Superoxide radical anion adduct of 5,5-dimethyl-1-pyrroline N-oxide (DMPO). 2. The thermodynamics of decay and EPR spectral properties

Frederick A. Villamena, John K. Merle, Christopher M. Hadad, Jay L. Zweier

Research output: Contribution to journalArticle

Abstract

The formation of the Superoxide radical anion (O 2 •-) adduct of the nitrone 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as detected by electron paramagnetic resonance (EPR) spectroscopy is one of the most common techniques for O 2 •- detection in chemical and biological systems. However, the nature of DMPO-O 2H has confounded spin-trapping investigators over the years, since there has been no independently synthesized DMPO-O 2H to date. A density functional theory (DFT) approach was used to predict the isotropic hyperfine coupling constants arising from the N, β-H, and γ-H nuclei of DMPO-O 2H using explicit interactions with water molecules as well as via a bulk dielectric effect employing the polarizable continuum model (PCM). Theoretical calculation on the thermodynamics of DMPO-O 2H decay shows favorable intramolecular rearrangement to form a nitrosoaldehyde and a hydroxyl radical as products, consistent with experimental observations. Some pathways for the bimolecular decomposition of DMPO-O 2H and DMPO-OH have also been computed.

Original languageEnglish (US)
Pages (from-to)6089-6098
Number of pages10
JournalJournal of Physical Chemistry A
Volume109
Issue number27
DOIs
StatePublished - Jul 14 2005
Externally publishedYes

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inorganic peroxides
Superoxides
adducts
Anions
Paramagnetic resonance
electron paramagnetic resonance
Thermodynamics
anions
thermodynamics
oxides
decay
hydroxyl radicals
Biological systems
5,5-dimethyl-1-pyrroline-1-oxide
Hydroxyl Radical
Density functional theory
trapping
Spectroscopy
density functional theory
continuums

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Superoxide radical anion adduct of 5,5-dimethyl-1-pyrroline N-oxide (DMPO). 2. The thermodynamics of decay and EPR spectral properties. / Villamena, Frederick A.; Merle, John K.; Hadad, Christopher M.; Zweier, Jay L.

In: Journal of Physical Chemistry A, Vol. 109, No. 27, 14.07.2005, p. 6089-6098.

Research output: Contribution to journalArticle

Villamena, Frederick A. ; Merle, John K. ; Hadad, Christopher M. ; Zweier, Jay L. / Superoxide radical anion adduct of 5,5-dimethyl-1-pyrroline N-oxide (DMPO). 2. The thermodynamics of decay and EPR spectral properties. In: Journal of Physical Chemistry A. 2005 ; Vol. 109, No. 27. pp. 6089-6098.
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abstract = "The formation of the Superoxide radical anion (O 2 •-) adduct of the nitrone 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as detected by electron paramagnetic resonance (EPR) spectroscopy is one of the most common techniques for O 2 •- detection in chemical and biological systems. However, the nature of DMPO-O 2H has confounded spin-trapping investigators over the years, since there has been no independently synthesized DMPO-O 2H to date. A density functional theory (DFT) approach was used to predict the isotropic hyperfine coupling constants arising from the N, β-H, and γ-H nuclei of DMPO-O 2H using explicit interactions with water molecules as well as via a bulk dielectric effect employing the polarizable continuum model (PCM). Theoretical calculation on the thermodynamics of DMPO-O 2H decay shows favorable intramolecular rearrangement to form a nitrosoaldehyde and a hydroxyl radical as products, consistent with experimental observations. Some pathways for the bimolecular decomposition of DMPO-O 2H and DMPO-OH have also been computed.",
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