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

The [Cu-2(2,2'-bipy)(2)(L-1)(4)] (1), [Cu-2(1,10-phen)(2)(L-1)(4)] (2), [Cu(2,2'-bipy)(L-2)(2)](n) (3) and [Cu-2(1,10-Phen)(2)(L-2)(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 mu-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 mu M), 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)Cl-2] (5) and [Cu(2,2'-bipy)Cl-2] (6) have also been obtained to establish the influence of insertion of tetrazole ligands in compounds on their cytotoxic properties.