Effect of N-donor sites of bis-pyridyl-bis-amide ligands on the architectures of three Anderson-type polyoxometalate-based metal–organic complexes

Three polyoxometalate-based metal–organic complexes [Co2(H2O)6(TeMo6O24)](3-H2dpyb)·2H2O (1), [M2(4-Hdpyb)2(H2O)6(TeMo6O24)]·6H2O [M = Co (2), Zn (3); 3-dpyb = N,N′-bis(3-pyridinecarboxamide)-1,4-butane, 4-dpyb = N,N′-bis(4-pyridinecarboxamide)-1,4-butane] have been hydrothermally synthesized and characterized by elemental analysis, IR, TG, powder diffraction and single-crystal X-ray diffraction analysis. The structure of complex 1 consists of 1D [Co2(H2O)6(TeMo6O24)] inorganic chains, which are joined together by the 3-dpyb ligands through weak hydrogen bonds to generate a 2D supramolecular network. Complexes 2 and 3 are isostructural; each [TeMo6O24]6− (TeMo6) polyoxoanion chelates either two cobalt or two zinc atoms to generate the discrete complexes [Co2(4-Hdpyb)2(H2O)6(TeMo6O24)] and [Zn2(4-Hdpyb)2(H2O)6(TeMo6O24)], respectively. The electrochemical properties, electrocatalytic and photocatalytic activities of the complexes have been investigated.