Abstract
Inclusion compounds of azo dyes which have a naphthalene nucleus were examined by 13C nuclear magnetic resonance (NMR). The azo dyes used form 1 : 1 complexes with cyclodextrin. The guest molecule is uniformly affected by the cavity, as if it were dissolved in a hydrophobic solvent. C-SO3-at the end of the molecule shows the largest shift and can be used as an index of inclusion. Almost all carbons of the guest molecule show low field shifts on inclusion, which are consistent with the 1H NMR behavior. Thus, the shift mechanism may be due not to a simple steric polarization effect, but to hydrophobic interaction with the host molecule. The host molecule is deformed at the glycosidic linkage rather than at the small diameter side of the cavity by the bulky naphthalene nucleus.
