Journal ArticleDOI
Kinetics of Fluorescence Quenching by Electron and H‐Atom Transfer
Dieter Rehm,Albert Weller +1 more
TLDR
In this article, the rate constants of 60 typical electron donor-acceptor systems have been measured in de-oxygenated acetonitrile and are shown to be correlated with the free enthalpy change, ΔG23, involved in the actual electron transfer process.Abstract:
Fluorescence quenching rate constants, kq, ranging from 106 to 2 × 1010 M−1 sec−1, of more than 60 typical electron donor-acceptor systems have been measured in de-oxygenated acetonitrile and are shown to be correlated with the free enthalpy change, ΔG23, involved in the actual electron transfer process
in the encounter complex and varying between + 5 and −60 kcal/mole. The correlation which is based on the mechanism of adiabatic outer-sphere electron transfer requires ΔG≠23, the activation free enthalpy of this process to be a monotonous function of ΔG23 and allows the calculation of rate constants of electron transfer quenching from spectroscopic and electrochemical data.
A detailed study of some systems where the calculated quenching constants differ from the experimental ones by several orders of magnitude revealed that the quenching mechanism operative in these cases was hydrogen-atom rather than electron transfer.
The conditions under which these different mechanisms apply and their consequences are discussed.read more
Citations
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Kinetic pathway investigations of three‐component photoinitiator systems for visible‐light activated free radical polymerizations
TL;DR: In this article, the authors investigated the key factors involved with visible-light activated free radical polymerizations involving three-component photoinitiators and 2-hydroxyethyl methacrylate.
Journal ArticleDOI
Photochemically catalyzed Diels–Alder reaction of arylimines with N-vinylpyrrolidinone and N-vinylcarbazole by 2,4,6-triphenylpyrylium salt: synthesis of 4-heterocycle-substituted tetrahydroquinoline derivatives
TL;DR: In this paper, photochemically promoted Diels-Alder reactions of N-arylimines with N-vinylpyrrolidinone and Nvinylcarbazole were achieved by using 2,4,6-triphenylpyrylium tetrafluoroborate as a catalyst to produce corresponding 2-oxopyrrolidsin-1-yl and carbazol-9-yltetrahydroquinolines in high yields.
Journal ArticleDOI
Electron paramagnetic resonance evidence of the generation of superoxide (O2.-) and hydroxyl (.OH) radicals by irradiation of a new photodynamic therapy photosensitizer, Victoria Blue BO.
TL;DR: Electron paramagnetic resonance experiments were performed on Victoria Blue BO, a cationic dye whose photocytotoxicity has been studied against the human leukaemic cell lines K-562 and TF-1, showing that, on illumination in aerated aqueous solution or DL-alpha-dipalmitoylphosphatidylcholine liposomes, photoexcited Victoria BlueBO is unable to generate 1O2.
Journal ArticleDOI
Photochemical and Photophysical Properties of C60 Dendrimers Studied by Laser Flash Photolysis
TL;DR: In this paper, the photochemical and photophysical properties of fullerene dendrimers were investigated by time-resolved fluorescence and timeresolved absorption methods, in addition to steady-state spectra.
Journal ArticleDOI
Flavonol dyes with different substituents in photopolymerization
TL;DR: In this paper, six flavonol dyes with different substituents were prepared by using the Algar-Flynn-Oyamada method, and steadystate photolysis and fluorescence quenching of 3HFs under the 385 nm LED light source showed that the proton transfer reaction preceded the charge transfer reaction between 3Hs and triethanolamine (TEOA) or iodonium salts (ONI), and groups with different electron properties could affect the photochemistry of 3HCs.
References
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Journal ArticleDOI
On the Theory of Oxidation‐Reduction Reactions Involving Electron Transfer. I
TL;DR: In this paper, a mechanism for electron transfer reactions is described, in which there is very little spatial overlap of the electronic orbitals of the two reacting molecules in the activated complex, and a quantitative theory of the rates of oxidation reduction reactions involving electron transfer in solution is presented.
Journal ArticleDOI
Chemical and Electrochemical Electron-Transfer Theory
TL;DR: In this article, a review of electron transfer reactions is presented, focusing on the absence of bond rupture in the reaction step, which is a unique feature of purely electron-transfer reactions.
Journal ArticleDOI
Polarographic Oxidation Potentials of Aromatic Compounds
E. S. Pysh,N. C. Yang +1 more
TL;DR: In this article, the oxidation half-wave potentials of fifty-three organic compounds were determined in acetonitrile at a rotating Pt electrode, and these values were correlated with ionization potentials, with interaction energies of charge transfer complexes with trinitrofluorenone, with Huckel coefficients of the resonance integral in the expression for the highest occupied molecular orbital energy level, and with pabsorption band spectra.
Journal ArticleDOI
Electron-transfer and complex formation in the excited state
TL;DR: In this paper, a broad structureless emission band about 5000 cm1 was observed to increase with increasing electron donor concentration at the expense of the fluorescence intensity of the hydrocarbon, thereby following the same Stern-Volmer-type relation as does the well known excimer fluorescence.