Solid state nuclear magnetic resonance最新文献

{"title":"Effect of cross polarization radiofrequency phases on signal phase","authors":"S. Chandra Shekar ,&nbsp;Wancheng Zhao ,&nbsp;Thomas K. Weldeghiorghis,&nbsp;Tuo Wang","doi":"10.1016/j.ssnmr.2021.101771","DOIUrl":"10.1016/j.ssnmr.2021.101771","url":null,"abstract":"<div><p><span>Utilizing phases of radio frequency (RF) pulses to manipulate spin dynamics is routine in NMR and MRI, leading to spectacular techniques like phase cycling. In a very different area, cross polarization (CP) also has a long history as part of a vast number of solid-state NMR pulse sequences. However, a detailed study devoted to the effect of CP RF phases on </span>NMR signal<span>, seems not to be readily available. From first principles, we arrive at a simple dependence of NMR signal on arbitrary CP RF phases, for static and MAS conditions, accompanied by experimental verification. In the process, the CP propagator emerges as a product of RF “pulses” and a period of “free precession”, conforming to coherence transfer pathway theory. The theoretical expressions may lend confidence for dealing with CP blocks with tunable phases in pulse sequences.</span></p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"117 ","pages":"Article 101771"},"PeriodicalIF":3.2,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39776728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of solid-state NMR techniques for structural characterization of metal-organic frameworks","authors":"Caiyan He ,&nbsp;Shenhui Li ,&nbsp;Yuqing Xiao ,&nbsp;Jun Xu ,&nbsp;Feng Deng","doi":"10.1016/j.ssnmr.2022.101772","DOIUrl":"10.1016/j.ssnmr.2022.101772","url":null,"abstract":"<div><p><span>Solid-state NMR can afford the structural information about the chemical composition, local environment, and spatial coordination at the atomic level, which has been extensively applied to characterize the detailed structure and host-guest interactions in metal-organic frameworks (MOFs). In this review, recent advances for the structural characterizations of MOFs using versatile solid-state NMR techniques were briefly introduced. High-field sensitivity-enhanced solid-state NMR method enabled the direct observation of metal centers in MOFs containing low-γ nuclei. Two-dimensional (2D) homo- and hetero-nuclear correlation </span>MAS NMR experiments provided the spatial proximity among linkers, metal clusters and the introduced guest molecules. Moreover, quantitative measurement of inter-nuclear distances using solid-state NMR provided valuable structural information about the connectivity geometry as well as the host-guest interactions within MOFs. Furthermore, solid-state NMR has exhibited great potential for unraveling the structure property of MOFs containing paramagnetic metal centers.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"117 ","pages":"Article 101772"},"PeriodicalIF":3.2,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39812758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying the quadrupolar interaction by 45Sc-NMR spectroscopy of single crystals","authors":"Otto E.O. Zeman,&nbsp;Thomas Bräuniger","doi":"10.1016/j.ssnmr.2022.101775","DOIUrl":"10.1016/j.ssnmr.2022.101775","url":null,"abstract":"<div><p><span>Single crystals of the compound [</span><span><math><msub><mrow><mrow><mo>{</mo><mrow><mi>S</mi><mi>c</mi><msub><mrow><mrow><mo>(</mo><mrow><msub><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow></msub><mi>O</mi></mrow><mo>)</mo></mrow></mrow><mrow><mn>5</mn></mrow></msub><mrow><mo>(</mo><mrow><mi>μ</mi><mo>-</mo><mi>O</mi><mi>H</mi></mrow><mo>)</mo></mrow></mrow><mo>}</mo></mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>]Cl₄ ⋅ 2H₂O were studied by ⁴⁵<span>Sc-NMR, with the effect of the quadrupolar coupling interaction on the spectra of the spin-7/2 nucleus analysed in the hierarchical framework of perturbation theory. Orientation-dependent spectra acquired at </span><em>B</em>₀ = 17.6 T showed strong second-order effects due to the comparatively large coupling constant of <em>χ</em> = |14.613 ± 0.006| MHz, with an associated asymmetry parameter of <em>η</em>_<em>Q</em> = 0.540 9 ± 0.000 4. By analysing the splittings of the ±3/2 satellites, which in good approximation are subjected to first-order effects only, the full quadrupolar coupling tensor could be determined. The second-order effects caused by this tensor were calculated according to theoretical predictions for all orientations, and subtracted from both the centres of gravity of the satellites, and the central transitions. This allowed extraction of the full chemical shift tensor, with the eigenvalues being <em>δ</em>₁₁ = (5.6 ± 0.9) ppm, <em>δ</em>₂₂ = (12.4 ± 0.9) ppm, and <em>δ</em>₃₃ = (38.5 ± 0.9) ppm. In spectra acquired at a lower magnetic field of <em>B</em>₀ = 9.4 T, third-order effects could be detected, and similarly quantified using analytical expressions.