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  Carbon-13 Chemical-Shift Correlation, Spin Diffusion and Self Diffusion in Isotopically Enriched Tropolone

Olender, Z., Reichert, D., Müller, A., Zimmermann, H., Poupko, R., & Luz, Z. (1996). Carbon-13 Chemical-Shift Correlation, Spin Diffusion and Self Diffusion in Isotopically Enriched Tropolone. Journal of Magnetic Resonance Series A, 120(1), 31-45. doi:10.1006/jmra.1996.0097.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-0019-A70D-9 Version Permalink: http://hdl.handle.net/11858/00-001M-0000-002D-ABDC-B
Genre: Journal Article

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JMagnResonA_120_1996_31.pdf (Any fulltext), 3MB
 
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 Creators:
Olender, Z., Author
Reichert, Detlef, Author
Müller, Andreas1, Author              
Zimmermann, Herbert2, Author              
Poupko, Raphy, Author
Luz, Zeev, Author
Affiliations:
1Research Group Prof. Dr. Haeberlen, Max Planck Institute for Medical Research, Max Planck Society, ou_1497739              
2Department of Molecular Physics, Max Planck Institute for Medical Research, Max Planck Society, ou_1497705              

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 Abstract: Carbon-13 one-dimensional magnetization transfer and two-dimensional rotor-synchronized exchange NMR experiments of magic-angle-spinning (MAS) samples of solid tropolone are reported. Experiments were performed on samples enriched to 25%13C in the carbonyl or the hydroxy carbons, as well as on a normal (unenriched) sample and a mixture of both. The result shows the presence of spin exchange between the two types of carbons as well as between similar carbons in crystallographically inequivalent, but symmetry-related sites. This effect is used to determine the relative orientations of the various chemical-shift tensors and, using the known crystal structure, also their orientation in the molecular frame. The rates of the spin exchange are relatively fast in the enriched sample, the magnetization transfer being highly nonexponential and almost independent of temperature. In the normal sample, the spin exchange is slow, the magnetization transfer is nearly exponential, and the rates depend strongly on temperature. In the isotopically mixed sample, the spin-exchange rates are intermediate. These results indicate that, at high carbon-13 concentration, spin exchange is dominated by spin diffusion, while in natural abundance it is dominated by thermally activated self diffusion. To simulate the spin-diffusion process, a method is introduced in which the dipolar interactions between all the carbon-13 nuclei in the crystal are considered. The results reproduce well the experimental magnetization decay curves in the (25%) enriched sample and provide kinetic parameters for the spin-diffusion process. In normal tropolone, the spin-exchange experiments confirm the occurrence of self diffusion in which the molecules undergo translational jumps between different sites in the lattice.

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Language(s): eng - English
 Dates: 1995-10-261996-01-162002-05-251996-05
 Publication Status: Published in print
 Pages: 15
 Publishing info: -
 Table of Contents: -
 Rev. Method: Peer
 Identifiers: eDoc: 666003
DOI: 10.1006/jmra.1996.0097
Other: 5509
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Title: Journal of Magnetic Resonance Series A
  Other : J. Magn. Reson. Ser. A
Source Genre: Journal
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Publ. Info: Orlando, Fla. : Academic Press
Pages: - Volume / Issue: 120 (1) Sequence Number: - Start / End Page: 31 - 45 Identifier: ISSN: 1064-1858
CoNE: https://pure.mpg.de/cone/journals/resource/954922651176