Synthesis and characterization of antimicrobial cationic surfactants: Aminopyridinium salts

Three antimicrobial 4-aminopyridinium salts were synthesized using two different processes in an effort to develop antimicrobial surface treatment agents for wool fibers. The structures of the salts were fully characterized using Fourier transform infrared, 1H nuclear magnetic resonance (NMR), and 13C NMR analysis. In addition, their thermal stability was determined using differential scanning calorimetry and thermogravimetric analysis. The antimicrobial efficacy of these compounds was evaluated using minimum inhibitory concentration as an indicator. All of the synthesized aminopyridinium salts showed antimicrobial activity against gram-negative bacteria, but in different levels depending on their structures. The salts possessing longer alkyl chains demonstrated better antimicrobial function. The melting points of the salts decreases as the alkyl chain length increases.