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"117 ","pages":"Article 101775"},"PeriodicalIF":3.2,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39855637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Protonation tuned dipolar order mediated 1H→13C cross-polarization for dissolution-dynamic nuclear polarization experiments","authors":"Stuart J. Elliott ,&nbsp;Quentin Stern,&nbsp;Olivier Cala,&nbsp;Sami Jannin","doi":"10.1016/j.ssnmr.2021.101762","DOIUrl":"https://doi.org/10.1016/j.ssnmr.2021.101762","url":null,"abstract":"<div><p><span>A strategy of dipolar order mediated nuclear spin polarization transfer has recently been combined with dissolution-dynamic nuclear polarization (</span><em>d</em><span>DNP) and improved by employing optimized shaped radiofrequency pulses and suitable molecular modifications. In the context of </span><em>d</em>DNP experiments, this offers a promising means of transferring polarization from high-gamma ¹H spins to insensitive ¹³C spins with lower peak power and lower energy compared with state-of-the-art cross-polarization schemes. The role of local molecular groups and the glassing matrix protonation level are both postulated to play a key role in the polarization transfer pathway via an intermediary reservoir of dipolar spin order. To gain appreciation of the mechanisms involved in the dipolar order mediated polarization transfer under <em>d</em>DNP conditions, we investigate herein the influence of the pivotal characteristics of the sample makeup: (<em>i</em>) revising the protonation level for the constituents of the DNP glass; and (<em>ii</em>) utilizing deuterated molecular derivatives. Experimental demonstrations are presented for the case of [1–¹³<span>C]sodium acetate. We find that the proton sample molarity has a large impact on both the optimal parameters and the performance of the dipolar order mediated cross-polarization sequence, with the </span>¹³C signal build-up time drastically shortened in the case of high solvent protonation levels. In the case of a deuterated molecular derivative, we observe that the nearby ²<span>H substituted methyl group is deleterious to the </span>¹H→¹³C transfer phenomenon (particularly at low levels of sample protonation). Overall, increased solvent protonation makes the dipolar order governed polarization transfer significantly faster and more efficient. This study sheds light on the influential sample formulation traits which govern the dipolar order-controlled transfer of polarization and indicates that the polarization transfer efficiencies of deuterated molecules can be boosted and reach high performances simply by adequate solvent protonation.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"116 ","pages":"Article 101762"},"PeriodicalIF":3.2,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91640813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A toolbox for improving the workflow of NMR crystallography","authors":"Patrick M.J. Szell ,&nbsp;Sten O. Nilsson Lill ,&nbsp;Helen Blade ,&nbsp;Steven P. Brown ,&nbsp;Leslie P. Hughes","doi":"10.1016/j.ssnmr.2021.101761","DOIUrl":"10.1016/j.ssnmr.2021.101761","url":null,"abstract":"<div><p>NMR crystallography is a powerful tool with applications in structural characterization and crystal structure verification, to name two. However, applying this tool presents several challenges, especially for industrial users, in terms of consistency, workflow, time consumption, and the requirement for a high level of understanding of experimental solid-state NMR and GIPAW-DFT calculations. Here, we have developed a series of fully parameterized scripts for use in Materials Studio and TopSpin, based on the .magres file format, with a focus on organic molecules (e.g. pharmaceuticals), improving efficiency, robustness, and workflow. We separate these tools into three major categories: performing the DFT calculations, extracting &amp; visualizing the results, and crystallographic modelling. These scripts will rapidly submit fully parameterized CASTEP jobs, extract data from the calculations, assist in visualizing the results, and expedite the process of structural modelling. Accompanied with these tools is a description on their functionality, documentation on how to get started and use the scripts, and links to video tutorials for guiding new users. Through the use of these tools, we hope to facilitate NMR crystallography and to harmonize the process across users.