Ultra-small gold nanoparticle-coupled MOF-808 enabled sensitive detection of bacteria at neutral pH

Metal-organic framework (MOF)-based mimics are considered star materials to replace natural enzymes. However, their activity is generally limited to acidic conditions, which severely restricts their applications in biological systems where neutral pH is commonly required. Herein, a Zr(IV)-based MOF (MOF-808)/gold nanoparticle (AuNP) hybrid (called Hybrid-60) that shows superior peroxidase-like (POD-like) activity in both acidic and neutral media was prepared by in-situ growth of ultra-small AuNPs (UsAuNPs, ∼3.5 nm) on MOF-808. In comparison with the conventional AuNPs and MOF-808 nanozymes, Hybrid-60 demonstrated ∼8.04- and ∼6.74-time enhanced POD-like activities and superior high activity under neutral conditions, which broke the pH limitation. Furthermore, Hybrid-60 exhibited good tolerance to extreme pH value, concentrated salinity, and high-temperature environments. Taking Staphylococcus aureus (S. aureus) as a model analyte, we developed a simple immune sandwich assay using Hybrid-60 as colorimetric nanotags (ISAHC). A dual recognition strategy using anti-S. aureus antibody and concanavalin A-labeled Hybrid-60 was proposed to specifically capture and high-affinity label the target S. aureus. Then, leveraging the high POD-like activity of Hybrid-60, a simple and specific detection of S. aureus at nearly neutral pH was realized with a wide linear range (1 × 102-1 × 105 CFU/mL) and a low detection limit (32 CFU/mL). Moreover, the ISAHC method enabled one to detect the target S. aureus in human urine and serum with satisfactory recoveries from 93.8 % to 111.0 %, which indicates its clinical applicability. This study provides a new approach to develop neutral nanozymes and facilitate the point-of-care detection of bacteria.

Teaching copolymerization catalysis to metal-organic frameworks by confining molecular catalysts in lattices

Copolymerization catalysis remains underexplored compared to the broad range of other catalytic reactions promoted by metal-organic frameworks (MOFs). Here, we report a lattice-confinement strategy that immobilizes a highly active molecular complex within MOFs, transforming them into effective heterogeneous catalysts for copolymerization-that couples cyclohexene oxide and CO2 into poly(cyclohexene carbonate) or integrates epoxide and phthalic anhydride into ester-ether copolymers. The encapsulated catalytically active species not only introduce new reaction patterns for MOFs but also enhance the structural robustness of the lattice, enabling the catalyst to be recycled multiple times.

Revolutionizing photocatalysis: Synthesis of innovative poly(N-tertiary-butylacrylamide)-graft-hydroxypropyl cellulose polymers for thermo-responsive applications via metal-free organic photoredox catalysis

In this study, we present a groundbreaking approach utilizing metal-free, visible light-mediated organic photoredox catalyzed atom transfer radical polymerization (O-ATRP) to synthesize cellulose-based stimuli-responsive polymers. Our method resulted in the successful synthesis of innovative metal-free poly(N-tertiary-butylacrylamide)-graft-hydroxypropyl cellulose (PNTBAM-g-HPC) polymers with exceptional control over molecular weight and narrow dispersity index (Đ) and explored their applications in organo-photocatalytic reactions. This approach addresses the limitations of traditional atom transfer radical polymerization method, which suffer from metal contamination and toxicity related problems. O-ATRP and organic photoredox catalysts have been sought to address these difficult challenges. In this study, we synthesized organic compound; 2,4,5,6-tetrakis(diphenylamino)isophthalonitrile (4DPIPN), which served as an organic photoredox catalyst, enabling the synthesis and application study of PNTBAM-g-HPC polymers via organic photoredox catalysis. Furthermore, by employing 4DPIPN, three different types of PNTBAM-g-HPC polymers were synthesized. Through thorough characterization techniques including FTIR, NMR, UV/Visible spectroscopy, TGA, and GPC analysis, we confirmed the successful synthesis of photocatalyst and three different types of PNTBAM-g-HPC polymers under O-ATRP conditions. By adjusting the molar ratios of PNTBAM side chains, we fine-tuned the LCST of HTA-20 polymers to 37.3 °C, demonstrating their thermoresponsive behavior. This synthetic approach shows great potential for applications in biosensors, pharmaceuticals, biomedical engineering, and drug delivery systems.

Aldehyde Directed In Situ Loading of Ag Nanodots Around the Open Metal Sites of MOFs for the Tandem Catalysis of Nitrate to Ammonia

Both spatial arrangement and intrinsic activity of electrocatalysts with dual-active sites are widely designed to match the coupling reaction between nitrate and water, in which most of the reactive intermediates can be optimized to achieve a high yield rate of ammonia. Herein, by introducing the aldehyde group inside metal-organic frameworks (MOFs) in advance, an aldehyde-induced method is achieved to direct the in situ nucleation of Ag nanodots depending on the mesopores of MOFs via a simple silver mirror reaction. The key point here is that the spatial arrangement between the aldehyde group and open metal sites is fixed end to end, which makes the aldehyde group a built-in redox-active site to drive the in situ nucleation of Ag nanodots next to the open metal sites of MOFs. Accordingly, by varying the metal sites of MOFs, a group of M-MOFs@Ag (M = Fe, Co, Ni, Cu, etc.) hybrids with dual active sites are acquired. Taking Ni-MOFs@Ag as an example, the interaction between Ni2+ and Ag sites makes it available for the tandem catalysis of nitrate-to-ammonia, in which the H· and NO2 - generated on the open Ni2+ sites and Ag nanodots, respectively, can migrate to each other to evolve into ammonia.

Development of polyoxometalate-loaded MOFs for heterogeneous catalysis and enhanced dye adsorption

This study focuses on the enhancement of MIL-117 functionality by incorporating a well-known polyoxometalate (POM), tetrabutylammonium octamolybdate [(n-C4H9)4N]4[Mo8O26]. Using an encapsulation method with conventional heating, Mo8O264- anions were for the first time successfully integrated into MIL-117 tubular channels (Mo8O26@MIL-117). Comprehensive characterization of the material through FTIR, XRD, BET, FE-SEM, EDX, and XPS confirmed the uniform distribution of Mo8O264- within MIL-117 without compromising its structural integrity. The Mo8O26@MIL-117 composite demonstrates exceptional catalytic performance in oxidative C-N bond formation and Paal-Knorr pyrrole synthesis, achieving high yields under optimized conditions with diverse amine substrates. Characterization and stability assessments confirm Mo8O26@MIL-117 as a robust and recyclable catalyst, maintaining structural integrity and catalytic activity over multiple cycles, highlighting its potential for sustainable applications in synthetic chemistry. The composite material was also evaluated for its efficacy in dye removal, specifically targeting methylene blue (MB) and Rhodamine B (RHB) from aqueous solutions. Mo8O26@MIL-117 exhibited superior adsorption capacity for MB compared to MIL-117 alone, demonstrating high efficiency even at elevated concentrations. The composite showed improved selectivity towards MB over RHB, highlighting its potential for selective dye removal in wastewater treatment applications.

