Paramagnetic oxygen species

This surface can now adsorb oxygen in an associative form. The presence of paramagnetic oxygen species has been detected with EPR and the species has been characterized as A similar species has also been detected on... 

Co—0—0—Co. When this jU-superoxocobaloxime is reacted with relatively strong Lewis bases decomposition takes place to give a diamagnetic species and a paramagnetic oxygenated product. (Base Co—0—0). The ESR spectrum of this oxygenated product is strikingly similar to superoxocobalamin 115). 

Electron paramagnetic resonance (continued) cobalt-thermolysin complex, 28 334, 335 exchange reactions, 31 106-107 glutamine synthetase, 28 358-364 invisible oxygen species, 31 94-95 metalloenzymes, 28 324, 326 metal particle size distribution, 36 99-100, 104... 

Electron paramagnetic resonance has played a major role in the characterization of adsorbed oxygen species and the use of 17Oz has enabled a major advance to be made in the understanding of the nature of the various oxygen species and how they can be bonded to the surface. The use of IR spectroscopy as a technique has tended to be neglected because of the... 

A second way to overcome this spin conservation obstacle is via reaction of 302 with a paramagnetic (transition) metal ion, affording a superoxometal complex (Fig. 4.1, Reaction (3)). Subsequent inter- or intramolecular electron-transfer processes can lead to the formation of a variety of metal-oxygen species (Fig. 4.2) which may play a role in the oxidation of organic substrates. 

BH4 = Tetrahydrobiopterin CAM = Cytotoxic activated macrophage cNOS = Constitutive nitric oxide synthase CPR = Cytochrome P450 reductase EDRF = Endothelial-derived relaxation factor EPR = Electron paramagnetic resonance spectroscopy IL-1 = Interleukin-1 iNOS = Inducible nitric oxide synthase EPS = Lipopolysaccharide, or endotoxin NMMA = ISp-monomethyl-L-arginine NOS = Nitric oxide synthase ROS = Reactive oxygen species SOD = Superoxide dismutase TNF = Tumor necrosis factor. 

The enhancement of the relaxation process in natural hydrated silicate minerals by paramagnetic species such as Fe may be due to their facilitating the interaction between the Si nucleus and the electron spin as a result of the relatively high mobility of the hydrated paramagnetic species. A similar effect has been reported in zeolites (Cook-son and Smith 1985, Klinowski etal. 1986), in which the relaxation rate is significantly shortened by the presence of paramagnetic oxygen molecules. 

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