Synchronous helical pulse sequences in magic-angle spinning nuclear magnetic resonance: Double quantum recoupling of multiple-spin systems

Brinkmann, Andreas; Edén, Mattias; Levitt, Malcolm H.

doi:10.1063/1.481458

Cited by 199 publications

(242 citation statements)

References 55 publications

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“…Consequently, the Jmultiplets, which are clearly resolved for the CO and the C b resonances in the single quantum-dimension, are not observed in the triple-quantum dimension of the 2D correlation spectra of Fig. 2a and 2b. Figure 3 shows numerical simulations of the triple-quantum filtering efficiency as a function of the delay t (with t = t 1 = t 2 ) for fully 13 C-labelled L-alanine, at different spinning frequencies in a magnetic field of 7.0 T. The simulations, which take in account the effect of the CSA and homonuclear dipolar interactions in addition to the J-couplings, were performed using the SIMPSON software [39] with the parameters given in [40,41] and neglecting both 1 H-13 C dipolar couplings and relaxation effects . The TQF efficiency expected from standard product operator algebra [38] for a liquid-like J-coupling Hamiltionan (Eq.…”

Section: Application To a Linear Three-spin System 321 Two-dimensiomentioning

confidence: 99%

“…The spinning frequencies are (a, d) 7, (b, e) 14 and (c, f) 34 kHz. The simulations were performed with SIMPSON [39] using the parameters given in [40,41] and neglecting relaxation effects. Powder averaging was performed using 615 {α M , β M } molecular orientational angles, chosen according to the ZCW scheme [50], and 10 values for the γ M angle.…”

Section: Appendixmentioning

confidence: 99%

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Triple-quantum correlation NMR experiments in solids using J-couplings

Fayon

Roiland

Emsley

et al. 2006

Journal of Magnetic Resonance

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We show that triple-quantum -single-quantum (TQ-SQ) correlation spectra of crystalline and disordered solids can be obtained under MAS using pulse sequences based on through-bond J-couplings. The feasibility of the experiments in coupled spin-½ systems is demonstrated for fully 13 C-labelled L-alanine and Pb 3 P 4 O 13 crystalline compounds, considered as model three-spin and four-spin systems, respectively. In the case of phosphate glasses, we show that the obtained TQ-SQ correlation spectra provide an improved description of the glass forming network connectivities and of the chain length distribution in the disordered network. IntroductionHomonuclear double-quantum correlation spectroscopy has been shown to be a valuable tool in solid-state NMR for determining atomic connectivities and studying the structure and dynamic of ordered or disordered materials [1,2]. In this context, various experiments have been developed to obtain two-dimensional (2D) double-quantum -singlequantum (DQ-SQ) correlation spectra of coupled spin-½ systems under magic angle spinning (MAS) which is required for enhanced spectral resolution and sensitivity. Many of these methods employ pulse sequences which reintroduce the MAS-averaged through-space homonuclear dipolar interaction, to obtain DQ-SQ correlation spectra which reflect the through-space atomic proximities [3][4][5][6][7][8][9][10]. Alternatively, pulse sequences based on throughbond isotropic J-couplings, like the INADEQUATE [11] and refocused INADEQUATE [12] experiments, have also been applied efficiently to obtain through-bond DQ-SQ correlation spectra for large range of materials [12][13][14][15][16][17][18][19][20][21][22][23].In the case of inorganic glasses, for which the characterization of medium range order remains challenging, the DQ-SQ correlation experiment allows to improve the structural description obtained from NMR spectroscopy by determining the pairwise connectivities between the basic building units of the disordered network. In phosphate glasses, homonuclear through-bond [22,23] and through-space [24-25] DQ-SQ correlation methods have been applied successfully to probe P-O-P connectivities between the various network former PO 4 tetrahedral units (Q n with n bridging oxygen atoms). These experiments provide enhanced spectral resolution relative to the conventional MAS spectra allowing the distinction between Q n units bonded to different types of PO 4 to be made and giving evidence of a chain length distribution in the disordered network [22][23][24][25].Nevertheless, information about longer range order, which could be obtained from a three-spin correlation experiment, remains desirable for a better description of the disordered glassy network. Recently, various dipolar recoupling pulse sequences have been proposed to obtain 1 H and 13 C homonuclear through-space triple-quantum -single-quantum (TQ-SQ) correlation spectra in solids [26][27][28][29][30]. A modified INADEQUATE experiment was also proposed to record 13 C through-bond TQ-SQ correlatio...

