Recent development of chiral ionic liquids for enantioseparation in liquid chromatography and capillary electrophoresis: A review

Ionic liquids (ILs), which are salts in a molten state below 100 °C, have become a hot topic of research in various fields because of their negligible vapour pressure, high thermal stability, and tunable viscosity. Chiral ionic liquids (CILs) can be applied in chromatography and capillary electrophoresis fields to improve the performance of enantiomeric separation, such as chiral stationary phases (CSPs) and mobile phase additives in high-performance liquid chromatography (HPLC); CSPs in gas chromatography (GC); and background electrolyte additives (BGE), chiral ligands and chiral selectors (CSs) in capillary electrophoresis (CE). This review focuses on the applications of CILs in HPLC and CE for the separation of enantiomers in the past five years. The mechanism for separating enantiomers was explained, and the prospect of the application of CILs in chiral liquid chromatography (LC) and CE analysis was also discussed.

Chiral separation on various modified amino alcohol-derived HPLC chiral stationary phases

3,5-Dinitrobenzoyl chloride was previously used for the preparation of (R)-phenylglycinol- and (S)-leucinol-derived chiral stationary phases. In this study, 3,5-bis(trifluoromethyl)benzoyl chloride, 2-furoyl chloride, 2-theonyl chloride, 10,11-dihydro-5H-dibenzo[b,f]azepine-5-carbonyl chloride, diphenylcarbamoyl chloride, and 1-adamantanecarbonyl chloride were used to prepare six new phenylglycinol-derived chiral stationary phases (CSPs) and five new leucinol-derived CSPs. Using these 11 CSPs, chiral separation of nine π-acidic amino acid derivatives and five π-basic compounds was performed, and the separation results were compared. An adamantyl-derived CSP showed good separation.