Synthesis and evaluation of antimicrobial activity of two Schiff bases derived from cyclohexylamine

Abstract

Design and development of novel materials with outstanding antimicrobial properties has transpired to hinder and regulate the growth of microorganisms. Indubitably, Schiff bases are the magic bullet that have efficient antimicrobial properties against various pathogenic strains. The Schiff bases, L1 and L2 reported herein were respectively synthesized by equimolar condensation of benzophenone with cyclohexylamine and 2,4-dihydroxybenzophenone with cyclohexylamine. The products were obtained in excellent yield of 66 and 75 %. The Schiff bases were subjected to solubility test, melting point determination and FT-IR spectroscopic analysis. They were found to show relative thermal stability with melting points of 220 and 195 oC and solubility in methanol, acetone and dimethylformamide of the solvents used. The FT-IR confirmed the formation of the Schiff bases with appearance of azomethine (C=N) peak at 1652 and 1592 cm-1. The in vitro antimicrobial activity of the Schiff bases was tested against two gram positive bacteria (Staphylococcus aureus and Streptococcus pyogens) and two gram negative (Pseudomonas aureginosa and Escherichia coli) as well as two fungi strains (Aspergillus niger and Candida albicans). The results reveal that the Schiff base L2 shows promising activity against all the pathogen under investigation. However, no activity was observed for L1 against the microbes except Streptococcus pyogens