Phenylcarbamoylated beta-CD: pi-acidic and pi-basic chiral selectors for HPLC.

Two types of chiral stationary phases for HPLC based on pi-acidic or pi-basic perphenylcarbamoylated beta-CDs were synthesized. The relative structural features of the two effective chiral selectors are discussed and compared in both normal-phase and RP modes. In addition, the nature and concentration of alcoholic modifiers were varied for optimal separation in normal phase and the structural variation of the analytes was also examined. The results showed that hydrogen bonding, steric effect and pi-acidic-pi-basic interaction contributed greatly to enantioseparation. Upon comparison, some of the differences in the separation behavior of the two types of chiral stationary phases might be due to the pi-acidic or pi-basic phenylcarbamate groups.