Half-sandwich triazolato Rh(III) compound of pyridylbenzimidazole ligand with cell selective toxicity towards Cryptococcus neoformans

Reactivity of azido terpyridine Pd(ii) and Pt(ii) complexes towards 4,4,4-trifluoro-2-butynoic acid: structural insight into the triazolato coordination mode

The mono- and binuclear azido terpyridine square-planar complexes of ionic formulas, [Pd2(N3)2L]2+ and [Pt(N3)L]+ (L = 1,4-bis(2,2':6',2''-terpyridin-4'yl)benzene), underwent the catalyst-free [3 + 2] cycloaddition coupling with 4,4,4-trifluoro-2-butynoic acid at ambient temperature affording the corresponding triazolate complexes. A mixture of triazolate isomers was generated by these inorganic click reactions. An increase in the solubility of the compounds was achieved by replacing the azido ligand with a triazolato ligand. By calculating the vibrational modes and comparing the total electronic and zero-point energy values, the local minimum structures of the complexes and the nature of the predominant triazolate isomer were verified. The theoretical work was complemented with natural bond analysis to get an insight into the natural charge and electronic arrangement of the metal ion, the hybridization of M-L bonds and strength of M-N bonds.

Pd(ii) and Pt(ii) complexes of tridentate ligands with selective toxicity against Cryptococcus neoformans and Candida albicans

Novel Pd(ii) and Pt(ii) complexes of the tridentate 2,6-bis(1-ethyl-benzimidazol-2'-yl)pyridine (L^BZ), and 4'-(2-pyridyl)-2,2':6',2''-terpyridine (L^PY) ligands were synthesized, characterized using a variety of analytical and spectroscopic tools, and screened for their potential antimicrobial properties against some bacterial and fungal strains as well as cytotoxicity against healthy human embryonic kidney (HEK293) cells. The electronic structures of the complexes were investigated by time-dependent density functional theory calculations. The free ligand L^PY and benzimidazole complexes exhibited selective toxicity against Cryptococcus neoformans and Candida albicans, while displaying no cytotoxicity against HEK293. In the case of Cryptococcus neoformans, the antifungal activities of the benzimidazole-based complexes (MIC = 1.58-2.62 μM) are higher than those of the reference drug fluconazole (26.1 μM).