Copper, nickel and zinc complexes of a new water-soluble thiosemicarbazone ligand: Synthesis, characterization, stability and biological evaluation

Abstract

New water soluble Schiff base thiosemicarbazone ligand, namely (sodium 4-hydroxy-3-{[(methylaminocarbonothioyl)hydrazono]methyl}-benzene sulfonate) (NaH2L) was obtained by the reaction of methylthiosemicarbazide with sulfonate salicylaldehyde and characterized by elemental analysis, spectroscopic methods (UV–Vis, FTIR, 1HNMR, and 13CNMR) and electrospray ionization mass spectrometry. The X-ray structure of NaH2L (NaH2L·CH3OH·0.5H2O) shows that sodium atoms are interconnected through sulfonate groups of the ligands into one-dimensional coordination polymer network. Reaction of the ligand with metal acetates produced following complexes: [Cu(HL)]2, NiHL and ZnHL. All complexes were characterized by means of elemental analysIs, IR spectroscopy, and ESI-Mass measurements. The dinuclear structure of the copper complex was determined by single-crystal X-ray crystallography and showed the square pyramidal geometry for each metal center. NaH2L, [Cu(HL)]2, and NiHL showed high solubility in water (50, 25 and 25g/L, respectively, at 25°C), while solubility of ZnHL was very low. NiHL was stable at all pH ranges for 4days while stability of NaH2L and [Cu(HL)]2 was decreasing at acidic and basic pHs. Among all this compounds, only NiHL showed some low antimicrobial activity. Antioxidant activity of the compounds for scavenging activity of DPPH• and ferric reducing antioxidant power (FRAP) was evaluated and the ligand indicated the strongest radical scavenging relative to the complexes and l-ascorbic acid as standard. The anti-proliferative effect of the ligand and their corresponding complexes was evaluated on the human leukemia cell lines, KG1-aand K562·The KG1-a cells underwent apoptosis upon a single dose (at IC50 value) of the NiHL as most active complex.