Synthesis, characterization and biological evaluation of novel antimony(III) iodide complexes with tetramethylthiourea and N-ethylthiourea

Abstract

Novel trivalent antimony(III) complexes with tetramethylthiourea (TMTU) and N-ethylthiourea (NETU) were synthesized by the reaction of antimony(III) iodide (SbI3). Antimony(III) iodide complexes of formulae {[SbI2(µ2-I)(TMTU)2]2} (1) and {[(NETU)SbI2(µ2-I)2(µ2-S-NETU)SbI2(NETU)]} (2) were characterized by spectroscopic techniques (FT-IR, FT-Raman, 1H and 13C NMR), TG-DTA analysis and X-ray diffraction (XRD) analysis. Single-crystal X-ray diffraction studies showed that the complexes existed as doubly bridged (1) and triply bridged (2) dimers. Crystal structure of the ligand N-ethylthiourea was also determined with single crystal X-ray diffraction analysis.Complexes 1 and 2 were evaluated for their in vitro cytotoxic activity against human adenocarcinoma cells HeLa (cervix). The toxicity of 1 and 2 was evaluated on normal human fetal lung fibroblast cells (MRC-5). Both complexes showed selectivity against the cancerous, than normal cells. The influence of 1 and 2, on the catalytic peroxidation of the linoleic acid by the enzyme lipoxygenase (LOX) was determined experimentally and theoretically. The complexes 1 and 2 exhibited higher activity than free ligands against LOX. The in vitro antibacterial activities of free ligands and their antimony(III) iodide complexes 1 and 2 were tested against two Gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853) and two Gram-positive (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212) bacteria. The complexes 1 and 2 were much more effective in terms of antimicrobial activity compared to the free ligands.