Inclusion of enantiomeric carvones in beta-cyclodextrin: a variable temperature H-1 NMR study in aqueous solution

In aqueous solution, the apparent association constant at room temperature for the 1:1 inclusion of S-(+)-carvone in beta-cyclodextrin is double of th at for R-(-)-carvone, whereas, at 45 degrees C, both enantiomers have assoc iation constants two orders of magnitude smaller, with the S-(+) inclusion being then slightly weaker than the R-(-) encapsulation. Calculations carri ed out at the molecular mechanics, AM1 and STO-3G levels confirm the prefer ential inclusion of the S-enantiomer and provide important clues for unders tanding chiral discrimination by beta-cyclodextrin.