Photophysics and photochemistry of nitroanthracenes. Part 1.—Primary processes in the photochemical reactions of 9-benzoyl-10-nitroanthracene and 9-cyano-10-nitroanthracene studied by steady-state photolysis and nanosecond laser photolysis

Hamanoue, Kumao; Nakayama, Toshihiro; Ushida, Kiminori; Kajiwara, Kanji; Yamanaka, Shigenobu

doi:10.1039/ft9918703365

Cited by 23 publications

(37 citation statements)

References 17 publications

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“…The NO radical will react with the most stable carbon radical to form a nitroso ketone, which is usually unstable and continues on to become anthraquinone. In the reaction with 10-chloro, cyano, benzoyl, and nitro substituted 9-nitroanthracenes, such a nitroso ketone intermediate was observed [191,193].…”

Section: Photoirradiation Of Nitro-pahsmentioning

confidence: 96%

“…It has been shown that a nitro-PAH with its nitro group adopting a perpendicular orientation reacts faster under light irradiation [189][190][191][192][193]. Nitro-PAHs with a perpendicular nitro group are less mutagenic than those with a parallel nitro group due to their inability to be metabolized into reactive intermediates that form covalent DNA adducts [187,194].…”

Section: Photoirradiation Of Nitro-pahsmentioning

confidence: 99%

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Phototoxicity and Environmental Transformation of Polycyclic Aromatic Hydrocarbons (PAHs)—Light-Induced Reactive Oxygen Species, Lipid Peroxidation, and DNA Damage

Xia

Sun

et al. 2012

Journal of Environmental Science and Health, Part C

196

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Polycyclic aromatic hydrocarbons (PAHs) are a class of mutagenic and tumorigenic environmental contaminants. Although the mechanisms by which PAHs induce cancer in experimental animals have been extensively studied and the metabolic activation pathways have been determined, the environmental fate of PAHs and the phototoxicity exerted by PAHs, as well as their photoreaction products formed in the environment, have received much less attention. In this review, the formation of oxygenated PAHs, PAH quinones, nitro-PAHs, and halogenated PAHs from photoreaction of environmental PAHs are addressed. Upon light irradiation, PAHs and all PAH photoreaction products can absorb light energy to reach photo-excited states, which react with molecular oxygen, medium, and coexisting chemicals to produce reactive oxygen species (ROS) and other reactive intermediates, such as oxygenated PAHs and free radicals. These intermediates, including ROS, induce lipid peroxidation, and DNA damage including DNA strand breakage, oxidation to 8-oxo-2'-deoxyguanosine, and DNA-adducts. Since these toxicological endpoints are associated with age-related diseases, including cancer, environmental PAHs concomitantly exposed to sunlight may potentially promote human skin damage, leading to ageing and skin cancers. Thus, we suggest that (i) in addition to the widely recognized metabolic pathways, more attention must be paid to photoreaction as an important activation pathway for PAHs, (ii) risk assessment of environmental PAHs should take into consideration the complex photochemical reactions leading to mixtures of products that are also phototoxic; and (iii) the study of structure-toxicity relationships should be expanded to cover the complex photoreactions and extrinsic factors that affect phototoxicity endpoints.

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Section: Photoirradiation Of Nitro-pahsmentioning

confidence: 96%

Section: Photoirradiation Of Nitro-pahsmentioning

confidence: 99%

Phototoxicity and Environmental Transformation of Polycyclic Aromatic Hydrocarbons (PAHs)—Light-Induced Reactive Oxygen Species, Lipid Peroxidation, and DNA Damage

Xia

Sun

et al. 2012

Journal of Environmental Science and Health, Part C

196

View full text Add to dashboard Cite

show abstract

“…However, this channel can be responsible for the observed photochemistry of 1NN in solution ͓see Fig. 10,[52][53][54][55] In the intramolecular rearrangement, a conformational relaxation in the excited state initially occurs where the nitro group becomes perpendicular to the aromatic moiety of the nitro-PAH. 49 Two mechanisms have been proposed to explain the formation of nitrogen ͑II͒ oxide ͑NO͒ and aryloxy ͑ArO͒ radicals in the photochemistry of nitro-PAHs: ͑1͒ an intramolecular rearrangement and ͑2͒ dissociation-recombination mechanisms.…”