Recent Advances in Immobilizing and Benchmarking Molecular Catalysts for Artificial Photosynthesis

Transition metal complexes have been widely used as catalysts or chromophores in artificial photosynthesis. Traditionally, they are employed in homogeneous settings. Despite their functional versatility and structural tunability, broad industrial applications of these catalysts are impeded by the limitations of homogeneous catalysis such as poor catalyst recyclability, solvent constraints (mostly organic solvents), and catalyst durability. Over the past few decades, researchers have developed various methods for molecular catalyst heterogenization to overcome these limitations. In this review, we summarize recent developments in heterogenization strategies, with a focus on describing methods employed in the heterogenization process and their effects on catalytic performances. Alongside the in-depth discussion of heterogenization strategies, this review aims to provide a concise overview of the key metrics associated with heterogenized systems. We hope this review will aid researchers who are new to this research field in gaining a better understanding.

Silicotungstate@ZIF-67 as an effective catalyst for an extraction and oxidative desulfurization system

Through a simple room-temperature process, different amounts of Keggin-type quaternary ammonium silicotungstate were successfully encapsulated into the metal-organic framework (MOF) material ZIF-67. The catalysts were characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and BET analysis. An extraction and catalytic oxidation desulfurization system was studied using H2O2 as an oxidant and a deep eutectic solvent (DES) as an extractant. Using the 43.06%-SiW12@ZIF-67 composite under optimal reaction conditions, DBT present in a model oil could be deeply and effectively removed. The catalyst was reused 6 times, and the desulfurization rate still exceeded 90%. Finally, a possible desulfurization mechanism is proposed.

Electronic, optical and charge transport properties of Zn-porphyrin-C60 MOFs: a combined periodic and cluster modeling

Density functional theory (DFT) calculations were performed on the 5,15 meso-positions of nine porphyrin-containing MOFs; Zn2(TCPB)-(NMe2-ZnP); (H4TCPB = 1,2,4,5-tetrakis(4-carboxyphenyl)benzene), (NMe2-ZnP = [5,15-bis[(4-pyridyl)-ethynyl]-10,20-bis-(dimethylamine) porphinato]zinc(II)) functionalized with nitrogen-, oxygen-, and sulfur-containing groups to study their effects on the electronic, optical and transport properties of the materials. The properties of these materials have also been investigated by encapsulating fullerene (C60) in their pores (C60@MOFs). The results indicate that the guest C60 in the MOF generates high photoconductivity through efficient porphyrin/fullerene donor-acceptor (D-A) interactions, which are facilitated by oxygen and sulfur functionalities. DFT calculations show that C60 interacts favorably in MOFs due to negative Eint values. Encapsulated C60 molecules modify the electronic band structure, affecting the conduction band and unoccupied states of MOFs corresponding to C60 p orbitals. TD-DFT calculations show that incorporating C60 promotes D-A interactions in MOFs, leading to charge transfer in the near-infrared and visible photoinduced electron transfer (PET) from porphyrins to C60. Nonequilibrium Green's function-based calculations for MOFs with sulfur group, with and without C60, performed using molecular junctions with Au(111)-based electrodes show increased charge transport for the doped MOF. These insights into tuning electronic/optical properties and controlling charge transfer can aid in the design of new visible/near-infrared MOF-based optoelectronic devices.

Encapsulation of the vanadium substituted Keggin polyoxometalates [α-PVW11O40]4- and [α-PV2W10O40]5- in HKUST-1

Two POM@MOF hybrid materials composed of a copper-based metal-organic framework (MOF) [Cu3(C9H3O6)2(H2O)3]n (HKUST-1) encapsulating vanadium-substituted Keggin polyoxometalates (POM), [α-PVW11O40]4- (PVW11) and [α-PV2W10O40]5- (PV2W10), were prepared and characterized. PVW11@HKUST-1 and PV2W10@HKUST-1 were synthesized hydrothermally by self-assembly of HKUST-1 in the presence of the preformed POMs, [α-PVW11O40]4- and [α-PV2W10O40]5-, respectively. The two POM@MOF composites were characterized by X-ray diffraction, TGA, BET surface area analysis and FT-IR and Raman spectroscopy. The electronic structure of the POM@MOF materials and their respective constituents is surveyed using solid state UV-vis reflectance spectroscopy. The UV-vis spectra order the oxidizing strength of the POM constituents ([α-PV2W10O40]5- > [α-PVW11O40]4-) and reveal the distinct electronic structure of the POM@MOF materials obtained by synthetic encapsulation of mono- and di-vanadium substituted Keggin polyoxotungstates in HKUST-1.

Experimental and computational aspects of molecular frustrated Lewis pairs for CO2 hydrogenation: en route for heterogeneous systems?

Catalysis plays a crucial role in advancing sustainability. The unique reactivity of frustrated Lewis pairs (FLPs) is driving an ever-growing interest in the transition metal-free transformation of small molecules like CO2 into valuable products. In this area, there is a recent growing incentive to heterogenize molecular FLPs into porous solids, merging the benefits of homogeneous and heterogeneous catalysis - high activity, selectivity, and recyclability. Despite the progress, challenges remain in preventing deactivation, poisoning, and simplifying catalyst-product separation. This review explores the expanding field of FLPs in catalysis, covering existing molecular FLPs for CO2 hydrogenation and recent efforts to design heterogeneous porous systems from both experimental and theoretical perspectives. Section 2 discusses experimental examples of CO2 hydrogenation by molecular FLPs, starting with stoichiometric reactions and advancing to catalytic ones. It then examines attempts to immobilize FLPs in porous matrices, including siliceous solids, metal-organic frameworks (MOFs), covalent organic frameworks, and disordered polymers, highlighting current limitations and challenges. Section 3 then reviews computational studies on the mechanistic details of CO2 hydrogenation, focusing on H2 splitting and hydride/proton transfer steps, summarizing efforts to establish structure-activity relationships. It also covers the computational aspects on grafting FLPs inside MOFs. Finally, Section 4 summarizes the main design principles established so far, while addressing the complexities of translating computational approaches into the experimental realm, particularly in heterogeneous systems. This section underscores the need to strengthen the dialogue between theoretical and experimental approaches in this field.

