Immobilization of enzymes on an organic-inorganic hybrid network consisting of Dawson-type polyoxotungstate and a zinc(ii)-biimidazole complex moiety

摘要

A new polyoxometalate (POM)-based organic-inorganic hybrid compound, {[(Zn(H(2)biim)(2))(3)(P2W18O62)]6H(2)O}(n) (1) (H(2)biim = 2,2-biimidazole), has been hydrothermally synthesized and characterized by physico-chemical and spectroscopic methods. The structure of compound 1 exhibits a two-dimensional (2-D) network character, in which each Dawson-type polyoxoanion [P2W18O62](6-) ({P2W18}) is connected with six [Zn(H(2)biim)(2)](2+) ({Zn(ii)-H(2)biim}) complex fragments, while each {Zn(ii)-H(2)biim} unit bridges two {P2W18} clusters, forming a 2-D network with a (6,3)-net topology. Compound 1 shows high enzyme-immobilizing capability for horseradish peroxidase (HRP). The maximum HRP load is 90.1 mg g(-1) under optimal conditions. Furthermore, the immobilized enzyme (HRP/1) exhibits high catalytic activity and good stability, which can be applied to detect trace amounts of H2O2 in solution with a low detection limit of 3.11 x 10(-3) mmol L-1.