Immobilization of Polyoxometalate in the Metal-Organic Framework rht-MOF-1: Towards a Highly Effective Heterogeneous Catalyst and Dye Scavenger

Self-assembly of Dawson-type H6P2W18O62@[Cu6O(TZI)3(H2O)6]4 for high-performance aerobic oxidation desulfurization of fuel

Because global sulfur emission has escalated, the development of high-efficiency deep desulfurization techniques has become imperative. Herein, to design a high-activity heterogeneous catalyst for the aerobic oxidation desulfurization (AODS) of fuel, Dawson-type polyoxometalate (H6P2W18O62 abbreviated as D-P2W18), characterized by its high activity and strong oxidative capacity, was applied to react with CuCl2·2H2O and H3TZI via a one-pot hydrothermal method. Consequently, blue crystalline H6P2W18O62@[Cu6O(TZI)3(H2O)6]4 (abbreviated as D-P2W18@rht-MOF-1; rht-MOF-1 = [Cu6O(TZI)3(H2O)6]4·nH2O) was afforded. X-ray diffraction analysis indicated that D-P2W18 was successfully encapsulated in two different cages of rht-MOF-1, which is distinct from the crystal structure of Keggin-type POMs@rht-MOF-1. It represents the first crystal structure of Dawson-type POMs@rht-MOF-1. When D-P2W18@rht-MOF-1 was employed as a catalyst for AODS under ambient oxygen pressure with the assistance of surfactant dioctadecyl dimethyl ammonium chloride (DODMAC), it demonstrated remarkable catalytic capability and recyclability for both model fuel and commercial diesel. Further, the AODS reaction mechanism, identified as a free radical oxidation-reduction process, was verified by way of radical quenching experiments, EPR and XPS analysis. This approach offers a feasible route for the synthesis of new Dawson-type POMs@MOFs of heterogeneous catalysts for highly active AODS of fuel.

A self-assembly solvothermal synthesis of SiMoVn@[Cu6O(TZI)3(H2O)6]4·nH2O for the efficient selective oxidation of various alkylbenzenes

A series of SiMoVn@rht-MOF-1 were isolated via a one-pot self-assembly solvothermal synthesis, exhibiting effective catalytic activity and excellent recyclability.

Effective Heterogeneous Oxidative Desulfurization Catalyzed by H3 PMo9 W3 O40 @rht-MOF-1

With the increasingly strict standard for sulfur content in fuel, it is necessary to develop high-efficiency catalyst for extractive and catalytic oxidative desulfurization systems (ECODS). Herein, a series of three remarkable complexes H₃ PMo_(12-n) W_n O₄₀ @rht-MOF-1 (1 a, n=1; 2 a, n=2; 3 a, n=3) have been designed and prepared. Complexes 1 a, 2 a and 3 a were characterized by single-crystal X-ray diffraction and FT-IR, PXRD, SEM, N₂ adsorption-desorption isotherms, etc. Upon complex 3 a was applied as catalyst, it exhibited remarkably high catalytic activity in the ECODS reactions of aromatic sulfur compounds under optimal conditions. On the basis of its excellent heterogeneity, the catalyst could be recycled for nine consecutive cycles without significant losing of activity centers. Then, the reaction kinetics and mechanism were investigated and the activation energy have been calculated and discussed. Further, the complex 3 a is employed to catalyze the ODS of commercial diesel oil. As a result, the desulfurization efficiency reached 90%. These results provided important structure data for study the structure-property relationship and potential heterogeneous catalyst applied in ODS in industry.

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.

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.

A polyoxometalate-encapsulated nanocage cluster organic framework built from {Cu4P2} units and its efficient bifunctional electrochemical performance

The first polyoxometalate-encapsulated twenty-four-nucleus organophosphorus-copper nanocage cluster organic framework has been constructed and it is shown to exhibit highly efficient bifunctional electrochemical performance.

Polyoxometalates as components of supramolecular assemblies

The non-covalent interaction of polyoxometalates (POMs) with inorganic- or organic-based moieties affords hybrid assemblies with specific physicochemical properties that are of high interest for both fundamental and applied studies, including the discovery of conceptually new compounds and unveiling the impact of their intra-supramolecular relationships on the fields of catalysis, molecular electronics, energy storage and medicine. This minireview summarises the recent advances in the synthetic strategies towards the formation of such non-covalent POM-loaded assemblies, shedding light on their key properties and the currently investigated applications. Four main emerging categories according to the nature of the conjugate are described: (i) POMs in metal-organic frameworks, (ii) POMs merged with cationic metal complexes, (iii) architectures generated with solely POM units and (iv) POMs assembled with organic molecular networks.

