Photochemical Electron Transfer Between Methylene Blue and Quinones

1994 ◽  
Vol 47 (2) ◽  
pp. 209 ◽  
Author(s):  
M Misran ◽  
D Matthews ◽  
P Valente ◽  
A Hope
Keyword(s):  
Methylene Blue ◽  
Electron Transfer ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Lipid Vesicles ◽  
Laser Flash ◽  
Electron Transfer Reaction ◽  
Vitamin K1 ◽  
Photochemical Oxidant ◽  
Back Electron Transfer

Methylene Blue is a well known photochemical oxidant. In this paper we present results of cyclic voltammetry and laser flash photolysis experiments which demonstrate that Methylene Blue may function also as a photochemical reductant. Laser flash photolysis studies of Methylene Blue were carried out in aqueous solution at pH 10, in ethanol and in aqueous dispersions of lipid vesicles in the presence of benzoquinol , benzoquinone and the long-chain naphthoquinone Vitamin K1. Both the quinones and the quinol affected the transient of the decay of triplet Methylene Blue to its ground electronic state. The transients were biphasic and characteristic of an initial electron transfer reaction between triplet Methylene Blue and the quinone or quinol , followed by back electron transfer between the products. For Vitamin K1 and Methylene Blue in ethanol the back electron transfer was very slow (lifetime about 4 ms). This slow back electron transfer is favourable to the use of this system for energy storage via photosynthetic solar energy conversion.

Photochemical Electron Transfer in the System Polypyrrole-Methylene Blue

1994 ◽  
Vol 47 (6) ◽  
pp. 1163 ◽  
Author(s):  
D Matthews ◽  
A Altus ◽  
A Hope
Keyword(s):  
Methylene Blue ◽  
Electron Transfer ◽  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Vitamin K1 ◽  
Photochemical Reduction ◽  
Long Chain

Methylene Blue incorporated into colloidal oxidized polypyrrole was investigated by absorption spectroscopy and laser flash photolysis. The absorption spectra of Methylene Blue and polypyrrole were unaffected by incorporation. Flash photolysis transients of Methylene Blue and triplet Methylene Blue in ethanol were affected by 1,4-benzoquinone and 1,4-benzoquinol but not by the long-chain naphthoquinone Vitamin K1. Incorporation of Methylene Blue in polypyrrole produced distinct changes in the flash photolysis transients of Methylene Blue and triplet Methylene Blue. Very long-lived transients, with lifetimes of the order of 10 ms, were observed. These effects were accompanied by long-lived changes in the absorption spectrum of Methylene Blue. The transients were modified by the addition of 1,4-benzoquinone but not 1,4-benzoquinol. The results indicate photochemical reduction of oxidized polypyrrole by triplet Methylene Blue with the production of stable long-lived species capable of reducing 1,4-benzoquinone.

Electron transfer sensitized photolysis of 'onium salts

1988 ◽  
Vol 66 (2) ◽  
pp. 319-324 ◽  
Author(s):  
R. J. DeVoe ◽  
M. R. V. Sahyun ◽  
Einhard Schmidt ◽  
N. Serpone ◽  
D. K. Sharma
Keyword(s):  
Electron Transfer ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Quantitative Model ◽  
Intersystem Crossing ◽  
Single Electron Transfer ◽  
Onium Salts ◽  
Encounter Complex ◽  
Back Electron Transfer

We have studied the anthracene-sensitized photolyses of both diphenyliodonium and triphenylsulphonium salts in solution using both steady-state and laser flash photolysis techniques. Photoproducts, namely, phenylated anthracenes along with iodobenzene or diphenylsulphide, respectively, are obtained from both salts with quantum efficiencies of ca. 0.1 at 375 nm. We infer the intermediacy of diphenyliodo and triphenylsulphur radicals formed by single electron transfer from the singlet-excited anthracene. We have developed a quantitative model of this chemistry, and identify the principal sources of inefficiency as back electron transfer, which occurs at nearly the theoretically limiting rate, intersystem crossing from the initially formed sensitizer–'onium salt encounter complex, and in-cage radical recombination.

