Synthesis, spectral properties, structural characterization and bioactivity of aqua-bis(4-pyridylmethanol)-bis(Xbenzoato)copper(II) complexes

Two novel and two previously prepared and published copper(II) complexes were synthetized using Xbenzoic acids (where X = 2-NO2, 2-Cl, 2-Br, 2-I) and 4-pyridylmethanol (4-PM): [Cu(2-NO2bz)2(4-PM)2(H2O)] 1, [Cu(2-Clbz)2(4-PM)2(H2O)] 2, [Cu(2-Brbz)2(4-PM)2(H2O)] 3 and [Cu(2-Ibz)2(4-PM)2(H2O)] 4. The structures of the newly prepared complexes 1 and 4 were determined by single-crystal X-ray analysis, and the intermolecular interactions were studied by Hirshfeld surface analysis for all complexes. All the complexes were characterized by IR, UV-vis and EPR spectroscopy (in solid-state and DMSO solution) and their redox properties were determined by cyclic voltammetry. The interaction of complexes 1-4 with calf-thymus DNA was monitored by diverse techniques (UV-vis spectroscopy, viscosity measurements) suggesting intercalation as the most possible mode of binding (Kb = 1.15×105-3.44×106 M-1). The cytotoxic effects of copper(II) complexes on lung carcinoma cells were determined by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] colorimetric technique. Furthermore, their SOD and catechol oxidase mimetic activity were studied.