Department of Chemical and Surfactants Technology, Institute of Advanced Chemistry of Catalonia IQAC- CSIC , Jordi Girona 18-26, 08034 Barcelona, Spain.
Facultat de Farmacia, Universitat de Barcelona , Joan XXIII, 08028 Barcelona, Spain.
Langmuir. 2017 Jul 5;33(26):6511-6520. doi: 10.1021/acs.langmuir.7b00505. Epub 2017 Jun 22.
Imidazolium-based ionic liquids (ILs) containing cleavable carbonate linkages, 1-alkyloxycarbonyloxyethyl-3-methylimidazolium chlorides with alkyl chains of 10, 12, and 14 carbon atoms, were synthesized, and their self-assembly behavior and antimicrobial activity were investigated. Differential scanning calorimetry and polarized optical microscopy studies reveal that carbonate-functionalized ILs form stable thermotropic smectic liquid-crystalline phases over a wide range of temperature. The surface activity and aggregation behavior of these new ILs were investigated by tensiometry, conductometry, potentiometry, and spectrofluorimetry. The size of aggregates was examined by dynamic light scattering (DLS). Carbonate-functionalized ILs display a higher adsorption efficiency and a lower critical micelle concentration (cmc) than simple alkyl-chain-substituted ILs. The insertion of a carbonate ester moiety in the alkyl side chain favors adsorption at the air-water interface and micellization in the bulk solution when compared to nonfunctionalized ILs. DLS measurements show that small micellelike aggregates are spontaneously formed above the cmc. Furthermore, carbonate-functionalized ILs were examined for their antimicrobial activity against a panel of clinically relevant microorganisms. Biological activity was found to increase with hydrophobicity. The presence of a carbonate ester moiety significantly enhances the antimicrobial efficiency as compared to nonfunctionalized ILs, with the susceptibility of Staphylococcus sp. toward the action of these compounds being particularly remarkable. It has been demonstrated that the functionalization of the alkyl side chain of the imidazolium salts can not only modify the aggregation behavior but also lead to differences in both efficiency and the spectrum of antimicrobial activity of amphiphilic ILs.
合成了含有可裂解碳酸酯键的咪唑鎓基离子液体（ILs），即 1-烷氧基羰氧基乙基-3-甲基咪唑氯盐，烷基链长分别为 10、12 和 14 个碳原子，并研究了它们的自组装行为和抗菌活性。差示扫描量热法和偏光显微镜研究表明，碳酸酯功能化的 ILs 在很宽的温度范围内形成稳定的热致向列型液晶相。通过张力计、电导率计、电位计和荧光光谱法研究了这些新型 ILs 的表面活性和聚集行为。通过动态光散射（DLS）检查了聚集体的大小。与简单的烷基链取代的 ILs 相比，碳酸酯功能化的 ILs 具有更高的吸附效率和更低的临界胶束浓度（cmc）。与非功能化的 ILs 相比，在烷基侧链中插入碳酸酯酯基有利于在气-水界面上的吸附和在本体溶液中的胶束化。DLS 测量表明，在 cmc 以上会自发形成小的胶束样聚集体。此外，还研究了碳酸酯功能化的 ILs 对一组临床相关微生物的抗菌活性。发现生物活性随疏水性的增加而增加。与非功能化的 ILs 相比，碳酸酯酯基的存在显著提高了抗菌效率，这些化合物对葡萄球菌属的作用尤其显著。已经证明，咪唑鎓盐的烷基侧链的功能化不仅可以改变聚集行为，还可以导致两亲性 ILs 的效率和抗菌活性谱的差异。
