Cationic covalent organic frameworks (COFs) hold great potential for ion conduction and catalysis, yet poor crystallinity from interlayer electrostatic repulsion severely limits their performance. Herein, we demonstrate that lattice-matched polyoxometalates (POMs) as multifunctional counterions can direct the crystallization of cationic COFs and introduce functional sites. In situ incorporation of Keggin-type POMs affords highly crystalline honeycomb frameworks (POM@vCOF-CR), whereas post-synthetic ion exchange yields amorphous materials. Further investigations reveal that POMs play multiple roles during the crystallization process: in-plane, they modulate monomer release to promote ordered growth; out-of-plane, they act as electrostatic anchoring centers to facilitate ordered stacking. Crucially, lattice-matching between the POM sublattice and the COF framework eliminates configurational degeneracy and dictates long-range ordering. This principle is further validated in a square-lattice pvCOF, where only the larger Preyssler-type POM can form a matched square sublattice that enables crystallization, whereas smaller Keggin-type POMs lead to orientational disorder and amorphous products. Benefiting from the ordered functional sites and transport pathways, the crystalline POM@vCOF-CR exhibits significantly enhanced electrocatalytic activity for ethylbenzene oxidation and improved lithium-ion conductivity compared to its amorphous counterpart. This work establishes a rational solution for constructing crystalline cationic COFs by using lattice-matched POMs, thereby enabling functional frameworks with enhanced performance.

Fullerenes are a unique class of stable molecular clusters whose structural evolution is constrained by the geometry and topology of pentagon-hexagon arrangements of sp2-hybridized carbons with (p-p)π conjugation. However, extending this geometry- and topology-driven structural evolution to other inorganic systems remains exceedingly rare, because it is highly challenging to achieve controlled assembly of distinct building units and precisely tune their numbers. Here, we report a family of metal-oxo clusters with V30Nb12, V26Nb8, V24Nb6, and V22Nb4 cluster cores. They are constructed from m {(Nb)V5} pentagons and l {(V)V4} squares linked through shared vanadium centers. These clusters show a stepwise pentagon decrease (m = 12 → 8 → 6 → 4) and square increase (l = 0 → 2 → 3 → 4) and follow a mathematically defined evolution rule l = 6 - m/2. Quantum-chemical analyses show that, similar to the curved (p-p)π-conjugation characteristic of carbon fullerenes, a spherical multicenter (d-p)π-conjugated network stabilizes these curved {(Nb)V5} pentagons and {(V)V4} squares. Together, these findings demonstrate that fullerene-like structural evolution is not restricted to carbon frameworks, but can emerge in metal-oxo clusters through multicenter (d-p)π-conjugation interaction.

Two new coordination polymers polyoxovanadate-based hybrid (POVH) {[Ni(1-Me-trz)(H2O)](2)(V2O6)(2)}(infinity) (1) and {Co(1-Me-trz)(H2O)(V2O6)}(infinity) (2) have been synthesized by introducing 1-methyl-1H-1,2,3-triazole (1-Me-trz) ligand and thoroughly characterized by single-crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), infrared spectroscopy (FT-IR), thermogravimetric (TG) analysis, elemental analysis (EA) and scanning electron microscopy (SEM) elemental mapping. The coordination polymer POVH 1 has a 2D two parallel network supramolecular structure, and POVH 2 has a interesting 3D supramolecular structure. Further, POVH 1 and 2 were used as heterogeneous catalysts in the oxidative hydroxylation of arylboronic acids to prepare phenols at room temperature using 30% aqueous H2O2 as oxidant and showed high catalytic activity with the yield of phenol up to >99%. Especially, the coordination polymer POVH 1 showed good substrate compatibility and versatility under optimized conditions and could be reused for at least three times without losing its activity. A plausible mechanism has also been proposed.