The applications of Keggin-based metal-organic compounds in sensing and catalysis

Environmental pollution and energy problems caused by excessive use of fossil fuels deviate from the theme of green and sustainable development. It is very promising to detect small molecules or catalyze the conversion of pollutants to obtain renewable energy by using photoelectric technology. Therefore, there is an urgent requirement to develop materials with low detection limits and high catalytic performance. Keggin polyoxometalate-based metal-organic compounds (POMOCs) hold great promise for sensing, and catalytic applications due to their controllable structure, remarkable reversible multi-electron transfer capability and multi-component synergistic activity. In this review, the applications of Keggin POMOCs in photocatalytic/electrocatalytic conversion of energy materials and the detection of metal ion/inorganic molecule are introduced. The different mechanisms of Keggin POM units and MOF units in sensors and catalysis are discussed. Additionally, the prospects of the Keggin POMOCs as electrode materials or catalysts for enhancing the performance of sensors and catalysts are discussed, which will provide a platform for further development of advanced Keggin POMOC material-based sensors and catalytic systems.

In Situ Implanting ZrW2O7(OH)2(H2O)2 Nanorods into Hierarchical Functionalized Metal-Organic Framework via Solvent-Free Approach for Upgrading Catalytic Performance

Host-guest catalyst provides new opportunities for targeted applications and the development of new strategies for preparing host-guest catalysts is highly desired. Herein, an in situ solvent-free approach is developed for implanting ZrW2O7(OH)2(H2O)2 nanorods (ZrW-NR) in nitro-functionalized UiO-66(Zr) (UiO-66(Zr)-NO2) with hierarchical porosity, and the encapsulation of ZrW-NR enables the as-prepared host-guest catalyst remarkably enhanced catalytic performance for both for oxidative desulfurization (ODS) and acetalization reactions. ZrW-NR@UiO-66(Zr)-NO2 can eliminate 500 ppm sulfur within 9 min at 40 °C in ODS, and can transform 5.6 mmol benzaldehyde after 3 min at room temperature in acetalization reaction. Its turnover frequencies reach 72.3 h-1 at 40 °C for ODS which is 33.4 times higher than UiO-66(Zr)-NO2, and 28140 h-1 for acetalization which is the highest among previous reports. Density functional theory calculation result indicates that the W sites in ZrW-NR can decompose H2O2 to WVI-peroxo intermediates that contribute to catalytic activity for the ODS reaction. This work opens a new solvent-free approach for preparing MOFs-based host-guest catalysts to upgrade their redox and acid performance.

Low thermal quenching of metal halide-based metal-organic framework phosphor for light-emitting diodes

Phosphor-converted white light-emitting diodes (PC-WLEDs) have attracted considerable attention in solid-state lighting and display. However, urgent issues of thermal quenching and high cost remain formidable challenges. Herein, a novel metal-organic framework (MOF) phosphor [CdCl2(AD)] was facilely prepared using a mixture of CdCl2 and acridine (AD) under solvothermal conditions. It shows intensive green emission with a long lifetime of 31.88 ns and quantum yield of 65% while maintaining 95% and 84% of its initial emission intensity after remaining immersed in water for 60 days and being heated to 150 °C, respectively. The low thermal quenching of this MOF material is comparable to or can even exceed that of commercial inorganic phosphors. The combination of experiments and theoretical calculations reveals that the alternating arrangement of delocalized AD π-conjugated systems and CdCl2 inorganic chains through strong coordination bonds and π⋯π stacking interactions imparts the MOF phosphor with high thermal stability and optoelectronic performance. The successful fabrication of green and white LED devices by coating [CdCl2(AD)] and/or N630 red phosphor on a 365/460 nm commercial diode chip suggests a promising and potential alternative to commercial phosphors.

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.

Post-synthetic Metalation on the Ionic TiO2 Surface to Enhance Metal-CO2 Interaction During Photochemical CO2 Reduction

During the photochemical CO2 reduction reaction, CO2 adsorption on the catalyst's surface is a crucial step where the binding mode of the [metal-CO2] adduct directs the product selectivity and efficiency. Herein, an ionic TiO2 nanostructure stabilized by polyoxometalates (POM), ([POM]x@TiO2), is prepared and the sodium counter ions present on the surface to balance the POMs' charge are replaced with copper(II) ions, (Cux[POM]@TiO2). The microscopic and spectroscopic studies affirm the copper exchange without altering the TiO2 core and weak coordination of copper (II) ions to the POMs' surface. Band structure analysis suggests the photo-harvesting efficiency of the TiO2 core with the conduction band edge higher than the reduction potential of CuII/I and multi-electron CO2 reduction potentials. Photochemical CO2 reduction with Cux[POM]@TiO2 results in 30 μmol gcat. -1 CO (79 %) and 8 μmol gcat -1 of CH4 (21 %). Quasi-in-situ Raman study provides evidence in support of CO2 adsorption on the Cux[POM]@TiO2 surface. 13C and D2O labeling studies affirm the {Cu-[CO2]-} adduct formation. Despite the photo-harvesting ability of Nax[POM]@TiO2 itself, the poor CO2 adsorption ability of sodium ions highlights the crucial role of copper ion CO2 photo-reduction. Characterization of the {M-[η2-CO2]-} species via surface tuning validates the CO2 activation and photochemical reduction pathway proposed earlier.

Metal-organic framework (MOF)/C-dots and covalent organic framework (COF)/C-dots hybrid nanocomposites: Fabrications and applications in sensing, medical, environmental, and energy sectors

Developing new hybrid materials is critical for addressing the current needs of the world in various fields, such as energy, sensing, health, hygiene, and others. C-dots are a member of the carbon nanomaterial family with numerous applications. Aggregation is one of the barriers to the performance of C-dots, which causes luminescence quenching, surface area decreases, etc. To improve the performance of C-dots, numerous matrices including metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), and polymers have been composited with C-dots. The porous crystalline structures, which are constituents of metal nodes and organic linkers (MOFs) or covalently attached organic units (COFs) provide privileged features such as high specific surface area, tunable structures, and pore diameters, modifiable surface, high thermal, mechanical, and chemical stabilities. Also, the MOFs and COFs protect the C-dots from the environment. Therefore, MOF/C-dots and COF/C-dots composites combine their features while retaining topological properties and improving performances. In this review, we first compare MOFs with COFs as matrices for C-dots. Then, the recent progress in developing hybrid MOFs/C-dots and COFs/C-dots composites has been discussed and their applications in various fields have been explained briefly.

Unique activity of a Keggin POM for efficient heterogeneous electrocatalytic OER

Polyoxometalates (POMs) have been well studied and explored in electro/photochemical water oxidation catalysis for over a decade. The high solubility of POMs in water has limited its use in homogeneous conditions. Over the last decade, different approaches have been used for the heterogenization of POMs to exploit their catalytic properties. This study focused on a Keggin POM, K6[CoW12O40], which was entrapped in a sol-gel matrix for heterogeneous electrochemical water oxidation. Its entrapment in the sol-gel matrix enables it to catalyze the oxygen evolution reaction at acidic pH, pH 2.0. Heterogenization of POMs using the sol-gel method aids in POM's recyclability and structural stability under electrochemical conditions. The prepared sol-gel electrode is robust and stable. It achieved electrochemical water oxidation at a current density of 2 mA/cm2 at a low overpotential of 300 mV with a high turnover frequency (TOF) of 1.76 [mol O2 (mol Co)-1s-1]. A plausible mechanism of the electrocatalytic process is presented.

