Inclusion by β-cyclodextrin of a pyrene-labeled dipeptide photoprobe

An alanyltryptophan dipeptide (1), labeled at the N-terminus with a pyrene moiety is bound strongly by β-cyclodextrin in water, leading to enhancement of the fluorescence of the photoprobe. The effect is ascribed to restriction of conformational freedom for the dipeptide and a consequent reduction in the rate of intramolecular electron transfer that occurs between pyrene and Trp/indole moieties.