Cu(II), Co(II), Mn(II) Complexes with 5-Phenyltetrazole and Polypyridyl Ligands: Synthesis, Characterization and Evaluation of the Cytotoxicity and Antimicrobial Activity

In this work, six new mixed-ligand Cu(II), Co(II), Mn(II) complexes with 5-phenyltetrazole (HL) and polypyridine ligands (phen – 1,10-phenanthroline, dmbipy – 2,2’-bi-4-picoline, dmphen – 4,7-dimethyl-1,10-phenanthroline, phendione – 1,10-phenanthroline-5,6-dione), namely, [Cu(dmbipy)(L)2] (1), [Cu2(dmphen)2(L)4] (2), [Cu(phendione)(L)2] (3), [Co3(phen)2(L)6] (4), [Mn3(phen)2(L)4(OAc)2] (5), [Mn(H2O)4(phen)]·phen·L2 (6), are reported. Complexes have been characterized by EPR and IR-spectroscopy, elemental, thermogravimetric and powder X-ray diffraction analysis. Molecular structures of [Cu(dmphen)2L]·L·6H2O (2a), [Co3(phen)2(HL)2(L)4(OH)2]·1.9EtOH·1.1DMSO (4a), [Mn3(phen)2(L)4(OAc)2]·H2O (5∙H2O ) and [Mn(H2O)4(phen)]·phen·L2 (6) have been determined by single crystal X–ray diffraction. The UV-vis spectroscopy has been applied to study the behavior of the compounds in solution. All complexes have been screened in vitro for their cytotoxic activity against human cancer cell lines: larynx carcinoma (Hep2), hepatocellular carcinoma (HepG2) and breast adenocarcinoma (MCF-7). Cu(II) complexes exhibit significant dose-dependent cytotoxic effect: [Cu2(dmphen)2(L)4] (2), [Cu(phendione)(L)2] (3) are found to be the most cytotoxic. The antimicrobial activity of complexes and ligands has been investigated against Escherichia coli, Staphylococcus aureus, Penicillium italicum and Colpoda steinii.