DESIGN AND STRUCTURAL CHARACTERIZATION OF KYNURENIC ACID-BASED ERBIUM(III) COMPLEXES: CORRELATING COORDINATION FEATURES WITH ANTIMICROBIAL EFFICACY

A series of rare-earth metal complexes incorporating a Kynurenic acid ligand were successfully synthesized and characterized using elemental analysis, molar conductance measurements, and spectroscopic techniques, including FT-IR, UV–Visible, and Mass spectroscopy. The analytical and spectral data confirmed the coordination of the ligand to the metal ions through the donor atoms, leading to the formation of stable coordination compounds. The antimicrobial activity of the synthesized complexes was evaluated against selected Gram-positive and Gram-negative bacterial strains as well as representative fungal pathogens using standard in-vitro assays. Comparative studies revealed that the metal complexes exhibited significantly enhanced antimicrobial activity relative to the free ligand. The observed improvement in biological efficacy may be attributed to increased lipophilicity and facilitated penetration of the complexes through microbial cell membranes upon chelation. Furthermore, variations in antimicrobial performance among the complexes indicate that the nature of the rare-earth ion and the coordination environment play important roles in determining biological activity. The findings demonstrate that quinoline-based rare-earth metal complexes represent a promising class of bioactive compounds with potential applications as antimicrobial agents.