Synthesis and Antimicrobial Screening of Metal-ligand Complexes Derivative from (2-chloroquinolin-3-yl)methylene)hydrazine) and their Biological Studies

This study presents the synthesis of a Schiff base ligand, 1,2-bis((2-chloroquinolin-3-yl)methylene)hydrazine, via a condensation reaction between an amine and a carbonyl compound. The resulting ligand was subsequently utilized to synthesize Cu(II), Co(II), and Ni(II) complexes. Characterization of the ligand was performed using analytical techniques such as ¹H NMR, FTIR, and mass spectrometry. Further structural analysis of the metal complexes was conducted through spectroscopic methods, including FTIR and UV. Their antifungal activity was assessed in vitro, revealing that the Ni(II) complex exhibited the highest efficacy against the tested fungal strains. Additionally, the Zn(II) complex demonstrated notable antifungal properties, with activity ranging from 14–35 µg/mL against Candida albicans, Candida glabrata, Aspergillus flavus, and Cryptococcus neoformans. The antibacterial potential of the complexes was also evaluated in vitro against three distinct bacterial strains. Compounds 6b and 6h displayed comparable potency to the reference drug Ampicillin against Escherichia coli, with IC50 values of 46 µg/mL. Furthermore, compound 6h exhibited similar activity to Ampicillin against Bacillus subtilis, with an IC50 value of 50 µg/mL.