Three ring-shaped Zr(iv)-substituted silicotungstates: syntheses, structures and their properties

Three Zr(iv)-substituted polyoxometalate nanoclusters, H-16(H(2)dap)(4)[{Zr-2(OH)(2)(alpha-SiW10O38)}(2){Zr-2(OH)(2)(beta-SiW10O38)}(2)]center dot 8H(2)O (1, dap = 1,3-diaminopropane), H17Na9[(Zr-2(OH)(2))(2)(Zr2BO(OH)(4))(2)(beta-SiW10O38)(4)]center dot 50H(2)O (2) and H20Na8[(Zr2BO(OH)(4))(2)(Zr2B2O2(OH)(5))(2)(beta-SiW10O38)(4)]center dot 40H(2)O (3), were made by a hydrothermal reaction of trivacant [A-alpha-SiW9O34](10-), Zr(4+)ions, and H(3)BO(3)under different alkaline conditions. Single-crystal X-ray structure analysis revealed that they are ring-shaped polyoxotungstate aggregates built by Zr-2(OH)(2)({Zr-2}) clusters and two types of dilacunary alpha-/beta-SiW10O38({alpha-/beta-SiW10}) fragments for1, {Zr-2}, {beta-SiW10}, and Zr2BO(OH)(4)({Zr2B}) clusters for2, and {beta-SiW10}, {Zr2B}, and Zr2B2O2(OH)(5)({Zr2B2}) clusters for3, respectively, showing that the Zr-B-O clusters, {Zr2B} and {Zr2B2}, have been introduced to the lacunary sites of polyoxometalates for the first time. The electrochemistry and electrocatalytic properties of2were studied, and it exhibited effective catalytic activities for the reduction of H2O2, NO2-, and BrO3-. Moreover, the catalysis of2for the oxidation reactions of various thioethers was investigated, and it was found that2possessed high conversion and remarkable selectivity.