Novel chiral ionic liquid stationary phases based on chiral imidazolium were prepared. The ionic liquid chiral selector was synthesized by ring opening of cyclohexene oxide with imidazole or 5,6-dimethylbenzimidazole, and then chemically modified by different substitute groups. Chiral stationary phases were prepared by bonding to the surface of silica sphere through thioene "click" reaction. Their enantioselective separations of chiral acids were evaluated by high-performance liquid chromatography. The retention of acid sample was related to the counterion concentration and showed a typical ion exchange process. The chiral separation abilities of chiral stationary phases were greatly influenced by the substituent group on the chiral selector as well as the mobile phase, which indicated that, besides ion exchange, other interactions such as steric hindrance, π-π interaction, and hydrogen bonding are important for the enantioselectivity. In this report, the influence of bulk solvent components, the effects of varying concentration, and the type of the counterion as well as the proportion of acid and basic additives were investigated in detail.

Ketorolac has been widely applied in clinical medicine for its antipyretic, analgesic and anti‐inflammatory pharmacological activity. Research showed that the analgesic effect of the S enantiomer is 230 times stronger than that of the R enantiomer. Getting the high‐purity S enantiomer of Ketorolac has profound significance but still remains a challenging topic. In this work, the separation of the R and S enantiomers of Ketorolac was investigated on polysaccharide‐based chiral stationary phases. Chiralcel AD‐H, OD‐H, OJ‐H and AS‐H columns were evaluated using polar organic and normal phase mode, respectively, in which the OJ‐H column showed the best performance with high selectivity and resolution for Ketorolac with α = 2.43 and RS = 9.04 by using methanol/formic acid (100:0.1, v/v) as the mobile phase. The influences of acid additive, composition of mobile phase and temperature were examined. The coating amount of cellulose tris‐(4‐methylbenzoate) has significant influence on the sample loadability. The high loadability of chiral stationary phases coated with 40% of cellulose tris‐(4‐methylbenzoate) allows preparative separation up to 16 mg on an analytical column of 250 × 4.6 mm id in a single run for Ketoroac using methanol/formic acid (100:0.1, v/v) as mobile phase, which shows a potential application in industrial preparation.

symmetric chiral compounds overlap themselves when rotating with an axis of 180° with an axis and have important applications in chiral catalysis and chiral separation fields. A novel symmetric stationary phase based on phenyl substituted L-proline derivatives was prepared and compared with the similar stationary phase based on mono-substituted brush-type stationary phase. The symmetric stationary phase showed higher enantiodiscrimination capability than the mono-substituted stationary phase for 31 acidic, neutral and alkaline analytes. The influence of the substitution groups on the terminal phenyl moiety on enantioselectivity was investigated. In summary, the best separation capability was achieved by the stationary phase with none substitution on the endmost phenyl ring. An unusual thermodynamic behavior of the enantioseparation property was observed on the symmetric stationary phase for some analytes, which showed the different separation mechanism comparing with the corresponding mono-substituted stationary phase. The appearance of this novel chiral stationary phase has an important significance in enriching the type of brush-type stationary phases and widening their applications.

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