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Section: Application To a Linear Three-spin System 321 Two-dimensiomentioning

confidence: 99%

Section: Appendixmentioning

confidence: 99%

Triple-quantum correlation NMR experiments in solids using J-couplings

Fayon

Roiland

Emsley

et al. 2006

Journal of Magnetic Resonance

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“…60,61,65,67,70 We used a combination of inversion supercycles, in which all rf phases are inverted in adjacent pulse sequence blocks, and "multiple-quantum" (MQ) phase cycles, in which the overall rf phase of consecutive pulse sequence blocks is incremented. 59,61,65,67,70 The nested supercycles are denoted …”

Section: Symmetry-based Heteronuclear Longitudinal Two-spin-order Dipmentioning

confidence: 99%

Sensitivity Enhancement and Heteronuclear Distance Measurements in Biological ¹⁷O Solid-State NMR

Brinkmann

Kentgens

2006

J. Phys. Chem. B

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In this contribution we present a comprehensive approach to study hydrogen bonding in biological and biomimetic systems through 17 O and 17 O-1 H solid-state NMR combined with density functional theory calculations of 17 O and 1 H NMR parameters. We explore the signal enhancement of 17 O in L-tyrosine‚HCl using repetitive double-frequency swept radio frequency pulses in solid-state NMR. The technique is compatible with high magnetic fields and fast magic-angle spinning of the sample. A maximum enhancement by a factor of 4.3 is obtained in the signal-to-noise ratio of the selectively excited 17 O central transition in a powdered sample of 17 O η -L-tyrosine‚HCl at an external field of 14.1 T and a spinning frequency of 25 kHz. As little as 128 transients lead to meaningful 17 O spectra of the same sample at an external field of 18.8 T and a spinning frequency of 50 kHz. Furthermore we employed supercycled symmetry-based pulse sequences on the protons to achieve heteronuclear longitudinal two-spin-order (I z S z ) recoupling to determine 17 O-1 H distances. These sequences recouple the heteronuclear dipolar 17 O-1 H couplings, where dipolar truncation is absent, while decoupling the homonuclear proton dipolar interactions. They can be applied at fast magic-angle-spinning frequencies up and beyond 50 kHz and are very robust with respect to 17 O quadrupolar couplings and both 17O and 1 H chemical shift anisotropies, which makes them suitable for the use at high external magnetic fields. The method is demonstrated by determining the 17 O η -1 H distance in L-tyrosine‚HCl at a spinning frequency of 50 kHz and an external field of 18.8 T.

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“…The integers n and ν may therefore be interpreted as space and spin winding numbers. 39 The sample rotates bodily through n full rotations, in the same time that it takes the radio-frequency phases to advance through ν full rotations, in N equal steps. This idea is conveyed for the cases of C7 1 2 and C14 5 4 in Figure 3.…”

Section: Cn νmentioning

confidence: 99%

“…A further extension of the symmetry theory led to a pallette of symmetries suitable for γ -encoded doublequantum recoupling, including methods which are applicable at high spinning frequencies. 39 The symmetry theorems were also used to treat the problem of heteronuclear decoupling in MAS solids, generating schemes competitive with the TPPM modulation method. 41, 45 In a related development, Spiess and co-workers showed that CRAMPS may be implemented at high MAS spinning frequencies by synchronizing the rf cycles with the sample rotation.…”

Section: Introductionmentioning

confidence: 99%