scholarly journals Computational Study on the Mechanism of the Electron-Transfer-Induced Repair of the (6–4) T–T Photoproduct of DNA by Photolyase: Possibility of a Radical Cation Pathway

2014 ◽  
Vol 87 (3) ◽  
pp. 390-399 ◽  
Author(s):  
Toshiaki Matsubara ◽  
Nozomi Araida ◽  
Daichi Hayashi ◽  
Hatsumi Yamada
Keyword(s):  
Electron Transfer ◽  
Radical Cation ◽  
Computational Study

Radical ions in photochemistry. 21. The photosensitized (electron transfer) tautomerization of alkenes; the phenyl alkene system

1989 ◽  
Vol 67 (4) ◽  
pp. 689-698 ◽  
Author(s):  
Donald R. Arnold ◽  
Shelley A. Mines
Keyword(s):  
Hydrogen Bond ◽  
Electron Transfer ◽  
Radical Cation ◽  
Radical Anion ◽  
Phenyl Group ◽  
Oxidation Potential ◽  
Original Position ◽  
Acetonitrile Solution ◽  
Steric Interaction ◽  
Ambident Anion

Alkenes, conjugated with a phenyl group, can be converted to nonconjugated tautomers by sensitized (electron transfer) irradiation. For example, irradiation of an acetonitrile solution of the conjugated alkene 1-phenylpropene, the electron accepting photosensitizer 1,4-dicyanobenzene, the cosensitizer biphenyl, and the base 2,4,6-trimethylpyridine gave the nonconjugated tautomer 3-phenylpropene in good yield. Similarly, 2-methyl-1-phenylpropene gave 2-methyl-3-phenylpropene, and 1-phenyl-1-butene gaveE- and Z-1-phenyl-2-butene. The reaction also works well with cyclic alkenes. For example, 1-phenylcyclohexene gave 3-phenylcyclohexene, and 1-(phenylmethylene)cyclohexane gave 1-(phenylmethyl)cyclohexene. The proposed mechanism involves the initial formation of the alkene radical cation and the sensitizer radical anion, induced by irradiation of the sensitizer and mediated by the cosensitizer. Deprotonation of the radical cation assisted by the base gives the ambident radical, which is then reduced to the anion by the sensitizer radical anion. Protonation of the ambident anion at the benzylic position completes the sequence. Reprotonation at the original position is an energy wasting step. Tautomerization is driven toward the isomer with the higher oxidation potential, which is, in the cases studied, the less thermodynamically stable isomer. The regioselectivity of the deprotonation step is dependent upon the conformation of the allylic carbon–hydrogen bond. The tautomerization of 2-methyl- 1-phenylbutene gave both 2-phenylmethyl-1-butène and 2-methyl-1-phenyl-2-butene (E and Z isomers), while 2,3-dimethyl- 1-phenylbutene gave only 3-methyl-2-phenylmethyl-1 -butene. In the latter case, steric interaction of the methyls on the isopropyl group prevents effective overlap of the tertiary carbon–hydrogen bond with the singly occupied molecular orbital, thus inhibiting deprotonation from this site. Keywords: photosensitized, electron transfer, alkene, tautomerization, radical cation.

Impact of the Extended 1,1′-Bipyridinium Structure on the Electron Transfer and π-Dimer Formation. Spectroelectrochemical and Computational Study

2015 ◽  
Vol 119 (32) ◽  
pp. 18056-18065 ◽  
Author(s):  
Ján Tarábek ◽  
Viliam Kolivoška ◽  
Miroslav Gál ◽  
Lubomír Pospíšil ◽  
Michal Valášek ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Computational Study ◽  
Dimer Formation

Transient Absorption Spectroscopy of the Electron Transfer Step in the Photochemically Activated Polymerizations of N-ethylcarbazole and 9-phenylcarbazole.

2021 ◽  
Author(s):  
Georgia Thornton ◽  
Ryan Phelps ◽  
Andrew Orr-Ewing
Keyword(s):  
Electron Transfer ◽  
Radical Cation ◽  
Absorption Spectroscopy ◽  
Electron Acceptor ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Transfer Step

The polymerization of photoexcited N-ethylcarbazole (N-EC) in the presence of an electron acceptor begins with an electron transfer (ET) step to generate a radical cation of N-EC (N-EC+.). Here, the...

scholarly journals Host–Guest-Induced Electron Transfer Triggers Radical-Cation Catalysis

2020 ◽  
Vol 142 (5) ◽  
pp. 2134-2139 ◽  
Author(s):  
Rebecca L. Spicer ◽  
Athanasios D. Stergiou ◽  
Tom A. Young ◽  
Fernanda Duarte ◽  
Mark D. Symes ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Radical Cation

Electron-Transfer Induced Repair of 6-4 Photoproducts in DNA:  A Computational Study

2007 ◽  
Vol 111 (12) ◽  
pp. 2351-2361 ◽  
Author(s):  
O. Anders Borg ◽  
Leif A. Eriksson ◽  
Bo Durbeej
Keyword(s):  
Electron Transfer ◽  
Computational Study

Proton and Electron Transfer Mechanisms in the Formation of Neutral and Charged Quinhydrone-Like Complexes: A Multilayered Computational Study

2014 ◽  
Vol 10 (11) ◽  
pp. 4883-4895 ◽  
Author(s):  
Vincenzo Barone ◽  
Ivo Cacelli ◽  
Alessandro Ferretti ◽  
Giacomo Prampolini ◽  
Giovanni Villani
Keyword(s):  
Electron Transfer ◽  
Computational Study ◽  
Transfer Mechanisms
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