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

Abstract 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 HL 1 – 5-phenyltetrazole, and HL 2 – 1 H -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 HL 1 and HL 2 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)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.