The β-phosphorus hyperfine coupling constant in nitroxide: part 3: titration of water by electron paramagnetic resonance

2015 ◽  
Vol 13 (46) ◽  
pp. 11393-11400 ◽  
Author(s):  
Gérard Audran ◽  
Lionel Bosco ◽  
Paul Brémond ◽  
Teddy Butscher ◽  
Jean-Michel Franconi ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Organic Solvent ◽  
Hyperfine Coupling ◽  
Hyperfine Coupling Constant ◽  
Coupling Constant ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

Titration of a few percent of water in an organic solvent is possible due to a large difference in aP.

A Study of the Effect of Solvent and Temperature on the Electron Paramagnetic Resonance Parameters and Linewidths of Copper(II)bis(Diethyldithiocarbamate)

1974 ◽  
Vol 52 (24) ◽  
pp. 4016-4024 ◽  
Author(s):  
F. Geoffrey Herring ◽  
Robert L. Tapping
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Hyperfine Coupling ◽  
Hyperfine Coupling Constant ◽  
Rotational Correlation Time ◽  
Coupling Constant ◽  
Paramagnetic Resonance ◽  
Axial Ligation ◽  
Effect Of Solvent ◽  
Isotropic Hyperfine Coupling ◽  
Electron Paramagnetic

The effect of varying solvent and temperature on the e.s.r. parameters and linewidths of copper(II) bis(diethyldithiocarbamate) has been studied. The temperature and solvent dependences of the isotropic hyperfine coupling constant (a0) have been interpreted in terms of vibronic and axial ligation effects. The rotational correlation time, τR, of Cu(DEDC)2 has been measured in the solvents employed. The values of τR measured at 300 K have been used to obtain the anisotropic interaction parameter, κ, which is found to correlate roughly with the dipole moment and molar refractivity of the solvent.

scholarly journals Electron Paramagnetic Resonance (EPR) Detection of Nitric Oxide Produced during Forebrain Ischemia of the Rat

1994 ◽  
Vol 14 (5) ◽  
pp. 715-722 ◽  
Author(s):  
Teiji Tominaga ◽  
Shinya Sato ◽  
Tomoko Ohnishi ◽  
S. Tsuyoshi Ohnishi
Keyword(s):  
Nitric Oxide ◽  
Electron Paramagnetic Resonance ◽  
Hyperfine Coupling ◽  
Hyperfine Coupling Constant ◽  
Forebrain Ischemia ◽  
Coupling Constant ◽  
Paramagnetic Resonance ◽  
Rat Forebrain ◽  
Electron Paramagnetic

To detect if nitric oxide (NO) is produced in rat forebrain ischemia, we applied an electron paramagnetic resonance (EPR) NO-trapping technique. We also performed a detailed characterization of the technique. Diethyldithiocarbamate (DETC) and Fe-citrate were used as NO-trapping reagents. Under controlled ventilation, forebrain ischemia was produced by occlusion of both carotid arteries combined with hemorrhagic hypotension at 50 mm Hg for 15 min. DETC and Fe were administered 30 min prior to the onset of ischemia. During ischemia, the cerebral cortex was removed, and EPR samples were prepared. At liquid nitrogen temperatures, the NO-Fe-DETC signal (a triplet signal centered at g = 2.039 with the hyperfine coupling constant aN of 13 G) was detected overlapping Cu-DETC signals. By perfusing various concentrations of an NO-generating agent, 1,1-diethyl-2-hydroxy-2-nitrosohydrazine, into the rat brains, the amount of the “trapped NO” was calibrated. The size of the NO-Fe-DETC signal was well correlated with the NO concentrations in the perfusate (correlation coefficient r = 0.998, p < 0.01). Based on this calibration curve, it was found that the amount of trapped NO during forebrain ischemia increased to seven times that of the control (control n = 5, forebrain ischemia n = 4, p < 0.005).

EPR Data on Ni(II) Doped Cu(II) Acetate Monohydrate Single Crystals: Evidence of Ni2+ — Cu2+ Exchange-Coupled Pairs

1984 ◽  
Vol 39 (11) ◽  
pp. 1061-1065 ◽  
Author(s):  
E. Buluggiu
Keyword(s):  
Single Crystals ◽  
Hyperfine Coupling ◽  
Hyperfine Coupling Constant ◽  
Magnetic Behaviour ◽  
Coupling Constant ◽  
Paramagnetic Resonance ◽  
Strongly Coupled ◽  
Definite Difference ◽  
Electron Paramagnetic ◽  
Made In

Electron paramagnetic resonance measurements on nickel(ll) doped copper(ll) acetate mono­hydrate single crystals have been made. In the liquid helium temperature range, spectra have been observed which may be assigned to Ni2+-Cu2+ strongly coupled mixed pairs in the state of total spin S = 1/2. This result represents a definite difference of magnetic behaviour from the case of the nickel(II) doped dicopper(II) tetra(μ-benzoato-O,O′)bis(quinoline) complex, which has the same sandwich dimeric structure but shows spectra indicative of a S=3/2 state. Apart from this difference, unusual EPR data are found such as pronounced misalignments of g with respect to the relevant pair axes and very large values of the hyperfine coupling constant of the copper nucleus, which characteristically recall that case.

