Intramolecular excited-state proton transfer in 3-hydroxyflavone. Hydrogen-bonding solvent perturbations

Journal Article · Sat Dec 31 23:00:00 EST 1983 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j150655a012· OSTI ID:5457774

McMorrow, D; Kasha, M

The phenomenon of excited-state proton transfer in 3-hydroxyflavone is shown to depend sensitively on traces of H-bonding impurities in hydrocarbon solvents. In extremely dry and highly purified hydrocarbon solvents, a unique tautomer yellow-green fluorescence (region I) is observed from 298 to 77 K, independent of solvent temperature and viscosity, in contradiction to the results of previous research. With traces of water present, three regions of fluorescence of 3-hydroxyflavone of 3-hydoxyflavone (2.0 x 10/sup -5/ M in methylcyclohexane (MCH)) can be observed, the tautomer yellow-green fluorescence (maximum at 523 nm) (region I), another green fluorescence (maximum at 497 nm) (region II) attributed to the solute anion, and a blue-violet fluorescence (maximum at 400 nm) (region III) attributed to the normal electromer of 3-hydroflavone. Excitation spectroscopy confirms the presence of a series of ground-state solvates which are correlated with the diverse luminescence behavior observed with water, alcohol, and ether both as trace impurities and as pure solvents. Potential energy curves for the various molecular species studied, and for various solvation modes, are used to reinterpret laser kinetic studies previously published. In particular the reported biexponential normal molecule fluorescence (III) decay, and tautomer fluorescence (I) rise time, are shown to represent a slow solvent-reorganization step from the polysolvated 3-hydroxyflavone and an ultrarapid intrinsic portion-transfer step for the intramolecularly H-bonded 3-hydroxyflavone.

• Research Organization: Florida State Univ., Tallahassee
• DOE Contract Number: AS05-78EV05855
• OSTI ID: 5457774
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 88:11; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
DATA
EMISSION SPECTROSCOPY
ENERGY
EXPERIMENTAL DATA
FLAVENOIDS
FLAVONES
FLUORESCENCE SPECTROSCOPY
HYDROGEN TRANSFER
HYDROXY COMPOUNDS
INFORMATION
MEDIUM TEMPERATURE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
POTENTIAL ENERGY
SOLVENT PROPERTIES
SPECTROSCOPY
VAN DER WAALS FORCES