Two Anderson-type polyoxometalate-induced various Co-complexes based on a rigid pyrazine-bis(triazole) ligand

Abstract

Two new Anderson-type polyoxometalate (POM)-based metal-organic complexes {Co2(H2pytty)2[CrMo6(OH)5O19](H2O)8}·10H2O (1), {Co5(pytty)2[TeMo6O24](H2O)16}·6H2O (2) (H2pytty = 3-(pyrazin-2-yl)-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl) have been synthesized under hydrothermal condition and characterized by IR spectra, elemental analyses, single crystal X-ray diffraction, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). Complex 1 is a 0D structure containing a cation [Co2(H2pytty)2]4+ and an isolated B-type [CrMo6(OH)5O19]4− anion. When A-type [TeMo6O24]6− was used, complex 2 shows a 2D layer with two kinds of 1D chains. No report on the combination of pyrazine-bis(triazole) and Anderson-type POM was found up to now. The electrochemical behaviour and electrocatalytic activities of two title complexes have been systemically studied and discussed. In addition, the redox potentials of complexes 1 and 2 are highly sensitive of pH and may be used as a kind of potential pH sensor.