Department of Chemical and Surfactant Technology, Institut de Quimica Avançada de Catalunya IQAC-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain.
Langmuir. 2013 Feb 26;29(8):2536-45. doi: 10.1021/la304752e. Epub 2013 Feb 11.
Two series of long chain imidazolium- and pyridinium-based ionic liquids containing an ester functional group in the alkyl side chain, 3-methyl-1-alkyloxycarbonylmethylimidazolium bromides (C(n)EMeImBr) and 1-alkyloxycarbonylmethylpyridinium bromides (C(n)EPyrBr), were synthesized and their thermal stability, aggregation behavior in aqueous medium, and antimicrobial activity investigated. The introduction of an ester group decreased the thermal stability of the functionalized ILs compared to simple alkyl chain containing ILs (1-alkyl-3-methylimidazolium bromides and 1-alkylpyridinium bromides). Tensiometry, conductimetry, and spectrofluorimetry were applied to study the self-aggregation of the amphiphilic ILs in aqueous solution. The ILs investigated displayed surface activity and the characteristic chain length dependence of the micellization process of surfactants. As compared to simple alkyl chain containing ILs bearing the same hydrocarbon chain, ester-functionalized ILs possess higher adsorption efficiency (pC(20)) and significantly lower critical micelle concentration (cmc) and surface tension at the cmc (γ(cmc)), indicating that the incorporation of an ester group promotes adsorption at the air/water interface and micelle formation. The antimicrobial activity was evaluated against Gram-negative and Gram-positive bacteria and fungi. ILs containing more than eight carbon atoms in the alkyl chain showed antimicrobial activity. Their efficiency as antimicrobial agents increased with the hydrophobicity of the amphiphilic cation being the C(12) homologous the most active compounds. The incorporation of an ester group particularly increased the biological activity against fungi.
两种含酯基侧链的长链咪唑鎓和吡啶鎓基离子液体系列，3-甲基-1-烷氧基羰基甲基咪唑溴盐（C(n)EMeImBr）和 1-烷氧基羰基甲基吡啶溴盐（C(n)EPyrBr），被合成并研究了它们的热稳定性、在水介质中的聚集行为和抗菌活性。与含有简单烷基链的 ILs（1-烷基-3-甲基咪唑溴盐和 1-烷基吡啶溴盐）相比，酯基的引入降低了功能化 ILs 的热稳定性。张力计、电导率计和荧光光谱法被应用于研究两亲性 ILs 在水溶液中的自聚集。所研究的 ILs 具有表面活性和表面活性剂胶束化过程的特征链长依赖性。与具有相同烃链的含有简单烷基链的 ILs 相比，酯基功能化 ILs 具有更高的吸附效率（pC(20)）和显著更低的临界胶束浓度（cmc）和 cmc 时的表面张力（γ(cmc)），表明酯基的引入促进了在气/水界面的吸附和胶束形成。抗菌活性被评估了对革兰氏阴性和革兰氏阳性细菌和真菌的活性。含烷基链上超过八个碳原子的 ILs 表现出抗菌活性。它们作为抗菌剂的效率随着两亲阳离子疏水性的增加而增加，其中 C(12)同系物是最活跃的化合物。酯基的引入特别增加了对真菌的生物活性。
