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 3apopoxd) ( L), and its three bicopper(II) complexes, [Cu 2(apopoxd)(bpy)]- (ClO 4)·H 2O (1), [Cu 2(apopoxd)(dabt)](ClO 4)·2H 2O ( 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. A novel dissymmetrical N-(2-aminopropyl)-N′-(2-oxidophenyl)oxamide (L), and its three bicopper(II) complexes have been synthesized and characterized. The anticancer activities and DNA-binding properties of the four compounds were investigated. [Display omitted] ► A new ligand, N-(2-aminopropyl)-N′-(2-oxidophenyl)oxamide was synthesized. ► Three bicopper(II) complexes of it with different terminal ligands were synthesized. ► The four compounds exhibit cytotoxicities against SMMC-7721 and A549 cell lines. ► The DNA-binding abilities are consistent with cytotoxicities in the order 3 > 2> 1 > L. ► The terminal ligands are very important in the DNA-binding and cytotoxic properties.