Mixed-ligand copper(II) complexes with tetrazole derivatives and 2,2′-bipyridine, 1,10-phenanthroline: Synthesis, structure and cytotoxic activity

Abstract

The [Cu2(2,2′-bipy)2(L1)4] (1), [Cu2(1,10-phen)2(L1)4] (2), [Cu(2,2′-bipy)(L2)2]n (3) and [Cu2(1,10-phen)2(L2)4] (4) complexes, where HL1 – 5-phenyltetrazole, and HL2 – 1H-tetrazole, have been synthesized. All complexes have been characterized by elemental analysis, IR, EPR spectroscopy and X-ray diffraction. The complexes possess distorted tetragonal-pyramidal coordination geometry. Compounds 1, 2, 4 show μ-5-phenyl-tetrazole/tetrazole bridged dinuclear structures, while compound 3 reveals polymeric structure. The effect of compounds on viability of the MCF-7 and Hep-2 cell lines was investigated in vitro. The study showed that tetrazole ligands HL1 and HL2 are non-toxic at tested concentrations (1–50 μM), while 1,10-phen and 2,2′-bipy posses cytotoxicity. All of the complexes exhibit significant dose-dependent cytotoxic effect and have the potential to act as efficient cytotoxic drugs. The complexes [Cu(1,10-phen)Cl2] (5) and [Cu(2,2′-bipy)Cl2] (6) have also been obtained to establish the influence of insertion of tetrazole ligands in compounds on their cytotoxic properties.