Polyoxometalate-Structured Materials: Molecular Fundamentals and Electrocatalytic Roles in Energy Conversion

Polyoxometalates (POMs), a kind of molecular metal oxide cluster with unique physical-chemical properties, have made essential contributions to creating efficient and robust electrocatalysts in renewable energy systems. Due to the fundamental advantages of POMs, such as the diversity of molecular structures and large numbers of redox active sites, numerous efforts have been devoted to extending their application areas. Up to now, various strategies of assembling POM molecules into superstructures, supporting POMs on heterogeneous substrates, and POMs-derived metal compounds have been developed for synthesizing electrocatalysts. From a multidisciplinary perspective, the latest advances in creating POM-structured materials with a unique focus on their molecular fundamentals, electrocatalytic roles, and the recent breakthroughs of POMs and POM-derived electrocatalysts, are systematically summarized. Notably, this paper focuses on exposing the current states, essences, and mechanisms of how POM-structured materials influence their electrocatalytic activities and discloses the critical requirements for future developments. The future challenges, objectives, comparisons, and perspectives for creating POM-structured materials are also systematically discussed. It is anticipated that this review will offer a substantial impact on stimulating interdisciplinary efforts for the prosperities and widespread utilizations of POM-structured materials in electrocatalysis.

Single-Molecule Magnet Behavior of Confined Dy(III) in a Mixed Heteroatom-Substituted Polyoxotungstate

Two heteroatom-templated Dy(III)-confined polyoxotungstates [H2N(CH3)2]7Na7[Dy2(H2O)7(W4O9)(HPSeW15O54)(α-SeW9O33)2]·31H2O (1) and [H2N(CH3)2]14K2Na18{[Dy2(H2O)13W14O40]2[α-SeW9O33]4[HPSeW15O54]2}·44H2O (2) were synthesized by a one-pot aqueous reaction and structurally characterized. The most distinctive structural feature of complexes 1 & 2 is the simultaneous presence of both trivacant Keggin [α-SeW9O33]8- and Dawson [HPSeW15O54]10- building blocks containing P(III)-Se(IV) heteroatoms. The trimeric polyanion of 1 can be represented as a fusion of two trivacant Keggin [α-SeW9O33]8- and Dawson [HPSeW15O54]10- building units encapsulating the [Dy2(H2O)7(W4O9)]12+ cluster. On the other hand, hexameric polyoxoanions of 2 are described as four trivacant Keggin [α-SeW9O33]8- and two Dawson [HPSeW15O54]10-, building units anchoring a [Dy4(H2O)26W28O80]20+ cluster. The magnetic investigation revealed the presence of significant magnetic anisotropy and slow relaxation of magnetization behavior for complex 1 with a phenomenological energy barrier, Ueff = 13.58 K in the absence of an external magnetic field, and Ueff = 24.57 K in the presence of a 500 Oe external dc magnetic field. On the other hand, complex 2 favors the QTM relaxation process in the absence of an external magnetic field and shows field-induced slow relaxation of magnetization with Ueff = 11.11 K at 1500 Oe applied dc field. The in-depth analysis of magnetic relaxation dynamics shows that the relaxation process follows the Orbach as well as Raman relaxation pathways. Further, the ab initio calculation of the studied complexes confirms that the highly axial ground and first excited energy states (containing pure highest mJ states) are responsible for the observed single-molecule magnet (SMM) behavior. Remarkably, this is the first example of a mixed heteroatom-based Dy(III)-substituted polyoxotungstate with both trimeric Keggin [α-SeW9O33]8- and Dawson [HPSeW15O54]10- building units showing SMM behavior.

Recent advances in lanthanide-based POMs for photoluminescent applications

Since the first formation of the famous "Peacock-Weakley" anions [Ln(W5O18)2]8/9-, a steady stream of breakthroughs have been made in the chemistry of multitalented lanthanide (Ln)-based polyoxometalates (POMs) for their potentially desirable properties. In particular, LnIII ions are generally recognised as the "vitamins of the modern industry" owing to their ability to cover a wide emission range, endowing Ln-based POMs with great potential for versatile and diverse luminescence-related applications. In this frontier, we discuss the synthesis strategies and intramolecular energy transfer in Ln-based POM derivatives. Then, the progressive improvements achieved with Ln-based POMs in photoluminescence applications are highlighted, focusing mainly on luminescent and fluorescent probes. Finally, the challenges for Ln-based POM materials for photoluminescence applications are discussed.

Bifunctional 3D POM-based coordination polymers for improved pseudocapacitance and catalytic oxidation performance

Developing novel high-efficiency supercapacitors as energy storage devices to solve the energy crisis is of vital significance. Meanwhile, designing highly active and selective oxidation catalysts for various sulfides is desirable but still a big challenge. To work out these problems, three novel 3D POM-based coordination polymers (POMCPs), formulated as [{Ag6(pytz)4}{SiMo12O40}] (1), [{Cu3(pytz)4}{SiMo12O40}]·5.5H2O (2) and [{Cu6(pytz)6}{SiMo12O40}]·2H2O (3) (pytz = 4-(5-(4-pyridyl)-1H-tetrazole)), are successfully prepared via a one-step synthetic strategy by changing different temperatures under hydrothermal or solvothermal conditions. In compounds 1 and 2, {SiMo12}, as 9-capped and 2-capped polyoxoanions, are engaged among the 2D Ag/Cu-organic sheets to generate the novel 3D POM-based coordination polymers. In addition, 1D Cu-organic chains are combined with 3-capped {SiMo12} polyoxoanions to construct 2D POM-based coordination polymers in 3. To our delight, as electrode materials for supercapacitors, the three compounds exhibit excellent specific capacitances of 261.76 F g-1, 248.82 F g-1 and 156.47 F g-1 at 0.5 A g-1, respectively. Besides, they can effectively and selectively catalyze the oxidation of various sulfides to sulfoxides.

