Synthesis and characterization of cationic monoazo dyes incorporating quaternary ammonium salts

摘要

Nine(three series)antimicrobial cationic monoazo dyes were prepared by a diazotization-coupling reaction involving two aromatic amino compounds(featuring different chain length alkyl quaternary ammonium salts)as diazo components,and N,N-dimethyl-benzeneamine and 1-phenyl-3-methyl-5-pyrazolone as coupling components.Structures of the nine dyes were determined by FTIR,~1H NMR,~(13)C NMR,and ESI-MS analysis,and have not been previously published.Wavelengths of maximum absorption(lambda_(max))and absorbance of three series dyes were tested by UV/vis spectrometer.It was found that alkyl chain length did not significantly affect lambda_(max),but did affect absorbance.Minimum inhibitory concentration(MIC)data showed the efficacy of these dyes against both Staphylococcus aureus and Escherichia coli.Nine dyes were especially sensitive to S.aureus.The aqueous solution of dye series 1 with N,N-dimethyl-benzeneamine as the coupling component had better antimicrobial efficacy than did the aqueous solution of dye series 2 and 3 with l-phenyl-3-methyl-5-pyrazolone as coupling component.Antimicrobial effect increased as hydrocarbon chain length increased,with other factors held constant.