Proton shuttles play a vital role in diverse chemical transformations; however, most known examples, such as water and small organic molecules, operate in homogeneous systems with colocated proton donor and acceptor sites. In contrast, recyclable proton shuttle catalysts with spatially separated donor and acceptor sites are highly desirable due to their enhanced flexibility in proton transfer but remain largely unexplored. Herein, we identify the polyoxoniobate K7HNb6O1913H2O (KNb6) as a special type of recyclable proton shuttle catalyst that enables rapid cleavage of lignin beta-O-4 ketone into value-added phenol (yield: 93%) and benzonitrile (yield: 73%) within 10 min, using NH2OHH2O as the N-source. Combined computational and experimental studies reveal that the unique surface of KNb6, featuring a proton-donating hydroxyl group (-OH) surrounded by multiple proton-accepting oxo ligands (O2-), facilitates a proton-shuttling mechanism that drives both C beta-O and C alpha-C beta bond cleavage of a ketoxime intermediate formed in situ. Moreover, KNb6 maintains a stable catalytic performance over multiple cycles and efficiently promotes the depolymerization of oxidized natural lignin. This work not only provides a robust and recyclable catalyst for biomass valorization but also offers insights into the design of recyclable proton transfer systems.

The first polyoxoniobate featuring the long-sought face-sharing octahedra, as observed in natural minerals, has been successfully synthesized using highly charged Te( iv ) ions.

Single-cluster catalysts (SCCs) provide atomically precise active sites and model systems for mechanistic studies, but achieving uniform dispersion of clusters on supports remains challenging. Herein, a cationic porphyrin-viologen covalent organic framework (PV) is employed to immobilize diverse polyoxometalate (POM) clusters within its ordered channels via electrostatic assembly, thereby establishing a modular platform for fabricating well-defined SCCs. As a representative example, the sandwich-type Cu4(PW9)2 cluster was uniformly immobilized on PV, yielding Cu4(PW9)2@PV with high loading and stability. This catalyst exhibits remarkable catalytic activity in the electrocatalytic reduction of furfural to furfuryl alcohol, achieving 96.4% selectivity. The compositional tunability of POMs, together with the generality of this strategy, facilitates systematic mechanistic investigations. Combined experimental and theoretical analyses (control experiments, kinetic isotope studies, electrochemical and spectral analyses, DFT calculations, etc.) reveal that Cu sites serve as the catalytic centers, while polyoxotungstate units act as electron-proton reservoirs, switching the reaction pathway from hydrogen atom transfer to proton-coupled electron transfer. This work not only establishes a modular platform for the rational design and synthesis of SCCs but also provides new insights into the catalytic process of biomass electroreduction.

The oxidative conversion of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) is an important reaction for the utilization of biomass resources. This process has garnered considerable research attention in both industry and academia, yet it still presents considerable challenges. To achieve an effective and mild oxidative upgrade of the HMF molecule, a multiorganic-ligand-functionalized polyoxovanadate catalyst, V6O6(OCH3)4(mIM)6(C6H5PO3)4 (P4V6), has been successfully prepared by using both oxygen- and nitrogen-containing ligands. P4V6, characterized by its unique candy-like structure, demonstrates remarkable catalytic performance in converting HMF, achieving 95% conversion and 94% selectivity toward DFF under an O2 atmosphere. Furthermore, P4V6 exhibits good stability and can be reused over five consecutive cycles without any substantial changes to its structure and catalytic performance. Comprehensive mechanistic investigations, supported by control experiments, kinetic studies, and spectral analyses, indicate a plausible four-step catalytic mechanism. This work provides a new perspective on the design of polyoxovanadate-based catalysts for biomass valorization.

An open hollow polyoxovanadate (POV) cage, V14Nb2P8, has been successfully constructed using {Nb(V5)} pentagons as building blocks. The POV cage features a crown-ether-like {V4P4O8} opening that can selectively coordinate with Cs+ ions. Additionally, it has a hollow cavity that acts as a molecular container to accommodate size-appropriate organic molecules.

