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

Abstract

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)]PF6, [Cu(6L)(bipy)]Cl·5H2O, [Cu(4'L)(bipy)]PF6, [Cu(6L)(dmap)2]PF6·2.5 H2O and [Cu(4'L)(dmap)2]PF6·H2O 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 HPO4/2- give O-donor complexes [Cu(6L)(ptp)], [Cu(4'L)(ptp)], [{Cu(6L)}2HPO4]·4H2O, and [{Cu(4'L)}2HPO4]·5H2O which have been characterized by physical and spectroscopic techniques, as have the precursor complexes [Cu(6L)(CH3COO)]·H2O, [Cu(4'L)(CH3COO)], Cu(6HL)(CF3COO)](CF3COO)·0.5H2O, [Cu(4'HL)(CF3COO)](CF3COO), [Cu(2'L)Cl2] and [Cu(2'L)(NO3)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.