Synthesis, Crystal Structure, and Antibacterial Activity of Four Novel Oxazolyl Acylhydrazones

Four novel oxazole acylhydrazones, namely 2,4-dihydroxybenzaldehyde-4-oxazole acylhydrazone (I), 2-hydroxy-3-methoxy-4-oxazole acylhydrazone (II), p-dimethylaminobenzaldehyde-4-oxazole acylhydrazone (III), and 2-acetylpyridine-4-oxazole acylhydrazone (IV) were synthesized and characterized by melting point tests, elemental analysis, IR, H-1 NMR and X-ray single crystal diffraction. The IR results illustrated that the four compounds had absorption peaks of acylhydrazone structure and existed as ketone structure. The 1H NMR spectra presented four compounds were expected to be the target compounds. The X-ray single crystal diffraction results showed that the crystals of I, II, and III belonged to monoclinic systems, P2(1)/c space group, whereas IV belonged to triclinic system, P(1) space group. Measurement of antibacterial activities for I, II, III, and IV against S. aureus, P. aeruginosa, B. subtilis and E. coli showed that I, II, and IV were more sensitive to S. aureus, and III had the strongest inhibition activity against B. subtilis.