Reactivity of metal-oxo clusters towards biomolecules: from discrete polyoxometalates to metal-organic frameworks

Metal-oxo clusters hold great potential in several fields such as catalysis, materials science, energy storage, medicine, and biotechnology. These nanoclusters of transition metals with oxygen-based ligands have also shown promising reactivity towards several classes of biomolecules, including proteins, nucleic acids, nucleotides, sugars, and lipids. This reactivity can be leveraged to address some of the most pressing challenges we face today, from fighting various diseases, such as cancer and viral infections, to the development of sustainable and environmentally friendly energy sources. For instance, metal-oxo clusters and related materials have been shown to be effective catalysts for biomass conversion into renewable fuels and platform chemicals. Furthermore, their reactivity towards biomolecules has also attracted interest in the development of inorganic drugs and bioanalytical tools. Additionally, the structural versatility of metal-oxo clusters allows for the efficiency and selectivity of the biomolecular reactions they promote to be readily tuned, thereby providing a pathway towards reaction optimization. The properties of the catalyst can also be improved through incorporation into solid supports or by linking metal-oxo clusters together to form Metal-Organic Frameworks (MOFs), which have been demonstrated to be powerful heterogeneous catalysts. Therefore, this review aims to provide a comprehensive and critical analysis of the state of the art on biomolecular transformations promoted by metal-oxo clusters and their applications, with a particular focus on structure-activity relationships.

Recent progress of MOF-functionalized nanocomposites: From structure to properties

Metal-organic frameworks (MOFs) are novel crystalline porous materials assembled from metal ions and organic ligands. The adaptability of their design and the fine-tuning of the pore structures make them stand out in porous materials. Furthermore, by integrating MOF guest functional materials with other hosts, the novel composites have synergistic benefits in numerous fields such as batteries, supercapacitors, catalysis, gas storage and separation, sensors, and drug delivery. This article starts by examining the structural relationship between the host and guest materials, providing a comprehensive overview of the research advancements in various types of MOF-functionalized composites reported to date. The review focuses specifically on four types of spatial structures, including MOFs being (1) embedded in nanopores, (2) immobilized on surface, (3) coated as shells and (4) assembled into hybrids. In addition, specific design ideas for these four MOF-based composites are presented. Some of them involve in situ synthesis method, solvothermal method, etc. The specific properties and applications of these materials are also mentioned. Finally, a brief summary of the advantages of these four types of MOF composites is given. Hopefully, this article will help researchers in the design of MOF composite structures.

Assembly of an iron-based complex into a metal-organic framework: a space confinement strategy for isolation of mono-iron complexes to protect from dimerization

Non-heme mononuclear iron complexes, especially when supported by tripodal tetradentate ligands, show promising C-H bond activation efficiency in catalytic reactions. Nevertheless, they intrinsically decay readily to their dinuclear form, and the dimerization process is inevitable in homogenous solution, which dramatically hinders their further application. Hence, we demonstrate that the mononuclear iron complex [(TPA)FeII-2L]2+ (L = labile ligands, mainly solvent molecules) was successfully encapsulated in a highly robust metal-organic framework UiO-66 via a two-step "ship-in-a-bottle" strategy. The nearly perfect size matching of the octahedral cages of the host UiO-66 provides ideal space confinement for the guest complex to protect from dimerization and dramatically increases the mono-nuclear complex stability compared to its un-confined state. The successful encapsulation of [(TPA)FeII-2L]2+ in UiO-66 was verified thoroughly by spectroscopy, microscopy, N2 adsorption, and electrochemistry characterization techniques. This work shows that encapsulating an unstable molecular complex in MOFs via a two-step "ship-in-a-bottle" strategy highlights opportunities for extending the heterogenization of homogeneous complexes.

Heterogenization of molecular catalysts within porous solids: the case of Ni-catalyzed ethylene oligomerization from zeolites to metal-organic frameworks

The last decade has seen a tremendous expansion of the field of heterogenized molecular catalysis, especially with the growing interest in metal-organic frameworks and related porous hybrid solids. With successful achievements in the transfer from molecular homogeneous catalysis to heterogenized processes come the necessary discussions on methodologies used and a critical assessment on the advantages of heterogenizing molecular catalysis. Here we use the example of nickel-catalyzed ethylene oligomerization, a reaction of both fundamental and applied interest, to review heterogenization methodologies of well-defined molecular catalysts within porous solids while addressing the biases in the comparison between original molecular systems and heterogenized counterparts.

Modulated synthesis of cesium phosphomolybdate encapsulated in hierarchical porous UiO-66 for catalysing alkene epoxidation

The hybrid composite of cesium phosphomolybdate (CsPM) encapsulated in hierarchical porous UiO-66 (HP-UiO-66) was synthesized using a modulated solvothermal method. A variety of characterization results demonstrated that the pore size distribution of CsPM@HP-UiO-66 is broader than traditional microporous CsPM@UiO-66 and cesium phosphomolybdate clusters are uniformly distributed in the octahedral cages of HP-UiO-66. The catalytic properties of the hybrid composite were investigated in alkene epoxidation reaction with tert-butyl hydroperoxide (t-BuOOH) as an oxidant. CsPM@HP-UiO-66 showed much higher catalytic activity for the alkene epoxidation reaction in comparison with the reference catalysts and could be easily reused by centrifugation and recycled for at least ten runs without significant loss in catalytic activity. The superior catalytic activity and stability of the hybrid composite CsPM@HP-UiO-66 should be mainly attributed to the hierarchical pores in the support HP-UiO-66 promoting the diffusion of alkene molecules, the uniform distribution of highly active CsPM clusters in the octahedral cages of HP-UiO-66, the introduction of cesium cations to form the insoluble cesium phosphomolybdate and the strong metal-support interactions (SMSI) between the CsPM clusters and the HP-UiO-66 framework.

Keggin-type polyoxometalate embedded polyvinylidene fluoride for thin film microextraction of organophosphorus pesticides

The present research is the first report on the application of Keggin-type phosphotungstic acid/polyvinylidene fluoride membrane. This compound as a simple, cost-effective and novel sorbent was used for the extraction and pre-concentration of two organophosphorus pesticides in real samples in the thin film solid-phase microextraction (TFME) method. TFME as one of the sub-branches of solid phase microextraction resolves the problems of SPME methods, including their limited absorption capacity. These extraction methods have a high surface-to-volume ratio, which improves their sensitivity compared to other geometries. Under optimal conditions, the limit of detections (LODs), the limit of quantifications (LOQs), and relative standard deviation (RSD) of this method varied in the ranges of 0.29-0.31 μg L-1, 0.96-1.0 μg L-1, and 3.9%-6.2%, respectively. This method showed a linear dynamic range (LDR) of 1.0-500 μg L-1 with a coefficient of determination (r2) above 0.9978. This promising method was used to analyze malathion and diazinon.

