Syntheses, structures, in vitro cytotoxicities and DNA-binding properties of four copper complexes based on a phenyl 2-pyridyl ketoxime ligand

Abstract

Four complexes [Cu6L6(µ4–O)2(dca)2] (1), [Cu3L3(µ3–OH)Cl2] (2), [Cu3L3(µ3–OH)(OAc)2]·py (3) and [Cu2L4] (4) (HL = phenyl 2-pyridyl ketoxime; dca = dicyanamide anion) have been synthesized and characterized by physicochemical and spectroscopic methods. The structures of all three complexes consist of a single or off-set stacked inverse 9-MC-3 metallacrown formed by three L− ligands and three Cu atoms, and all of the Cu atoms are located in square planar or square pyramidal geometries with different apical ligands. In complex 4, four L− ligands link two Cu atoms to form a dinuclear structure, and the Cu atoms adopt square pyramidal coordination geometry. The in vitro cytotoxicities against four cell lines (A549, HL-60, HT-29 and HCT-116) have been assayed by colorimetric MTT assay. In addition, all four complexes interact strongly with calf thymus DNA, which may be directly responsible for their antitumor activities.