Synthesis, structure, and DNA-binding studies of a dicopper(II) complex with N-phenolato-N′-[2-(dimethylamino) ethyl]oxamide as ligand

A new mu-oxamido-bridged dicopper(II) complex, [Cu2(pdmaeox)(bpy)(H2O)](pic) center dot H2O [H3pdmaeox = N-phenolato-N'-[2-(dimethylamino)ethyl]oxamide, Hpic = 2,4,6-trinitrophenol, bpy = 2,2'-bipyridine], has been synthesized and characterized by elemental analyses, molar conductivity measurement, infrared, and electronic spectra studies, and X-ray single-crystal diffraction. The complex crystallizes in the triclinic system, P 1 space group, with crystallographic data: a = 10.7815(2) angstrom, b = 11.3598(2) angstrom, c = 14.1389(3) angstrom, and z = 2. In [Cu2(pdmaeox)(bpy)(H2O)]+, one copper(II) resides in the inner site with a square-planar coordination geometry and the other is chelated by the two exo-oxygen atoms of the cis-pdmaeox3- ligand in a square-pyramidal environment. The Cu center dot center dot center dot Cu separation through cis-pdmaeox3- bridge is 5.1834(4) angstrom. The crystal structure is stabilized by hydrogen bonds and - stacking interactions. The interaction of the dicopper(II) complex with herring sperm-DNA (HS-DNA) has been investigated by electronic absorption titration, fluorescence titration, electrochemical titration, and viscosity measurements. The results reveal that the interaction of the dicopper(II) complex with HS-DNA might be electrostatic binding. The effects of bridging ligand on the interaction of the dinuclear complex with HS-DNA were preliminarily investigated.