Synthesis, structural characterization, and evaluation of biological activity of organotin(IV) complexes with 2-hydroxy-5-methoxybenzaldehyde-N(4)-methylthiosemicarbazone

• Organotin(IV) complexes of 2-hydroxy-5-methoxybenzaldehyde-N(4)-methylthiosemicarbazone are synthesized.
• Newly synthesized compounds are characterized by various spectroscopic methods.
• We report the molecular structures of the ligand and its diphenyltin(IV) complex.
• X-ray crystal studies indicated tin(IV) atom is five-coordinated and adopts a distorted trigonal bipyramidal geometry.
• Organotin(IV) complexes can be considered as a potential anticancer agents.

The reaction of organotin(IV) chloride(s) with 2-hydroxy-5-methoxybenzaldehyde-N(4)-methylthiosemicarbazone [H2dmmt, (1)] in the presence of potassium hydroxide yielded four new stable complexes, namely, [MeSnCl(dmmt)] (2), [BuSnCl(dmmt)] (3), [PhSnCl(dmmt)] (4), and [Ph2Sn(dmmt)] (5). The new compounds were characterized using CHN analyses, molar conductivity, UV–Vis, FT–IR, and 1H, 13C, and 119Sn NMR spectral studies. The molecular structures of H2dmmt (1) and its complex 5 were determined using X-ray crystallography. The X-ray crystal studies of complex 5 showed the trigonal bipyramidal geometry around the tin(IV) atom. The solid-state structure of complex 5 revealed that the dinegative tridentate ligand (1) is coordinated with the tin(IV) moiety via phenolic-O, azomethine-N, and thiolate-S atoms. The biological activities of the organotin(IV) complexes were investigated against a human colorectal (HCT 116) cell line and exhibited strong cytotoxic activities in the following order: 5 > 4 > 2 > 3 > H2dmmt. The organotin(IV) complexes (2–5) showed significant activity when compared with the standard drug, 5-fluorouracil (IC50 = 7.58 μM), and the parent ligand (IC50 = 7.19 μM). These results show that organotin(IV) complexes may be designed as new metal-based drugs in the future.

The synthesis, characterization and cytotoxic activity of organotin(IV) complexes with 2-hydroxy-5-methoxybenzaldehyde-N(4)-methylthiosemicarbazone are reported. X-ray study revealed that the dinegative tridentate ligand (1) is coordinated to Sn(IV) centre via phenolic-O, azomethine-N and thiolate-S atoms. The Sn(IV) atom is penta-coordinated in solution for all organotin(IV) complexes. The biological activities of the organotin(IV) complexes were investigated against human colorectal (HCT 116) cell line and exhibited strong cytotoxic activities.Figure optionsDownload as PowerPoint slide