Cuproptosis, characterized by the accumulation of copper (Cu) ions and mitochondrial respiration modulation, holds great potential in cancer therapy. As a newly defined mode of cell death regulation, the mechanisms of copper efflux and high intracellular levels of reducing substances may impair cuproptosis efficacy. To address this, a nanocomposite designated POM/Cu-SS@HA was constructed, comprising sandwich-type polyoxometalate (POM) Na[(CH 3 ) 2 NH 2 ] 13 H[Sc 3 (H 2 O) 2 Te 2 W 24 O 90 ]·92H 2 O ( Sc 3 Te 2 W 24 ), disulfide-bridged copper-based complexes (Cu-SS), and hyaluronic acid (HA) for targeted delivery. This system induces cuproptosis through copper accumulation, leading to lipoylated protein aggregation and iron–sulfur cluster protein depletion, while concurrently facilitating photothermal therapy (PTT) and apoptosis. The POM ( Sc 3 Te 2 W 24 ) cluster exhibited potent antitumor effects via p53-dependent apoptotic pathway reactivation. In vitro studies demonstrated over 85.6% inhibition rate against 4T1 breast cancer cells when combining POM/Cu-SS@HA with 808 nm NIR irradiation. In vivo results showed 92.8% tumor growth suppression compared to the controls. Transcriptome analysis further identified altered expression profiles in glutathione (GSH) metabolism and mitochondrial function-related genes, confirming the dual induction of cuproptosis and apoptosis. These findings establish a synergistic nanotherapeutic strategy with enhanced efficacy for breast cancer treatment.

The oxidative depolymerization of beta-O-4 linkages into value-added aromatic chemicals is of great importance for lignin valorization. However, achieving highly selective and rapid cleavage of beta-O-4 linkages under mild conditions remains a challenge. Herein, cobalt-cobalt oxides (Co-CoOx) supported on N-doped carbon (CoMA/C900) combined with a green and recyclable base K7HNb6O19 (KNb6) have shown remarkable activity for the one-step oxidative cleavage of lignin beta-O-4 linkages. Under relatively mild conditions (100 degrees C, 0.2 MPa O2), a lignin beta-O-4 alcohol model compound was almost completely converted within 3 h, affording a narrow product distribution of phenol (yield: 99%) and methyl benzoate (yield: 98%). Based on the control experiments, kinetic study, and spectroscopic analysis, a synergistic oxidative cleavage mechanism was proposed: CoMA/C900 activates molecular oxygen to form a superoxide radical, while basic KNb6 promotes deprotonation of secondary alcohol, and they synergistically catalyze the oxidation of beta-O-4 alcohol and the rapid cleavage of C beta-O and C alpha-C beta bonds. During the reaction, the oxidation of beta-O-4 alcohol to beta-O-4 ketone is the rate-determining step, while the cleavage of PP-one to phenol and methyl benzoate can be completed within 15 min. Moreover, the CoMA/C900-KNb6 catalyst is recyclable at least three times and highly active for the oxidative cleavages of other lignin models and organosolv birch lignin.

The striking aesthetic appeal of fullerene-like clusters has captured the interest of researchers. Nevertheless, the assembly of fullerene-like polyoxovadanadate (POV) cages remains a significant challenge due to the scarcity of suitable pentagonal motif. Herein, we have successfully synthesized the first fullerene-like all-inorganic POV cage, {(V2 O)V30 Nb12 O102 (H2 O)12 } (V30 Nb12 ), by introducing Nb into the POVs. V30 Nb12 is assembled by 12 heterometallic {(Nb)V5 } pentagons through sharing V centers with Ih symmetry, reminiscent of C60 . To our knowledge, the fullerene-like V30 Nb12 not only represents the highest-nuclearity POV cage but also stands as the first niobovanadate cluster. Notably, V30 Nb12 exhibits excellent solution stability, as confirmed by ESI-MS, FT-IR and UV/Vis spectra. As there is no protection organic ligand on its outer surface, V30 Nb12 can be further modified with Cu-complexes to form a fullerene-like cluster based zigzag chain (Cu-V30 Nb12 ).