Section: G the Possibility Of A Branched Electronic Relaxation Pathwaymentioning

confidence: 99%

On the origin of ultrafast nonradiative transitions in nitro-polycyclic aromatic hydrocarbons: Excited-state dynamics in 1-nitronaphthalene

Reichardt

Vogt²,

Crespo‐Hernández³

2009

The Journal of Chemical Physics

124

236

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The electronic energy relaxation of 1-nitronaphthalene was studied in nonpolar, aprotic, and protic solvents in the time window from femtoseconds to microseconds. Excitation at 340 or 360 nm populates the Franck-Condon S(1)(pipi( *)) state, which is proposed to bifurcate into two essentially barrierless nonradiative decay channels with sub-200 fs lifetimes. The first main decay channel connects the S(1) state with a receiver T(n) state that has considerable npi( *) character. The receiver T(n) state undergoes internal conversion to populate the vibrationally excited T(1)(pipi( *)) state in 2-4 ps. It is shown that vibrational cooling dynamics in the T(1) state depends on the solvent used, with average lifetimes in the range from 6 to 12 ps. Furthermore, solvation dynamics competes effectively with vibrational cooling in the triplet manifold in primary alcohols. The relaxed T(1) state undergoes intersystem crossing back to the ground state within a few microseconds in N(2)-saturated solutions in all the solvents studied. The second minor channel involves conformational relaxation of the bright S(1) state (primarily rotation of the NO(2)-group) to populate a dissociative singlet state with significant charge-transfer character and negligible oscillator strength. This dissociative channel is proposed to be responsible for the observed photochemistry in 1-nitronaphthalene. Ground- and excited-state calculations at the density functional level of theory that include bulk and explicit solvent effects lend support to the proposed mechanism where the fluorescent S(1) state decays rapidly and irreversibly to dark excited states. A four-state kinetic model is proposed that satisfactorily explains the origin of the nonradiative electronic relaxation pathways in 1-nitronaphthalene.

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“…Upon absorption of light energy, the molecule is promoted to excited singlet state, which intersystem crosses to the excited triplet state. The nitro group rearranges to a nitrite in the excited triplet state24,31,35. Breaking of the N-O bond of nitrite forms a nitroso radical and an oxygen-centered radical in the anthracene moiety.…”

Section: Resultsmentioning

confidence: 99%

“…The NO radical will react with the most stable carbon radical on the opposite site of the nitro group in a concerted fashion and form a nitroso ketone, which is usually unstable and continues on to become anthraquinone. In the reaction with 10-chloro, cyano, benzoyl, and nitro substituted 9-nitroanthracenes, such a nitroso ketone intermediate was observed21,24,31.…”

Section: Introductionmentioning

confidence: 96%

Photochemical reaction of 9-nitro-substituted anthracene-like molecules 9-methyl-10-nitroanthracene and 12-methyl-7-nitrobenz[a]anthracene

Stewart

Jiao

Valente

et al. 2009

Journal of Photochemistry and Photobiology A: Chemistry

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Photophysics and photochemistry of nitroanthracenes. Part 1.—Primary processes in the photochemical reactions of 9-benzoyl-10-nitroanthracene and 9-cyano-10-nitroanthracene studied by steady-state photolysis and nanosecond laser photolysis

Cited by 23 publications

References 17 publications

Phototoxicity and Environmental Transformation of Polycyclic Aromatic Hydrocarbons (PAHs)—Light-Induced Reactive Oxygen Species, Lipid Peroxidation, and DNA Damage

Phototoxicity and Environmental Transformation of Polycyclic Aromatic Hydrocarbons (PAHs)—Light-Induced Reactive Oxygen Species, Lipid Peroxidation, and DNA Damage

On the origin of ultrafast nonradiative transitions in nitro-polycyclic aromatic hydrocarbons: Excited-state dynamics in 1-nitronaphthalene

Photochemical reaction of 9-nitro-substituted anthracene-like molecules 9-methyl-10-nitroanthracene and 12-methyl-7-nitrobenz[a]anthracene

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