Bidentate N,O Chelated Yttrium(III) Complexes: Structural Elucidation, Antifungal Activity, and Cytotoxic Evaluation

In this study, a series of mixed-ligand Yttrium(III) complexes were synthesized using 1-nitroso-2-naphthol as the primary ligand and amino acids L-threonine, L-leucine, and L-serine as secondary bidentate ligands. The resulting compounds were thoroughly characterized using a combination of analytical techniques, including FTIR, UV-Visible spectroscopy, elemental composition, molar conductivity, magnetic susceptibility and thermal analysis. Spectral and analytical results confirmed chelation through electron donating nitrogen and oxygen donor atoms, with thermal analysis indicating ligand bound water molecules. The chelated complexes showed non-electrolytic behavior in DMF. Additionally, magnetic susceptibility data, in conjunction with electronic absorption spectra, confirmed their diamagnetic nature and highlighted transitions characteristic of ligand-to-metal charge transfer phenomena. The antifungal activity of the synthesized chelated complexes was examined using the agar well diffusion method in accordance with the CLSI M07-A11 protocol against Candida albicans. All complexes demonstrated moderate activity, with inhibition zones and MIC values indicating structure-dependent variations, though none outperformed the standard reference drugs. Furthermore, cytotoxicity was assessed using the MTT assay on NIH 3T3 normal Fibroblast cells. The complexes exhibited dose-dependent responses, showing minimal toxicity at lower concentrations, thereby indicating a favorable safety profile.