z-logo
Premium
Stepwise Two‐Photon Excitation of 1,5‐Dihydroflavin Mononucleotide: Study of Flavosemiquinone Properties
Author(s) -
HanineLmoumene Chaibia El,
Lindqvist Lars
Publication year - 1997
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.1751-1097.1997.tb03194.x
Subject(s) - chemistry , photoionization , photochemistry , radical , absorbance , protonation , dissociation (chemistry) , microsecond , excitation , solvated electron , quantum yield , photodissociation , analytical chemistry (journal) , fluorescence , ionization , ion , radiolysis , physics , organic chemistry , chromatography , astronomy , quantum mechanics , electrical engineering , engineering
— Photoionization of 1,5‐dihydroflavin mononucleotide in aqueous solution, leading to formation of hydrated electrons and flavosemiquinone radicals, was studied by nanosecond laser photolysis (excitation at LD = 354.7 nm). Analysis of the laser fluence dependence of the photoionization yield indicates that the reaction is a stepwise two‐photon reaction with the fluorescent state of the flavin as intermediate step. Extinction coefficients of the neutral and anionic flavosemiquinone were obtained from transient absorbance measurements at 310‐660 nm. The pro‐tolytic dissociation constant of the neutral radical was determined from a study at pH 7.3‐10.3 of the spectral evolution in the submicrosecond time range due to de‐protonation of this radical. The value pK a = 8.7 0.1 was obtained. The formation of tautomeric species of the neutral flavosemiquinone was suggested based on the existence of a spectral evolution of this species during the first microseconds after excitation.

This content is not available in your region!

Continue researching here.

Having issues? You can contact us here