Ultrafast measurements of excited state intramolecular proton transfer (ESIPT) in room temperature solutions of 3-hydroxyflavone and derivatives

Year: 2001

Authors: Ameer-Beg S., Ormson S.M., Brown R.G., Matousek P., Towrie M., Nibbering E.T.J., Foggi P., Neuwahl F.V.R.

Autors Affiliation: Centre for Photochemistry, University of Central Lancashire, Preston, Lanes PR1 2HE, United Kingdom; Central Laser Facility, CLRC Rutherford-Appleton Laboratory, Didcot, Oxfordshire 0X11 OQX, United Kingdom; Max-Born-Institut Für Nichtlineare Optik Und Kurzzeitspektroskopie, Rudower Chaussee 6, D-12489 Berlin, Germany; LENS, Largo E. Fermi 2, Florence, Italy; School of Applied Sciences, University of Glamorgan, Pontypridd, Mid Glamorgan CF37 1DL, United Kingdom

Abstract: Ultrafast pump-probe studies of room-temperature solutions of 3-hydroxyflavone (3-HF) and some 4\’-substituted derivatives have been undertaken. Transient absorption attributable to the two zwitterionic forms of the excited tautomer arising from excited-state intramolecular proton transfer (ESIPT) was observed across most of the visible spectral region. For 3-HF in methylcyclohexane and acetonitrile, the ESIPT was found to be so rapid that it was only possible to assign a time constant of 35 fs to the process. In ethanol, however, a time constant of 60 fs was determined. The slower ESIPT in this solvent was attributed to the greater strength of the solute-solvent interactions. For the derivatives of 3-HF in all three solvents, the ESIPT step was also found to be instrument-limited. In addition to the femtosecond kinetics, there was also a picosecond component of the kinetics that is attributed to ESPT in molecules that are intermolecularly hydrogen bonded to the solvent.

Journal/Review: JOURNAL OF PHYSICAL CHEMISTRY A

Volume: 105 (15)      Pages from: 3709  to: 3718

KeyWords: Excited state intramolecular proton transfer (ESIPT), Acetonitrile; Derivatives; Ethanol; Hydrogen bonds; Light absorption; Optical pumping; Solutions; Solvents, Aromatic compounds
DOI: 10.1021/jp0031101

Citations: 237
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