Organo-Functionalized Lacunary Double Cubane-Type Oxometallates: Synthesis, Structure, and Properties of [(MII Cl)2 (VIV O)2 {((HOCH2 CH2 )(H)N(CH2 CH2 O))(HN(CH2 CH2 O)2 )}2 ] (M=Co, Zn)

Organofunctionalized tetranuclear clusters [(MII Cl)2 (VIV O)2 {((HOCH2 CH2 )(H)N(CH2 CH2 O))(HN(CH2 CH2 O)2 )}2 ] (1, M=Co, 2: M=Zn) containing an unprecedented oxometallacyclic {M2 V2 Cl2 N4 O8 } (M=Co, Zn) framework have been prepared by solvothermal reactions. The new oxo-alkoxide compounds were fully characterized by spectroscopic methods, magnetic susceptibility measurement, DFT and ab initio computational methods, and complete single-crystal X-ray diffraction structure analysis. The isostructural clusters are formed of edge-sharing octahedral {VO5 N} and trigonal bipyramidal {MO3 NCl} units. Diethanolamine ligates the bimetallic lacunary double cubane core of 1 and 2 in an unusual two-mode fashion, unobserved previously. In the crystalline state, the clusters of 1 and 2 are joined by hydrogen bonds to form a three-dimensional network structure. Magnetic susceptibility data indicate weakly antiferromagnetic interactions between the vanadium centers [Jiso (VIV -VIV )=-5.4(1); -3.9(2) cm-1 ], and inequivalent antiferromagnetic interactions between the cobalt and vanadium centers [Jiso (VIV -CoII )=-12.6 and -7.5 cm-1 ] contained in 1.

U-type π-conjugated phosphorescent ligand sensitized lanthanide metal-organic frameworks for efficient white-light-emitting diodes

Lanthanide metal-organic framework (Ln-MOF) based phosphors for light-emitting diodes (LEDs) play an important role in the fields of solid-state lighting and display. The rational design of organic antennae to address the drawback of low extinction coefficients of the lanthanide ions is highly desired. In this work, we provide a new design strategy to achieve an energy transfer molecule with a through-space conjugated folded structure, which can strengthen the skeleton rigidity and facilitate triplet state energy transfer. Consequently, one U-type π-conjugated molecule 2,6-bis(3,5-dicarboxylphenoxy) pyridine (H4L) was selected as a light gatherer to sensitize lanthanide ions for the construction of Ln-MOFs [Ln(HL)(H2O)3]n (Eu-MOF and Tb-MOF), which exhibit a long-lived luminescence lifetime (0.88 ms for Eu-MOF and 1.31 ms for Tb-MOF) and high quantum yields (50.87% for Eu-MOF and 85.64% for Tb-MOF). Furthermore, a white LED device with a colour rendering index (89) was fabricated using the mixture of Ln-MOFs with a commercial blue phosphor.

Computational Study into the Effects of Countercations on the [P8W48O184]40- Polyoxometalate Wheel

Porous metal oxide materials have been obtained from a ring-shaped macrocyclic polyoxometalate (POM) structural building unit, [P8W48O184]40-. This is a tungsten oxide building block with an integrated "pore" of 1 nm in diameter, which, when connected with transition metal linkers, can assemble frameworks across a range of dimensions and which are generally referred to as POMzites. Our investigation proposes to gain a better understanding into the basic chemistry of this POM, specifically local electron densities and locations of countercations within and without the aforementioned pore. Through a rigorous benchmarking process, we discovered that 8 potassium cations, located within the pore, provided us with the most accurate model in terms of mimicking empirical properties to a sufficient degree of accuracy while also requiring a relatively small number of computer cores and hours to successfully complete a calculation. Additionally, we analyzed two other similar POMs from the literature, [As8W48O184]40- and [Se8W48O176]32-, in the hopes of determining whether they could be similarly incorporated into a POMzite network; given their close semblance in terms of local electron densities and interaction with potassium cations, we judge these POMs to be theoretically suitable as POMzite building blocks. Finally, we experimented with substituting different cations into the [P8W48O184]40- pore to observe the effect on pore dimensions and overall reactivity; we observed that the monocationic structures, particularly the Li8[P8W48O184]32- framework, yielded the least polarized structures. This correlates with the literature, validating our methodology for determining general POM characteristics and properties moving forward.

Defect-Mediated Synergistic Effect of POM/UiO-66(Zr) Host-Guest Catalysts for Robust Deep Desulfurization at Ambient Temperature

Stable platforms of host-guest catalysts are indispensable in the field of heterogeneous catalysis, however, clarifying the specific effect of host remains challenging. Herein, polyoxometalate (POM) is encapsulated in three types of UiO-66(Zr) with different controlled densities of defects by the aperture opening and closing strategy at ambient-temperature. It is found that catalytic activity of POM for oxidative desulfurization (ODS) at room temperature is turned on when encapsulated in the defective UiO-66(Zr), and the sulfur oxidation efficiency shows an obvious increasing trend (from 0.34 to 10.43 mmol g-1 h-1 ) with the increased concentration of defects in UiO-66(Zr) host. The as-prepared catalyst with the most defective host displays ultrahigh performance which removed 1000 ppm sulfur with exceptionally diluted oxidant at room-temperature within 25 min. The turnover frequency can reach 620.0 h-1 at 30 °C, which surpassed all the reported MOFs based ODS catalysts. A substantial guest/host synergistic effect mediated by the defective sites in UiO-66(Zr) is responsible for the enhancement. Density functional theory calculations reveal that OH/OH2 capped on the open Zr sites of host UiO-66(Zr) can decompose H2 O2 to OOH group and enables the formation of WVI -peroxo intermediates that determine the ODS activity.

Interfacial chemistries in metal-organic framework (MOF)/covalent-organic framework (COF) hybrids

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have been attracting tremendous attention in various applications due to their unique structural properties. Recent interest has been focused on their combination as hybrids to enable the engineering of new classes of frameworks with complementary properties. This review gives a comprehensive summary on the interfacial chemistries in MOF/COF hybrids, which play critical roles in their hybridization. The challenges and perspectives in the field of MOF/COF hybrids are also provided to inspire more efforts in diversifying this hybrid family and their cross-disciplinary applications.

Embedding Hierarchical Pores by Mechanochemistry in Carbonates with Superior Chemoselective Catalysis and Stability

Hierarchical porosity of carbonates can facilitate their performance in massive applications as compared to their corresponding bulk samples. Traditional solution-based precipitation is typically utilized to fabricate porous carbonates. However, this tactic is generally employed under humid conditions, which demand soluble metal precursors, solvents, and extended dry periods. A salt-assisted mechanochemistry is exploited in contemporary work to settle the shortcomings. Enlighted by solid-state technology, this approach eliminates the utilization of solvents, and the process of ball milling can create pores in 5 min. A range of highly porous carbonates and their derivatives are acquired, with several materials surpassing recording surface areas (e.g., H-CaCO3: 108 m2/g, SrCO3: 125 m2/g, BaCO3: 172 m2/g, Pd/H-CaCO3 catalyst: 101 m2/g). The results display that Pd/H-CaCO3 shows superior catalytic efficiency in the synthesis of aniline (turnover frequency [TON] = 1.33 × 104/h-1, yield ≥ 99%, and recycle stability: 11 cycles) and dye degradation. Combining mechanochemistry and salt-assisted tactic provides a facile and efficient pathway for processing porous materials.

