Thiol–ene click chemistry derived cationic cyclodextrin chiral stationary phase and its enhanced separation performance in liquid chromatography

• First demonstration of a novel native CD CSP with cationic imidazolium on the linking bridges.
• Cationic moiety strongly enhances the retention and resolution towards anti-charged analytes.
• Thiolether linkage and cationic moiety exhibit good stability under various conditions.
• This CSP affords improved separation compared to the previous triazole-bridged CD-CSP.

This work is the first demonstration of a simple thiol–ene click chemistry to anchor vinyl imidazolium β-CD onto thiol silica to form a novel cationic native cyclodextrin (CD) chiral stationary phase (CSP). The CSP afforded high enantioseparation ability towards dansyl (Dns) amino acids, carboxylic aryl compounds and flavonoids in chiral HPLC. The current CSP demonstrates the highest resolving ability (selectivity >1.1, resolution >1.5) towards Dns amino acids in a mobile phase buffered at pH = 6.5, with the resolution of Dns-dl-leucine as high as 6.97. 2,4-dichloride propionic acid (2,4-ClPOPA) was well resolved with the selectivity and resolution of 1.37 and 4.88, respectively. Compared to a previously reported native CD-CSP based on a triazole linkage, the current cationic CD-CSP shows a stronger retention and higher resolution towards acidic chiral compounds, ascribed to the propitious strong electrostatic attraction. Stability evaluation results indicated that thiol–ene reaction can provide a facile and robust approach for the preparation of positively charged CD CSPs.