C2 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 C2 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 C2 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 C2 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.
Keywords: C2 symmetric; chiral stationary phase (CSP); enantiomer separation; proline derivatives.