Exploring the role of sandwich-type polyoxometalates in {K10(PW9O34)2M4(H2O)2}@PCN-222 (M = Mn, Ni, Zn) for electroreduction of CO2 to CO

To overcome the drawbacks of high solubility and instability of polyoxometalates (POMs) in aqueous solution and to expand their application in the electrocatalytic reduction of CO₂ (ECR), we assemble sandwich-type POMs, K₁₀[(PW₉O₃₄)₂M₄(H₂O)₂] (M = Mn, Ni, Zn, shortened as P₂W₁₈M₄), into the hexagonal channel of a porphyrin-based metal-organic framework (MOF) PCN-222 to form P₂W₁₈M₄@PCN-222 composites. Their ECR behavior displays polyoxoanion-dependent activity. P₂W₁₈Mn₄@PCN-222 demonstrates a faradaic efficiency of 72.6% for the CO product (FE_CO), more than four times that of PCN-222 (FE_CO = 18.1%), and exhibits exceptional electrochemical stability over 36 h. P₂W₁₈Ni₄@PCN-222 and P₂W₁₈Zn₄@PCN-222 slightly increase (26.9%) and decrease (3.2%) in FE_CO, respectively. We combine the results with density functional theory (DFT) calculations to help understand the intrinsic reasons which reveals that the rate-determining step (RDS) reaction energy of P₂W₁₈Mn₄@PCN-222 and P₂W₁₈Ni₄@PCN-222 is significantly reduced compared to that of PCN-222. It is different in P₂W₁₈Zn₄@PCN-222. Frontier molecular orbitals electron distribution results hint at directional electron transfer from P₂W₁₈Mn₄/P₂W₁₈Ni₄ to the porphyrin ring active center in PCN-222, promoting the electro-reduction of CO₂ activity. By contrast, P₂W₁₈Zn₄ may accumulate electrons from PCN-222, thus facilitating the hydrogen evolution reaction (HER). This work reveals the critical role of sandwich-type POMs in manipulating the electron transfer pathway during the electrocatalytic process. Our findings would broaden the scope of POM applications in electrochemical carbon dioxide reduction.

Mixed-linker strategy for suppressing structural flexibility of metal-organic framework membranes for gas separation

Structural flexibility is a critical issue that limits the application of metal-organic framework (MOF) membranes for gas separation. Herein we propose a mixed-linker approach to suppress the structural flexibility of the CAU-10-based (CAU = Christian-Albrechts-University) membranes. Specifically, pure CAU-10-PDC membranes display high separation performance but at the same time are highly unstable for the separation of CO₂/CH₄. A partial substitution (30 mol.%) of the linker PDC with BDC significantly improves its stability. Such an approach also allows for decreasing the aperture size of MOFs. The optimized CAU-10-PDC-H (70/30) membrane possesses a high separation performance for CO₂/CH₄ (separation factor of 74.2 and CO₂ permeability of 1,111.1 Barrer under 2 bar of feed pressure at 35°C). A combination of in situ characterization with X-ray diffraction (XRD) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, as well as periodic density functional theory (DFT) calculations, unveils the origin of the mixed-linker approach to enhancing the structural stability of the mixed-linker CAU-10-based membranes during the gas permeation tests.

Recent Advances in Confining Polyoxometalates and the Applications

Polyoxometalates (POMs) are widely used in catalysis, energy storage, biomedicine, and other research fields due to their unique acidity, photothermal, and redox features. However, the leaching and agglomeration problems of POMs greatly limit their practical applications. Confining POMs in a host material is an efficient tool to address the above-mentioned issues. POM@host materials have received extensive attention in recent years. They not only inherent characteristics of POMs and host, but also play a significant synergistic effect from each component. This review focuses on the recent advances in the development and applications of POM@host materials. Different types of host materials are elaborated in detail, including tubular, layered, and porous materials. Variations in the structures and properties of POMs and hosts before and after confinement are highlighted as well. In addition, an overview of applications for the representative POM@host materials in electrochemical, catalytic, and biological fields is provided. Finally, the challenges and future perspectives of POM@host composites are discussed.

Microchemical environmental regulation of POMs@MIL-101(Cr) promote photocatalytic nitrogen to ammonia

The polyoxometalates (POMs) have been shown to be highly effective as reactive sites for photocatalytic nitrogen fixation reactions. However, the effect of POMs regulation on catalytic performance has not been reported yet. Herein, a series of composites (SiW₉M₃@MIL-101(Cr) (M = Fe, Co, V, Mo) and D-SiW₉Mo₃@MIL-101(Cr), D, Disordered) were obtained by regulating transition metal compositions and arrangement in the POMs. The ammonia production rate of SiW₉Mo₃@MIL-101(Cr) is much higher than that of other composites, reaching 185.67 μmol·h^-1·g^-1_cat in N₂ without sacrificial agents. The structural characterization of composites reveals that the increase of the electron cloud density of W atom in composites is the key to improve the photocatalytic performance. In this paper, the microchemical environment of POMs was regulated by transition metal doping method, thereby promoting the efficiency of photocatalytic ammonia synthesis for the composites, which provides new insights into the design of POM-based photocatalysts with high catalytic activity.

Molecular Catalysis of Energy Relevance in Metal-Organic Frameworks: From Higher Coordination Sphere to System Effects

The modularity and synthetic flexibility of metal-organic frameworks (MOFs) have provoked analogies with enzymes, and even the term MOFzymes has been coined. In this review, we focus on molecular catalysis of energy relevance in MOFs, more specifically water oxidation, oxygen and carbon dioxide reduction, as well as hydrogen evolution in context of the MOF-enzyme analogy. Similar to enzymes, catalyst encapsulation in MOFs leads to structural stabilization under turnover conditions, while catalyst motifs that are synthetically out of reach in a homogeneous solution phase may be attainable as secondary building units in MOFs. Exploring the unique synthetic possibilities in MOFs, specific groups in the second and third coordination sphere around the catalytic active site have been incorporated to facilitate catalysis. A key difference between enzymes and MOFs is the fact that active site concentrations in the latter are often considerably higher, leading to charge and mass transport limitations in MOFs that are more severe than those in enzymes. High catalyst concentrations also put a limit on the distance between catalysts, and thus the available space for higher coordination sphere engineering. As transport is important for MOF-borne catalysis, a system perspective is chosen to highlight concepts that address the issue. A detailed section on transport and light-driven reactivity sets the stage for a concise review of the currently available literature on utilizing principles from Nature and system design for the preparation of catalytic MOF-based materials.

