Synthesis, characterization, and antimicrobial evaluation of new Schiff bases derived from vanillic acid conjugated to heterocyclic 4H-1,2,4-triazole-3-thiol

Abstract

A multistep synthesis was established for the preparation of a new vanillic acid-1, 2, 4-triazole-3-thiol conjugate (4). Finally, several aromatized aldehydes reacted with compound (4) to produce Schiff bases derivatives (5–11). The purpose of this research is to prepare new vanillic acid derivatives with 1, 2, 4-triazole-3-thiol heterocyclic ring structures and to evaluate their antimicrobial activity in a preliminary assessment. Fourier-transform infrared (FT-IR) and proton nuclear magnetic resonance spectroscopy (1H-NMR) were used to verify the structures of the newly synthesized compounds. all the final synthesized compounds (5–11) were tested for antimicrobial activity. The findings of this study demonstrate the viability of synthesizing vanillic acid combined with a 1, 2, 4-triazole-3-thiol ring derivative, which then reacted with various aldehydes to yield several new Schiff bases derivatives. Finally, the presence of an electron-withdrawing group at the fourth position (p-chloro group) of the aromatic ring improves the antibacterial activity of the derivative of the vanillic acid-triazole conjugate. Compound 8 with para chloro substituted Schiff base derivative showed potent activity when compared to other final derivatives but of no activity toward K. pneumonia.