Abstract Polyoxometalate (POM)-based hydrogels are emerging organic-inorganic hybrid materials that combine the biological functions of POMs with the biocompatibility and tunable mechanical properties of polymer networks. This review summarizes recent advances in their composition design, network engineering, and biomedical applications. Particular emphasis is placed on four representative applications, including wound healing, antimicrobial therapy, localized cancer treatment, and bioelectronics, highlighting the catalytic, redox, photothermal, and electrochemical properties of POMs. The major challenges for clinical translation are also discussed, including the hydrolytic stability of POMs under physiological conditions, the biological contributions of degradation products, scalable manufacturing, and regulatory considerations. Future research should shift from empirical exploration toward mechanism-guided material design. With continued advances in interdisciplinary technologies, POM-based hydrogels are expected to evolve into versatile platforms for precision biomedical applications.
Self-assembled monolayers (SAMs) have markedly enhanced the power conversion efficiency (PCE) of inverted perovskite solar cells (PSCs); however, the desorption of SAMs limits the long-term stability of the devices. Herein, Lindqvist-type polyoxometalates (POMs) [VnW6u2212nO19](n+2)u2212 (n = 1u20133) were incorporated into SAMs. By leveraging vanadium to establish V(V)/V(IV) redox couples, the electron cloud density of the Vu2013Ou2013W bridging oxygens was significantly enhanced, promoting tridentate anchoring between the SAMs and indium tin oxide via proton-coupled electron transfer (PCET). This increased the anchoring ratio from 29.93% to 53.98% while reducing the desorption rate from 30.7% to 5.6%. The robustly anchored SAMs facilitate the crystallization of high-quality perovskites and effectively suppress interfacial defects, significantly improving the hole-extraction efficiency and increasing the PCE from 23.68% to 25.15% under continuous AM 1.5 G illumination. Moreover, the device stability was markedly enhanced, with the target retaining 90.7% of its initial efficiency after 1200 h of continuous maximum power point tracking (compared to 53.8% for the control). This study demonstrates that POMs can effectively suppress the desorption of SAMs and reduce interfacial losses, offering new insights for fabricating highly efficient and stable PSCs.
Hydrogen evolution reaction (HER) in electrocatalytic water splitting for producing green hydrogen has recently emerged as a promising approach to address the current energy and environmental challenges. In this study, we prepared and characterized the mononuclear Pt-polyoxometalate clusters [Pt1Mo6(OH)6O18](NH4)2 (PtMo6) and [Pt1Mo6(OH)3O18)O3C5H9]TBA2 (PtMo6-L, TBA: tetrabutylammonium) as HER electrocatalysts with enhanced activity. The HER performance of PtMo6-L coated onto glassy carbon is superior to that of naked PtMo6 and comparable to that of commercial 20 wt.% Pt/C, with an overpotential of 37 mV@10 mAu00B7cmu22122 and a Tafel slope of 42 mVu00B7decu22121. The HER follows the Heyrovskyu2013Volmer mechanism over PtMo6-L, similar to Pt/C, but the Tafelu2013Volmer mechanism over PtMo6. Experimental and density functional theory calculation results indicate that the Ptu2013Ou2013H group in the polyoxometalate clusters is the active site for the HER. Moreover, mechanistic studies reveal that the negatively charged C5H9-bonded O1 in PtMo6-L is prone to proton adsorption and activation, thereby enhancing electrocatalytic HER activity. Overall, this study provides new insights into the polyoxometalate structureu2013electrocatalytic property relationship at the precise atomic and molecular levels, advancing HER research.
Abstract The catalytic oxidation of sulfur-containing compounds constitutes a pivotal research frontier with broad implications across biomedicine, environmental remediation, and chemical defense. Polyoxometalates (POMs), well-defined anionic metal–oxygen clusters exhibiting tunable redox activity, high acidity and structural robustness, represent promising molecular catalytic units for selective sulfur oxidation. Yet their practical application is frequently hampered by, aggregation and limited recoverability under reaction conditions, particularly in polar media. Porous framework materials, notably metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), offer structurally precise, modular scaffolds for the spatial confinement and stabilization of POMs. Host–guest composites engineered via encapsulation within framework cavities or channel walls not only suppress POM degradation and leaching but also synergistically enhance active-site accessibility, substrate diffusion and orientation, and interfacial charge-transfer kinetics. Existing reviews predominantly focus on single host systems or specific applications (e.g. only fuel oxidative desulfurization), failing to systematically encompass all three core research fields. This review comprehensively summarizes recent advances in POM@MOF and POM@COF composites in the fields of bioactive sulfide synthesis, fuel desulfurization and chemical warfare agent purification. The intrinsic correlations between host-guest interactions and catalytic performance, stability, as well as reaction mechanisms are discussed, and the future development directions in this field are prospected, aiming to facilitate the industrial application of related technologies.
