Cyclodextrin clicked chiral stationary phases with functionalities-tuned enantioseparations in high performance liquid chromatography

Abstract

In this work, two cyclodextrin (CD) chiral stationary phases (CSPs) have been developed by clicking per-4-chloro-3-methylphenylcarbamoylated mono-6(A)-azido-β-CD (CSP1) and per-5-chloro-2-methylphenylcarbamoylated mono-6(A)-azido-β-CD (CSP2) onto alkynylated silica support. The enantioslectivies of the as-obtained new CSPs have been evaluated using 29 model racemates including aromatic alcohols, flavonoids, β-blocker and FMOC-amino acids in both reversed-phase (RP) and normal-phase (NP) high performance liquid chromatography (HPLC). The CD functionalities tuned enantioselectivities were elucidated in different HPLC elution modes. Higher chiral resolutions were achieved in RP-elution mode with the aid of the inclusion complexation in comparison to NP-elution mode. The π-π stacking interaction and dipole-dipole interaction provided by phenylcarbamate moieties can also contribute to the enantioseparation.

Keywords: Chiral stationary phase; Click chemistry; Cyclodextrin; Enantioselectivity.