Article Dans Une Revue Solid State Nuclear Magnetic Resonance Année : 2016

Accurate NMR determination of C–H or N–H distances for unlabeled molecules

Résumé

Cross-Polarization with Variable Contact-time (CP-VC) is very efficient at ultra-fast MAS (νR≥60 kHz) to measure accurately the dipolar interactions corresponding to C–H or N–H short distances, which are very useful for resonance assignment and for analysis of dynamics. Here, we demonstrate the CP-VC experiment with 1H detection. In the case of C–H distances, we compare the CP-VC signals with direct (13C) and indirect (1H) detection and find that the latter allows a S/N gain of ca. 2.5, which means a gain of ca. 6 in experimental time. The main powerful characteristics of CP-VC methods are related to the ultra-fast spinning speed and to the fact that most of the time only the value of the dipolar peak separation has to be used to obtain the information. As a result, CP-VC methods are: (i) easy to set up and to use, and robust with respect to (ii) rf-inhomogeneity thus allowing the use of full rotor samples, (iii) rf mismatch, and (iv) offsets and chemical shift anisotropies. It must be noted that the CP-VC 2D method with indirect 1H detection requires the proton resolution and is thus mainly applicable to small or perdeuterated molecules. We also show that an analysis of the dynamics can even be performed, with a reasonable experimental time, on unlabeled samples with 13C or even 15N natural abundance.
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hal-04554666 , version 1 (22-04-2024)

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Yusuke Nishiyama, M. Malon, Marek J. Potrzebowski, Piotr Paluch, Jean-Paul Amoureux. Accurate NMR determination of C–H or N–H distances for unlabeled molecules. Solid State Nuclear Magnetic Resonance, 2016, Solid State Nuclear Magnetic Resonance, 73, pp.15-21. ⟨10.1016/j.ssnmr.2015.06.005⟩. ⟨hal-04554666⟩
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