Monodentate Coordination of N, N′‐Disubstituted Thiocarbamide Ligands: Syntheses, Structural Analyses, In Vitro Cytotoxicity and DNA Damage Studies of Cu(I) Complexes

Structural analysis of three novel substituted thiocarbamide ligands N‐(naphthyl)‐N′‐(isobutoxycarbonyl) thiocarbamide (H 2 L 1 ) , N‐(4‐methoxyphenyl)‐N′‐(isobutoxycarbonyl) thiocarbamide ( H 2 L 2 ) & N‐(2‐methoxy‐4‐nitrophenyl)‐N′‐(isobutoxycarbonyl) thiocarbamide (H 2 L 3 ) and their copper(I) complexes [(H 2 L 1 ) 2 CuCl] (1) , [(H 2 L 2 ) 2 CuCl] (2) and [(H 2 L 3 ) 2 CuCl] (3) was performed using various spectroscopic techniques (FT−IR, 1 H and 13 C NMR, UV‐Visible),TG analysis and single crystal X‐ray studies of (H 2 L 1 ) and [(H 2 L 1 ) 2 CuCl] (1) . The copper(I) complexes possess trigonal planar geometry coordinating through two thione sulfur atoms from two ligand molecules and one chloride ion. Two intramolecular hydrogen bonding interactions present between (−N1H) and carbonyl oxygen (−N2H) and coordinated chlorine stabilize the trigonal planar structure of the complexes. Cyclic voltammogram of complexes 1–3 displayed quasireversible redox behaviour corresponding to Cu I /Cu II couple. Determination of in vitro cytotoxicity of ligands and their complexes using five human carcinoma cell lines 2008, C13* (cervical carcinoma), A2780, A2780/CP and IGROV‐1 (ovarian carcinoma) revealed that copper(I) complexes were more potent inhibitors than the ligands against all the cell lines. The most effective were complexes 2 and 3 . The comet assay test of complexes 2 and 3 against 2008, C13* and IGROV‐1 cell lines indicated significant damage to the DNA structure.