Abstract

One of the most widely studied systems exhibiting proton transfer (PT) has been 3-hydroxyflavone (3HF). Proton transfer in 3HF was first proposed [1] to explain the observation of two distinct fluorescence bands in the blue and green spectral regions following the absorption of a UV photon. The blue, or near UV fluorescence is thought to arise from the normal form of the molecule, whereas emission from the tautomer is the more strongly Stokes shifted green fluorescence (Fig. 1). Careful studies have shown that the blue, normal emission appears only when 3HF is in hydrogen bonding solvents or in the presence of hydrogen bonding impurities. [2] In non-polar solvents, even at low temperatures, only the green tautomer emission is observed.

© 1992 The Author(s)