Arylation of heterocyclic compounds by benzimidazole-based N-heterocyclic carbene-palladium(II) complexes

Novel Ag(I)-NHC complex: synthesis, in vitro cytotoxic activity, molecular docking, and quantum chemical studies

The importance of organometallic complexes in cancer biology has attracted attention in recent years. In this paper, we look for the in vitro cytotoxic capability of novel benzimidazole-based N-heterocyclic carbene (NHC) precursor (1) and its Ag(I)-NHC complex (2). For this purpose, these novel Ag(I)-NHC complex (2) was characterized by spectroscopic techniques (¹H, ¹³C{¹H} nuclear magnetic resonance (NMR), and Fourier-transform infrared spectroscopy (FT-IR)). Then, in vitro cytotoxic activities of NHC precursor (1) and Ag(I)-NHC complex (2) were investigated against MCF-7, MDA-MB-231 human breast, DU-145 prostate cancer cells, and L-929 healthy cells using MTT assay for 24, 48, and 72 h incubation times. Ag(I)-NHC complex (2) showed promising in vitro cytotoxic activity against all cell lines for three incubation times, with IC₅₀ values lower than 5 µM. It was also determined that (NHC) precursor (1) were lower in vitro cytotoxic activity than Ag(I)-NHC complex (2) against all cell lines. Selectivity indexes (SI_s) of Ag(I)-NHC complex (2) against cancer cells were found higher than 2 for 24 and 48 h incubation time. Besides, the electronic structure and spectroscopic data of the newly synthesized precursor and its Ag-complex have been supported by density functional theory (DFT) calculations and molecular docking analysis. After, the anticancer activity of these compounds has been discussed considering the results of the frontier molecular orbital analysis. We hope that the obtained results from the experiments and computational tools will bring a new perspective to cancer research in terms of supported by quantum chemical calculations.

Synthesis, in vitro anticancer activities, and quantum chemical investigations on 1,3-bis-(2-methyl-2-propenyl)benzimidazolium chloride and its Ag(I) complex

1,3- Bis-(2-methyl-2-propenyl)benzimidazolium chloride and its Ag(I) complex are synthesized and the structures are elucidated using spectroscopies techniques. The molecular and crystal structures of the benzimidazolium salt are confirmed by X-ray crystallography. The molecular geometries of the benzimidazolium and its Ag(I) salt are analyzed using the B3LYP functional with the 6–311+G(d,p)/LANL2DZ basis set. The observed Fourier transform infrared and nuclear magnetic resonance isotropic shifts are compared with the calculated values. Besides, the quantum chemical identifiers, significant intramolecular interactions, and molecular electrostatic potential plots are used to show the tendency/site of the chemical reactivity behavior. The three-dimensional Hirshfeld surfaces and the associated two-dimensional fingerprint plots are applied to obtain an insight into the behavior of the interactions in the crystal. Both compounds are tested for their in vitro anticancer activities against DU-145 and MCF-7 cancer cells and L-929 non-cancer cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.