Novel nonsymmetrically benzimidazolium salts and their silver(I)-N-heterocyclic carbene complexes: Synthesis, DFT study and Anticancer activities

•Novel Silver-NHC Complexes.•Elemental analysis, LC-MS, FT-IR, 1H NMR, and 13C NMR techniques.•Anticancer activities on hepatocellular carcinoma (HePG2), lung adenocarcinoma (A549) and breast adenocarcinoma (MCF7) and healthy cell line (HF).•Comparison of activity according to the structure of complexes and cell line types. A series of unsymmetrically substituted N-heterocyclic carbene (NHC) precursors were synthesized from the action of 5,6-dimethylbenzimidazole or benzimidazole with various alkyl halides in DMF at 80 °C for 72 h . These compounds were used to synthesize NHC–silver(I) complexes (3) by reacting these NHC precursors with Ag2O in DMC.The prepared compounds were structurally verified by several spectroscopic techniques including 1H NMR, 13C NMR, FT-IR, LC-MS, and C, H, N analysis. The structures of the NHC precursors and their corresponding silver(I) complexes were also investigated theoretically using density functional theory (DFT) at the BLYP/TZ2P level to optimize geometries and assess electronic properties via Voronoi Deformation Density (VDD) charge analysis. Additionally, 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.