Simple one step synthesis of gemini cationic surfactant-based ionic liquids: Physicochemical, surface properties and biological activity

In this work three gemini cationic surfactant-based ionic liquids were synthesized in one step. Alkylation of tridodecylamine was performed with 1,2-dibromoethane, 1,3-dibromopropane, and 1,6-dibromohexane in ethanol. Chemical structures of synthesized cationic surfactant-based ionic liquids were characterized using FTIR and 1H NMR. The effect of spacer length of these types of ionic liquids on physicochemical properties such as melting point, density and viscosity has been investigated. The surface tension at different temperatures was measured and the surface parameters including: the critical micelle concentration (CMC), effectiveness (πcmc), efficiency (Pc20), maximum surface excess (Γmax) and minimum surface area (Amin), were calculated. Adsorption and micellization thermodynamic parameters were calculated and shown that the two processes are spontaneous. It is clear that the synthesized surfactant ionic liquid showed their tendency towards adsorption at the interfaces and also micellization in the bulk of their solutions. The antimicrobial activity of the synthesized surfactant ionic liquids against gram-negative and gram-positive bacteria as well as fungi was evaluated. The efficiency of these compounds as antimicrobial agents was increased with the hydrophobicity and spacer length of the gemini ionic liquids.