A new series of pyridinium cationic gemini surfactants was prepared by quaternization of the 2,2'-(alpha,omega-alkanediyl)bispyridines with N-alkylating agents, whose reactivity is briefly discussed. Particularly useful was the use of long-chain alkyl triflates (trifluoromethanesulfonates) for both overcoming the sterical hindrance in the pyridines and obtaining higher synthetic yields. Well-known 4,4'-(alpha,omega-alkanediyl)bis(1-alkylpyridinium) structures showed narrow temperature ranges for practical applications, due to their high Krafft points, while the new 2,2'-(alpha,omega-alkanediyl)bis(1-alkylpyridinium) series, accounted for good surface active properties. Due to the Krafft points below 0 degrees C, they could be exploited as solutions in water at any temperature. The characterization of the behavior of the series was performed by conductivity measurements. Some of the proposed structures exhibited unusual surface active behavior, which was interpreted in terms of particular conformational arrangements.

A series of surfactants with tuned polarity were prepared, including a new class of compounds: gluco-pyridinium surfactants. Pure anomers were obtained by chromatographic separation. The conductivity and surface tension of surfactant solutions in water were measured, and provided interesting information regarding their aggregation behavior. Peculiarities were observed in the premicellar range. Tensidic parameters correlated with antimicrobial activity. A few parameters, mainly the hydrophobicity of the headgroup, may play a role in finding more efficient antimicrobial structures.

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[reaction: see text] In this work, we report the synthesis of a new series of glucocationic surfactants, a class of surfactants we introduced very recently. The preparation of the surfactants is based on the synthesis of the 2-bromoethyl-2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside, whose preparation was studied in order to improve yields and stereoselectivity of this key intermediate. These glucocationic amphiphiles were prepared and studied as a model of cationic surfactants marked with a carbohydrate moiety. The use of carbohydrates as markers on cationic lipids was recently introduced to induce recognition by specific receptors, present on the surface of cell membranes. The chemicophysical characterization of these model structures can give more insight on the aggregation behavior. Conductivity and surface tension measurements were performed in order to characterize the compounds from the amphiphilic point of view. The results showed a different effect of the glucosidic moiety on the cmc value with respect to the glucopyridinium cationic surfactants. The surfactants also showed the tendency to form premicellar aggregates in solution when the hydrophobicity is raised.

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