Synthesis, crystal structure and proton conductivity of one Cu(II) coordination complex based on 2,2′-bipyridine-4,4′-diphosphonic acid

Abstract

One proton-conductive Cu(II) coordination complex [Cu(H3L)Cl]n, in which H4L = 2,2′-bipyridine-4,4′-diphosphonic acid, was synthesized under hydrothermal condition. The product was structurally characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction analyses. The result of single-crystal X-ray diffraction analyses revealed that along c direction Cu2+ and Cl− atoms are joined together to be one infinite zigzag chain [CuCl]∞+. In b direction, adjacent [CuCl]∞+ chains are linked by [H3L]- ligands to be 2D layer. Along a direction, via hydrogen bonds of exposed phosphonic groups, 2D layers are stacked to be three-dimensional supramolecular network. This complex exhibits good proton conductivities 1.97 × 10−3–4.32 × 10−3 S cm−1 at 100 °C in the relative humidity range 35–98%. Moreover, at room temperature, the PXRD and TG analyses were employed to characterize the complex.