Synthesis, structure and antibacterial, antifungal activities of some hydrazones synthesized from 4-hydroxy-3-nitrobenzaldehyde

Eight hydrazones 7a-h containing benzo[d]thiazole were synthesized in high yield by the condensation reaction of N-(5-(benzo[d]thiazol-2-yl)-2-(2-hydrazinyl-2-oxoethoxy)phenyl)acetamide (6) derived from 4-hydroxy-3-nitrobenzaldehyde with aromatic aldehydes under microwave irradiation. Structures of these derivatives 7a-h were elucidated by IR, NMR, and MS analysis. NMR spectra showed that in solution, hydrazones may exist in two conformations EN-C(O)ZN-C(O)EC=N and ZN-C(O)ZN-C(O)EC=N, the relative ratio of these two conformations is about 3:2. Four compounds 7a, 7c, 7e, 7g were screened for antimicrobial activities. Compounds 7c, 7e, and 7g exhibited weak antibacterial and antifungal activity against B. subtillis and S. cerevisiae, E. coli, or P. aeruginosa at 200 µg/L.