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Sensitization of Peroxynitrite Chemiluminescence by the Triplet Carbonyl Sensitizer Coumarin‐525. Effect of CO 2
Author(s) -
Sharov Victor S.,
Driomina Elena S.,
Briviba Karlis,
Sies Helmut
Publication year - 1998
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.1751-1097.1998.tb05286.x
Subject(s) - peroxynitrite , chemistry , photochemistry , chemiluminescence , excited state , coumarin , yield (engineering) , organic chemistry , superoxide , physics , materials science , nuclear physics , metallurgy , enzyme
— The flash of spontaneous chemiluminescence (CL) that reflects the formation of electronically excited intermediates during the decay of peroxynitrite (ONOO) to nitrate was investigated. The half‐decay time of the CL flash (0.5 ± 0.1 s) was in agreement with the half‐life of peroxynitrite obtained in stopped‐flow experiments. The spontaneous CL intensity was linearly dependent on peroxynitrite concentration. The yield of spontaneous CL from peroxynitrite decay, 2 × 10 ‐9 photons/peroxynitrite at pH 9.5, was strongly enhanced by a sensitizer of triplet carbonyl CL, coumarin‐525 (C‐525). The maximal yield of sensitized CL was calculated to be 3 × 10 ‐6 photons/ peroxynitrite molecule for infinite concentration of C‐525. The dependence of both spontaneous and sensitized CL on pH has a maximum at about pH 9.5. Bubbling with CO 2 or addition of NaHCO 3 considerably enhanced the flash of CL, and it is concluded that the reaction of the peroxynitrite anion with CO 2 is a major pathway leading to the formation of an electronically excited intermediate of peroxynitrite.