Surface-up click access to allylimidazolium bridged cyclodextrin dimer phase for efficient enantioseparation.

In this work, a novel allylimidazolium-bridged bis(β-cyclodextrin) chiral stationary phase was fabricated via a surface-up thiol-ene click chemistry reaction between 7-SH-β-cyclodextrin and 1-allylimidazole-β-cyclodextrin bonded on silica surface. The structure of allylimidazolium-bridged bis(β-cyclodextrin) chiral stationary phase was characterized by Fourier transform infrared spectra, 13 C NMR, thermogravimetric analysis and elemental analysis. Its chiral chromatographic performances were systematically evaluated by separating 35 racemic analytes including isoxazolines, dansyl-amino acids and flavanones under reversed-phase HPLC. Compared with the corresponding bottom and top layer of the β-cyclodextrin stationary phase, the allylimidazolium-bridged bis(β-cyclodextrin) chiral stationary phase afforded significantly accentuated chiral recognition ability due to its abundant hydrogen bond sites, electrostatic interactions and ssynergistic inclusion. Furthermore, allylimidazolium-bridged bis(β-cyclodextrin) chiral stationary phase showed better enantioseparation ability compared to other reported bridged cyclodextrin stationary phases. In particular, Ar-Phs and dansyl-amino acid could be completely separated by allylimidazolium-bridged bis(β-cyclodextrin) chiral stationary phase with high resolutions (Rs) of 1.14-7.20 and 3.16-5.82, respectively. Molecular docking reveals the good enantioseparation ability arises from the different interaction mode and the synergistic effect of allylimidazolium-bridged bis(β-cyclodextrin) chiral stationary phase. This article is protected by copyright. All rights reserved.