Models of Chiral Recognition by Cyclodextrins

As saccharides, CyDs are chiral and exhibit dtiral recognition, that is they form dia-stereomeric complexes, usually of different stability, with enantiomeric spedes. 

Owing to the nature of chromatographic processes, relatively small values of AAG suffice to afford observable chromatographic separations. A value of 50 small calories (note that today the limit is 10 not 50, HD) affords a separation of 1.09, easily observable on a high-efficiency HPLC system. 

There is justifiable skepticism concerning the validity of any mechanism purporting to explain such small energy differences, despite a strong tendency among workers in the field to advance chiral recognition rationales, even when comparatively few data are available upon which to base such a rationale Typically, chromatographic separation of enantiomers in- 

HD) and analyte for which free energies are small with respect to kT. This implies that the molecules are relatively free to tumble with respect to each other and exert relatively little mutual conformational control It is es- 

These statements determine the author s whole attitude to models of chiral recognition, presented below, based both on experimental data and/or on calculations. 

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