A structural and biological study on the new 3,5-diacetyl-1,2,4-triazol bis(p-chlorophenylthiosemicarbazone) ligand and its bimetallic complexes

Abstract

Preparation and characterization of the new ligand 3,5-diacetyl-1,2,4-triazol bis(⁴N-p-chlorophenylthiosemicarbazone), H₅L¹, and its bimetallic complexes [Pd(μ-H₃L¹)]₂ and [Pt(μ-H₃L¹)]₂, are described. The molecular structure of the complexes, determined by single crystal X-ray crystallography, reveals that each ligand coordinates, in an asymmetric dideprotonated form, to the metal ions in a square planar geometry. The new compounds synthesized have been evaluated for antiproliferative activity in vitro against NCI-H460, T-47D, A2780 and A2780cisR human cancer cell lines. The cytotoxicity data suggest that these compounds may be endowed with important antitumor properties, especially H₅L¹, since they exhibit excellent antiproliferative activity surpassing the activity of cisplatin against three of the four tumor cell lines studied. The DNA binding ability of H₅L¹ and [Pt(μ-H₃L¹)]₂ with calf thymus DNA in Tris-HCl buffer solution (pH = 7.2) was explored by UV-Vis absorption spectroscopy and viscosity measurements. These data indicated that both compounds bind to DNA by a groove binding mode.