Greater Fluorescence from Styrylpyridinium Dye upon Complexation with Cyclodextrin Derivatives through a π-π Interaction

The fluorescence of 4-(4′-dimethylamino)styryl-1-methylpyridinium (C1SP) was enhanced by more than 33-fold by complexation with β-cyclodextrin (β-CD) bearing a naphthalene, pyrene, or phenylboronic acid group. The great enhancement of the fluorescence of C1SP was due to a π-π stacking interaction, by which the bond rotation of C1SP was effectively suppressed. The results indicate that C1SP and structurally related hemicyanine dyes potentially become powerful fluorescent indicators for aromatic compounds through the π-π stacking interaction in water.