Femtosecond observation of intramolecular charge- and proton-transfer reactions in a hydroxyflavone derivative

In this Letter, we report on direct observation of ultrafast intramolecular charge-transfer (ICT) reaction versus proton motion in 4'-dimethylaminoflavonol (DAMF) in solution. In an apolar medium, upon femtosecond excitation of a non planar structure of DMAF the ICT does not occur, and an abnormally slow (2 ps) proton motion takes place. In polar solvents, the ICT is very fast (100-200 fs) and the formed structure is stabilised in an extent that proton motion takes place in few or tens of ps. To our best knowledge, this is the first observation of competitive and related charge and proton transfers dynamics. (C) 2004 Elsevier B.V. All rights reserved.