Abstract The advent of atomically precise metal nanoclusters has effectively bridged the gap between single atom and conventional nanoparticle catalysts. Such metal nanoclusters have been widely applied as highly efficient electrocatalysts, offering an ideal platform in which all atoms, from metal core to surface ligands, are clearly resolved, enabling the probing of catalytic mechanisms at the atomic level. Bimetallic nanoclusters usually display better catalytic performance compared to the monometallic counterparts thanks to the synergistic catalytic effect. Among them, AgCu nanoclusters (NCs) have stood out as promising model catalysts due to their relatively lower costs (compared to Au, Pt and Pd), enriched structure diversity and wide spectrum of catalytic applications. These attributes render them not only as exemplary model catalysts for fundamental research but also as highly promising electrocatalysts for complex reactions that can generate highly valuable chemicals. This review provides a comprehensive overview of recent advances in the structural anatomy and electrocatalytic applications of atomically precise AgCu NCs. It begins with an examination of structurally defined archetypes, and then delves into their exemplary performance in key electrocatalytic processes, including CO2 reduction, nitrate reduction, and C–N bond construction, with a focus on the unique role of bimetallic synergy in enhancing activity, selectivity, and stability (Scheme 1). The review also outlines pathways for the rational design of next–generation AgCu NCs–based electrocatalysts for sustainable energy development and the electrosynthesis of valuable chemicals.
Abstract Five octanuclear homometallic or heterometallic clusters based on thiacalix[4]arene (TC4A): {[Ni8(TC4A)2(μ6-CO3)2(μ2-CH3CO2)3(μ2-CO3)(DMA)4]}∙(CH3CN)2 (1) (DMA = N,N-Dimethylamine), {[Ni5.81Co2.19(TC4A)2(μ6-CO3)2(μ2-HCO2)2(μ2-Cl)2(DMA)4]}∙2DMF∙2CH3CN (2) (DMF = N,N-Dimethylformamide), {[Ni4.06Co3.94(TC4A)2(μ6-CO3)2(μ2-HCO2)2(μ2-Cl)2(DMA)4]}∙2DMF∙2CH3CN (3), {[Ni2Co6(TC4A)2(μ6-CO3)2(μ2-HCO2)2(μ2-Cl)2(DMA)4]}∙2DMF∙2CH3CN (4), {[Co8(TC4A)2(μ6-CO3)2(μ2-HCO2)3(μ2-CO3)2(DMA)4]}∙6DMF (5) have been synthesized via the solvothermal method. Single crystal X-ray diffraction structural analyses indicate that all compounds consisted of two badminton-like secondary building units (SBUs) [M4(TC4A)], (M = Co, Ni, Co/Ni), which are linked by two μ6-CO32- anions in a tail-to-tail manner, forming a chair-like octanuclear metal cluster. Their structures were further evidenced by FT-IR, UV-Vis, XPS, PXRD and so on. Magnetism studies of compounds 1-5 indicate that there is an antiferromagnetic interaction between their metal ions, and the measured magnetic susceptibility χMT of compounds 1 to 5 increases as the cobalt content rises in the range of 50-300 K. The structures and magnetic properties of the Co(II)/Ni(II) cluster supported by TC4A can be conveniently tuned by varying the molar ratio of Ni(II) to Co(II), providing a straightforward approach to construct heterometallic clusters based on TC4A.
