Preparation of a Novel Class of Cationic Gemini Imidazolium Surfactants Containing Amide Groups as the Spacer: Their Surface Properties and Antimicrobial Activity

A class of novel cationic Gemini imidazolium surfactants containing amide groups as the spacer were synthesized from ethylenediamine and 1-bromoalkane(C 8 , C 10 , C 12 , C 14 , C 16 ) by N -alkylation to get N , N ′-dialkyl ethylenediamine ( 1a–e ), 1a–e was further reacted with chloroacetyl chloride by N -acylation to get N , N ′-(ethane-1,2-diyl)bis(2-chloro- N -alkylacetamide) ( 2a–e ), which was further reacted respectively with 1-methyl imidazole by quaternized to form the surfactant molecule, N , N ′-((ethane-1,2-diyl)bis(alkyl-azanediyl)bis(2-oxoethane-2,1-diyl)) bis(1-methyl-1 H -imidazol-3-ium) dichloride. The structures of intermediates ( 1a–e ) and ( 2a–e ) were characterized by IR and 1 H NMR. The structures of the surfactants ( 3a–e ) were characterized by IR, 1 H-NMR and 13 C-NMR and element analysis. The critical micelle concentrations (CMC) of 3a–e were determined by the conductivity method at 25 °C. The CMC values decreased with increasing the length of the hydrophobic chain. The surfactants ( 3a–e ) showed good foaming stability, emulsion ability and wetting ability. The surfactants ( 3a–e ) also have good antimicrobial activity against Staphylococcus aureus , Escherichia coli and Bacillus subtilis .