Fluorobenzylidene-1,2,4-triazol-3-one Derivatives: Synthesis, Characterization, Antimicrobial Activity, and Molecular Docking Study

Abstract

A series of three fluorobenzylidene-1,2,4-triazol-3-one derivatives & horbar;(E)-4-[(2-fluorobenzylidene)amino]- (1), (E)-4-[(3-fluorobenzylidene)amino]- (2), and (E)-4-[(4-fluorobenzylidene)amino]-5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one (3)& horbar;were synthesized and characterized by FTIR and 1H and 13C NMR spectroscopy. Of the three synthesized isomeric (E)-4-(fluorobenzylideneamino)-5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one derivatives, isomers 1 and 2 are novel compounds, and compound 3 is previously known. A theoretical study was performed using the DFT/B3LYP/6-311++G(d,p) method. The molecular structures of compounds 1-3 were optimized, and their structural parameters were determined. Experimental FT-IR and NMR data were compared with calculated values, which confirmed the molecular structures and supported the experimental findings. The antibacterial and leishmaniacidal activities of compounds 1-3 were evaluated by the microdilution assay. Streptococcus pneumoniae was the most susceptible bacterium, while compound 2 was less effective against the tested bacteria than the other derivatives. Molecular docking analysis identified key molecular interactions responsible for the antileishmanial activity of compound 1, demonstrating a high binding affinity for Trypanothione reductase (TRe).