Abstract Aimed at exploring new organically derivatized POMs, three heterocyclic hydrazides functionalized hexamolybdates (TBA)3[Mo6O18(=N=NCOC5H4N)] (1) (TBA = tetrabutylammonium), (TBA)3[Mo6O18(=N=NCOC4H3S)] (2) and (TBA)3[Mo6O18(=N=NCOC4H3N2)] (3) were prepared via the reflux reaction of corresponding heterocyclic hydrazides and octamolybdates in the dry acetonitrile. Their structures were determined by single crystal X-ray diffraction, all compounds can be viewed as one terminal oxo atom of hexamolybdates being substituted by corresponding heterocyclic hydrazides via the Mo=N multiple bond. There are three conformational isomers of [Mo6O18(=N=NCOC5H4N)]3- with the approximate symmetry of Cs or C1 in the asymmetric unit of compound 1, but only one anion cluster of [Mo6O18(=N=NCOC4H3S)]3- with the approximate symmetry of Cs in the asymmetric unit of compound 2. Their structures are further evidenced by FT-IR, UV-Vis, ESI MS, 1H NMR spectroscopy and so on. Antitubercular activity tests manifest that all compounds demonstrate enhanced inhibitory activities compared to that of hexamolybdates and L2, but it still inferior to L1 and L3. Considering their large molecular weight, their molar inhibitory activity is close or superior to the ligands of L1 and L3. Our current work provides a promising way to develop POMs with biological activities through the molecular hybridization of organic medicines and POMs via covalent bond.
Developing novel, low-cost, and high-performance proton exchange membranes (PEMs) to replace commercial Nafion is of great significance. By grafting quaternary ammonium cations onto the side chains of polybenzimidazole, abundant charge carriers and proton hopping sites are provided for proton transport, accelerating proton migration and thereby enhancing the proton conductivity of composite membranes made from this material. Furthermore, polyoxometalates (POMs) are introduced through electrostatic interactions, and their exceptional proton-conducting properties further improve the proton conductivity of the composite membranes, with the maximum proton conductivity reaching 0.123 Su00B7cmu22121. This work demonstrates that POM-based materials can serve as excellent proton carriers, expanding the selection of active materials for composite membranes and providing new references for the fabrication of novel proton exchange membranes.
The coexistence of multiple noncovalent interactions, such as ionic interactions, hydrogen bonding, and u03C0u2013u03C0 stacking, provides rich opportunities for constructing supramolecular architectures while presenting challenges in controlling assembly outcomes. Herein, we employ hydrogen bond-functionalized Anderson-type polyoxometalates and terpyridyl-based metal complexes as complementary building blocks. By varying the solvent, temperature, and assembly time, we achieve distinct supramolecular structures. Rapid assembly in water yields a kinetically trapped two-dimensional hexagonal ionic framework. By contrast, assembly in N,N-dimethylformamideu2013water mixtures under ambient or hydrothermal conditions leads to four thermodynamically stable ionic crystals, each characterized by unique packing arrangements governed by u03C0u2013u03C0 stacking and hydrogen-bonding interactions. This study demonstrates that a single co-assembly system can generate diverse, well-defined architectures under different assembly conditions, offering a practical strategy for the controlled construction of complex supramolecular materials.
The incorporation of lanthanides into polyoxometalates (POMs) is a fascinating area of research due to their unique chemical and physical properties, as well as their potential applications. Polyoxopalladate (POP) clusters feature flexible central cavities and coordination geometries dictated by their central metal ion templates and external capping groups. Two primary structure types have been reported: {Pd-12} cubes and {Pd-15} stars, which can accommodate various central metal ions, ranging from common transition metals in the +2 oxidation state to less conventional lanthanides in the +3 oxidation state. This work explores POP clusters containing cerium ions, leading to the discovery of two new structure types: [CePd13O9(SeO3)(9)(H2O)](6-) (1) and [Ce3Pd22O16(SeO3)(16)](8-) (2). Cluster 1 adopts a fused "star-cube" structure, combining half {Pd-15} star and half {Pd-12} cube with Ce4+ as the central template. 2 exhibits a twisted dumbbell-shaped structure (D-2d symmetry), where two Ce4+-centred {CePd11} cubes are bridged by a third Ce4+ ion at the cluster core. Parallel experiments with other lanthanides yielded two propeller-like chiral POPs [LnPd(12)O(7)(SeO3)(8)Cl(H2O)(2)](4-) (Ln = Eu3+ (3); Ln = Gd3+ (4)), both displaying C-3 symmetry. Notably, this represents one of the rare instances in POP chemistry where a capping ligand (SeO32-) directly coordinates to the central lanthanide ions (Eu3+ and Gd3+). The twisted coordination of this capping ligand induces a uniform tilt in a set of {PdO4} planes, resulting in the clusters' propeller-like chirality. In contrast, similar reaction conditions for Tb3+ produced [TbPd12O8(SeO3)(8)](5-) (5), a normal cubic structure.