Silicon phthalocyanine-azobenzene-[60]fullerene light harvesting pentad: synthesis, characterization and electron transfer reaction studied by laser flash photolysis

2013 ◽  
Vol 17 (11) ◽  
pp. 1055-1063 ◽  
Author(s):  
Mohamed E. El-Khouly ◽  
Jong-Hyung Kim ◽  
Kwang-Yol Kay ◽  
Shunichi Fukuzumi
Keyword(s):  
Electron Transfer ◽  
Transfer Reaction ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Light Harvesting ◽  
Visible Spectrum ◽  
Laser Flash ◽  
Electron Transfer Reaction ◽  
Strong Light ◽  
Silicon Phthalocyanine

Electron-transfer reaction of the newly synthesized light harvesting pentad composed of silicon phthalocyanine (SiPc) that is connected with two fullerene C 60 and two azobenzene units to form SiPc -(azobenzene)2-( C 60)2 pentad has been studied by laser flash photolysis and other complementary techniques. This combination between SiPc , azobenzene and C 60 in the examined SiPc -(azobenzene)2-( C 60)2 pentad leads to strong light absorption over the whole visible spectrum. Photoexcitation of the pentad results in rapid formation of the charge-separated state by photoinduced electron transfer from the singlet-excited state of the SiPc moiety to the C 60 moiety. The charge-separated state has a lifetime of 2.50 ns in benzonitrile.

Laser flash-photolysis of methylene blue solutions

1979 ◽  
Vol 44 (7) ◽  
pp. 2015-2023 ◽  
Author(s):  
Viktor Řehák ◽  
Jaroslav Poskočil
Keyword(s):  
Methylene Blue ◽  
Electron Transfer ◽  
Energy Transfer ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Kinetic Measurements ◽  
Methanolic Solution ◽  
Triplet Excimer

Besides population and relaxation of T1 state of methylene blue in methanolic solution it has been possible to observe increase and decomposition of a transient with longer lifetime which is probably a triplet excimer of the dyestuff. Kinetic measurements have enabled to determine the lifetime of the T1 excimer, rate constants of energy-transfer to oxygen and electron-transfer from pyrrolidine to T1 of the dyestuff.

Intramolecular photoinduced electron transfer reactions of zinc(II) porphyrin dyads studied with a sub-ns time resolution

2020 ◽  
Vol 24 (09) ◽  
pp. 1099-1104
Author(s):  
Kei Sakakibara ◽  
Kenta Tomida ◽  
Tatsuo Nakagawa ◽  
Takeyoshi Yagyu ◽  
Hideo D. Takagi ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Time Resolution ◽  
Photoinduced Electron Transfer ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Electron Transfer Reaction ◽  
Transfer Reactions ◽  
Electron Transfer Reactions ◽  
Nanosecond Time Resolution

We report the dynamics of a intramolecular photoinduced electron transfer reaction of Zn(II)-porphyrin dyads that have a 2,2[Formula: see text]-bipyridine moiety at the periphery in the presence of Cu[Formula: see text] in methanol studied using laser flash photolysis with a sub-nanosecond time resolution. The photoinduced electron transfer reactions were observed from the excited [Formula: see text] and [Formula: see text] states of the Zn(II)-porphyrin to the Cu(II)-2,2[Formula: see text]-bipyridine moiety, and the structural dependence of the reactivity were discussed in terms of the distance between the electron donating and accepting centers.

Laser flash photolysis studies of intramolecular electron transfer in milk xanthine oxidase

Biochemistry ◽  
1983 ◽  
Vol 22 (23) ◽  
pp. 5270-5279 ◽  
Author(s):  
Anjan Bhattacharyya ◽  
Gordon Tollin ◽  
Michael Davis ◽  
Dale E. Edmondson
Keyword(s):  
Electron Transfer ◽  
Xanthine Oxidase ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Intramolecular Electron Transfer
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