Novel Nonsymmetrically benzimidazolium salts and their silver(I)-N-heterocyclic carbene complexes: Synthesis, crystal structure, DFTstudies and anticancer activities

Abstract

Due to the success of Ag-NHCs in biological applications, interest in the synthesis and applications of such compounds is increasing rapidly. Therefore, in this study, preparation and structural definition of silver(I)–NHC complexes were accomplished. These complexes were synthesized by combining a metal source, Ag₂O, with imidazolium salts in dichloromethane. A comprehensive characterization process was carried out for both the ligands and their resulting complexes. This involved utilizing various analytical techniques, such as elemental analysis, LC-MS, FTIR and NMR spectroscopy. Further, structure of the 3 h complex was determined by X-ray crystallography. A single-crystal of 3 h shows that coordination geometry is a slightly distorted linear coordination geometry around the silver(I) center. Furthermore, our combined experimental and theoretical approach provided insights into the crystal structure, coordination geometry, and intermolecular interactions stabilizing the complex’s lattice. Density functional theory (DFT) optimization revealed its geometry, while time-dependent DFT (TD-DFT) calculations shed light on its optical properties. Furthemore the newly synthesized ligands and silver(I) complexes were evaluated for their in vitro anticancer activity against three human cancer cell lines including hepatocellular carcinoma (HePG2), lung adenocarcinoma (A549) and breast adenocarcinoma (MCF7). Most of the newly synthesized silver(I) complexes exhibited better activity than the ligands, and the results have been compared with Cisplatin as a reference drug.