Synthesis and application of amino alcohol-derived chiral ionic liquids, as additives for enantioseparation in capillary electrophoresis

In this study, three functionalized chiral ionic liquids (CILs) derived from l-valinol, l-prolinol and l-phenylalaninol, namely N,N,N-trimethyl-l-valinol-bis(trifluoromethanesulfon)imide ([TMLV]⁺[Tf₂N]^-, CIL1), N,N-dimethyl-l-prolinol-bis(trifluoromethanesulfon)imide ([DMLP]⁺[Tf₂N]^-, CIL2) and N,N,N-trimethyl-l-phenylalaninol-bis(trifluoromethanesulfon)imide ([TMLP]⁺[Tf₂N]^-, CIL3), were synthesized and subsequently utilized for enantiomeric separation in capillary electrophoresis (CE) with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) as chiral selector for the first time. Compared with traditional single HP-β-CD separation system, the synergistic system exhibited substantially improved separations of six tested drugs. Using the CIL1/HP-β-CD as a model system, the influence of crucial parameters including the type and proportion of organic modifier, CILs concentration, HP-β-CD concentration and buffer pH was investigated in detail. Additionally, molecular modeling with AutoDock was applied to elucidate the enhanced enantioselectivity in the presence of CILs, which has certain guiding value in predicting the migration order of the enantiomers and studying the interactions important for the chiral recognition.