Superoxide radical anion adduct of 5,5-dimethyl-1-pyrroline N-oxide (DMPO). 2. The thermodynamics of decay and EPR spectral properties.
The formation of the superoxide radical anion (O2*-) 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 O2*- detection in chemical and biological systems. However, the nature of DMPO-O2H has confounded spin-trapping investigators over the years, since there has been no independently synthesized DMPO-O2H to date. A density functional theory (DFT) approach was used to predict the isotropic hyperfine coupling constants arising from the N, beta-H, and gamma-H nuclei of DMPO-O2H 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-O2H 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-O2H and DMPO-OH have also been computed.
Villamena
Frederick A
FA
Center for Biomedical EPR Spectroscopy and Imaging, The Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University, Columbus, Ohio 43210, USA. villamena-1@medctr.osu-edu
Merle
John K
JK
Hadad
Christopher M
CM
Zweier
Jay L
JL
D000838:Anions / Q000737:chemistry; D003497:Cyclic N-Oxides / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D017665:Hydroxyl Radical / Q000737:chemistry; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013113:Spin Labels; D019097:Spin Trapping; D013481:Superoxides / Q000737:chemistry*; D013816:Thermodynamics
D000838:Anions; D003497:Cyclic N-Oxides; D013113:Spin Labels; D013481:Superoxides; D017665:Hydroxyl Radical; C017245:5,5-dimethyl-1-pyrroline-1-oxide