A novel dicobalt-substituted tungstoantimonate polyoxometalate: Synthesis, characterization, and photocatalytic water oxidation properties

The one-pot assembly reaction of a trilacunary, lone-pair-containing [B-alpha-SbW9O33](9-) precursor with Co2+ ions in an aqueous medium led to the isolation of a novel {SbO3(H2O)(3)} bridging, dicobalt-substituted, sandwich-type tungstoantimonate {Co2Sb2(H2O)(10)[B-beta-SbW9O33](2)}(4-) (la). This compound was structurally characterized in the solid state by single-crystal X-ray diffraction, elemental analyses, thermogravimetric analysis, and IR spectroscopy. The most remarkable feature was that la comprises two trilacunary [B-beta-SbW9O33](9-) fragments trapping a novel, centrally symmetric, rhomb-like {Co2Sb2} belt with 10 terminal water molecules. When combined with the photosensitizer [Ru(bpy)(3)](2+) and the sacrificial electron acceptor S2O82-, la exhibited efficient catalytic activity for water oxidation with a remarkable turnover number (TON) of 193, initial turnover frequency (TOFinitial) of 5.3 s(-1), O-2 yield of 30.8%, and quantum yield (phi(QY)) of 36.2% under light-driven conditions. (C) 2019, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.