Enhancement of separation performance for ofloxacin enantiomers by a biphasic recognition chiral extraction system

Despite greatly improved separation performance towards many mixtures, utilizing biphasic recognition chiral extraction (BRCE) systems in enantiomer separation remains challenging due to inadequate comprehension of chiral recognition and biphasic synergism mechanisms. In this work, using ofloxacin enantiomers as a case study, separation performance of BRCE system is systematically examined from experimental and theoretical aspects. The BRCE system, comprising di‐p‐toluoyl‐l‐tartaric acid and β‐cyclodextrin as hydrophobic and hydrophilic selectors, achieves maximum enantioselectivity and enantiomeric excess values of 2.4 and 26% under optimal conditions. Five‐stage counter‐current extraction and reverse extraction significantly improve the enantiomeric excess value up to 91%. Molecular simulations reveal that to construct an enhanced BRCE system, two chiral selectors should have opposite recognition abilities for target enantiomers and weak interactions between themselves. This work provides guidance on selecting suitable selectors for construction of an enhanced BRCE system not only for separating ofloxacin enantiomers but also other enantiomers.