A new single-urea-bound chiral stationary phase based on 3,5-dimethylphenylcarbamoylated β-cyclodextrin was prepared through the Staudinger reaction of mono (6 -azido-6 -deoxy)-per(3,5-dimethylphenylcarbamoylated) β-cyclodextrin and 3-aminopropyl silica gel under CO atmosphere. The new phase exhibited good enantioseparation performance for 33 analytes using normal-phase HPLC conditions; 19 of them were baseline separated. Effects of structure of analytes, alcoholic modifiers, and acidic/basic additives on separation performances of this new cyclodextrin chiral stationary phase have been studied in detail. The results showed that the retention and resolution of acidic and basic analytes on the CSP were greatly affected by the additives. Peak symmetry for some analytes could be improved by simultaneously adding acidic and basic additives to the mobile phase. This work expands the potential applications of the cyclodextrin-based chiral stationary phases in the normal-phase HPLC.
Two new polysaccharide-derived chiral selectors, namely, 6-azido-6-deoxy-3,5-dimethylphenylcarbamoylated amylose and 6-azido-6-deoxy-3,5-dimethylphenyl carbamoylated cellulose, were synthesized under homogeneous conditions and immobilized onto aminized silica gel by the Staudinger reaction, resulting in two new immobilized polysaccharide chiral stationary phases (CSPs). Their enantioseparation performances were investigated under normal-phase mode by HPLC. Among 17 analytes, baseline separations of 12 pairs of enantiomers are achieved on the immobilized cellulose CSP, which demonstrates that this new cellulose material exhibits almost the same enantioseparation performance as the coated cellulose CSP. In addition, the amylose-derived CSP presents limited enantiorecognition ability but certain complementarity with the immobilized and coated cellulose-based materials. Neither metolachlor nor paclitaxel side chain acids are separated on two cellulose-derived CSPs, but effective separations are obtained on the immobilized amylose column.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.