THE SYNTHESIS AND CHARACTERIZATION OF A PYRIDINE-LINKED CYCLODEXTRIN DIMER

A cyclodextrin dimer has been synthesized in an overall 29% yield from beta-cyclodextrin. This compound contains a pyridine bridge that link s the secondary faces of two cyclodextrin units. A complete H-1 and C- 13 NMR analysis was performed using a combination of one- and two-dime nsional NMR pulse sequences. The results are consistent with the notio n that each beta-cyclodextrin moiety contains seven spectrally unique sugar residues. In addition, an analysis of key coupling constants sug gest that the modified sugar moiety in the individual cyclodextrin uni ts has undergone a chair inversion. This analysis represents the first complete NMR characterization of a cyclodextrin dimer. Finally, the b inding properties of the cyclodextrin dimer for several guest molecule s are reported. To the best of our knowledge, the association constant obtained with ethyl orange (1.6 +/- 0.2 x 10(7)) represents the large st formation constant ever reported for a dye molecule with a cyclodex trin-based host.