Excited state proton transfer of beta-cyclodextrin encapsulated carbazole in the presence of urea

Excited state proton transfer (ESPT) reaction of carbazole (CAZL) in aqueous beta-cyclodextrin (beta CD), in the presence of urea, has been studied by both steady state as well, as time resolved methods. The unstructured anionic emission band from the excited fluorophore and the rate constants for the individual protropic processes reveal that urea expels the probe from the cyclodextrin microenvironment to the bulk aqueous phase. The same has also been established from the quenching study of the same fluorophore by iodide ion. (C) 1997 Elsevier Science B.V.