ELECTRON NUCLEAR DOUBLE-RESONANCE DETECTION OF DISTINCT MULTIMODAL INCLUSION COMPLEXES OF BETA-CYCLODEXTRIN WITH A NITROXIDE SPIN ADDUCT PROBE

Observation and identification of multimodal inclusion complexes of beta-cyclodextrin with a nitroxide spin adduct probe are reported. When a nitroxide radical having three different functional groups attached to the nitroxyl function is dissolved in an aqueous solution of beta-cyclodextrin, electron nuclear double resonance (ENDOR) signals from three distinct complexes are detected. These are assigned to multimodal inclusion complexes in which each functional group of the nitroxide occupies the void space of beta-cyclodextrin. Since both the nitroxide probe and cyclodextrin are chiral, the complexation results in the formation of diastereomers. In some cases the ENDOR spectrum from a diastereomer is also observed.