Design, Spectroscopic Characterization, and Cytotoxic Assessment of Schiff Base Metal Complexes Originating from Benzimidazole Derivative

Abstract

A benzimidazole-based Schiff base ligand, (E)-2-(1H-benzo[d]imidazol-2-yl)-N-((pyridin-2-yl)methylene)benzenamine (L), was prepared through the condensation of 2-(o-aminophenyl)benzimidazole with pyridine-2-carboxaldehyde. This ligand was subsequently complexed with Co(II), Ni(II), Cu(II), Zn(II), Ru(II), and Pd(II) ions to produce a series of coordination compounds represented in Fig:1. The resulting complexes were isolated in good yields and showed stability under ambient conditions. Each compound underwent comprehensive characterization, including elemental analysis, FT-IR, UV–Vis, ¹H and ¹³C NMR, EPR, ESI–MS, magnetic susceptibility, and thermogravimetric analysis. The collected data suggested octahedral coordination geometries for the Co(II) and Ru(II) derivatives, tetrahedral structures for the Ni(II) and Zn(II) complexes, and square-planar arrangements for the Cu(II) and Pd(II) species. Cytotoxic properties were evaluated against the MCF-7 human breast cancer cell line using the MTT assay. Metal coordination enhanced the biological activity of the ligand, with Zn(II), Pd(II), and Cu(II) complexes showing the greatest potency. Notably, the Zn(II) complex displayed the lowest IC₅₀ value, making it a promising candidate for further study. These results indicate that Schiff base metal complexes incorporating benzimidazole may offer valuable leads in the development of new anticancer agents.