New metal complexes with 5-(1H-imidazol-4-ylmethyl)aminoisophthalic acid: Syntheses, structures, electrochemistry and electrocatalysis

Three new coordination polymers {[Cu(HL)(H2O)]·H2O}n (1), [Ag(H2L)]n (2), and {[Co(HL)(phen)(H2O)]·8H2O}n (3) [H3L = 5-(1H-imidazol-4-ylmethyl)aminoisophthalic acid, phen = 1,10-phenanthroline] have been synthesized under hydrothermal conditions. The results of X-ray diffraction analysis revealed that complex 1 displays (3, 3)-connected 2D network with (4, 82) topology, while complexes 2 and 3 have infinite 1D chain structure, in which one of the two carboxylic groups of H2L−/HL2− is uncoordinated. The 2D layers of 1 or the 1D chains of 2 and 3 are further linked together by hydrogen bonds and π–π interactions to form 3D supramolecular frameworks. Moreover, the electrochemical properties of complexes 1 and 2 have been studied by modified glassy carbon electrodes of 1 (Cu-GCE) and 2 (Ag-GCE), and the results indicate that the Cu-GCE and Ag-GCE show one-electron redox peaks. In addition, both Cu-GCE and Ag-GCE have good electrocatalytic activities toward the reduction of H2O2 in phosphate buffer (pH 5.5) solution.