A closed hollow capsule structure assembled by double acetate-decorated Anderson-like polyanions

An inorganic–organic hybrid vanadotungstate, Na6[VW6O22(CH3COO)3]·11H2O (1), was synthesized in aqueous solution and characterized by infrared spectrum, elemental analysis, thermogravimetric analysis, X-ray photoelectron spectroscopy, and single-crystal X-ray diffraction. The result of the single-crystal X-ray diffraction analysis reveals that the polyanion of 1 is an acetate single-sided decorated Anderson-like polyoxotungstate with a VV in the central tetrahedral position. For better understanding of the characteristic distinction between 1 and the classical Anderson-type polyanion, we synthesized a triol ligand single-side anchored on the Anderson-type polyoxometalate, [(n-C4H9)4N]3{AlMo6O18(OH)3[(CH2O)3CNHCOC5H4N]}·8H2O (2), as a comparison. One interesting architectural feature of 1 is that two polyanions [VW6O22(CH3COO)3]6− are linked by six sodium cations on the same plane to form a closed hollow capsule structure with the inner major axis of 8.54 Å and minor axis of 3.11 Å. As basic building blocks, the closed hollow capsule moieties are assembled into 1D chain-like structures through direct Na−O bonds without additional linkers. The electrochemical behavior of 1 was investigated in pH 4.8 buffer solution to investigate its potential application in electrochemical catalysis; 1 has good catalytic activity for oxidation of thioanisole.