QSAR studies on antimony(III) halide complexes with N-substituted thiourea derivatives

Abstract

The synthesis, characterization and biological studies of three novel antimony(III) complexes (SbX3, X=Cl and Br) with N-substituted thioureas; N,N-dimethylthiourea (DMTU) and N,N-diethylthiourea (DETU) of formulae [fac-SbCl3(DMTU)3] (1), [mer-SbBr3(DMTU)3] (2) and b,c,d-Cl-[SbCl3(DETU)2] (3) are reported. The compounds were characterized by melting point (m.p.), elemental analysis (e.a.), molar conductivity, FT-IR, FT-Raman, 1H, 13C NMR, UV–Vis spectroscopic techniques and Thermogravimetric–Differential Thermal Analysis (TG–DTA). The crystal structures of complexes were also determined by X-ray diffraction. Complexes 1 and 2 are monomers with octahedral (Oh) geometry around the metal ion, which is formed by three sulfur and three halide atoms. However the coordination mode of the ligands varied around the metal centers. Thus, 1 possesses the facial isomeric form, while 2 the meridional form. In case of 3 two sulfur atoms from thiourea ligands and three chlorides form a trigonal pyramidal geometry b,c,d-Cl-[SbCl3(DETU)2] which finally turns to be a polymeric one through μ–Cl bonds and Oh geometry around each Sb ion. A chloride counter anion neutralizes the whole complex. Complexes 1–3 were evaluated for their in vitro cytotoxic activity against human breast (MCF-7) and cervix (HeLa) adenocarcinoma cells. The toxicity of the complexes was studied against human fetal lung fibroblast cells (MRC-5). The apoptotic type of the cells death was confirmed by cell cycle arrest. The influence of 1–3 upon the catalytic peroxidation of linoleic acid to hyperoxolinoleic acid by the enzyme lipoxygenase (LOX) was kinetically studied. QSAR study reveals a linear correlation between experimental and calculated IC50 values. The model predict the activity of Sb complexes successfully, if log(IC50)>0.