Singlet oxygen quenching by stable nitroxy radicals

Darmanyan, A. P.; Татиколов, А. С.

doi:10.1016/0047-2670(86)87005-8

Cited by 40 publications

(33 citation statements)

References 19 publications

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“…Stern-Volmer analysis of the phosphorescence decays yielded the quenching rate constants (k q∆ NO , see Table 1) which are in agreement with published values for other solvents. 23, 24 The rate constants for the quenching of 1 O 2 by nitroxides are collected in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Chemically Induced Dynamic Electron Polarization Generated through the Interaction between Singlet Molecular Oxygen and Nitroxide Radicals

et al. 2005

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An absorptive chemically induced dynamic electron polarization (CIDEP) was generated by the quenching of singlet oxygen by nitroxide radicals (TEMPO derivatives). The spin polarization decay time of the nitroxide (measured by time-resolved EPR) correlates with the lifetime of singlet oxygen (measured by singlet oxygen phosphorescence spectroscopy). In addition, a deuterium isotope effect on the spin polarization decay time was observed, a signature of singlet oxygen involvement. With use of isotope labeled nitroxides ( 15 N, 14 N), the relative spin polarization efficiencies of TEMPO, 4-oxo-TEMPO, and 4-hydroxy-TEMPO by singlet oxygen were determined. The relative spin polarization efficiencies (per quenching event) decrease in the order 4-hydroxy-TEMPO > TEMPO > 4-oxo-TEMPO, whereas an opposite trend was observed for the total quenching rate constants of singlet oxygen by the nitroxides where the order is 4-hydroxy-TEMPO < TEMPO < 4-oxo-TEMPO.

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Section: Introductionmentioning

confidence: 99%

Chemically Induced Dynamic Electron Polarization Generated through the Interaction between Singlet Molecular Oxygen and Nitroxide Radicals

et al. 2005

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“…Several shots were typically averaged for improved signal to noise. Singlet oxygen luminescence was recorded at 1.27 µm at 90°to the excitation beam, 31 and quantum yields were determined by extrapolating the intensities of emission to the center of the laser pulse. Singlet oxygen yields were linear with laser energy.…”

Section: Methodsmentioning

confidence: 99%

Charge Transfer Interactions in the Generation of Singlet Oxygen O₂(¹Δ_g) by Strong Electron Donors

1999

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The quenching rate constant of the triplet state by molecular oxygen and the efficiency of singlet oxygen generation have been measured for 12 amines in cyclohexane and benzene. For the best electron donors, the average rate constant for quenching by energy transfer is 6.0 × 10 9 M -1 s -1 . For the same compounds, the rate constant of quenching via enchancement of internal conversion is 1.2 × 10 10 M -1 s -1 . The energy transfer component of the total quenching rate constant is almost twice as fast as the maximum from the standard Porter model. The mechanisms of quenching via quintet, singlet, and triplet channels are discussed for amines and aromatic hydrocarbons, and intersystem crossing out of the quintet manifold is proposed.

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“…The greatest number of stable free radicals were examined in [9], albeit only for the quenching of singlet molecular oxygen. The greatest number of stable free radicals were examined in [9], albeit only for the quenching of singlet molecular oxygen.…”

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confidence: 99%

Quenching of Porphyrin Triplet and Singlet Oxygen by Stable Nitroxide Radicals: Importance of Steric Hindrance

Vidóczy¹,

Baranyai²

2001

HCA

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Dedicated to Professor AndreÂ M. Braun on the occasion of his 60th birthdayTo study the nature of quenching, we used stable nitroxide radicals (most of which contain piperidine or pyrrolidine rings) as quenchers of triplet hematoporphyrin as well as of singlet molecular oxygen. A characteristic feature of quenching triplet porphyrin is a near-diffusion-limited rate constant, whereas the rate constant for quenching singlet oxygen is about three orders of magnitude lower. Accessibility of the nitroxide moiety in radicals was characterized quantitatively based on semi-empirical calculations (at AM1 level), with the use of van der Waals radii of the species. While variation in the rate constant values for quenching triplet porphyrin can be fully explained by the steric hindrance of the neighbouring groups of the nitroxide radical, no such effect can be observed in quenching singlet oxygen.

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Singlet oxygen quenching by stable nitroxy radicals

Cited by 40 publications

References 19 publications

Chemically Induced Dynamic Electron Polarization Generated through the Interaction between Singlet Molecular Oxygen and Nitroxide Radicals

Chemically Induced Dynamic Electron Polarization Generated through the Interaction between Singlet Molecular Oxygen and Nitroxide Radicals

Charge Transfer Interactions in the Generation of Singlet Oxygen O₂(¹Δ_g) by Strong Electron Donors

Quenching of Porphyrin Triplet and Singlet Oxygen by Stable Nitroxide Radicals: Importance of Steric Hindrance

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Singlet oxygen quenching by stable nitroxy radicals

Cited by 40 publications

References 19 publications

Chemically Induced Dynamic Electron Polarization Generated through the Interaction between Singlet Molecular Oxygen and Nitroxide Radicals

Chemically Induced Dynamic Electron Polarization Generated through the Interaction between Singlet Molecular Oxygen and Nitroxide Radicals

Charge Transfer Interactions in the Generation of Singlet Oxygen O2(1Δg) by Strong Electron Donors

Quenching of Porphyrin Triplet and Singlet Oxygen by Stable Nitroxide Radicals: Importance of Steric Hindrance

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Charge Transfer Interactions in the Generation of Singlet Oxygen O₂(¹Δ_g) by Strong Electron Donors