Synthesis and structure of new bicopper(II) complexes bridged by N-(2- aminopropyl)-N'-(2-oxidophenyl)oxamide: the effects of terminal ligands on structures, anticancer activities and DNA-binding properties.

A novel dissymmetrical N,N'-bis(substituted)oxamide ligand, N-(2-aminopropyl)-N'-(2-oxido- phenyl)oxamide (H(3)apopoxd) (L), and its three bicopper(II) complexes, [Cu(2)(apopoxd)(bpy)]- (ClO(4))·H(2)O (1), [Cu(2)(apopoxd)(dabt)](ClO(4))·2H(2)O (2), and [Cu(2)(apopoxd)(phen)(2)](ClO(4)) (3) (bpy = 2,2'-bipyridine; dabt = 2,2'-diamino-4,4'-bithiazole; phen = 1,10-phenanthroline) have been synthesized and characterized. The crystal structures of the three bicopper(II) complexes have been determined by X-ray single-crystal diffraction. In complexes 1 and 2, the cis-apopoxd(3-) ligands bridge two copper(II) ions in square-planar geometries with the corresponding separations of 5.1868(3) and 5.2016(4) Å, respectively. While in complex 3, the apopoxd(3-) ligand adopting a trans conformation bridges the two copper(II) ions in distorted square-pyramid environments with a Cu · · · Cu distance of 5.2508(7) Å. The anticancer activities and DNA-binding properties of L and the three complexes were investigated.