scholarly journals Triarylmethyl Radicals: An EPR Study of 13C Hyperfine Coupling Constants

2017 ◽  
Vol 231 (4) ◽  
Author(s):  
Andrey A. Kuzhelev ◽  
Victor M. Tormyshev ◽  
Olga Yu. Rogozhnikova ◽  
Dmitry V. Trukhin ◽  
Tatiana I. Troitskaya ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Epr Spectroscopy ◽  
Hyperfine Coupling ◽  
Coupling Constants ◽  
Spin Labels ◽  
Spin Probes ◽  
Paramagnetic Resonance ◽  
Hyperfine Coupling Constants ◽  
Electron Paramagnetic ◽  
Triarylmethyl Radicals

AbstractTriarylmethyl (TAM) radicals are widely used in electron paramagnetic resonance (EPR) spectroscopy as spin labels and in EPR imaging as spin probes for

scholarly journals Direct enantiomeric discrimination through antisymmetric hyperfine coupling

2021 ◽  
Author(s):  
Piotr Garbacz ◽  
Juha Vaara
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Hyperfine Coupling ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Paramagnetic Resonance ◽  
Molecular Chirality ◽  
Enantiomeric Discrimination ◽  
Electron Paramagnetic

A chirality-sensitive effect induced by antisymmetric hyperfine coupling, which lifts the intrinsic insensitivity of electron paramagnetic resonance spectroscopy to molecular chirality, is described.

The Electron Paramagnetic Resonance Spectrum of γ-Irradiated Dimethyl Malonic Acid

2004 ◽  
Vol 59 (1-2) ◽  
pp. 103-104 ◽  
Author(s):  
Biray Aşik ◽  
Mehmet Birey
Keyword(s):  
Magnetic Field ◽  
Electron Paramagnetic Resonance ◽  
Electron Paramagnetic Resonance Spectrum ◽  
Single Crystals ◽  
Malonic Acid ◽  
Hyperfine Coupling ◽  
Resonance Spectrum ◽  
Coupling Constants ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

The electron paramagnetic resonance of γ -Irradiated single crystals of dimethyl malonic acid [(CH3)2C(COOH)2] has been studied for different orientations of the crystal in a magnetic field. The radicals produced by gamma irradiation have been investigated between 123 and 300 K. The spectra were found to be temperature independent, and radiation damage centres were attributed to [(CH3)2C(COOH)2]+ radicals. The g factor and hyperfine coupling constants were found to be almost isotropic with average values g = 2.0036, a(COOH)2 = 0.5 mT, a(CH3)2 = 2.1 mT, respectively, and spin density ρ = 91% of the [(CH3)2C(COOH)2]+ radical.

scholarly journals Purification and properties of formate dehydrogenase from Pseudomonas aeruginosa. Electron-paramagnetic-resonance studies on the molybdenum centre

1987 ◽  
Vol 243 (1) ◽  
pp. 235-239 ◽  
Author(s):  
P M A Gadsby ◽  
C Greenwood ◽  
A Coddington ◽  
A J Thomson ◽  
C Godfrey
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Electron Paramagnetic Resonance ◽  
Hyperfine Coupling ◽  
Formate Dehydrogenase ◽  
Sodium Dithionite ◽  
Paramagnetic Resonance ◽  
Low Concentrations ◽  
Purification And Properties ◽  
Electron Paramagnetic ◽  
Fold Excess

Formate dehydrogenase from Pseudomonas aeruginosa contains molybdenum, a [4Fe-4S] cluster and cytochrome b. This paper reports the detection of molybdenum as Mo(V) by e.p.r. spectroscopy. In order to generate Mo(V) signals, addition of amounts of excess formate varying between 10- and 50-fold over enzyme, followed by 200-fold excess of sodium dithionite, were used. Two Mo(V) species were observed. One, the major component, has g1 = 2.012, g2 = 1.985 and g3 = 1.968, appeared at low concentrations of formate and increased linearly in intensity with increasing concentrations of formate up to 25-fold excess over the enzyme. At higher formate concentration this signal disappeared. The appearance and disappearance of this Mo(V) signal seems to parallel the state of reduction of the [4Fe-4S] clusters. A second, minor, Mo(V) species with g-values g1 = 1.996, g2 = 1.981 and g3 = 1.941 appears at a constant level during the formate-dithionite titration. No evidence has been obtained for nuclear hyperfine coupling to protons. The major Mo(V) species has unusual e.p.r. signals compared with other molybdenum-containing enzymes, except for that observed in the formate dehydrogenase from Methanobacterium formicicum [Barber, Siegel, Schauer, May & Ferry (1983) J. Biol. Chem. 258, 10839-10845]. The present work suggests that the enzyme is acting as a CO2 reductase, with dithionite as an electron donor to a [4Fe-4S] cluster, which in turn donates electrons to molybdenum, producing a Mo(V) species with CO2 bound to the metal.

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