Cationic cyclodextrin as versatile chiral selector for enantiomeric separation in capillary electrophoresis

A novel cationic cyclodextrin, mono-6A-(3-methoxypropan-1-ammonium)-6A-β-cyclodextrin chloride, has been developed and used as chiral selector in capillary electrophoresis (CE). This chiral selector has three recognition sites: β-CD, ammonium cation and methoxy group in the sidearm to contribute three corresponding driving forces including inclusion complexation, electrostatic interaction and hydrogen bonding. This elegantly designed CD exhibits outstanding enantioselectivities in CE for a wide range of acidic and ampholytic racemates due to the extra hydrogen bonding for the chiral recognition. Under optimum pH 6.0, chiral resolutions over 10 can be readily achieved for acidic racemates with CD concentration below 10 mM. This cationic CD exhibits great potential for versatile chiral separation in CE. The finding in this study may be applied to construct new host–guest systems for practical applications.

► The synthesis of a cationic single-isomer cyclodextrin (CD) as chiral selector.
► The strong chiral recognition of new CD by NMR study.
► The outstanding enantioseparation abilities (chiral resolution over 20) towards both acidic and ampholytic racemates.
► Chiral resolutions over 10 readily achieved with 2.5 mM CD.