CHROMATOGRAPHIC STUDIES ON THE INCLUSION OF ISOMERIC DIMETHYLNAPHTHALENES BY BETA-CYCLODEXTRIN AND GAMMA-CYCLODEXTRIN

Reversed-phase high performance liquid chromatography and gas-liquid chromatography have been applied to studies on the complexation of cyclodextrins with isomeric dimethylnaphthalenes. Both beta and gamma-cyclodextrins have been found to form inclusion complexes with dimethylnaphthalenes. With the exception of the complex of 1,8-dimethylnaphthalene with beta-cyclodextrin, all the other complexes under investigation are of moderate stability. The remarkable affinity of beta=cyclodextrin for 1,8-dimethylnaphthalene has been observed by both GC and HPLC. The stability constant of this complex was always about 1.5-2.0 orders of magnitude greater than the corresponding value for the other isomers. The chromatographic data suggest that there is an especially good fit of the 1,8-dimethylnaphthalene molecule into the beta-cyclodextrin cavity. The importance of studying the complicated phenomena of complexation by cyclodextrin using various experimental and theoretical methods is stressed.