Syntheses, structures and electrochemical properties of two co-crystal copper(II) melamine complexes

Two new co-crystal copper(II) melamine complexes, [Cu(HBA)2(MA)2] [Cu(HBA)2] (1) and [Cu2(OAc)4(MA)·(H2O)]2[Cu(HPE)2] (2), MA, melamine; HBA, 2-hydroxybenzaldehyde; HPE, 1-(2-hydroxyphenyl)ethanone, have been synthesized and characterized by elemental analysis, IR and single crystal X-ray diffraction. Crystal structural analysis reveals that 1 and 2 all are co-crystal complexes and composed of two neutral coordination units. In 1, two mononuclear units adopt square planar and distorted octahedral coordination environments, respectively. In 2, one is a mononuclear unit with a square planar geometry and the other is a dinuclear unit with a paddle wheel structure in which the apical positions are rarely occupied by two different donor ligands. The 2D supramolecular structures are formed through strong hydrogen bonds with different modes. The electrochemical behaviors of complexes 1 and 2 were investigated.