Two Keggin-based cobalt complexes with a semi-rigid bis-imidazolyl-bis-amide ligand: Structures, electrochemical properties and adsorption activities for dyes

摘要

Two new Keggin-type polyoxometalate (POM)-based cobalt complexes with a semi-rigid bis-imidazolyl-bis-amide ligand, [Co2L2(H2O)(4)][SiW12O40]center dot L center dot 8H(2)O (1) and [CoL2(H2O)(2)][(HPW10W2O39)-W-VI-O-V]center dot 5H(2)O (2) (L = 1, 4-bis (1H-imidazole-4-carboxamido)metaphenylene), have been synthesized under hydrothermal condition, and characterized by IR, PXRD and single crystal X-ray diffraction analysis. The title complexes display different 3D supramolecular structures, which contain 1D metal-organic chain or POM-based inorganic chain. Complex 1 contains three kinds of segments, namely, 1D [CoL(H2O)(2)](n)(2+) chain, discrete [SiW12O40](4-) polyoxoanion and L ligand. While in the presence of [PW12O40](3-) polyoxoanion, a kind of POM-based inorganic chain was constructed in compound 2, and a discrete [CoL2(H2O)(2)](2+) metal-organic fragment was formed, which was different from that in 1. The results indicate that the POMs show great effect on the formation of final various segments and structures. The electrochemical properties and adsorption activities for dyes of complexes 1 and 2 have been investigated.