'Click' preparation of a novel 'native-phenylcarbamoylated' bilayer cyclodextrin stationary phase for enhanced chiral differentiation

This paper reports an effective approach for the fabrication of a novel hybrid bilayer cyclodextrin (CD) chiral stationary phase (CSP), where native and perphenylcarbamoylated-beta-CD were successively immobilized onto silica surface via a two-step click approach to form a bilayer CD structure. By decorating the bulky phenylcarbamoylated CD onto the unmodified CD silica, the CSP can provide multiple interaction sites such as H-bonding (-OH, C=O, -NH-), steric effects, pi-pi, dipole-dipole and inclusion complexation interactions, which help to broaden the CSP's enantioselectivity profile and enhance the enantioselectivity to some specific analytes. A group of enantiomer pairs such as isoxazolines, bendroflumethiazide, indoprofen, diperodon, fenoterol, atropine, styrene oxide and dansyl amino acids can be baseline or partially separated on the current CSP under reversed phase high performance liquid chromatography (RP-HPLC). The selectivity and resolution of 4NPh-OPr reached 5.25 and 13.97, which is an exciting achievement for the enantioseparations by CD CSPs. (C) 2015 Elsevier B.V. All rights reserved.