Resolution in 13C NMR of organic solids using high-power proton decoupling and magic-angle sample spinning

VanderHart, David L.; Earl, William L.; Garroway, A. N.

doi:10.1016/0022-2364(81)90178-5

Cited by 286 publications

(351 citation statements)

References 61 publications

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“…It is well known that resonance peak broadening occurs in the case of 13 C observation with 1 H-13 C dipolar decoupling because of the interference between the strength of the radio-frequency irradiation and the molecular motion. [6][7][8] The similar frequency of the molecular motion and the radio-frequency irradiation reduces the efficiency of the decoupling. Because radio-frequency irradiation is not employed for 1 H measurements, the broadening observed at 10 kHz MAS is presumably ascribed to the interference between the strength of the 1 H-1 H dipolar interaction and the MAS rate.…”

Section: Resultsmentioning

confidence: 99%

Influence of magic angle spinning on T1H of SBR studied by solid state 1H NMR

Asano

Hori

Kitamura

et al. 2012

Polym J

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We have investigated the influence of the high centrifugal pressure caused by fast magic-angle spinning (MAS) on the molecular motion of styrene-butadiene rubbers (SBR) filled with SiO 2 (SBR/Si composite) though solid-state magic-angle spinning nuclear magnetic Resonance ( 1 H MAS NMR) measurements. Because the 1 H-1 H dipolar interaction of elastomers is weak compared with that of glassy polymers, a narrower 1 H linewidth is observed under fast MAS. The temperature dependence of the 1 H spin-lattice relaxation time (T 1 H ) revealed that the T 1 H minimum increases with the MAS rate. Furthermore, we observed a difference in the temperature dependence of T 1 H between end-chain-modified SBR and normal (unmodified) SBR in the SBR/Si composites. The temperature dependence of T 1 H is described by the Bloembergen-Purcell-Pound theory, with the assumption that the correlation time obeys the Williams-Landel-Ferry empirical theory. The fitting showed that the molecular motion does not change significantly until a MAS rate of 20 kHz, with the motional mode changing considerably at a MAS rate of 25 kHz. The motion of SBR in the unmodified SBR/Si composite was greatly affected by the fast MAS rates. Furthermore, the plot of the estimated centrifugal pressure versus the T 1 H minimum resembled the stress-strain curve. This result enables the detection of macroscopic physical deformation by the microscopic parameter INTRODUCTIONSolid-state NMR is useful for the investigation of the molecular motion of the functional groups of elastomers and polymers. In particular, the recent development of the magic-angle spinning (MAS) technique allows a sample rotor to be spun much faster than 20 kHz. Thus, we can detect the high-resolution 1 H signals of rubbers and elastomers under the fast rates that are possible in MAS because these fast MAS rates effectively reduce the signal broadening that arises from the relatively weak 1 H-1 H dipolar interaction of elastomers (in comparison with that of glassy solid polymers).Generally, spin-lattice relaxation time (T 1 ) is observed to study molecular motion. In the case of rare spins such as 13 C, however, it is time-consuming to observe the signals and measure an accurate T 1 with a good signal-to-noise ratio. In contrast, proton signals are intense enough to allow quick analysis of molecular motion through the T 1 measurement. However, for a glassy solid polymer, the strong 1 H-1 H dipolar interaction obscures the individual functional group signals, even with fast MAS. For rubbers and elastomers under fast MAS, in contrast, each peak assigned to a respective functional group can be detected because of the weak 1 H-1 H dipolar interaction. Furthermore, it is easy to detect 1 H-T 1 ( 1 H spin-lattice relaxation time (T 1 H )) accurately. In contrast, it is well known that MAS causes the temperature of the inner sample to increase because of friction between the MAS and the air. In addition, it has recently been reported that fast MAS causes

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Section: Resultsmentioning

confidence: 99%

Influence of magic angle spinning on T1H of SBR studied by solid state 1H NMR

Asano

Hori

Kitamura

et al. 2012

Polym J

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“…Other sources might involve the anisotropic magnetic susceptibility (Cowans and Grutzner 1993;Garroway 1977;Vanderhart et al 1981). The estimated molecular weight at which solidstate NMR yields a more favourable resolution compared to solution-state NMR experiments therefore represents an upper limit that is implied by the current technology.…”

Section: Resultsmentioning

confidence: 99%

Narrow carbonyl resonances in proton-diluted proteins facilitate NMR assignments in the solid-state

2010

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HNCO/HNCACO type correlation experiments are an alternative for assignment of backbone resonances in extensively deuterated proteins in the solid-state, given the fact that line widths on the order of 14-17 Hz are achieved in the carbonyl dimension without the need of high power decoupling. The achieved resolution demonstrates that MAS solid-state NMR on extensively deuterated proteins is able to compete with solution-state NMR spectroscopy if proteins are investigated with correlation times s c that exceed 25 ns.

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“…These magnetic susceptibility broadenings are often the limiting factor in dilute-spin solid-state NMR, 32,33 and previous studies of 1 H natural linewidths as a function of spin rate and static magnetic field have suggested that they are also FIG. 9.…”

Section: Inhomogeneous Contributions To 1 H Linewidthsmentioning

confidence: 93%

“…Inhomogeneous contributions to dilute-spin linewidths have been studied in detail for 13 C MAS NMR, 32,33 and so it is not necessary to revisit this existing work, given that the inhomogeneous broadenings are seen to be the same on both rare and abundant spins. It should be noted, however, that a broadening of, say, 0.3 ppm due to susceptibility effects or sample disorder has a much smaller impact on 13 C NMR, with its large chemical shift range, in comparison to 1 H NMR.…”

Section: Inhomogeneous Contributions To 1 H Linewidthsmentioning

confidence: 99%

Origins of linewidth in H1 magic-angle spinning NMR

Zorin

Brown

Hodgkinson

2006

The Journal of Chemical Physics

127

116

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A detailed study of the factors determining the linewidth (and hence resolution) in H1 solid-state magic-angle spinning NMR is described. Although it has been known from the early days of magic-angle spinning (MAS) that resolution of spectra from abundant nuclear spins, such as H1, increases approximately linearly with increasing sample rotation rate, the difficulty of describing the dynamics of extended networks of coupled spins has made it difficult to predict a priori the resolution expected for a given sample. Using recently developed, highly efficient methods of numerical simulation, together with experimental measurements on a variety of test systems, we propose a comprehensive picture of H1 resolution under MAS. The “homogeneous” component of the linewidth is shown to depend primarily on the ratio between an effective local coupling strength and the spin rate, modified by geometrical factors which loosely correspond to the “dimensionality” of the coupling network. The remaining “inhomogeneous” component of the natural linewidth is confirmed to have the same properties as in dilute-spin NMR. Variations in the NMR frequency due to chemical shift effects are shown to have minimal impact on H1 resolution. The implications of these results for solid-state NMR experiments involving H1 and other abundant-spin nuclei are discussed.

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Resolution in 13C NMR of organic solids using high-power proton decoupling and magic-angle sample spinning

Cited by 286 publications

References 61 publications

Influence of magic angle spinning on T1H of SBR studied by solid state 1H NMR

Influence of magic angle spinning on T1H of SBR studied by solid state 1H NMR

Narrow carbonyl resonances in proton-diluted proteins facilitate NMR assignments in the solid-state

Origins of linewidth in H1 magic-angle spinning NMR

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