Graphical Abstract

By introducing a new “V”-like semirigid bis-imidazole-bis-amide ligand, 4,4’-bis(1H-imidazole-4-carboxamide)phenylmethane (L), into a reaction system containing Anderson-type polyoxoanions, three polyoxometalate-based metal–organic complexes (POMOCs) with different metal ions were successfully synthesized under solvothermal conditions. The as-prepared POMOCs [Zn2L2(H2O)4][Zn(H2O)2(TeMo6O24)]·9H2O (1), [Ni(H2O)6][Ni2L2(H2O)2[AlMo6(OH)6O18]2]·9H2O (2), and [Co(H2O)6][Co2L2(H2O)2[AlMo6(OH)6O18]2]·11.5H2O (3) show sandwich-like supramolecular structures. Complexes 2 and 3 are isostructural, having two [ML(H2O)2]2+ chains with [AlMo6(OH)6O18]3− polyoxoanions as pendants arranged in an interdigital mode to construct the sandwich-like architecture, whereas in complex 1 the anionic [Zn(H2O)2(TeMo6O24)]4− chain is sandwiched by two cationic [ZnL(H2O)2]2+ chains to generate the supramolecular structure. POMOCs 1–3 display excellent electrochemical sensing behavior for Cr(VI), Fe(III), BrO3−, and NO2− ions and efficient catalytic performance in sulfide oxidation. The effect of the central metal on the electrochemical sensing and sulfide oxidation performance and that of the special architecture of 1 on the detection ability are discussed.
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