Organic/Inorganic Species Synergistically Supported Unprecedented Vanadomolybdates

Vanadomolybdates (VMos), comprised of Mo and V in high valences with O bridges, are one of the most important types of polyoxometalates (POMs), which have high activity due to their strong capabilities of gaining/losing electrons. Compared with other POMs, the preparation of VMos is difficult due to their relatively low structural stability, especially those with unclassical architectures. To overcome this shortcoming, in this study, triol ligands were applied to synthesize VMos through a beaker reaction in the presence of V₂O₅, Na₂MoO₄, and organic species in the aqueous solution. The single-crystal X-ray diffraction results indicate that two VMo clusters, Na₄{V₅Mo₂O₁₉[CH₃C(CH₂O)₃]}∙13H₂O and Na₄{V₅Mo₂O₁₉[CH₃CH₂C(CH₂O)₃]}∙13H₂O, with a similar architecture, were synthesized, which were both stabilized by triol ligand and {MoO₆} polyhedron. Both clusters are composed of five V ions and one Mo ion in a classical Lindqvist arrangement with an additional Mo ion, showing an unprecedented hepta-nuclear VMo structure. The counter Na⁺ cations assemble into one-dimensional channels, which facilitates the transport of protons and was further confirmed by proton conductivity experiments. The present results provide a new strategy to prepare and stabilize VMos, which is applicable for developing other compounds, especially those with untraditional architectures.

A New Family of Polyoxometalates: Tris-functionalized Lindqvist-Type Hexatungstovanadates

We successfully designed and obtained a new family of polyoxometalates (POMs) containing mixed-metal elements and a trialkoxyl (TRIS) ligand via a very simple one-pot process under mild condition. Single-crystal X-ray diffraction revealed that this family belongs to compact Lindqvist-type hexatungstovanadates. In particular, the hydroxyl-containing product can be further functionalized through esterification. Not only does this work open a broad door for unusual POM clusters involving vanadium and tungsten atoms in the future, but also the design concept of this work also provides new insight for the synthesis and further exploration of POMs.

A Giant Mo/Ta/W Ternary Mixed-Addenda Polyoxometalate with Efficient Photocatalytic Activity for Primary Amine Coupling

The reactivity and properties of polyoxometalates (POMs) vary remarkably as a function of the kind of addenda atoms, so the design and synthesis of new mixed-addenda POMs is a promising approach for the further development of the POM-related areas. In the present work, the first Mo/Ta/W ternary mixed-addenda POM (NH₄)₄₁H₇[K₃(H₂O)₃(P₂W₁₅Ta₃O₆₂)₆(Mo₂O₄CH₃CO₂)₃(MoO₃)₂]·85H₂O (1), which is composed of 6 {P₂W₁₅Ta₃O₆₂} linked by 3 {Mo^V₂O₄(OOCCH₃)⁺} and 2 {Mo^VIO₃} via 18 novel Mo-O-Ta bridges has been synthesized. The precursor {P₂W₁₅Ta₃}, which has lower redox potential, is crucial for the formation of 1. The red-brown solid sample of 1 shows strong absorption in the visible region. The visible-light responsive charge transfer from benzylamine to 1 was observed experimentally. 1 was proved to be an efficient photocatalyst under simulated sunlight (AM 1.5G) radiation for the oxidative coupling of primary amines to imines using atmospheric O₂.

Polyoxometalate-encapsulated twenty-nuclear silver-tetrazole nanocage frameworks as highly active electrocatalysts for the hydrogen evolution reaction

Two unprecedented polyoxometalate (POM)-encapsulated twenty-nuclear silver-tetrazole nanocage frameworks have been successfully synthesized, which exhibit high activity in the hydrogen evolution reaction.

β-{Cr[RC(CH2O)3]2Mo6O18}3−: the first organically-functionalized β isomer of Anderson-type polyoxometalates

The first organically-functionalized butterfly-shaped β isomer of Anderson-type polyoxometalates was discovered, which will enrich polyoxometalates chemistry.