Effect of fluorination on the cytotoxic potentials of benzimidazolium-based N-heterocyclic carbene ligands and their silver(I) complexes

[Display omitted] •A new series of fluorinated benzimidazolium-based N-heterocyclic silver(I) complexes was synthesised.•All complexes exhibited remarkable growth inhibition against HeLa, MCF-7 and MDA-MB-231 cells.•The position and number of fluorine atoms modulated cytotoxic potentials of the benzimidazolium salts and complexes.•The use of fluorinated metal complexes in the potential production of anticancer metallodrugs. The current study reports a new series of fluorinated benzimidazolium salts and their silver(I) complexes. The ligands were prepared via N-alkylation of 1-decylbenzimidazole with benzyl/fluorinated benzyl bromides. In situ deprotonation of the salts with silver oxide and metathesis reaction with potassium hexafluorophosphate yielded the mononuclear silver(I)–NHC complexes. All compounds were characterized using FTIR and NMR spectroscopies, CHN elemental analysis and liquid chromatography-time-of-flight mass spectrometry (LCMS-TOF). The in vitro cytotoxic activities of the ligands and complexes against human cervical cancer (HeLa), estrogen-positive human breast cancer (MCF-7) and triple-negative human breast cancer (MDA-MB-231) cells were evaluated using the MTT assay. All compounds exhibited remarkable growth inhibition against these cells, superior to etoposide, a clinical anticancer drug. Fluorination exerted different growth inhibition effects against HeLa, MDA-MB-231 and MCF-7 cells. Fluorination modulated the growth inhibition potencies of the salts and complexes against HeLa but had no enhancement effect against MCF-7 and MDA-MB-231. Incorporating silver(I) ions enhanced the cytotoxicity of the complexes against all tested cell lines (IC50: 0.46–1.36 µM).