Back Efecte Overhauser nuclear Catalan Kern-Overhauser-Effekt German Efecto Overhauser nuclear Spanish Effet Overhauser nucléaire French Effetto nucleare Overhauser Italian オーバーハウザー効果 Japanese Jądrowy efekt Overhausera Polish Ядерный эффект Оверхаузера Russian Ефект Овергаузера Ukrainian Hiệu ứng Overhauser Vietnamese
The nuclear Overhauser effect (NOE) is the transfer of nuclear spin polarization from one population of spin-active nuclei (e.g. 1H, 13C, 15N etc.) to another via cross-relaxation. A phenomenological definition of the NOE in nuclear magnetic resonance spectroscopy (NMR) is the change in the integrated intensity (positive or negative) of one NMR resonance that occurs when another is saturated by irradiation with an RF field. The change in resonance intensity of a nucleus is a consequence of the nucleus being close in space to those directly affected by the RF perturbation.
The NOE is particularly important in the assignment of NMR resonances, and the elucidation and confirmation of the structures or configurations of organic and biological molecules. The 1H two-dimensional NOE spectroscopy (NOESY) experiment and its extensions are important tools to identify stereochemistry of proteins and other biomolecules in solution, whereas in solid form crystal x-ray diffraction typically used to identify stereochemistry.[1][2][3] The heteronuclear NOE is particularly important in 13C NMR spectroscopy to identify carbons bonded to protons, to provide polarization enhancements to such carbons to increase signal-to-noise, and to ascertain the extent the relaxation of these carbons is controlled by the dipole-dipole relaxation mechanism.[4]
- ^ Noggle, Joseph H.; Schirmer, Roger E. (1971). The Nuclear Overhauser Effect: Chemical Applications. Academic Press. ISBN 9780125206501.
- ^ Neuhaus, David; Williamson, Michael P. (2000). The Nuclear Overhauser Effect in Structural and Conformational Analysis, 2nd ed. Wiley-VCH.
- ^ Claridge, Timothy D.W. (2016). High Resolution NMR Techniques in Organic Chemistry, 3rd ed. Elsevier. p. 315. ISBN 978-0080999869.
- ^ Kulhmann, Karl F.; Grant, David M.; Harris, Robin K. (1970). "Nuclear Overhauser Effects and 13C Relaxation Times in 13C {H} Double Resonance Spectra". Journal of Chemical Physics. 52 (7): 3439–3448. doi:10.1063/1.1673508.