Electron Transfer and Singlet Oxygen Mechanisms in the Photooxygenation of Dibutyl Sulfide and Thioanisole in MeCN Sensitized byN-Methylquinolinium Tetrafluoborate and 9,10-Dicyanoanthracene. The Probable Involvement of a Thiadioxirane Intermediate in Electron Transfer Photooxygenations

2003 ◽  
Vol 125 (52) ◽  
pp. 16444-16454 ◽  
Author(s):  
Enrico Baciocchi ◽  
Tiziana Del Giacco ◽  
Fausto Elisei ◽  
Maria Francesca Gerini ◽  
Maurizio Guerra ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Singlet Oxygen

Singlet oxygen and electron-transfer in photooxidations

1990 ◽  
Vol 9 ◽  
pp. 75
Author(s):  
Christopher S. Foote ◽  
Richard Kanner
Keyword(s):  
Electron Transfer ◽  
Singlet Oxygen

Oxidation of sulfides and disulfides under electron transfer or singlet oxygen photosensitization using soluble or grafted sensitizers

2002 ◽  
Vol 1 (5) ◽  
pp. 347-354 ◽  
Author(s):  
S. Lacombe ◽  
H. Cardy ◽  
M. Simon ◽  
A. Khoukh ◽  
J. Ph. Soumillion ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Singlet Oxygen ◽  
Oxidation Of Sulfides

Determination of Singlet Oxygen and Electron Transfer Mediated Mechanisms of Photosensitized Protein Damage by Phosphorus(V)porphyrins

2015 ◽  
Vol 28 (2) ◽  
pp. 262-267 ◽  
Author(s):  
Kazutaka Hirakawa ◽  
Hironobu Umemoto ◽  
Ryo Kikuchi ◽  
Hiroki Yamaguchi ◽  
Yoshinobu Nishimura ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Singlet Oxygen ◽  
Protein Damage

Nonradical oxidation in persulfate activation by graphene-like nanosheets (GNS): Differentiating the contributions of singlet oxygen (1O2) and sorption-dependent electron transfer

2020 ◽  
Vol 393 ◽  
pp. 124725 ◽  
Author(s):  
Shishu Zhu ◽  
Chao Jin ◽  
Xiaoguang Duan ◽  
Shaobin Wang ◽  
Shih-Hsin Ho
Keyword(s):  
Electron Transfer ◽  
Singlet Oxygen ◽  
Persulfate Activation

scholarly journals Vacancy-enhanced generation of singlet oxygen for photodynamic therapy

2019 ◽  
Vol 10 (8) ◽  
pp. 2336-2341 ◽  
Author(s):  
Shanyue Guan ◽  
Li Wang ◽  
Si-Min Xu ◽  
Di Yang ◽  
Geoffrey I. N. Waterhouse ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Photodynamic Therapy ◽  
Oxygen Vacancy ◽  
Singlet Oxygen ◽  
Band Gap ◽  
Ruthenium Complex

Oxygen vacancy introduced defects in the band gap of BiOBr–H allow facile electron transfer from a photo-excited ruthenium complex to the semiconductor, thereby increasing ROS yields and PDT efficiency.

scholarly journals Surface-Doped Graphitic Carbon Nitride Catalyzed Photooxidation of Olefins and Dienes: Chemical Evidence for Electron Transfer and Singlet Oxygen Mechanisms

Catalysts ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 639 ◽  
Author(s):  
Apostolos Chatzoudis ◽  
Vasileios Giannopoulos ◽  
Frank Hollmann ◽  
Ioulia Smonou
Keyword(s):  
Electron Transfer ◽  
Energy Transfer ◽  
Singlet Oxygen ◽  
Carbon Nitride ◽  
Solvent Polarity ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Electron Transfer Mechanism ◽  
Heterogeneous Nature ◽  
Chemical Evidence

A new photocatalytic reactivity of carbon-nanodot-doped graphitic carbon nitride (CD-C3N4) with alkenes and dienes, has been disclosed. We have shown that CD-C3N4 photosensitizes the oxidation of unsaturated substrates in a variety of solvents according to two competing mechanisms: the energy transfer via singlet oxygen (1O2) and/or the electron transfer via superoxide (O·−2). The singlet oxygen, derived by the CD-C3N4 photosensitized process, reacts with alkenes to form allylic hydroperoxides (ene products) whereas with dienes, endoperoxides. When the electron transfer mechanism operates, cleavage products are formed, derived from the corresponding dioxetanes. Which of the two mechanisms will prevail depends on solvent polarity and the particular substrate. The photocatalyst remains stable under the photooxidation conditions, unlike the most conventional photosensitizers, while the heterogeneous nature of CD-C3N4 overcomes usual solubility problems.

scholarly journals What is β–carotene doing in the photosystem II reaction centre?

2002 ◽  
Vol 357 (1426) ◽  
pp. 1431-1440 ◽  
Author(s):  
Alison Telfer
Keyword(s):  
Electron Transfer ◽  
Photosystem Ii ◽  
Excitation Energy ◽  
Triplet State ◽  
Singlet Oxygen ◽  
Spin Exchange ◽  
Primary Electron ◽  
Triplet States ◽  
Reaction Centre ◽  
Β Carotene

During photosynthesis carotenoids normally serve as antenna pigments, transferring singlet excitation energy to chlorophyll, and preventing singlet oxygen production from chlorophyll triplet states, by rapid spin exchange and decay of the carotenoid triplet to the ground state. The presence of two β–carotene molecules in the photosystem II reaction centre (RC) now seems well established, but they do not quench the triplet state of the primary electron–donor chlorophylls, which are known as P 680 . The β–carotenes cannot be close enough to P 680 for triplet quenching because that would also allow extremely fast electron transfer from β–carotene to P + 680 , preventing the oxidation of water. Their transfer of excitation energy to chlorophyll, though not very efficient, indicates close proximity to the chlorophylls ligated by histidine 118 towards the periphery of the two main RC polypeptides. The primary function of the β–carotenes is probably the quenching of singlet oxygen produced after charge recombination to the triplet state of P 680 . Only when electron donation from water is disturbed does β–carotene become oxidized. One β–carotene can mediate cyclic electron transfer via cytochrome b 559. The other is probably destroyed upon oxidation, which might trigger a breakdown of the polypeptide that binds the cofactors that carry out charge separation.

Recent Advances in the Mode of Action of Diphenyl Ethers and Related Herbicides

1990 ◽  
Vol 45 (5) ◽  
pp. 503-511 ◽  
Author(s):  
René Scalla ◽  
Michel Matringe ◽  
Jean-Michel Camadro ◽  
Pierre Labbe
Keyword(s):  
Electron Transfer ◽  
Singlet Oxygen ◽  
Mode Of Action ◽  
Membrane Lipids ◽  
Protoporphyrin Ix ◽  
Protoporphyrinogen Oxidase ◽  
Electron Transfer Chain ◽  
Diphenyl Ethers ◽  
Transfer Chain ◽  
Photosynthetic Electron Transfer

Several hypotheses have been proposed to explain the light-dependent phytotoxicity of diphenyl ethers and related herbicides: inhibition of photosynthesis; activation of herbicides by light, by the photosynthetic electron transfer chain or by excited forms of carotenoids; and interaction with the biosynthesis of tetrapyrrole pigments. It is shown that the most likely mode of action consists in inhibiting the enzyme protoporphyrinogen oxidase. As a consequence, protoporphyrinogen is oxidized non-enzymatically to protoporphyrin IX. The latter molecule is a powerful photosensitizer, able to generate singlet oxygen in the light and thus to induce peroxidative destruction of membrane lipids.

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