Synthesis of stable chromium(V) complexes of tertiary hydroxy acids

Krumpolc, M.; Rocek, Jan

doi:10.1021/ja00506a013

Cited by 187 publications

(127 citation statements)

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“…Although it is well-accepted that there are no stable compounds of Cr(V) or Cr(IV) (21), there is kinetic evidence that one-electron reduction of HCrO4 -in acid solution gives H3CrO4 (22). More stable Cr(IV) intermediates were observed on reduction of CrO3 by citric acid (23). More recently, Mytych et al (24) have identified transient Cr(V) and Cr(IV) species during the photochemical reduction of Cr(VI) by aliphatic alcohols using flash photolysis techniques.…”

Section: Resultsmentioning

confidence: 99%

Reduction of Cr(VI) at a Polyaniline Film: Influence of Film Thickness and Oxidation State

Farrell

Breslin

2004

Environ. Sci. Technol.

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Hexavalent chromium [Cr(VI)] is highly toxic, carcinogenic, and mutagenic to living organisms. In this paper, the reduction of Cr(VI) to the much less toxic trivalent state [Cr(III)] was studied at polyaniline films grown to different thickness. Much higher rates of Cr(VI) reduction were observed for the "thick" polyaniline films. This was explained in terms of the morphology of the polymer and the higher surface area of polymer in contact with the Cr(VI) solution. For "thin" polyaniline films, the Cr(VI) reduction reaction was found to obey pseudo-first-order kinetics for the duration of exposure. However, in the case of thick polyaniline layers, the Cr(VI) reduction reaction followed a twostage process, with each stage obeying pseudo-firstorder kinetics. This was explained in terms of oxidation of the polymer from the leucoemeraldine to the emeraldine state and then further oxidation of the polymer from the emeraldine to the pernigraniline state. Much higher rates of Cr(VI) reduction were observed on oxidation of the polymer from the leucoemeraldine to the emeraldine state.

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Section: Resultsmentioning

confidence: 99%

Reduction of Cr(VI) at a Polyaniline Film: Influence of Film Thickness and Oxidation State

Farrell

Breslin

2004

Environ. Sci. Technol.

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“…A small amount of an organic radical, e.g. the sodium salt of bis(2-hydroxy-2-ethylbutyrato)-oxochromate (abbreviated as EHBA-Cr V ) (Krumpolc & Rožek, 1979) together with the biological macromolecule of interest is added to a glycerol/ water mixture and rapidly frozen to a glassy platelet in a liquid-nitrogen-cooled copper mould. The data shown in Fig.…”

Section: Nuclear Spin Contrastmentioning

confidence: 99%

Small-angle scattering and its interplay with crystallography, contrast variation in SAXS and SANS

Stuhrmann

2007

Acta Cryst Sect A

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Methods of contrast variation are tools that are essential in macromolecular structure research. Anomalous dispersion of X-ray diffraction is widely used in protein crystallography. Recent attempts to extend this method to native resonant labels like sulfur and phosphorus are promising. Substitution of hydrogen isotopes is central to biological applications of neutron scattering. Proton spin polarization considerably enhances an existing contrast prepared by isotopic substitution. Concepts and methods of nuclear magnetic resonance (NMR) become an important ingredient in neutron scattering from dynamically polarized targets.

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“…15 for a eld of 2.5 T. As mentioned above, the large quadrupole splitting of the nitrogen system necessitates a more careful calculation of the nitrogen polarization in terms of the spin temperature including the second order term in Eq. (23). The correction is at most a few per mill for nitrogen polarizations of 20 % and less for lower polarizations.…”

Section: Measurement Of the 14 N Polarizationmentioning

confidence: 95%

“…3.2). The butanol material was doped by dissolving in it the paramagnetic complex EHBACr(V) [23]. The mass composition by w eight of the target material was 78.5% 1-butanol, 12% 2-butanol, 5% water, and 4.5% EHBA-Cr(V) for the normal butanol material.…”

Section: Target Materialsmentioning

confidence: 99%

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The polarized double cell target of the SMC

Adams

Adeva

Arık

et al. 1999

Nuclear Instruments and Methods in Physics Research Section A:

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The polarized target of the Spin Muon Collaboration at CERN was used for deep inelastic muon scattering experiments during 1993 to 1996 with a polarized muon beam to investigate the spin structure of the nucleon. Most of the experiments were carried out with longitudinal target polarization and 190 GeV muons, and some were done with transverse polarization and 100 GeV muons. Protons as well as deuterons were polarized by dynamic nuclear polarization DNP in three kinds of solid materials butanol, ammonia, and deuterated butanol, with maximum degrees of polarization of 94, 91, and 60 , respectively. Considerable attention was paid to the accuracies of the NMR polarization measurements and their analyses. The achieved accuracies were between 2.0 and 3.2 . The SMC target system with two cells of opposite polarizations, each cell 65 cm long and 5 cm in diameter, constitutes the largest polarized target system ever built and facilitates accurate spin asymmetry measurements. The design considerations, the construction and its performance over the years are reviewed.To be submitted to NIM A D.

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Synthesis of stable chromium(V) complexes of tertiary hydroxy acids

Cited by 187 publications

References 0 publications

Reduction of Cr(VI) at a Polyaniline Film: Influence of Film Thickness and Oxidation State

Reduction of Cr(VI) at a Polyaniline Film: Influence of Film Thickness and Oxidation State

Small-angle scattering and its interplay with crystallography, contrast variation in SAXS and SANS

The polarized double cell target of the SMC

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