Quenching of porphyrin triplet and singlet oxygen by stable nitroxide radicals: Importance of steric hindrance

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

To 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.

Original languageEnglish
Pages (from-to)2640-2652
Number of pages13
JournalHelvetica Chimica Acta
Volume84
Issue number9
DOIs
Publication statusPublished - 2001

Fingerprint

Singlet Oxygen
Porphyrins
porphyrins
Quenching
quenching
Oxygen
oxygen
Rate constants
Hematoporphyrins
piperidine
Molecular oxygen
nitroxyl
radii
rings

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

@article{2b02eca3774d4dcbb82c8b968fc77171,
title = "Quenching of porphyrin triplet and singlet oxygen by stable nitroxide radicals: Importance of steric hindrance",
abstract = "To 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.",
author = "T. Vid{\'o}czy and P. Baranyai",
year = "2001",
doi = "10.1002/1522-2675(20010919)84:9<2640::AID-HLCA2640>3.0.CO;2-V",
language = "English",
volume = "84",
pages = "2640--2652",
journal = "Helvetica Chimica Acta",
issn = "0018-019X",
publisher = "Verlag Helvetica Chimica Acta AG",
number = "9",

}

TY - JOUR

T1 - Quenching of porphyrin triplet and singlet oxygen by stable nitroxide radicals

T2 - Importance of steric hindrance

AU - Vidóczy, T.

AU - Baranyai, P.

PY - 2001

Y1 - 2001

N2 - To 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.

AB - To 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.

UR - http://www.scopus.com/inward/record.url?scp=0034767077&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0034767077&partnerID=8YFLogxK

U2 - 10.1002/1522-2675(20010919)84:9<2640::AID-HLCA2640>3.0.CO;2-V

DO - 10.1002/1522-2675(20010919)84:9<2640::AID-HLCA2640>3.0.CO;2-V

M3 - Article

AN - SCOPUS:0034767077

VL - 84

SP - 2640

EP - 2652

JO - Helvetica Chimica Acta

JF - Helvetica Chimica Acta

SN - 0018-019X

IS - 9

ER -