Synthesis and Antimicrobial Activity of Quaternary Ammonium Silane Coupling Agents

Fourteen novel silane coupling agents with a quaternary ammonium group introduced into the molecule, [CH2=CHCH2N+(CH3)(CnH2n+1)(CH2)3Si(OCH3)3]X- (n-X, n=10–18, X=Cl, Br, or I), were synthesized with the aim of using these agents to make material surfaces antimicrobial for a long period of time. Measurements of the minimum inhibitory concentrations (MIC) against 12 kinds of fungi and bacteria revealed that the coupling agent with a C10 alkyl chain and Cl- or Br- counter-ion (10-Cl or 10-Br) has the highest antimicrobial activity among the n-X agents synthesized, but 14-Cl and 14-Br showed the highest activity on a modified porcelain plate.