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Excited‐state Acidity of Bifunctional Compounds. 7. Long Distance, Solvent‐assisted Excited‐state Proton Transfer in Olivacine
Author(s) -
Cabo Jaqueline L. do,
Faria Herbert B.,
Portugal Samira G. M.,
Silva Marco A. A.,
Brinn Ira M.
Publication year - 1999
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1999.tb03343.x
Subject(s) - excited state , bifunctional , proton , chemistry , photochemistry , state (computer science) , solvent , atomic physics , organic chemistry , catalysis , computer science , physics , quantum mechanics , algorithm
— By use of fluorescence spectroscopy and time‐correlated single photon counting, solvent‐assisted excited‐state proton transfer (ESPT) has been observed for olivacine in two organic solvents, 1,4‐dioxane and methanol. Because of spectral overlap, factor analysis was used to determine the emission spectrum of the proton‐transferred (PT) species. The ESPT is not observed in the nonpolar solvent n ‐hexane. For the first time in a system of this type, the individual excited‐state rate constants have been calculated exactly from time‐resolved single photon counting results. Because the PT process involves a path of more than 6 Å, its individual rate constant is extremely low, approximately 10 7 s −1 .