scholarly journals Adenine Radical Cation Formation by a Ligand-Centered Excited State of an Intercalated Chromium Polypyridyl Complex Leads to Enhanced DNA Photo-oxidation

2021 ◽  
Vol 143 (36) ◽  
pp. 14766-14779
Author(s):  
Frederico A. Baptista ◽  
Dorottya Krizsan ◽  
Mark Stitch ◽  
Igor V. Sazanovich ◽  
Ian P. Clark ◽  
...  
Keyword(s):  
Excited State ◽  
Radical Cation ◽  
Photo Oxidation ◽  
Polypyridyl Complex

scholarly journals Emission spectroscopy of a ruthenium(ii) polypyridyl complex adsorbed on calcium niobate lamellar solids and nanosheets

2015 ◽  
Vol 17 (27) ◽  
pp. 17962-17966 ◽  
Author(s):  
Kazuhiko Maeda ◽  
Takayoshi Oshima ◽  
Osamu Ishitani
Keyword(s):  
Excited State ◽  
Conduction Band ◽  
Morphological Feature ◽  
Emission Spectroscopy ◽  
Preparation Method ◽  
Electron Injection ◽  
Polypyridyl Complex ◽  
Calcium Niobate

Electron injection from the excited state of a Ru(ii) polypyridyl complex occurs not only in the conduction band of HCa2Nb3O10 but also surface traps whose density is strongly dependent on both the morphological feature and the preparation method of HCa2Nb3O10.

The importance of conformation in the reactivity of radical cations. Changing configuration at saturated carbon centres

1992 ◽  
Vol 70 (1) ◽  
pp. 272-279 ◽  
Author(s):  
Allyson L. Perrott ◽  
Donald R. Arnold
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Molecular Mechanics ◽  
Radical Cation ◽  
Trans Isomer ◽  
Radical Cations ◽  
Singlet Excited State ◽  
Photostationary State ◽  
Configurational Isomerization ◽  
Cis Isomer

Irradiation of an acetonitrile solution of cis 1-methyl-2-phenylcyclopentane (1bcis); 1,4-dicyanobenzene (2), an electron-accepting photosensitizer; and 2,4,6-collidine (3), a nonnucleophilic base, leads to configurational isomerization of the cyclopentane; the photostationary state lies > 99% in favour of the trans isomer. The mechanism proposed for this reaction involves formation of the radical cation of 1bcis by photoinduced electron transfer to the singlet excited state of 2, deprotonation of the radical cation assisted by the base 3, reduction of the resulting benzylic radical by the radical anion [Formula: see text], and reprotonation of the benzylic anion to give both the cis and the trans isomers of 1b. The photostationary state is controlled by the relative rates of deprotonation of the radical cations of 1bcis and trans; these rates are dependent upon the extent of overlap of the SOMO of the radical cation, which is largely associated with the phenyl ring, and the benzylic carbon–hydrogen bond. Molecular mechanics calculations (MM3 and MMP2) are used to calculate the preferred conformations of the isomers. The required orbital overlap is 31% effective with the global minimum conformation of the cis isomer and essentially ineffective for the low-lying conformations of the trans isomer. This proposed mechanism is supported by Stem–Volmer quenching studies, which indicate that both isomers quench the singlet excited state of 2 at the diffusion-controlled rate, and by deuterium incorporation studies. When irradiation of the cis isomer is carried out in acetonitrile–methanol-O-d as solvent, isomerization is accompanied by deuterium exchange at the benzylic position; the trans isomer is stable under these conditions. Keywords: photosensitized electron transfer, radical cation, deprotonation, configurational isomerization, conformation, molecular mechanics (MM3).

Novel Photoreactions of 2-Aza-1,4-dienes in the Triplet Excited State and via Radical-Cation Intermediates. 2-Aza-di-π-methane Rearrangements Yielding Cyclopropylimines andN-Vinylaziridines

2003 ◽  
Vol 68 (17) ◽  
pp. 6661-6671 ◽  
Author(s):  
Diego Armesto ◽  
Olga Caballero ◽  
Maria J. Ortiz ◽  
Antonia R. Agarrabeitia ◽  
Mar Martin-Fontecha ◽  
...  
Keyword(s):  
Excited State ◽  
Radical Cation ◽  
Triplet Excited State

Tryptophan Photo-Oxidation by Clay-Adsorbed Sensitizers

Clay Minerals ◽  
1988 ◽  
Vol 23 (2) ◽  
pp. 205-212 ◽  
Author(s):  
J. Cenens ◽  
R. A. Schoonheydt
Keyword(s):  
Methylene Blue ◽  
Excited State ◽  
Rose Bengal ◽  
External Surface ◽  
Adsorption Site ◽  
Photo Oxidation ◽  
Dye Aggregation ◽  
Wyoming Bentonite

AbstractThe photo-oxidation of tryptophan (TRP), photosensitized by methylene blue (MB) exchanged on hectorite, Wyoming bentonite and laponite is strongly influenced by three factors: (i) Fe(III) in the structure, which quenches the excited state of MB; (ii) the adsorption site of MB, as photo-oxidation only takes place with MB on the external surface; (iii) dye aggregation, which reduces the yield. Rose bengal (RB), chemically anchored on the external surface of Barasym does not sensitize the photo-oxidation of TRP.

scholarly journals Anatomy of the Photochemical Reaction: Excited-State Dynamics Reveals the C–H Acidity Mechanism of Methoxy Photo-oxidation on Titania

2015 ◽  
Vol 6 (9) ◽  
pp. 1624-1627 ◽  
Author(s):  
Grigory Kolesov ◽  
Dmitry Vinichenko ◽  
Georgios A. Tritsaris ◽  
Cynthia M. Friend ◽  
Efthimios Kaxiras
Keyword(s):  
Excited State ◽  
Photochemical Reaction ◽  
Excited State Dynamics ◽  
Photo Oxidation

Bimolecular Hole Transfer from the Trimethoxybenzene Radical Cation in the Excited State

2007 ◽  
Vol 111 (22) ◽  
pp. 4743-4747 ◽  
Author(s):  
Xichen Cai ◽  
Mamoru Fujitsuka ◽  
Tetsuro Majima
Keyword(s):  
Excited State ◽  
Radical Cation ◽  
Hole Transfer
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