As important building blocks in natural products and organic synthesis, thioethers have a wide range of potential applications. Herein, polyoxometalate-based ionic liquids (POM-ILs-SO3H) derived from N-alkyl imidazole were synthesized and used for the first time for the thiolation of alcohols to construct C-S bonds in a series of benzyl thioethers. This type of POM-ILs-SO3H catalyst exhibited high catalytic activity, providing up to 98% yield of thioether within 1 h at 70 degrees C. The alkyl chain length of the imidazole had a certain effect on the solubility of the POM-ILs-SO3H catalysts in the reaction solvent, and then affected their catalytic activity. The catalytic system had a wide substrate scope and was suitable for the reaction of tertiary and secondary benzyl alcohols with thiophenols or cycloalkyl thiols. In particular, [PIMPS]3PW12O40 (PIM = 1-propylimidazole, PS = propane sulfonate) as a reversible phase transformation-type catalyst, combining the advantages of homogeneous and heterogeneous catalysts, exhibited high activity and good recyclability with only a slight decrease in the yield after five runs. Additionally, a carbocation mechanism was proposed for the thiolation reaction of alcohols. [PIMPS]3PW12O40 was used as a reversible phase transformation-type catalyst for the thiolation of alcohols to synthesize a series of benzyl thioethers and exhibited high activity and good recyclability.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The controlled synthesis and exploration of the biomass valorization properties of organo-functionalized ionictype polyoxometalates has been attracting considerable interest, but it still poses a challenge. Herein, three imidazole-functionalized ionic-type Pd-polyoxovanadates, [Pd(eIM)4][V6O16(eIM)4] (IPP-1), [Pd(mIM)4]2(H2V10O28)center dot 3H2O (IPP-2) and [Pd(mIM)4]2(V4O12)center dot 4H2O (IPP-3) (mIM = 1-methylimidazole, eIM = 1-ethylimidazole) with [V6O16(eIM)4]2-, [H2V10O28]4- and [V4O12]4- clusters were skillfully designed and successfully isolated, respectively. Importantly, IPP-1 represents the first ionic-type combination of a Pd-complex with an organo-functionalized {V6O16(eIM)4} cluster, and it exhibits remarkable catalytic activity towards the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF), achieving an impressive conversion of 93 % and selectivity of 98 % under atmospheric O2. It can be reused at least five times without any loss of activity. Control experiments confirm that such exceptional catalytic activity originate from the cooperative effect between Pd-complex and {V6O16(eIM)4}. Based on spectroscopic results and density functional theory calculations, a plausible mechanism involving two parallel pathways has been proposed.

The rampant misuse of chemical warfare agents (CWAs) poses a grave threat to the safety of both military personnel and civilians. Therefore, the effective degradation of CWAs to nontoxic products has emerged as a key area of focus for researchers. Polyoxometalates (POMs) and POM-based composites, with their diverse structures and adjustable acid-base and redox properties, have risen as highly promising candidates for accelerating the decontamination of CWAs and their simulants. In this review, we provide an comprehensive overview of the detection and degradation of CWAs and their simulants using POM-based materials through different pathways (oxidation and hydrolysis). Given the unpredictable nature of the employed CWAs in real-world scenarios, extensive discussions have also been conducted regarding the use of multi-functional POM-based catalysts. Particularly, we thoroughly discuss the design principles and catalytic mechanisms of POM-based catalysts for diverse detoxification pathways. Drawing upon the current advancements in this field, we present an analysis of the existing challenges and future prospects pertaining to the POM-catalyzed decontamination systems. We hope that this review will inspire further exploration of green and sustainable catalysts for the degradation of CWAs.

