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Z/E PHOTOISOMERIZATION OF UROCANIC ACID*
Author(s) -
Morrison H.,
Avnir D.,
Bernasconi C.,
Fagan G.
Publication year - 1980
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.1751-1097.1980.tb04046.x
Subject(s) - photoisomerization , urocanic acid , photostationary state , isomerization , chemistry , photochemistry , aqueous solution , triplet state , organic chemistry , molecule , enzyme , histidine , catalysis
— The E ⇆ Z photoisomerization of the title compound (UA) (a naturally occurring sunscreen) has been studied in aqueous solution. At a UA concentration of 6m M and using 313nm excitation, φ E→z = 0.52, φ Z→E = 0.47 and the photostationary state is 34% E. Under these conditions, loss of UA is minimal. Low energy triplet quenchers fail to impede the isomerization, but the reaction can be induced by several triplet sensitizers. The E T for UA is estimated to be approximately 55 kcal/mol.