pH-dependent assembly of two polyoxometalate-based coordination polymers: structures and electrocatalytic properties

Two new polyoxometalate-based coordination polymers have been synthesized at different pHs under identical hydrothermal conditions, (Hbib)[Cu2(bib)2(PMo12O40)] (1) and (Hbib)2[Cu(bib) (PMo12O40)]·2H2O (2) (bib = 4-bis(imidazol-1-yl) benzene). Their structures were determined by single crystal X-ray diffraction analyses and characterized by routine methods. When the pH was adjusted to 2.0 − 2.5, 1 was obtained, which exhibits a 1-D rail-like chain. Compound 2 was obtained at pH of 2.5 − 3.2 and exhibits a 2-D layer with (44) sql net. The pH of the reaction plays a key role in the assembly of the polyoxometalate-based coordination polymer. The electrochemical experiments indicate that 2-based carbon paste electrode possesses high catalytic efficiency and high stability towards reduction of iodate and oxidation of ascorbic acid.