Synthesis, characterization and evalution of biological activity of some substituted hetrocyclic compounds and their metal(II) complexes

This work describes the preparation of some oxadiazole derivatives using the following steps: The first step involves preparing pyridine anhydride 1, which was treated with carboxylic acid to form compound 2. Ester 3, which was formed in the second step, served as the substrate for the reaction with N2H4.H2O in the third step to give the benzohydrazide 4, which had been reacted with benzaldehyde to obtain Schiff base (5). Furthermore, the acetylmethylation of (5) leads to the formation of 1,3,4-oxadiazole. IR, (1H, 13C) NMR spectroscopic, besides the C.H.N. analysis, gave us strong evidence of the structural clarity of the synthesized molecules (1-6), which were used as ligands in a 2:1 molar ratio with CoCl2.6H2O, NiCl2.6H2O and ZnCl2 to assemble 7-15. Analytical methods, such as melting point, conductance dimensions, C.H.N., metal content, infrared, electronic spectra, nuclear magnetic resonance, magnetic characteristics, and thermal analysis, are associated with the characterization of the prepared complexes. Conductance dimensions suggested the non-conductive nature of all the compounds. Magnetic susceptibility and electronic spectra indicated an octahedral geometry for all complexes. Certain synthesized compounds have also counteracted the growth of four different species of bacteria. Some compounds have stronger antibacterial action than free ligands towards tested microbes. KEY WORDS: Benzohydrazide, Biological activity, Schiff base, Heterocyclic compounds, Oxadiazole Bull. Chem. Soc. Ethiop. 2025, 39(5), 841-857. DOI: https://dx.doi.org/10.4314/bcse.v39i5.4