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RELATIVE REACTIVITIES OF THE EXCITED STATES OF FUROCOUMARINS FOR [2+2] PHOTOCYCLOADDITION REACTION WITH TETRAMETHYLETHYLENE
Author(s) -
Shim Sang Chul,
Kang HO Kwon
Publication year - 1987
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.1751-1097.1987.tb05402.x
Subject(s) - excited state , chemistry , singlet state , photochemistry , quenching (fluorescence) , furocoumarins , triplet state , cycloaddition , fluorescence , atomic physics , physics , organic chemistry , quantum mechanics , catalysis
— The Stern‐Volmer constants for fluorescence quenching by tetramethylethylene decrease in the order DMC ≫ DHP > F‐2 > 8‐MOP. The same order was observed for the quantum yields of [2+2] cycloaddition reaction with tetramethylethylene on direct irradiation. In [2+2] photocycloaddition of F‐2 with tetramethylethylene in ethanol, the ratio of quantum yields deduced from singlet and triplet states of F‐2; φ 3 0 /φ 1 0 , is about 5. The excited triplet state is the reactive state for the [2+2] photocycloaddition of F‐2 with tetramethylethylene in solution but the excited singlet state of F‐2 becomes very important in biological conditions.