A Multifunctional Dual-Luminescent Polyoxometalate@Metal-Organic Framework EuW10@UiO-67 Composite as Chemical Probe and Temperature Sensor

The luminescent [EuW10O36]9- polyoxometalate has been introduced into the cavities of the highly porous zirconium luminescent metal-organic framework UiO-67 via a direct synthesis approach, affording the EuW10@UiO-67 hybrid. Using a combination of techniques (TGA, BET, elemental analysis, EDX mapping,…) this new material has been fully characterized, evidencing that it contains only 0.25% in europium and that the polyoxometalate units are located inside the octahedral cavities and not at the surface of the UiO-67 crystallites. Despite the low amount of europium, it is shown that EuW10@UiO-67 acts as a solid-state luminescent sensor for the detection of amino-acids, the growth of the emission intensity globally following the growth of the amino-acid pKa. In addition, EuW10@UiO-67 acts as a sensor for the detection of metallic cations, with a high sensitivity for Fe3+. Noticeably, the recyclability of the reported material has been established. Finally, it is shown that the dual-luminescent EuW10@UiO-67 material behave as a self-calibrated-ratiometric thermometer in the physiological range.

Self-Assembly in Polyoxometalate and Metal Coordination-Based Systems: Synthetic Approaches and Developments

Utilizing new experimental approaches and gradual understanding of the underlying chemical processes has led to advances in the self-assembly of inorganic and metal–organic compounds at a very fast pace over the last decades. Exploitation of unveiled information originating from initial experimental observations has sparked the development of new families of compounds with unique structural characteristics and functionalities. The main source of inspiration for numerous research groups originated from the implementation of the design element along with the discovery of new chemical components which can self-assemble into complex structures with wide range of sizes, topologies and functionalities. Not only do self-assembled inorganic and metal–organic chemical systems belong to families of compounds with configurable structures, but also have a vast array of physical properties which reflect the chemical information stored in the various “modular” molecular subunits. The purpose of this short review article is not the exhaustive discussion of the broad field of inorganic and metal–organic chemical systems, but the discussion of some representative examples from each category which demonstrate the implementation of new synthetic approaches and design principles.

Simulations of hydrogen, carbon dioxide, and small hydrocarbon sorption in a nitrogen-rich rht-metal–organic framework

Detailed theoretical insights into the gas-sorption mechanism of Cu-TDPAH are presented for the first time.

A simple and novel protocol for Li-trapping with a POM/MOF nano-composite as a new adsorbent for CO2 uptake

A novel recipe for lithium trapping over a POM/MOF hybrid composite to enhance carbon capture is presented

Evolutionary Metal Oxide Clusters for Novel Applications: Toward High-Density Data Storage in Nonvolatile Memories

Because of current fabrication limitations, miniaturizing nonvolatile memory devices for managing the explosive increase in big data is challenging. Molecular memories constitute a promising candidate for next-generation memories because their properties can be readily modulated through chemical synthesis. Moreover, these memories can be fabricated through mild solution processing, which can be easily scaled up. Among the various materials, polyoxometalate (POM) molecules have attracted considerable attention for use as novel data-storage nodes for nonvolatile memories. Here, an overview of recent advances in the development of POMs for nonvolatile memories is presented. The general background knowledge of the structure and property diversity of POMs is also summarized. Finally, the challenges and perspectives in the application of POMs in memories are discussed.

Heterogeneous catalysis by tungsten-based heteropoly compounds

In this review, the recent works on heterogeneous catalytic applications of polyoxotungstates in liquid-phase organic reactions are reviewed.

Coordination polymer-based supercapacitors with matched energy levels: enhanced capacity under visible light illumination in the presence of methanol

A device with matched energy levels, FTO/CP 1/RuO₂ showed a much larger specific capacity than the individual components in the presence of visible light and methanol.

Polyoxometalate-MgF2 hybrids as heterogeneous solid acid catalysts for efficient biodiesel production

A series of highly active and stable Keggin heteropolyacid catalysts were prepared through mixing of 12-tungstophosphoric acid (TPA) with magnesium fluoride (MgF₂).

Luminescence and white-light emitting luminescent sensor of tetrafluoroterephthalate-lanthanide metal–organic frameworks

H₂TFBDC lanthanide complexes emitting white light was synthesized and a luminescent sensor for the detection of benzaldehyde has been produced.

Two new silver triazole frameworks with polyoxometalate templates

Using the same ingredients, two new silver–triazole frameworks with Keggin POMs templates have been synthesized, in which Keggin POMs templates represent the highest coordination number in1and terminal oxygen coordination number in2up to date.