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

Abstract

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), N¹,N²-bis(1-phenylethylidene)ethane-1,2-diamine (HL⁵), N¹(Z),N²(Z)-N¹,N²-bis(1-phenylethylidene)benzene-1,2-diamine (HL⁶) and N¹,N⁴-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 HL^1-5 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.