Chiral recognition by fluorescent chemosensors based on N-dansyl-amino acid-modified cyclodextrins

Four kinds of N-dansyl-amino acid-modified beta-cyclodextrins (beta-CDs) were prepared as fluorescent chemosensors for chiral discrimination. The use of an amino acid as a spacer improved binding affinities and chiral discrimination abilities of the chemosensors. N-dansyl-l-Phe-modified beta-CD showed high d-selectivity for norbornane derivatives and N-dansyl-d-Phe-modified beta-CD showed high l-selectivity for menthol. Microcalorimetric titration results indicate that the chemosensors selectively accommodate the enantiomer that induces the least unfavorable entropy change on making an inclusion complex.