A Crystalline Catalyst Based on a Porous Metal-Organic Framework and 12-Tungstosilicic Acid: Particle Size Control by Hydrothermal Synthesis for the Formation of Dimethyl Ether

Hierarchically Ordered Macro-Microporous Polyoxometalate-Based Metal-Organic Framework Single Crystals

Facile construction of ordered macroporous polyoxometalate-based metal-organic frameworks (POM@MOFs) to break the intrinsic microporous restriction is significant but remains challenging. On one hand, the POMs introduced improve the structural stability and modify the pores of MOFs, e.g., introducing functional catalytic and adsorptive units. Meanwhile, the acidic POMs severely affect the nucleation and growth of the POM@MOFs, resulting in complicated synthesis and difficult assembly control. Herein, a general approach has been developed to fabricate ordered macroporous POM@MOF single crystals, involving close-packed polystyrene (PS) nanosphere templates. The artificially selected polar solvents exerting strong solvent effect with POMs weaken the affinity between POMs and metal ions, thereby effectively stabilizing the precursors from assembly before filling into the PS template interstices. The weak alkaline carboxylate used regulates the in situ nucleation and growth of POM@MOFs through deprotonation of the ligands as well as coordinating modulation, affording a series of hierarchically cuboctahedral POM@MOF single crystals with ordered macropores (ca. 180 nm) and intrinsic micropores after template removal. The ordered macroporous structure and thinned microporous skeleton markedly improve mass diffusion properties, while the integral single-crystal lattice retains superior stability.

Heterogenisation of polyoxometalates and other metal-based complexes in metal–organic frameworks: from synthesis to characterisation and applications in catalysis

This review provides a thorough overview of composites with molecular catalysts (polyoxometalates, or organometallic or coordination complexes) immobilised into MOFs via non-covalent interactions.

The role of metal–organic porous frameworks in dual catalysis

Metal–organic frameworks (MOFs) are a valuable group of porous crystalline solids with inorganic and organic parts that can be used in dual catalysis.

Superparamagnetic MOF@GO Ni and Co based hybrid nanocomposites as efficient water pollutant adsorbents

A series of highly efficient adsorbents were developed using Ni₃(BTC)₂ and Co₃(BTC)₂ metal-organic frameworks (MOFs) and Fe₃O₄ magnetic nanoparticles (MNPs) to functionalize graphene oxide (GO). XRD results show high crystallinity of the prepared nanomaterials and the successful decoration of Ni₃(BTC)₂ and Co₃(BTC)₂ MOFs over the GO substrate (BTC = benzene-1,3,5-tricarboxylic acid). SEM and TEM imaging show the successful formation of nanoscale MOFs and Fe₃O₄ MNPs over GO. IR spectroscopy supports the characterization and successful preparation of the Fe₃O₄/MOF@GO hybrid composite nanoadsorbents. The prepared composite nanoadsorbents were used to sorb Methylene Blue (MB) as a model for common organic pollutants in water and common ions (Na⁺, Ca²⁺, Mg²⁺, SO₄^2-, SiO₃^2-) from a brackish water model. The adsorbed concentration at equilibrium of MB of the prepared composite nanoadsorbents increases by an average of 30.52 and 13.75 mg/g for the Co and Ni composite, respectively, when compared to the MOFs parent materials. The adsorbed amount of sulfate ions increases by 92.1 mg/g for the Co composite and 112.1 mg/g for the Ni composite, when compared to graphene oxide. This adsorption enhancement is attributed to suppressed aggregation through increased dispersive forces in the MOFs due to the presence of GO, formation of nanoscale MOFs over the GO platform, and the hindering of stacking of the graphene layers by the MOFs. Leaching tests show that the release of Co and Ni ions to water is reduced from 105.2 and 220 mg/L, respectively, in the parent MOF materials to 0.5 and 16.4 mg/L, respectively, in the composite nanoadsorbents. These findings show that the newly developed composite nanoadsorbents can sorb organic pollutants, and target sulfate and silicate anions, which makes them suitable candidates for water and wastewater treatments.

POM@MOF Hybrids: Synthesis and Applications

The hybrid materials that are created by supporting or incorporating polyoxometalates (POMs) into/onto metal–organic frameworks (MOFs) have a unique set of properties. They combine the strong acidity, oxygen-rich surface, and redox capability of POMs, while overcoming their drawbacks, such as difficult handling, a low surface area, and a high solubility. MOFs are ideal hosts because of their high surface area, long-range ordered structure, and high tunability in terms of the pore size and channels. In some cases, MOFs add an extra dimension to the functionality of hybrids. This review summarizes the recent developments in the field of POM@MOF hybrids. The most common applied synthesis strategies are discussed, together with major applications, such as their use in catalysis (organocatalysis, electrocatalysis, and photocatalysis). The more than 100 papers on this topic have been systematically summarized in a handy table, which covers almost all of the work conducted in this field up to now.

Strategies for Incorporating Catalytically Active Polyoxometalates in Metal-Organic Frameworks for Organic Transformations

Polyoxometalates (POMs) can benefit from immobilization on solid supports to overcome their difficulty in processability and stability. Among the reported solid supports, metal-organic frameworks (MOFs) offer a crystalline, versatile platform for depositing highly active POMs. The combination of these structures can at times benefit from the combined reactivity of both the POM and MOF, sometimes synergistically, to improve catalysis while balancing desirable properties like porosity, substrate diffusion, or stability. In this Review, we survey the strategies for immobilizing POMs within MOF structures, with an emphasis on how physical and catalytic properties of the parent materials are affected in the composite when employed in organic transformations.

