A new Ag(I) complex based on asymmetric azine-type ligand as a promising anticancer agent: Synthesis, X-ray structure, and DFT calculations

A newly synthesized Ag(I) complex based on thiazole-azine ligand (THP) is reported. Its structure is confirmed using different spectral tools to be [Ag(THP)(H2O)]BF4, in which the Ag(I) is coordinated with one bidentate NN-chelate (THP) and one water molecule. Hence, the coordination geometry is identified as distorted trigonal planar. The complex crystallized in monoclinic crystal system and P2(1) space group. In addition, theoretical calculations including Hirshfeld surface, natural bond orbital (NBO), and atoms in molecules (AIM) analyses, were performed. Hirshfeld surface analysis revealed H<middle dot><middle dot><middle dot>H (26.7%) and H<middle dot><middle dot><middle dot>F (22.3%) interactions are being the most prominent. Additionally, the calculated natural charge of Ag(I) was found to be 0.702 e, resulting from its coordination with the surrounding ligands. The estimated NBO energies (E-(2)) for the bonds between Ag(I) and donor atoms range from 24.99 to 30.72 kcal/mol. The AIM study indicated that the bonds around Ag(I) possess some covalent character. The Ag(I) complex exhibited higher activity against all tested cancer cells and microbes (except A. fumigatus) compared to its free ligand. Notably, the cytotoxicity of the new complex against HCT-116 cell line (7.23 +/- 0.59 mu M) was found superior to that for cisplatin (17.77 +/- 1.63 mu M). The selectivity index (SI) values are 16.70, 0.26, and 6.13 for [Ag(THP)(H2O)]BF4, THP, and AgBF4, respectively. Hence, the Ag(I) complex is the best candidate as safe anticancer agent. In addition, the new complex (DIZ = 12-19 mm) has enhanced antimicrobial effects relative to the free THP.