Solvent effects on singlet oxygen yield from n,.pi.* and .pi.,.pi.* triplet carbonyl compounds

Darmanyan, A. P.; Foote, Christopher S.

doi:10.1021/j100121a029

Cited by 76 publications

(78 citation statements)

References 10 publications

(12 reference statements)

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“…Table 1. The results of TRNIR direct method are in accordance with literature values [37][38][39]. However, the quantum yield of benzophenone evaluated by indirect method TEMPO/EPR was significantly higher.…”

Section: Photoinduced Electron Transfersupporting

confidence: 89%

Scope and limitations of the TEMPO/EPR method for singlet oxygen detection: the misleading role of electron transfer

Nardi

Manet

Monti

et al. 2014

Free Radical Biology and Medicine

198

104

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Section: Photoinduced Electron Transfersupporting

confidence: 89%

Scope and limitations of the TEMPO/EPR method for singlet oxygen detection: the misleading role of electron transfer

Nardi

Manet

Monti

et al. 2014

Free Radical Biology and Medicine

198

104

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“…This high value is fully in accord with earlier suggestions [48][49][50][51][52][53] that a pp* triplet is required for highly efficient singlet oxygen formation. Similar values were reported for other b-lapachones.…”

Section: Laser Flash Photolysis Studiessupporting

confidence: 92%

The photochemical reactivity of triplet β-lapachone-3-sulfonic acid towards biological substrates

Netto‐Ferreira¹,

Lhiaubet‐Vallet²,

Silva³

et al. 2010

J. Braz. Chem. Soc.

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A reatividade fotoquímica do ácido 3-sulfônico da b-lapachona (1) frente a amino ácidos, bases nucleicas ou nucleosídeos foi determinada empregando a técnica de fotólise por pulso de laser de nanossegundo. A excitação (l = 355 nm) de soluções deaeradas de 1, em acetonitrila, resultou na formação do seu estado excitado triplete, o qual foi suprimido eficientemente por L-triptofano, éster metílico de L-triptofano, L-tirosina, éster metílico de L-tirosina e éster metílico de L-cisteína (k q ≅ 10 9 L mol -1 s -1). Para L-triptofano, L-tirosina e seus ésteres metílicos novos transientes foram formados no proceso de supressão, os quais foram atribuídos ao par de radicais resultante de uma transferência inicial de elétron do amino ácido, ou dos seus ésteres metílicos, à quinona excitada, seguida por uma transferência de próton rápida. Não foi possível a obtenção de constantes de velocidade de supressão para timina e timidina, em acetonitrila, o que pode ser devido tanto ao caráter p p* de 1 quanto ao baixo valor para a sua energia triplete. Por outro lado, a supressão de 1 por 2'-deoxaguanosina foi tão eficiente quanto para triptofano ou tirosina (k q ≅ 10 9 L mol -1 s -1). O rendimento quântico para a formação de oxigênio singlete ( 1 O 2 ) a partir de 1 foi determinado empregando-se estudos de emissão resolvida no tempo na região do infravermelho próximo, tendo-se obtido um valor consideravelmente alto para este rendimento quântico (F D = 0,7).The photochemical reactivity of b-lapachone-3-sulfonic acid (1) towards amino acids, nucleobases or nucleosides has been examined employing the nanosecond laser flash photolysis technique. Excitation (l = 355 nm) of degassed solutions of 1, in acetonitrile, resulted in the formation of its corresponding triplet excited state. This transient was efficiently quenched by L-tryptophan, L-tryptophan methyl ester, L-tyrosine, L-tyrosine methyl ester and L-cysteine methyl ester (k q ≅ 10 9 L mol -1 s -1). For L-tryptophan, L-tyrosine and their methyl esters new transients were formed in the quenching process, which were assigned to the corresponding radical pairs resulting from an initial electron transfer from the amino acids, or their esters, to the excited quinone, followed by a fast proton transfer. No measurable quenching rate constants could be observed in the presence of thymine or thymidine, in acetonitrile solution, which is probably due to the p p* character of triplet 1 as well as to its low triplet energy. On the other hand, the rate constant obtained when 1 was quenched by 2'-deoxyguanosine is reasonably fast (k q ≅ 10 9 L mol -1 s -1). The quantum efficiency of singlet oxygen ( 1 O 2 ) formation from 1 was determined employing time-resolved near-IR emission studies upon laser excitation and showed a considerably high value (F D = 0.7).Keywords: laser flash photolysis, ortho-quinones, triplet excited state, coupled electron/ proton transfer IntroductionQuinones show several biological and pharmacological activities, 1-9 with their mechanism of action being related to redo...

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“…1. The results of TRNIR direct method are in accordance with literature values [23,110,111]. However, the quantum yield of benzophenone evaluated by indirect method TEMPO/EPR was significantly higher.…”

Section: Determination Of Singlet Oxygen Quantum Yield By Trnir or Tesupporting

confidence: 89%

“…The obtained results reveal that the method leads to significant overestimation of singlet oxygen production when the singlet or triplet excited state of the photosensitizers are efficiently quenched by TEMP, acting as electron donor. [34] c from ref [111] d from ref [110] e from ref [23] …”

Section: Production Ofmentioning

confidence: 99%

Mechanistic Studies on the Phototoxicity of Rosuvastatin, Itraconazole and Imatinib

Nardi¹

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Solvent effects on singlet oxygen yield from n,.pi.* and .pi.,.pi.* triplet carbonyl compounds

Cited by 76 publications

References 10 publications

Scope and limitations of the TEMPO/EPR method for singlet oxygen detection: the misleading role of electron transfer

Scope and limitations of the TEMPO/EPR method for singlet oxygen detection: the misleading role of electron transfer

The photochemical reactivity of triplet β-lapachone-3-sulfonic acid towards biological substrates

Mechanistic Studies on the Phototoxicity of Rosuvastatin, Itraconazole and Imatinib

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