Synthesis, crystal structure, cytotoxicities and DNA-binding properties of a tetracopper(II) complex with N-benzoato-N'-[2-(2-hydroxyethylamino)ethyl-amino]oxamide ligand

A new dissymmetrical N,N'-bis(substituted)oxamide ligand, N-benzoato-N'-[2-(2- hydroxyethylamino)ethyl]oxamide (H(3)bhyox), and its tetranuclear copper(II) complex, [Cu-4(bhyox)(2)(dabt)(2)](ClO4)(2) (1) have been synthesized and characterized (dabt = 2,2'-diamino- 4,4'-bithiazole). The crystal structures of H(3)bhyox and complex 1 have been determined by X-ray single-crystal diffraction. Complex 1 has a cyclic tetranuclear cation with an embedded inversion center, in which the Cu-Cu separations through the oxamido and carboxyl bridges are 5.2246(6) and 5.3141(6) , respectively. Both Cu(II) centers at the inner and outer sites of the cis-bhyox(3-) ligand have square pyramidal geometries. There is a 3D hydrogen-bonding network in the crystal. The cytotoxicities and DNA-binding properties of H(3)bhyox and complex 1 were studied. Both compounds can interact with HS-DNA by intercalation, and the DNA-binding affinities are consistent with their in vitro cytotoxicities.