This review paper shows the dominant role of the cyclodextrins in the chiral separations using capillary columns (GC, SFC, CE). The cyclodextrins (CDs) have extremely broad chiral selectivity spectra because they have several different chiral recognition sites in various arrangements and various interaction modes. Their chiral selectivity features can further improve with their various substitutions. Their selectivities are moderate therefore they need high efficiency separations (capillary columns) for good chiral resolutions. The shape selectivity of cyclodextrins is also shown with non-chiral isomers too. The utility of the cyclodextrins is demonstrated with several examples based on the personal observations of authors and critical review of literature. The theoretical backgrounds of their chiral recognitions (e.g. H-bond interaction, inclusion, induced fit) are discussed in depth. This paper is not application oriented but is dealing with mostly on the physical and chemical background of separations using CDs.
The authors concluded that the flexible structures of cyclodextrins produce moderate chiral selectivity which can be compensated by the high efficiency of capillary columns of GC and CE to achieve good resolutions of the enantiomer pairs. This is the reason why the overwhelming part of the chiral separations uses cyclodextrins as chiral selective agents in GC and CE.
Zoltán Juvancz, Rita Bodáné-Kendrovics, Lajos Szente, Dóra Maklári (2021) Cyclodextrins as Dominant Chiral Selective Agents in the Capillary Separation Techniques. Periodica Polytechnica Chemical Engineering, 65(4), 580–594. https://doi.org/10.3311/PPch.18067