Cyclodextrins interactions with chiral molecules

Polysaccharide derivatives used as CSPs interact with chiral analytes in much the same manner as cyclodextrins. These molecules have been shown to exhibit high chiral recognition ability in HPLC [155]. The main advantage of CEC over HPLC is the enhanced efficiency. In chiral separations, slow mass transfer kinetics between the CSP and chiral analytes have somewhat diminished the efficiency advantage of the technique. The goal of using polysaccharide derivatives... 

Derivatized cyclodextrins can interact with chiral substances in a number of different ways. If, the positions 2 and 6 are alkylated (pentylated), very dispersive (hydrophobic) centers are introduced that can strongly interact with any alkyl chains contained by the solutes. After pentylation of the 2 and 6 positions has been accomplished, the 3-position hydroxyl group can then be trifluoroacetylated. This stationary phase is widely used and it has been found that the derivatized y-cyclodextrin is more chirally selective than the /3 material. It has been successfully used for the separation of both very small and very large chiral molecules. The cyclodextrin hydroxyl groups can also be made to react with pure S hydroxypropyl groups and then per-... 

Cyclodextrin stationary phases utilize cyclodextrins bound to a soHd support in such a way that the cyclodextrin is free to interact with solutes in solution. These bonded phases consist of cyclodextrin molecules linked to siUca gel by specific nonhydrolytic silane linkages (5,6). This stable cyclodextrin bonded phase is sold commercially under the trade name Cyclobond (Advanced Separation Technologies, Whippany, New Jersey). The vast majority of all reported hplc separations on CD-bonded phases utilize this media which was also the first chiral stationary phase (csp) developed for use in the reversed-phase mode. 

Sufficient chiral recognition also requires interaction of other functional groups around the chiral center with the lip of the cyclodextrin cavity, and possibly even with secondary cyclodextrin molecules. 

Aroma compounds originate from biosynthetic pathways inside an animal, a botanical body, and other life-forms as well as enzymes and thus frequently carry chiral components within the molecule. Determination of such enantiomeric properties can, in many cases, be accomplished using a GC column with a chiral stationary phase (CSP) application.75-79 These columns, usually called chiral GC column, will provide diastereometric interaction that could lead to resolution of enantiomers. Commercially available chiral GC columns predominantly utilize cyclodextrin derivatives as CSPs. Chiral columns consisting of multiple cyclodextrin derivatives intending synergic effect in resolution property80 are also successful in the market. In practice, these columns are mainly operated as secondary columns in MDGC technique. 

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