Homonuclear Decoupling in <sup>1</sup>H NMR of Solids by Remote Correlation

Moutzouri, Pinelopi; Paruzzo, Federico M.; Almeida, Bruno Simões de; Stevanato, Gabriele; Emsley, Lyndon

doi:10.1002/ange.201916335

Cited by 7 publications

(8 citation statements)

References 27 publications

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“…Time evolution under such a zeroquantum Hamiltonian does not lead to line splitting, but a line shift has been shown for the rank-one part of the J coupling (Andrew and Farnell, 1968), which also has a purely zero-quantum Hamiltonian (Mehring, 1983). This fact has also been mentioned in a recent paper about homonuclear J decoupling in solids (Moutzouri et al, 2020). As a consequence of this, the second-order Hamiltonian will not only lead to a line broadening, but also a shift of the line that depends on the spinning frequency.…”

Section: +ĥmentioning

confidence: 68%

“…Experimental observations of the residual homogeneous line width as a function of spinning frequency show that it can often be approximated by a linear correlation with the inverse of the spinning frequency with some deviation that indicates a partial inverse quadratic dependence (Nishiyama, 2016;Sternberg et al, 2018;Penzel et al, 2019;Schledorn et al, 2020). This has been attributed to third-order contributions to the effective Hamiltonian or to chemical-shift effects (Sternberg et al, 2018;Moutzouri et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Residual dipolar line width in magic-angle spinning proton solid-state NMR

et al. 2021

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Abstract. Magic-angle spinning is routinely used to average anisotropic interactions in solid-state nuclear magnetic resonance (NMR). Due to the fact that the homonuclear dipolar Hamiltonian of a strongly coupled spin system does not commute with itself at different time points during the rotation, second-order and higher-order terms lead to a residual dipolar line broadening in the observed resonances. Additional truncation of the residual broadening due to isotropic chemical-shift differences can be observed. We analyze the residual line broadening in coupled proton spin systems based on theoretical calculations of effective Hamiltonians up to third order using Floquet theory and compare these results to numerically obtained effective Hamiltonians in small spin systems. We show that at spinning frequencies beyond 75 kHz, second-order terms dominate the residual line width, leading to a 1/ωr dependence of the second moment which we use to characterize the line width. However, chemical-shift truncation leads to a partial ωr-2 dependence of the line width which looks as if third-order effective Hamiltonian terms are contributing significantly. At slower spinning frequencies, cross terms between the chemical shift and the dipolar coupling can contribute in third-order effective Hamiltonians. We show that second-order contributions not only broaden the line, but also lead to a shift of the center of gravity of the line. Experimental data reveal such spinning-frequency-dependent line shifts in proton spectra in model substances that can be explained by line shifts induced by the second-order dipolar Hamiltonian.

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Section: +ĥmentioning

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Residual dipolar line width in magic-angle spinning proton solid-state NMR

et al. 2021

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“…It is reported that the coherence transfer efficiency of the INEPT pulse sequence is significantly improved with the use of 1 H homonuclear decoupling schemes under the fast-MAS conditions . It is also shown that homogeneous 1 H line width can be reduced by an anti-z-COSY experiment, which was introduced initially to suppress multiple homonuclear scalar couplings in solution NMR . In silico narrowed 1 H spectra can be obtained by simultaneously fitting the experimental 1 H line shape at various MAS frequencies and predicting 1 H spectra free of homogeneous broadening …”

Section: Evolution Of Fast Very Fast and Ultrafast Mas Probesmentioning

confidence: 99%

“…The anti-z-cosy experiment was proposed in solution-state NMR to obtain homonuclear decoupled proton spectra, albeit at reduced sensitivity, increased acquisition time, and dimensionality . Emsley and co-workers recently adapted the solution state anti-z-COSY experiments to solids at UFMAS . They observed a factor of 2 narrowing in proton line widths at different MAS frequencies.…”

