Synthesis and Spectral Studies of Acetophenone Schiff Bases and Evaluation of their Antimicrobial Activities

Seven acetophenone derived Schiff bases with different amines were synthesized including, (Z)-2-[(1-phenylethylidene)amino] benzoic acid (HL1), (Z)-4-[(1-phenylethylidene) amino] benzoic acid (HL2), (E)-N-(1-phenylethylidene) naphthalen-2-amine (HL3), (E)-1-phenyl-2-(1-phenylethylidene) hydrazine (HL4), N-1, N-2-bis(1-phenylethylidene)ethane-1,2-diamine (HL5), N-1 (Z), N-2 (Z)-N-1, N-2-bis(1-phenylethylidene) benzene-1,2-diamine (HL6) and N-1, N-4-bis(1-phenylethylidene) benzene-1,4-diamine (HL7) and characterized by spectral studies (IR, MS and NMR) and elemental analysis. Their antimicrobial activity was extensively investigated against 20 Gram-negative and 10 Gram-positive bacterial strains. Schiff bases HL1-5 showed good antibacterial activity against almost all bacterial strains. HL3 showed remarkable activity against Enterococcus sp., Citrobacter freundii, Salmonella typhi and Pseudomonas aurantiaca. HL4 gave incredible inhibition against Enterobacter aerogenes. HL7 demonstrated notable activity against Staphylococcus aureus. (E)-N-(1-phenylethylidene) naphthalen-2-amine (HL3) is reported for the first time.