Nitrogen, sulfur and oxygen donor adducts with copper(II) complexes of antitumor 2-formylpyridinethiosemicarbazone analogs: Physicochemical and cytotoxic studies

The preparation of N-, S- and O-donor ligand adducts with CuX +(HX=6-methyl-2-formylpyridinethiosemicarbazone (6HL); 2-formylpyridine-2 ′-methylthiosemicarbazone (2′L); 2-formylpyridine-4′-methylthiosemicarbazone (4′HL)) is described. The N-donors, 2,2′-bipyridyl (bipy), 4-dimethylaminopyridine (dmap) give the complexes [Cu(6L)(bipy)]PF 6, [Cu(6L)(bipy)]Cl·5H 2O, [Cu(4′L)(bipy)]PF 6, [Cu(6L)(dmap) 2]PF 6·2.5 H 2O and [Cu(4′L)(dmap) 2]PF 6·H 2O which have been characterized by physical and spectroscopic techniques. Pentafluorothiophenolate (pftp) gives S-donor complexes [CuX(pftp)] (X=6L and 4′L) and thiolato co-ordination is proposed on the basis of spectroscopic evidence. Paratritylphenolate (ptp) and HPO 2− 4 give O-donor complexes [Cu(6L)(ptp)], [Cu(4′L)(ptp)], [{Cu(6L)} 2HPO 4]·4H 2O, and [{Cu(4 ′L)} 2HPO 4]·5H 2O which have been characterized by physical and spectroscopic techniques, as have the precursor complexes [Cu(6L)(CH 3COO)]·H 2O, [Cu(4′L)(CH 3COO)], Cu(6HL)(CF 3COO)](CF 3COO)·0.5H 2O, [Cu(4′HL)(CF 3COO)](CF 3COO), [Cu(2′L)Cl 2] and [Cu(2′L)(NO 3) 2]. Protonation constants for the ligands and some of their complexes have been determined. 2-Formylpyridinethiosemicarbazone (HL) complexes of silver, gold, zinc, mercury, cadmium and lead are also discussed. Cytotoxicity against the human tumor cell line HCT-8 and antiviral data for selected compounds are presented.