Nitrogen-15 NMR of pyridine in high magnetic: Fields

Schweitzer, Dieter; Spiess, Hans Wolfgang

doi:10.1016/0022-2364(74)90155-3

Cited by 45 publications

(32 citation statements)

References 26 publications

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“…The ratio of T2X/T2z = 0.7 shows a gas like motional anisotropy. It is important to note that this ratio is consistent with experiment [20] and simulation.…”

Section: Reorientational Motionsupporting

confidence: 88%

Investigation of the Structure of Liquid Pyridine: a Molecular Dynamics Simulation, an RISM, and an X-ray Diffraction Study

Bakó

Radnai

Pálinkás

1996

Zeitschrift Für Naturforschung A

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The structure of liquid pyridine is investigated by molecular dynamics simulation and the RISM integral equation methods. The calculated total radial distribution functions (RDF) are compared with the experimental RDF's, obtained by X-ray diffraction measurement. It is shown that the local structure of liquid pyridine is mainly determined by the dipole-dipole interaction between the molecules. The local order is characterized by the pair distribution functions, angular correlation functions and orientational distributions. Dynamical properties (self-diffusion coefficients, rotational correlation times and reorientational correlation times) calculated on the basis of MD results are in good agreement with experimental data.

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“…The ratio of T2X/T2z = 0.7 shows a gas like motional anisotropy. It is important to note that this ratio is consistent with experiment [20] and simulation.…”

Section: Reorientational Motionsupporting

confidence: 88%

Investigation of the Structure of Liquid Pyridine: a Molecular Dynamics Simulation, an RISM, and an X-ray Diffraction Study

Bakó

Radnai

Pálinkás

1996

Zeitschrift Für Naturforschung A

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“…The initial 13 C polarization at the time the sample was injected into the NMR tube was also fitted, giving a best match when set to approximately 14000 and -8000 -consistent with other enhancements achieved using this dissolution DNP hardware and methods. Fitting the post-dissolution data also required a τ c ; Figure 6 leads to correlation times of 2.75 ± 0.25 ps, a reasonable fit to the τ c = 1.85 ps value previously measured for pure pyridine at a slightly different temperature [22].…”

Section: Resultsmentioning

confidence: 99%

Heteronuclear Cross‐Relaxation Effects in the NMR Spectroscopy of Hyperpolarized Targets

Donovan¹,

Lupulescu²,

Frydman³

2014

ChemPhysChem

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Dissolution DNP enables high-sensitivity solution phase NMR experiments on long-lived nuclear spin species such as 15 N and 13 C. This report explores certain features arising in solution-state 1 H NMR, upon polarizing low-γ nuclear species. Following solid state hyperpolarization of both 13 C and 1 H, solution-phase 1 H NMR experiments on dissolved samples revealed transient effects whereby peaks arising from protons bonded to the naturally-occurring 13 C nuclei, appeared larger than the typically dominant 12 C-bonded 1 H resonances. This enhancement of the satellite-peaks was examined in detail, with respect to a variety of mechanisms that could potentially originate it. Both two-and three-spin phenomena active in the solid state could lead to this kind of effect; still, experimental observations revealed that the enhancement originates from 13 C→ 1 H polarization transfer processes active in the liquid state. Kinetic equations based on modified heteronuclear cross-relaxation models were examined, and found to describe well the distinct patterns of growth and decay shown by the 13 C-bound 1 H NMR satellite resonances. The dynamics of these novel cross-relaxation phenomena were determined, and their potential usefulness as tools for investigating hyperpolarized ensembles and for obtaining enhanced-sensitivity 1 H NMR traces, is explored.

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“…Another possible mechanism is the rotational modulation of the shielding anisotropy (20), and indeed this mechanism may be effective, resulting in the small contribution to spin lattice relaxation of glutamine (COI5NH2). suggestion has to be obtained from a frequency dependence of T1 (3,20).…”

Section: J2-7t T2mentioning

confidence: 99%

15N nuclear magnetic resonance investigations on amino acids.

Blomberg¹,

Mäurer²,

Rüterjans³

1976

Proc. Natl. Acad. Sci. U.S.A.

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ABSTRACT'5N nuclear magnetic resonance investigations of some amino acids were carried out in order to check the applicability of this method to biological problems. Because the natural abundance of the '5N isotope is not sufficient to get readable spectra in a reasonable time, 95% 15N isotope-enriched samples were used for the measurements. Besides ifie chemical shift values, the line widths, and the nuclear Overhauser enhancement factors, spin lattice relaxation times of the correspondent 15N resonances were measured as functions of pH and temperature.The functional groups that bear the 15N nucleus reveal characteristic differences in the measured uantities. The exchange behavior of protons attached to the AN with protons of the solvent water permits certain insights into the mechanism of these processes. The various contributions to spin lattice relaxation of the investigated '5N resonances are discussed. Although 15N nuclear magnetic resonance (NMR) spectroscopy appears to be very useful for investigating structures of nitrogen-containing molecules, the low natural abundance and unfavorable sensitivity of the 15N nucleus have limited its application (1). This is especially true with biologically relevant molecules, inasmuch as these substances are usually available only in fairly small quantities. Some progress may, however, be obtained by the enrichment of the 15N isotope to increase the signal-to-noise ratio of 15N NMR. Several authors have shown that 15N NMR in general and in particular of amino acid residues or other biologically important molecules may reveal data not only of molecular structure, i.e., values of the chemical shift or coupling constants, but also data of the dynamic behavior of the investigated molecule (2-6). The purpose of this paper is to report new results of 15N NMR work on various amino acids. Effects of chemical exchange, chemical shifts, coupling constants, line shapes, nuclear Overhauser enhancements, and nuclear relaxation rates of 15N-enriched glycine, lysine, glutamine, arginine, and proline have been measured as a function of pH and temperature.EXPERIMENTAL SECTION 15N-enriched (95%) glycine, glutamine (-CO15NH2), lysine (-a-15NH2), proline, and arginine [-NH-C-(15NH2)2] were purchased from Rohstoff Einfuhr GmbH., Dusseldorf, Germany.For all measurements the amino acids were dissolved in doubly distilled water; the pH value was adjusted with HCI and NaOH (reagent grade). In order to avoid paramagnetic impurities all solutions were shaken after the pH adjustment with Chelex 100 (Bio-Rad) according to the procedure of Irving and Lapidot (7). After removal of paramagnetic impurities the solution was transferred to an NMR sample tube (Wilmad, N.J.

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Nitrogen-15 NMR of pyridine in high magnetic: Fields

Cited by 45 publications

References 26 publications

Investigation of the Structure of Liquid Pyridine: a Molecular Dynamics Simulation, an RISM, and an X-ray Diffraction Study

Investigation of the Structure of Liquid Pyridine: a Molecular Dynamics Simulation, an RISM, and an X-ray Diffraction Study

Heteronuclear Cross‐Relaxation Effects in the NMR Spectroscopy of Hyperpolarized Targets

15N nuclear magnetic resonance investigations on amino acids.

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