Abstract
Reactions of 2-(1-hydrazonoethyl)pyridine with silver salts AgX (X = NO3 over bar or ClO4 over bar ) proceeded via the hydrolysis of the pyridine ligand and the formation of the dinuclear [AgL1](2)(ClO4)(2) (1) and [AgL1(NO3)](2) (2) complexes of the azine ligand, 1,2-bis(1-(pyridin-2-yl)ethylidene)hydrazine (L-1). The structures of the obtained complexes were determined by single crystal X-ray diffraction. The azine ligand (L-1) is acting as a bidentate ligand and connects the two Ag-sites via the pyridine and the azine nitrogen atoms. In complex 1, the Ag(I) ion is tetra-coordinated, while in complex 2 the Ag(I) ion is penta-coordinated due to the presence of additional interaction with one of the oxygen atoms of the nitrate ion. As a result, the azine ligand is significantly twisted in complex 2 compared to complex 1. The optimized geometries of three conformers of L-1 were calculated using DFT calculations, and their kinetic and thermodynamic stability were analyzed. It was found that a free rotation of L-1 is required prior to the chelation of the Ag(I) ion. The packing in complex 1 is controlled by H horizontal ellipsis H, O horizontal ellipsis H, and Ag horizontal ellipsis O interactions, but in complex 2, the O horizontal ellipsis H and N horizontal ellipsis H interactions are the most significant. Complex 2 has better antifungal activity against Aspergillus fumigatus and Candida albicans than the antifungal drug Ketoconazole. Also, the nitrato complex 2 has a promising antioxidant activity compared to the perchlorate complex 1. The cytotoxicity against colon carcinoma HCT-116 cell line is higher for complex 1 (IC50 = 19.72 +/- 0.94 mu g/ml) than complex 2 (IC50 = 68.31 +/- 2.97 mu g/ml).