Section: Other Topicsmentioning

confidence: 99%

“…93 It is also shown that homogeneous 1 H line width can be reduced by an anti-z-COSY experiment, which was introduced initially to suppress multiple homonuclear scalar couplings in solution NMR. 94 In silico narrowed 1 H spectra can be obtained by simultaneously fitting the experimental 1 H line shape at various MAS frequencies and predicting 1 H spectra free of homogeneous broadening. 95 2.3.3.…”

Section: Homogeneous Line-broadeningmentioning

confidence: 99%

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Ultrafast Magic Angle Spinning Solid-State NMR Spectroscopy: Advances in Methodology and Applications

et al. 2022

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Solid-state NMR spectroscopy is one of the most commonly used techniques to study the atomic-resolution structure and dynamics of various chemical, biological, material, and pharmaceutical systems spanning multiple forms, including crystalline, liquid crystalline, fibrous, and amorphous states. Despite the unique advantages of solid-state NMR spectroscopy, its poor spectral resolution and sensitivity have severely limited the scope of this technique. Fortunately, the recent developments in probe technology that mechanically rotate the sample fast (100 kHz and above) to obtain “solution-like” NMR spectra of solids with higher resolution and sensitivity have opened numerous avenues for the development of novel NMR techniques and their applications to study a plethora of solids including globular and membrane-associated proteins, self-assembled protein aggregates such as amyloid fibers, RNA, viral assemblies, polymorphic pharmaceuticals, metal–organic framework, bone materials, and inorganic materials. While the ultrafast-MAS continues to be developed, the minute sample quantity and radio frequency requirements, shorter recycle delays enabling fast data acquisition, the feasibility of employing proton detection, enhancement in proton spectral resolution and polarization transfer efficiency, and high sensitivity per unit sample are some of the remarkable benefits of the ultrafast-MAS technology as demonstrated by the reported studies in the literature. Although the very low sample volume and very high RF power could be limitations for some of the systems, the advantages have spurred solid-state NMR investigation into increasingly complex biological and material systems. As ultrafast-MAS NMR techniques are increasingly used in multidisciplinary research areas, further development of instrumentation, probes, and advanced methods are pursued in parallel to overcome the limitations and challenges for widespread applications. This review article is focused on providing timely comprehensive coverage of the major developments on instrumentation, theory, techniques, applications, limitations, and future scope of ultrafast-MAS technology.

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Pure Isotropic Proton NMR Spectra in Solids using Deep Learning

et al. 2023

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The resolution of proton solid-state NMR spectra is usually limited by broadening arising from dipolar interactions between spins. Magic-angle spinning alleviates this broadening by inducing coherent averaging. However, even the highest spinning rates experimentally accessible today are not able to completely remove dipolar interactions. Here, we introduce a deep learning approach to determine pure isotropic proton spectra from a two-dimensional set of magic-angle spinning spectra acquired at different spinning rates. Applying the model to 8 organic solids yields highresolution 1 H solid-state NMR spectra with isotropic linewidths in the 50-400 Hz range.

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Homonuclear Decoupling in ¹H NMR of Solids by Remote Correlation

Cited by 7 publications

References 27 publications

Residual dipolar line width in magic-angle spinning proton solid-state NMR

Residual dipolar line width in magic-angle spinning proton solid-state NMR

Ultrafast Magic Angle Spinning Solid-State NMR Spectroscopy: Advances in Methodology and Applications

Pure Isotropic Proton NMR Spectra in Solids using Deep Learning

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Homonuclear Decoupling in 1H NMR of Solids by Remote Correlation

Cited by 7 publications

References 27 publications

Residual dipolar line width in magic-angle spinning proton solid-state NMR

Residual dipolar line width in magic-angle spinning proton solid-state NMR

Ultrafast Magic Angle Spinning Solid-State NMR Spectroscopy: Advances in Methodology and Applications

Pure Isotropic Proton NMR Spectra in Solids using Deep Learning

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Homonuclear Decoupling in ¹H NMR of Solids by Remote Correlation