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Deuterium NMR is NMR spectroscopy of deuterium (2H or D), an isotope of hydrogen.[1] Deuterium is an isotope with spin = 1, unlike hydrogen-1, which has spin = 1/2. The term deuteron NMR, in direct analogy to proton NMR, is also used.[2] Deuterium NMR has a range of chemical shift similar to proton NMR but with poor resolution, due to the smaller magnitude of the magnetic dipole moment of the deuteron relative to the proton. It may be used to verify the effectiveness of deuteration: a deuterated compound will show a strong peak in 2H NMR but not proton NMR.
2H NMR spectra are especially informative in the solid state because of its relatively small quadrupole moment in comparison with those of bigger quadrupolar nuclei such as chlorine-35. This allows for the whole spectrum to be excited with practically achievable pulses of a few microseconds in duration. However, since the natural abundance of 2H is only 0.016%, the sample must usually be 2H-enriched to achieve a strong enough signal. For a given C-D moiety, the quadrupolar splitting in the 2H NMR spectrum depends in a simple way on the angle between the C-D bond and the applied static magnetic field.[2] Thus, 2H NMR can probe orientation distributions in partially ordered deuterated polymers.[2] Changes in C-D bond orientation due to molecular motions have pronounced effects on the spectral line shape.[2] One example is the use of 2H NMR to study lipid membrane phase behavior.
References
edit- ^ Mantsch, Henry H.; Saitô, Hazime; Smith, Ian C. P. (1977). "Deuterium magnetic resonance, applications in chemistry, physics and biology". Progress in Nuclear Magnetic Resonance Spectroscopy. 11 (4): 211–272. doi:10.1016/0079-6565(77)80010-1. ISSN 0079-6565.
- ^ a b c d Spiess, H. W. (1985). "Deuteron NMR – A new Tool for Studying Chain Mobility and Orientation in Polymers", Advances in Polymer Science 66: 23-57. DOI: 10.1007/3-540-13779-3_16.
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