Surface, thermodynamic and biological activities of some synthesized Gemini quaternary ammonium salts based on polyethylene glycol

• Three Gemini cationic surfactants were synthesized via two steps reaction.
• All the synthesized Gemini quaternary ammonium salts (G600Br, G1000Br and G1500Br) were investigated for their surface properties by surface tension, interfacial tension, emulsion stability foaming power and thermodynamic parameters.
• The effects of quaternary nitrogen head group nature and poly ethylene glycol spacer on the antimicrobial activity against pathogenic bacteria and fungi was discussed.

Quaternary ammonium salts are frequently used as antimicrobial agents that disrupt cell membrane through the binding of their ammonium cations to anionic sites in the outer tissue of bacteria. This article describes the synthesis of Gemini quaternary ammonium salts (G600Br, G1000Br and G1500Br). The chemical structures of synthesized Gemini quaternary ammonium salts were confirmed using FT-IR and 1HNMR spectra. The surface activity of the synthesized surfactants were determined from the surface and interfacial tension measurements. The surface parameter including: the critical micelle concentration (CMC), effectiveness (πcmc), efficiency (Pc20), maximum surface excess (Γmax) and minimum surface area (Amin), were calculated from the surface tension measurements, also, the foaming and emulsification power were measured. The thermodynamic parameters of micellization and adsorption showed their tendency towards adsorption at the interfaces and also micellization in the bulk of their solutions. Screening tests of the synthesized compounds showed that the compounds exhibit an effective antimicrobial activity on a variety of bacteria including Gram-positive bacteria (Bacillus subtilis and Micrococcus luteus), Gram-negative bacteria (Bordetella pertussis and Escherichia coli) and Fungi (Candida albicans and Aspergillus niger).

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