Spectroscopic studies of inclusion of 4H-1-benzopyran-4-thione in a β-cyclodextrin cavity

Spectral and photophysical properties of 4H-1-benzopyran-4-thione (BFT) in aqueous solutions of β-cyclodextrin (β-CD) and in some solvents have been investigated by stationary methods. Both fluorescence and phosphorescence of BPT are observable at room temperature. Results indicate the formation of an inclusion complex. Spectral shifts in the absorption spectrum and the shape of the phosphorescence spectrum mostly depend on the polarity of environment whereas the photophysical properties of the second excited singlet state depend on other structural properties of the medium, which allows us to investigate interactions between water molecules and complexed molecules. These properties make BFT a very convenient probe in the investigation of photophysics of inclusion complexes.