The triplet—triplet absorption of cyclohexadiene-1,3 and ergosterol. Sensitized total ground state depletion of dienes by triplet energy transfer from the ruby laser excited 2-fluorenylphenylketone

Tóth, Mihály

doi:10.1016/0301-0104(80)85219-0

Cited by 7 publications

(2 citation statements)

References 14 publications

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“…For CMPPH 3b , the isosbestic points are observed at 309 and 308 nm in MeOH and EtOH, respectively, and both shift by 9 nm on irradiation. To be certain about the participation of the triplet excited state in the dehalogenation process of CPZ, some of these photoreactions were performed in the presence of 0.35 m m the triplet quencher 1,3 cyclohexadiene ( E T = 52.6 kcal mol −1 [42]), keeping all experimental conditions constant. In this case, no photodestruction was observed, confirming that the photodehalogenation occurs from the 3 CPZ*.…”

Section: Resultsmentioning

confidence: 99%

Photodegradation of 2‐chloro Substituted Phenothiazines in Alcohols

García

Piñero

Oyola

et al. 2009

Photochem & Photobiology

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The mechanisms that trigger the phototoxic response to 2-chlorophenothiazine derivatives are still unknown. To better understand the relationship between the molecular structure of halogenated phenothiazines and their phototoxic activity, their photophysics and photochemistry were studied in several alcohols. The photodestruction quantum yields were determined under anaerobic conditions using monochromatic light (313 nm). Absorption-and emission-spectroscopy, 1 H-and 13 C-NMR and GC-MS were used to characterize the photoproducts and reference compounds. An electron transfer mechanism had been previously proposed by Bunce et al. (J. Med. Chem. 22,[202][203][204] to explain the large difference between the photodestruction quantum yield of 2-chlorpromazine (u = 0.46) and 2-chlorphenothiazine (u = 0.20). According to these authors, the alkylamino chain transfers an electron to the phenothiazine moiety. Our results demonstrate that this mechanism is incorrect, because the photodestruction quantum yields of all chlorinated derivatives of this study are the same under the same conditions of solvent and irradiation wavelength. The quantum yield has no dependence on the 10-substituent, but it depends on the solvent. The percentage of each photoproduct, on the other hand, strongly depends on that substituent, but not very much on the solvent. Finally, it is demonstrated that the phototoxic effect of chlorinated phenothiazines is not related to the photodechlorination, although both processes share the same transient.

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Section: Resultsmentioning

confidence: 99%

Photodegradation of 2‐chloro Substituted Phenothiazines in Alcohols

García

Piñero

Oyola

et al. 2009

Photochem & Photobiology

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“…Besides, irradiation of N -acetylindole and CHD in the presence of the sensitizer did not give 4a . Energy transfer from the BT π,π* triplet excited state ( E T = 63 kcal/mol) to 3a ( E T = 52 kcal/mol) led to CHD dimers in 38% yield with an isomer distribution typical of a triplet-sensitized dimerization ( anti -[2 + 2], syn -[2 + 2] and exo -[4 + 2] adducts obtained in a 3:1:1 ratio) . For comparison, irradiation during 1 h of BT in the presence of CHD, in the absence of indole, led to complete diene dimerization with the same isomer distribution (run 2, Table )…”

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confidence: 99%