Singlet and triplet reactivity in the photoinduced electron transfer from aromatic amines to chlorobenzenes

Ávila, Vicente; Cosa, Juan J.; Chesta, Carlos A.; Previtali, Carlos M.

doi:10.1016/1010-6030(91)85107-r

Cited by 14 publications

(9 citation statements)

References 32 publications

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“…Although there have been few studies showing a specific role of the inner-sphere barrier, its importance has been suggested in the electron transfer to a halogenated compound R-Cl that leads to stretching of the C-Cl bond and eventual dissociation of the negative ion.6•7 A contribution from the inner-sphere reorganization has been invoked to explain the difference in the triplet and singlet reactivities in the electron transfer from aromatic amines to chlorobenzenes. 8 We do not have, therefore, many examples on this subject, and knowledge is still qualitative.…”

Section: Introductionmentioning

confidence: 99%

Rates and efficiencies of contact-ion-pair formation in photolyzed mixtures of TMPD with halogenated compounds in nonpolar solvents

Shimamori¹,

Hanamuro²,

Tatsumi³

1993

J. Phys. Chem.

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Time variation of microwave dielectric absorption has been examined for photolyzed solutions of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) admixed with halogen-containing compounds AX (AX = CC4, In solutions with CC14, C2H5I, C6H5I, CsHsBr, and C6HsC1, the dielectric absorption signals show first-order growths with appreciable intensities, indicating formation of a contact ion pair (CIP) TMPD+X-( X denotes a halogen atom) by reactions of these compounds with the excited triplet state of TMPD. On the contrary, no measurable amplitudes were detected for ClHsBr, C Z H~C I , C&F, and C6F6, showing that stable CIP cannot be formed with these compounds. Kinetic analyses indicate that the rate constants for the CIP formation are in the order CC4 (diffusion limit) > C6H5I > C2HsI > C&Br > C6H5Cl and that the efficiencies for the C I P formation also depend on the compound AX. These differences among the halogenated compounds cannot be explained on the basis of overall free-energy change of the reaction, but rather they correlate with the nature of dissociative electron attachment to the molecule AX.

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Section: Introductionmentioning

confidence: 99%

Rates and efficiencies of contact-ion-pair formation in photolyzed mixtures of TMPD with halogenated compounds in nonpolar solvents

Shimamori¹,

Hanamuro²,

Tatsumi³

1993

J. Phys. Chem.

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“…Avila et al, 22 and previously Vogelmann,23 found differing singlet and triplet reactivities in the bimolecular electron-transfer reactions which were attributed to possible differences in the inner-sphere reorganization energies of the singlet and triplet reactant states. Mauzerall et al 24 have constructed a molecule with four symmetrical linkages between a zinc porphyrin and a quinone, forming a cage.…”

Section: Introductionmentioning

confidence: 83%

“…where the fast component is attributed to the decay of 3P*AQ and the slow one to the decay of unoxidized 3P*AQH2•7 &et can be evaluated as the difference of the fast rate constant from the PAQ decay kf and the first-order rate constant from the 3P*AQH2 decay kf kfsff kf-kf (22) To test whether treatment with lead dioxide added any extra quenching impurities, a comparison was made of tetratolylporphyrin (TTP) plus imidazole in methylene chloride without and with lead dioxide treatment. The latter did not show any significant change in the decay rate.…”

Section: Theorymentioning

confidence: 99%

Intramolecular Photochemical Electron Transfer. 8. Decay of the Triplet State in a Porphyrin-Quinone Molecule.

Fraser¹,

Bolton²

1994

J. Phys. Chem.

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“…The formation of CARB in the current study can be happened, also, by a free-radical mechanism [26]. Where, free radicals such as, Cl and Ph can be formed by the DPA -sensitized cleavage of a C-Cl bond of chlorobenzenes, via quenching energy transfer [36][37][38][39][40][41]. Based on the previous consumption [26], these formed free radicals (Cl and Ph) can participate in CARB formation according to the following free radical mechanism:…”

Section: Cyclization Of Dpa To Carbazole Via a Freeradical Pathwaymentioning

confidence: 99%

“…(9) It should be mentioned that, these radicals can be formed by electron transfer quenching from the excited singlet and triplet complexes state of many aromatic amines to chlorobenzenes [36][37][38][39][40][41]. Up to our knowledge, the formation of CARB in ɤirradiated oxygen free Aniline / Chlorobenzene mixtures has never studied before.…”

Section: Cyclization Of Dpa To Carbazole Via a Freeradical Pathwaymentioning

confidence: 99%

Formation of Carbazole in ɤ- irradiated Aniline / Chlorobenzene mixtures

Sife-Eldeen

2020

Egypt. J. Chem.

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In this study, Gas chromatographic/mass spectrometric study indicated that carbazole (CARB) is formed in oxygen free ɤirradiation of aniline / chlorobenzene mixtures. It seems that ɤ-radiation induces the formation of CARB in these mixtures via intramolecular dehydrocyclization of diphenylamine (DPA). The yield of CARB estimated via gas chromatography (GC), was found to be dependent on anilinechlorobenzene molar ratio. Where, the maximum CARB yield was found at 1:1 molar ratio of anilinechlorobenzene. At this reactants molar ratio, the effect of absorbed radiation dose and dose rate on the yield of carbazole was studied. The yield of CARB increases, linearly, as the absorbed dose is increased up to about 50 kGy. The Gvalue (5.8μM/J) of CARB was determined. It was found that, the yield of CARB increase as the absorbed dose rate increases (0.226 -0.904kGy/h). So, it can be concluded that CARB is formed, mainly, in the spurs. The mechanism of the CARB formation was discussed.

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Singlet and triplet reactivity in the photoinduced electron transfer from aromatic amines to chlorobenzenes

Cited by 14 publications

References 32 publications

Rates and efficiencies of contact-ion-pair formation in photolyzed mixtures of TMPD with halogenated compounds in nonpolar solvents

Rates and efficiencies of contact-ion-pair formation in photolyzed mixtures of TMPD with halogenated compounds in nonpolar solvents

Intramolecular Photochemical Electron Transfer. 8. Decay of the Triplet State in a Porphyrin-Quinone Molecule.

Formation of Carbazole in ɤ- irradiated Aniline / Chlorobenzene mixtures

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