Deazaflavin photocatalyzed methyl viologen reduction in water. A laser flash-photolysis study

1982 ◽  
Vol 86 (13) ◽  
pp. 2406-2409 ◽  
Author(s):  
Antone J. W. G. Visser ◽  
Janos H. Fendler
Keyword(s):  
Methyl Viologen ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash

Photochemistry of Free-Base Porphyrin Linked to Methyl Viologen

1992 ◽  
Vol 57 (1) ◽  
pp. 26-32 ◽  
Author(s):  
N. M. Guindy ◽  
F. M. Elzawawy ◽  
D. Y. Sabry
Keyword(s):  
Methyl Viologen ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Phenyl Group ◽  
Laser Flash ◽  
Porphyrin Ring ◽  
Free Base ◽  
Intramolecular Quenching ◽  
Quenching Efficiency ◽  
Triton X

The photochemistry of free-base meso-tetraphenylporphyrin linked to methyl viologen via an alkoxy chain (n = 3) at the ortho, meta or para-position of one meso-phenyl group, in Triton X-100 micellar aqueous solutions is reported. The appended viologen does not quench the porphyrin fluorescence nor its triplet excited state due to the different solubilization of both parts of the molecule in the medium where the porphyrin ring resides in the hydrophobic phase and the alkoxy linker protrudes into the rather diffuse outer phase of detergent oxyethylene units, while the viologen moiety penetrates into the aqueous layer. However, laser flash photolysis measurements show that in the presence of nicotinamide dinucleotide, NADH, the porphyrin ring is reduced to phlorin due to the penetration of NADH into the organic phase. For porphyrin-tetraviologen in which a viologen molecule is linked to each of the porphyrin meso-position via alkoxy chain, fluorescence quenching could be achieved. The values of the quenching efficiency are high (94% in acetonitrile) compared to intramolecular quenching and are dependent upon the solvent viscosity.

Effect of Aggregation on Bacteriochlorin a Triplet-state Formation: A Laser Flash Photolysis Study¶

2002 ◽  
Vol 76 (5) ◽  
pp. 480 ◽  
Author(s):  
Xavier Damoiseau ◽  
Francis Tfibel ◽  
Maryse Hoebeke ◽  
Marie-Pierre Fontaine-Aupart
Keyword(s):  
Triplet State ◽  
State Formation ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash

A Laser Flash Photolysis and Pulse Radiolysis Study of Primary Photochemical Processes of Flumequine¶

2000 ◽  
Vol 72 (4) ◽  
pp. 451 ◽  
Author(s):  
M. Bazin ◽  
F. Bosca ◽  
M. L. Marin ◽  
M. A. Miranda ◽  
L. K. Patterson ◽  
...  
Keyword(s):  
Pulse Radiolysis ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Photochemical Processes

Laser Flash Photolysis Studies of the UVA Sunscreen Mexoryl® SX

1999 ◽  
Vol 70 (3) ◽  
pp. 292
Author(s):  
Ann Cantrell ◽  
David J. McGarvey ◽  
Louise Mulroy ◽  
T. George Truscott
Keyword(s):  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash

Singlet Methylene Removal Rate Constants from the (0,1,0) Vibrational Level: Enhancement via Complex-Mediated Vibrational Relaxation

2001 ◽  
Vol 215 (6) ◽  
Author(s):  
M.A. Buntine ◽  
G.J. Gutsche ◽  
W.S. Staker ◽  
M.W. Heaven ◽  
K.D. King ◽  
...  
Keyword(s):  
Vibrational Level ◽  
Rate Constants ◽  
Vibrational Relaxation ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Removal Rate ◽  
Laser Flash ◽  
Laser Absorption ◽  
Photolysis Laser ◽  
Singlet Methylene

The technique of laser flash photolysis/laser absorption has been used to obtain absolute removal rate constants for singlet methylene,

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.

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