SYNTHESIS OF NOVEL DANSYL APPENDED CYCLODEXTRINS - SELF-INCLUSION ANDSENSOR PROPERTIES

The synthesis of three dansyl appended cyclodextrin derivatives, diffe ring in the spacer length between cyclodextrin and the dansyl moiety, is described, In compound 4 the fluorophore is directly attached to th e cyclodextrin. Compound 5 contains an ethyl spacer and compound 6 a t riethylene glycol spacer, These compounds are designed to detect neutr al organic guest molecules like cyclohexanol and adamantanecarboxylic acid in water by fluorescence spectroscopy, At neutral pH none of the compounds is sensitive towards guest molecules, For compound 4 this is due to the fact that the dansyl group is located outside the cyclodex trin cavity, For compunds 5 and 6 the low sensitivity is the result of a strong self-inclusion of the dansyl group, Lowering the pH results in protonation of the dimethylamino group of the dansyl moiety, which makes the self-inclusion less favourable leading to a strongly increas ed;response towards guests, This phenomenon allows the sensors to be s witched on and off by lowering or increasing the pH of the solution. C ompound 6 is able to detect adamantanecarboxylic acid at 5 x 10(-7) mo l(-1) dm(3) concentration at pH 1.