Construction of Anderson−type polyoxometalate−based complexes involving in situ ligand transformation with capacitive and electrochemical sensing performances

Abstract

For developing polyoxometalate−based hybrids as potential energy storage and electrochemical materials, 3, 5−di(1H−imidazol−1−yl)benzonitrile (DICN) and 5−(1H−imidazol−1−yl)isophthalonitrile (IMIPN) as precursors were employed, and three Anderson−type polyoxometalate−based complexes, [{Cu3(H2O)8(HDIBA)2}{TeMo6O24}]·6H2O (1), [{Cu4(H2O)10(HIMIPA)2}{TeMo6O24}]·2H2O (2) and Ni(H2O)6[{Ni2(H2O)4(H2IMIPA)2}{TeMo6O24}]·4H2O (3), were prepared under hydrothermal condition. The initial DICN and IMIPN were transformed in situ into 3,5−di(1H−imidazol−1−yl)benzoic acid (HDIBA) and 5−(1H−imidazol−1−yl)isophthalic acid (H2IMIPA). In 1, the polyoxometalate−based inorganic chains containing single−bridged copper linkages were extended by the imidazole groups of HDIBA ligand, but the chains in 2 and 3 embodied the double−bridged copper and nickel linkages, further linked by the imidazole and carboxyl groups from HIMIPA ligand. Complexes 1−3 demonstrated outstanding capacitive performances (i.e., specific capacitances of 944 F·g–1 for 1, 1548.6 F·g–1 for 2 and 718.6 F·g–1 for 3 at 1 A·g–1), as well as electrochemical sensing activities for bromate. The results provided a feasible way for the design and synthesis of Anderson−type POM−based complexes used as high−performing electrode materials in energy store and sensor−related applications.