Excited state chemistry of flavone derivatives in a confined medium: ESIPT emission in aqueous media.

The excited state behavior of two flavone derivatives 3-hydroxyflavone and 4'-N,N-diethylaminoflavonol in a confined medium indicates that supramolecular effects could alter the nature of the fluorescence emission. Within the octa acid host the neutral unionized species of these two dyes are present showing large Stokes shifted emission due to intramolecular proton transfer, a pattern different from that in aqueous medium.