Electron-transfer reactions of chlorophyll a and porphyrin triplets with radicals in aqueous micellar solutions

Journal Article · Thu Nov 11 04:00:00 EST 1982 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100220a016· OSTI ID:6537906

Levanon, H; Neta, P

The reactivity of the photoexcited triplet states of chlorophyll a (Chla), ZnTPP, and MgTPP (P/sup T/) with radicals was studied in neutral micelles by pulse radiolysis and photolysis (PRAP) spectroscopy. Steady-state triplet concentration was produced by a 2-ms light pulse, and the system was then subjected to a 10-ns electron pulse to form the radicals (CH/sub 3/)/sub 2/COH, Br/sub 2//sup -/. and MV/sup +/. from the proper solutes. The triplet states were found to undergo one-electron reduction by (CH/sub 3/)/sub 2/COH and oxidation by Br/sub 2//sup -/. with second-order rate constants approaching the diffusion-controlled limit and significantly more rapidly than the reactions of the ground states. The reaction of the triplet states (P/sup T/) with MV/sup +/. radicals was found to result in an overall recovery of the ground-state P from P/sup T/. The mechanism of this process is discussed in terms of two steps of electron transfer. P/sup T/ + MV/sup +/. ..-->.. P/sup -/. + MV/sup 2 +/ ..-->.. P + MV/sup +/.

• Research Organization: Univ. of Notre Dame, IN
• OSTI ID: 6537906
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 86:23; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500 -- Photochemistry
ABSORPTION SPECTRA
AROMATICS
AZINES
BIPYRIDINES
CARBOXYLIC ACIDS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHLOROPHYLL
CONDENSED AROMATICS
DECOMPOSITION
ELECTRON TRANSFER
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
KINETICS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
PYRENE
PYRIDINES
REACTION KINETICS
SPECTRA