Polyoxometalate-based frameworks for photocatalysis and photothermal catalysis

Polyoxometalate-based frameworks (POM-based frameworks) are extended structures assembled from metal-oxide cluster units and organic frameworks that simultaneously possess the virtues of POMs and frameworks. They have been attracting immense attention because of their diverse architectures and charming topologies and also due to their probable application prospects in the areas of catalysis, separation, and energy storage. In this review, the recent progress in POM-based frameworks including POM-based metal organic frameworks (PMOFs), POM-based covalent organic frameworks (PCOFs), and POM-based supramolecular frameworks (PSFs) is systematically summarized. The design and construction of a POM-based framework and its application in photocatalysis and photothermal catalysis are introduced, respectively. Finally, our brief outlooks on the current challenges and future development of POM-based frameworks for photocatalysis and photothermal catalysis are provided.

Exploring the Reactivity of Polyoxometalates toward Proteins: From Interactions to Mechanistic Insights

The latest advances in the study of the reactivity of metal-oxo clusters toward proteins showcase how fundamental insights obtained so far open new opportunities in biotechnology and medicine. In this Perspective, these studies are discussed through the lens of the reactivity of a family of soluble anionic metal-oxo nanoclusters known as polyoxometalates (POMs). POMs act as catalysts in a wide range of reactions with several different types of biomolecules and have promising therapeutic applications due to their antiviral, antibacterial, and antitumor activities. However, the lack of a detailed understanding of the mechanisms behind biochemically relevant reactions-particularly with complex biological systems such as proteins-still hinders further developments. Hence, in this Perspective, special attention is given to reactions of POMs with peptides and proteins showcasing a molecular-level understanding of the reaction mechanism. In doing so, we aim to highlight both existing limitations and promising directions of future research on the reactivity of metal-oxo clusters toward proteins and beyond.

Hydroxyl radical-dominated selective oxidation of ethylbenzene over a photoactive polyoxometalate-based metal-organic framework

Realizing photo-promoted saturated C-H functionalization is a significant challenge. [Cu^I₃(H₂O)₆(TPT)₂][H₂BW₁₂O₄₀]·28H₂O was assembled by combining electron reservoir [BW₁₂O₄₀]^5- with photosensitizer TPT. The continuous coordination bonds and π-π stacking interactions facilitate hole-electron separation and electron transfer, and allow it to exhibit high photocatalytic activity toward ethylbenzene oxidation with O₂/H₂O as oxidants.

Oriented Design of Transition-Metal-Oxide Hollow Multishelled Micropolyhedron Derived from Bimetal-Organic Frameworks for the Electrochemical Detection of Multipesticide Residues

Transition-metal oxides (TMOs) with a hollow multishelled structure have emerged as highly potential materials for high-performance electrochemical sensing, benefiting from their superior electronic conductivity, exceptionally large specific surface area, excellent stability, and electrochemistry properties. In particular, binary TMOs are expected to outperform unitary TMOs due to the synergistic effect of the different metals. Herein, MnCo₂O_4.5 hollow quadruple-shelled porous micropolyhedrons (MnCo₂O_4.5 HoQS-MPs) were prepared and employed to construct an ultrasensitive sensing platform for a multipesticide assay. Profiting from complex hollow interior structures and abundant active sites, the MnCo₂O_4.5 HoQS-MPs manifest outstanding electrochemical properties as electrode materials for the pesticide assay. The MnCo₂O_4.5 HoQS-MP-based biosensor demonstrated remarkable performance for monocrotophos, methamidophos, and carbaryl detection, with wide linear ranges, as well as low detection limits. This work unveils a new pathway for the ultrasensitive detection of pesticides and demonstrates tremendous potential for detecting other environmentally deleterious chemicals.

Tris-decorated multi-iron polyoxotungstates

Solution-stable tris(hydroxymethyl)aminomethane-functionalized Fe^III-containing polyoxotungstates exhibit an unusual anchoring mode of triol moieties, with one -NH₂ and one -CH₂OH group remaining accessible for post-functionalization or chemisorption. The redox-active title compounds have been isolated under unusually mild reaction conditions and characterized in the solid state and in aqueous solutions.

Synthesis and Structure of a Copper-Based Functional Network for Efficient Organic Dye Adsorption

In the work, by incorporating polyoxometalates (POMs) into a copper(II)-based network, a novel three-dimensional (3D) porous framework, [Cu₁₇Cl₃(trz)₁₂]H₃[GaW₁₂O₄₀]·9H₂O (Cu-GaW-TRZ), was successfully prepared and explored for the adsorption of dyes. The adsorption capacity of Cu-GaW-TRZ was calculated as 13.11 mg/g, and the dye adsorption rate equaled 96.2% for the adsorption of methylene blue (MB). Furthermore, this recyclable adsorbent is stable enough without obvious loss of adsorption capacity for at least five runs. Meanwhile, the structure of the macropores is suitable for the entry of large molecular dyes, and [GaW₁₂O₄₀]^5- also can achieve efficient adsorption for cationic dyes. The results displayed a pseudo-second-order kinetic model and were well matched for MB adsorption onto Cu-GaW-TRZ. The free energy, entropy, and enthalpy of the thermodynamic parameters for the adsorption of MB were calculated, which revealed that the adsorption process was befitting for the adsorption of MB.

CoW Bimetallic Carbide Nanocatalysts: Computational Exploration, Confined Disassembly-Assembly Synthesis and Alkaline/Seawater Hydrogen Evolution

Earth-abundant tungsten carbide exhibits potential hydrogen evolution reaction (HER) catalytic activity owing to its Pt-like d-band electronic structure, which, unfortunately, suffers from the relatively strong tungsten-hydrogen binding, deteriorating its HER performance. Herein, a catalyst design concept of incorporating late transition metal into early transition metal carbide is proposed for regulating the metal-H bonding strength and largely enhancing the HER performance, which is employed to synthesize CoW bi-metallic carbide Co₆ W₆ C by a "disassembly-assembly" approach in a confined environment. Such synthesized Co₆ W₆ C nanocatalyst features the optimal Gibbs free energy of *H intermediate and dissociation barrier energy of H₂ O molecules as well by taking advantage of the electron complementary effect between Co and W species, which endows the electrocatalyst with excellent HER performance in both alkaline and seawater/alkaline electrolytes featuring especially low overpotentials, elevated current densities, and much-enhanced operation durability in comparison to commercial Pt/C catalyst. Moreover, a proof-of-concept Mg/seawater battery equipped with Co₆ W₆ C-2-600 as cathode offers a peak power density of 9.1 mW cm^-2 and an open-circuit voltage of ≈1.71 V, concurrently realizing hydrogen production and electricity output.