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Excited State Processes in 1‐Deazariboflavin Studied by Ultrafast Fluorescence Kinetics
Author(s) -
Slavov Chavdar,
Mansurova Madina,
Holzwarth Alfred R.,
Gärtner Wolfgang
Publication year - 2010
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.1751-1097.2009.00646.x
Subject(s) - chemistry , fluorescence , excited state , photochemistry , tautomer , moiety , time resolved spectroscopy , protonation , acetonitrile , fluorescence spectroscopy , derivative (finance) , hydrogen bond , solvent , analytical chemistry (journal) , stereochemistry , molecule , organic chemistry , ion , physics , quantum mechanics , nuclear physics , financial economics , economics
The photochemical reactions of the 1‐deaza derivative of riboflavin (RF) have been studied by sub‐ps time‐resolved fluorescence spectroscopy. A potential effect of the solvent polarity and hydrogen bonding capability on the excited state (ES) dynamics was tested by measuring 1‐deaza RF in water and, after acetylation of the sugar moiety, also in acetonitrile. Opposite to former reports, which indicated no fluorescence after laser excitation (Spencer et al. [1977] Biochemistry 16 : 3586–3594), we find a significant fluorescence in either solvent. For both compounds, the fluorescence decays are biexponential with lifetimes in the ps time domain (1.8 and 12.5 ps for 1‐deaza RF, and 3 and 87 ps for Ac 4 ‐1‐deaza RF). In addition, a third, independent fluorescence decay was observed for both compounds. The remarkably slower second decay process for the measurements of the tetra‐acetyl derivative in acetonitrile points to the involvement of hydrogen bonding or changes in the protonation/tautomerization state in the ES. In contrast to the parent compound (RF), no triplet state formation can be detected for 1‐deaza RF, making the internal conversion and the fluorescence the only decay processes of the ES.