Synthesis, structure, cytotoxic activities and DNA-binding properties of tetracopper(II) complexes with dissymmetrical N,N′-bis(substituted)oxamides as ligands

► Two tetracopper(II) complexes with different bridging ligands were synthesized. ► Complex 1 was characterized by single-crystal X-ray diffraction. ► The two complexes exhibit cytotoxicities against SMMC-7721 and A549 cell lines. ► The DNA-binding abilities are consistent with cytotoxicities in order of 1 > 2. ► Bridging ligands are of great importance in the bioactivities of the complexes.