New palladium (II) complexes of thiosemicarbazones: Synthesis, DNA and HSA binding and cytotoxicity activity studies

Four palladium(II) complexes (I-IV) were synthesized by the reaction of 5-substitute salicylidene (-OCH3, -Br, - Cl, -NO2)-N-isopropyl-S-propyl thiosemicarbazones (LI-IV) with Li2[PdCl4] in ethanol. When 5-OCH3-N-isopropyl-S-propyl thiosemicarbazone (LI) was used as ligand, a [Pd(L)Cl2] complex (complex I) was obtained. In this complex, thiosemicarbazone behaved as bidentate ligand and coordinated to the palladium center with N and S atoms. When other ligands, (-Br, -Cl and -NO2 substituent; respectively LII, LIII and LIV) were used, complexes with the general formula [Pd(L)Cl] and in which thiosemicarbazones behaved tridentate (with O, N and S atoms) were obtained. The ligands and complexes were characterized by using analytical and spectroscopic methods. The molecular structure of complex I was also identified by single crystal X-ray diffraction method which revealed that the Pd(II) central atom was coordinated by thiosemicarbazone ligand through N and S donor atoms and two additional chlorido ligands. All ligands and complexes were subjected to DNA and albumin binding studies, and their antioxidant properties have been evaluated. Complex I and the corresponding ligand LI as the most promising candidates have been selected for the cytotoxicity against the endometrial cancer cell line AN3CA.