on iron oxide-doped carbon.

Cellular Uptake, Intracellular Trafficking, and Stability of Biocompatible Metal-Organic Framework (MOF) Particles in Kupffer Cells.

Rapid intracellular degradation of current drug-delivery nanocarriers presents a challenge for achieving ideal controlled drug-release kinetics. Recent in vivo studies have shown that porous hybrid metal-organic frameworks (MOFs), belonging to the Materials of Institute Lavoisier (MIL) family, display prolonged biodegradation behavior. In this study, we investigated stability of these materials in Kupffer cells, a relevant target for the treatment of several life-threatening immune-mediated liver diseases.

Solvent-Free Synthesis of ZIFs: A Route toward the Elusive Fe(II) Analogue of ZIF-8.

Herein we report the synthesis of an elusive metal-organic framework, the iron(II) analogue of ZIF-8 with the formula Fe(2-methylimidazolate), here denoted as MUV-3. The preparation of this highly interesting porous material, inaccessible by common synthetic procedures, occurs in a solvent-free reaction upon addition of an easily detachable template molecule, yielding single crystals of MUV-3. This methodology can be extended to other metals and imidazolate derivatives, allowing the preparation of ZIF-8, ZIF-67, and the unprecedented iron(II) ZIFs Fe(2-ethylimidazolate) and Fe(2-methylbenzimidazolate).

Charge Mobility and Dynamics in Spin-Crossover Nanoparticles Studied by Time-Resolved Microwave Conductivity.

We use the electrodeless time-resolved microwave conductivity (TRMC) technique to characterize spin-crossover (SCO) nanoparticles. We show that TRMC is a simple and accurate means for simultaneously assessing the magnetic state of SCO compounds and charge transport information on the nanometer length scale. In the low-spin state from liquid nitrogen temperature up to 360 K the TRMC measurements present two well-defined regimes in the mobility and in the half-life times, in which the former transition temperature T occurs near 225 K.

GraftFast Surface Engineering to Improve MOF Nanoparticles Furtiveness.

Controlling the outer surface of nanometric metal-organic frameworks (nanoMOFs) and further understanding the in vivo effect of the coated material are crucial for the convenient biomedical applications of MOFs. However, in most studies, the surface modification protocol is often associated with significant toxicity and/or lack of selectivity. As an alternative, how the highly selective and general grafting GraftFast method leads, through a green and simple process, to the successful attachment of multifunctional biopolymers (polyethylene glycol (PEG) and hyaluronic acid) on the external surface of nanoMOFs is reported.

A Smart Metal-Organic Framework Nanomaterial for Lung Targeting.

Despite high morbidity and mortality associated with lung diseases, addressing drugs towards lung tissue remains a pending task. Particle lung filtration has been proposed for passive lung targeting and drug delivery. However, toxicity issues derived from the long-term presence of the particles must be overcome.

Adaptability of the metal(iii,iv) 1,2,3-trioxobenzene rod secondary building unit for the production of chemically stable and catalytically active MOFs.

The use of a 5,10,15,20-tetrakis(3,4,5-trihydroxyphenyl)porphyrin has yielded a new MOF based on M-1,2,3-trioxobenzene chains that can be made of M = Zr(iv) or RE(iii) (RE = rare earth), showing a very high and limited chemical stability, respectively. The robust metallated Zr-analogue, Co-MIL-173(Zr), has proven to be a heme-like heterogeneous catalyst suitable for aerobic oxidation of hydrocarbons.

Gas confinement in compartmentalized coordination polymers for highly selective sorption.

Discrimination between different gases is an essential aspect for industrial and environmental applications involving sensing and separation. Several classes of porous materials have been used in this context, including zeolites and more recently MOFs. However, to reach high selectivities for the separation of gas mixtures is a challenging task that often requires the understanding of the specific interactions established between the porous framework and the gases.

Unravelling the chemical design of spin-crossover nanoparticles based on iron(ii)-triazole coordination polymers: towards a control of the spin transition.

A systematic study of the key synthetic parameters that control the growth of spin-crossover (SCO) nanoparticles (NPs) using the reverse micelle technique has been undertaken in the system [Fe(Htrz)(trz)](BF)·HO, (Htrz = 1,2,4-triazole). This has permitted us to modulate the physical properties of the NPs in a controlled and reproducible manner. In particular, a control over the size of the NPs (in the range 4 to 16 nm) has been achieved by varying the water to surfactant molar ratio.

Near Room-Temperature Memory Devices Based on Hybrid Spin-Crossover@SiO2 Nanoparticles Coupled to Single-Layer Graphene Nanoelectrodes.

The charge transport properties of SCO [Fe(Htrz)2 (trz)](BF4 ) NPs covered with a silica shell placed in between single-layer graphene electrodes are reported. A reproducible thermal hysteresis loop in the conductance above room-temperature is evidenced. This bistability combined with the versatility of graphene represents a promising scenario for a variety of technological applications but also for future sophisticated fundamental studies.