The electrochemical coupling of biomass platform molecules to biofuels provides a promising method for addressing energy crises and environmental issues. However, achieving high yields of C-C coupling products under ambient conditions remains a challenge. Herein, we present a highly efficient electrocatalyst, [Cu(pz)](3)[PW12O40] (Cu-PW12), fabricated by combining a Cu-pz complex (pz = pyrazine), a redox catalytic center, with Keggin-type PW12O40, and an electron sponge. Cu-PW12 exhibits remarkable catalytic activity for the electroreductive C-C coupling of furfural (FF), a bulk and low-cost biomass platform chemical, to produce a jet fuel precursor, hydrofuroin (HDF). Under neutral and ambient conditions, over 99% of FF is converted and the selectivity of HDF reaches 91.2%. Furthermore, experimental and theoretical studies, including control experiments, kinetic isotope studies, electrochemical and spectral analyses, and DFT calculations, reveal a synergistic catalysis effect between Cu center and PW12. The introduction of PW12 not only facilitates electron transfer, improving FF conversion, but also changes the rate-determining step, favoring the formation of HDF. Under turnover conditions, the Cu-PW12 catalyst is initially reduced and then FF is reduced by the Cu center to ketyl radical after protonation on the electrode surface. Finally, the self-coupling of two ketyl radicals in solution leads to the generation of HDF.

TiO2-coated triangle Au with a core-shell structure (Au@TiO2) was synthesized using the sol-gel method. After hydrothermal crystallization, the particle size expanded to 300 nm with crystallization of the shell TiO2 into a mesoporous anatase phase, while the morphology of the triangle Au particle remained unchanged. The structure and properties of the samples were characterized using powder X-ray diffraction (PXRD), zeta potential, high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), photoluminescence (PL) spectroscopy, photocurrent (i-t) measurements, and methylene blue (MB) photodegradation tests. The results revealed that the photocatalytic degradation rate of crystallized triangle Au@TiO2 was significantly higher than that of the amorphous material. Specifically, 1 mg center dot mL(-1) Au@c-TiO2 achieved complete degradation of 60 mg center dot L-1 MB after one hour of visible light irradiation. An electron paramagnetic resonance (EPR) experiment was conducted, indicating that center dot O-2(-) and center dot OH are the active species responsible for the degradation process. By combining experimental results with finite-difference time-domain (FDTD) analysis, we proposed a mechanism for the photodegradation process.

Polyoxometalates (POMs) have conducive properties such as controlled Brønsted and Lewis acidity, high thermal stability, nontoxic nature, tunable solubility, and less corrosiveness. POMs have been extensively applied in catalytic organic reactions and have an exciting prospect for industrial applications. This review summarized recent progress in the application of POMs as acid catalysts for various organic reactions including CC bond formation, CN bond formation, CO bond formation, heterocyclic synthesis reactions, cyanosilylation and hydrolysis reactions. Various POMs catalysts including heteropoly acids (HPAs) and cationic functionalized HPAs with Brønsted acidity, HPAs supported on non-precious metal support with Brønsted acidity (or both Brønsted and Lewis acidity), transition metal substituted POMs with Lewis acidity were applied in above reactions. This review attempts to provide up-to-date information about POMs acid-catalyzed organic reactions and propose future prospects.

Electrocatalytic oxidation of organic molecules to value-added chemicals has attracted recent attention. Although a series of transition metal based electrocatalytic materials have been developed, the lack of precise structure information generates great challenges in understanding the catalytic mechanism at a molecular level. Herein, we present the synthesis and characterization of a molecular electrocatalyst, Na2K6H14[(VO)6(α-TeNb9O33)2]·31H2O·2.5C2H8N2 (abbreviated as V6(TeNb9)2), where a reduced {V6} ring is sandwiched by two trivacant Keggin-type {α-TeNb9O33}. V6(TeNb9)2 as heterogeneous electrocatalyst can selectively convert 95% of thioanisole to sulfoxide with the Faraday efficiency up to 98%. Notably, the important role of the embedded {V6} ring in the electrocatalytic oxidation was illustrated by comparing with {Nb6} ring sandwiched catalyst, Na5K7H4[(NbO)6(α-TeNb9O33)2]·17H2O (abbreviated as Nb6(TeNb9)2). Mechanism studies reveal that during the electrocatalytic oxidation process water is the only oxygen source and a key intermediate PhCH3S+• is involved.