H5PV2Mo10O40 encapsulated into Cu3(BTC)2 as an efficient heterogeneous nanocrystalline catalyst for styrene epoxidation

The nanocrystalline catalyst HPMoV@Cu₃(BTC)₂ prepared using a liquid-assisted grinding method showed excellent catalytic activity for the epoxidation of styrene in O₂.

Applications of water stable metal–organic frameworks

A comprehensive review is given on the applications of water stable metal–organic frameworks in areas of adsorption, membrane separation, sensing, catalysis, and proton conduction.

A polyoxometalate-based inorganic–organic hybrid material: synthesis, characterization structure and photocatalytic study

A new polyoxometalate (POM)-based inorganic–organic hybrid compound, [Ag2(bib)3][H2SiW12O40] (1), has been hydrothermally synthesized and characterized by routine methods. Single-crystal X-ray diffraction analysis reveals that inorganic supramolecular chains constructed of POM and [Ag2(bib)3] subunits are fused together via the Ag cations forming a 3D supramolecular structure. The structure possesses the moganite-type topology. The photocatalytic properties have been investigated through the oxidative decomposition of Rhodamine-B dye.

Metal-organic framework composites: from fundamentals to applications

Metal-organic frameworks (MOFs) are a class of crystallized porous polymeric materials consisting of metal ions or clusters linked together by organic bridging ligands. Due to their permanent porosity, rich surface chemistry and tuneable pore sizes, MOFs have emerged as one type of important porous solid and have attracted intensive interests in catalysis, gas adsorption, separation and storage over the past two decades. When compared with pure MOFs, the combination of MOFs with functional species or matrix materials not only shows enhanced properties, but also broadens the applications of MOFs in new fields, such as bio-imaging, drug delivery and electrical catalysis, owing to the interactions of the functional species/matrix with the MOF structures. Although the synthesis, chemical modification and potential applications of MOFs have been reviewed previously, there is an increasing awareness on the synthesis and applications of their composites, which have rarely been reviewed. This review aims to fill this gap and discuss the fabrication, properties, and applications of MOF composites. The remaining challenges and future opportunities in this field, in terms of processing techniques, maximizing composite properties, and prospects for applications, have also been indicated.

Heterogeneous Catalysis of Polyoxometalate Based Organic-Inorganic Hybrids

Organic–inorganic hybrid polyoxometalate (POM) compounds are a subset of materials with unique structures and physical/chemical properties. The combination of metal-organic coordination complexes with classical POMs not only provides a powerful way to gain multifarious new compounds but also affords a new method to modify and functionalize POMs. In parallel with the many reports on the synthesis and structure of new hybrid POM compounds, the application of these compounds for heterogeneous catalysis has also attracted considerable attention. The hybrid POM compounds show noteworthy catalytic performance in acid, oxidation, and even in asymmetric catalytic reactions. This review summarizes the design and synthesis of organic–inorganic hybrid POM compounds and particularly highlights their recent progress in heterogeneous catalysis.

Polyoxometalate-based metal–organic coordination networks for heterogeneous catalytic desulfurization

Single crystals and nanocrystals of polyoxometalate-based metal-organic coordination networks for heterogeneous catalytic desulfurization.

Recent advances in porous polyoxometalate-based metal–organic framework materials

POM-based MOF materials, which combine the advantages of both POMs and MOFs, have received increasing attention. In this review, we present the recent developments in porous POM-based MOF materials for the first time, including their classification, synthesis strategies and applications, especially in the field of catalysis.

Methane storage in advanced porous materials

The need for alternative fuels is greater now than ever before. With considerable sources available and low pollution factor, methane is a natural choice as petroleum replacement in cars and other mobile applications. However, efficient storage methods are still lacking to implement the application of methane in the automotive industry. Advanced porous materials, metal-organic frameworks and porous organic polymers, have received considerable attention in sorptive storage applications owing to their exceptionally high surface areas and chemically-tunable structures. In this critical review we provide an overview of the current status of the application of these two types of advanced porous materials in the storage of methane. Examples of materials exhibiting high methane storage capacities are analyzed and methods for increasing the applicability of these advanced porous materials in methane storage technologies described.

Facile solvothermal synthesis of porous cubic Cu microparticles as copper catalysts for Rochow reaction

Porous cubic Cu microparticles were synthesized by a facile solvothermal method using Cu(CH(3)COO)(2)·H(2)O as the Cu precursor and NaOH in a solution containing ethanol, ethylene glycol, and water. The synthesis conditions were investigated and a growth process of porous cubic Cu microparticles was proposed. The catalytic properties of the porous Cu microparticles as model copper catalysts for Rochow reaction were explored. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, temperature-programmed reduction, and nitrogen adsorption. It was found that the morphology and structure of the porous cubic Cu microparticles are highly dependent on the reaction time and temperature as well as on the amount of reactants added. Compared to the commercial Cu microparticles with irregular morphology and dense internal structure, porous cubic Cu microparticles show much higher dimethyldichlorosilane selectivity and Si conversion via Rochow reaction, which are attributed to the enhanced formation of active Cu(x)Si phase and gas transportation in the presence of the pore system within microparticles, demonstrating the significance of the pore structure of the copper catalysts in catalytic reactions of organosilane synthesis.