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"116 ","pages":"Article 101761"},"PeriodicalIF":3.2,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39695597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of the structure and dynamics at various parts of the antibacterial drug molecule cefpodoxime proxetil","authors":"Krishna Kishor Dey ,&nbsp;Manasi Ghosh","doi":"10.1016/j.ssnmr.2021.101752","DOIUrl":"10.1016/j.ssnmr.2021.101752","url":null,"abstract":"<div><p><span>The structure and dynamics of cefpodoxime proxetil<span> are elucidated by measuring chemical shift anisotropy (CSA) tensor, spin-lattice relaxation time, and local correlation time at twenty-one crystallographically different </span></span>¹³C nuclei sites. The principal components of CSA tensor of cefpodoxime proxetil are extracted by the two-dimensional phase adjusted sinning sideband (2DPASS) cross-polarization magic angle spinning (CP-MAS) solid-state NMR experiment, and the spin-lattice relaxation time is measured by the method outlined by Torchia(T1CP). The local correlation time is calculated by bearing in mind that the spin-lattice relaxation mechanism of ¹³C nuclei is mainly governed by the CSA interaction and the heteronuclear dipole-dipole interaction. The aminothiazole ring, <span><math><mrow><mi>β</mi></mrow></math></span><span>-lactam ring, and dihydrothiazine ring provide stability to the drug molecule and increase the affinity of the drug to penicillin-binding proteins (PBPs) receptors. The principal components of CSA parameters, spin-lattice relaxation time, and local correlation time vary substantially for carbon nuclei residing on these three rings. These signify that not only the electronic environment, but the molecular conformation<span>, and the local dynamics are also altered within the ring. The substitution of the acyl side chain, oxime group, and the aminothiazole ring at the C7 position of the </span></span><span><math><mrow><mi>β</mi></mrow></math></span><span><span>-lactam ring enhances the antibacterial activity<span> and the binding affinity of the drug. A huge variation of the spin-lattice relaxation time and local correlation time is observed in those regions. The change in the electron </span></span>charge distribution and nuclear spin dynamics at different parts of the drug molecule is clear by CSA and spin-lattice relaxation measurements, which will enrich the field “NMR crystallography”.</span></p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"115 ","pages":"Article 101752"},"PeriodicalIF":3.2,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2021.101752","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39269282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"125Te NMR for structural investigations in phase change materials: Optimization of experimental conditions coupled to NMR shift prediction","authors":"J. Lizion ,&nbsp;A. Piarristeguy ,&nbsp;R. Laskowski ,&nbsp;P. Blaha ,&nbsp;R. Escalier ,&nbsp;M. Ménétrier ,&nbsp;A. Pradel ,&nbsp;G. Silly","doi":"10.1016/j.ssnmr.2021.101751","DOIUrl":"10.1016/j.ssnmr.2021.101751","url":null,"abstract":"<div><p><span><span>Phase Change Materials as those of the Ge-Sb-Te </span>ternary system are of great interest for technological applications. Properties of these compounds are strongly related to presence of vacancies and structural investigations remain challenging. In this paper we evidence that </span>¹²⁵<span>Te NMR in natural abundance and using commercial systems at intermediate field (14.1 ​T) together with NMR parameters prediction can contribute to improve understanding of electronic structure of such systems. GeTe is a typical phase change material, whose structure contains germanium vacancies, even in its stoichiometric form, giving it metallic properties. Here, we use nominal Ge</span>₅₀Te₅₀ and Ge₄₈Te₅₂<span> crystalline samples as an example to optimize the WURST-CPMG technique, a powerful technique to record wide NMR spectra which has not yet been used on </span>¹²⁵Te. The goal was to minimize the time devoted to experiments as well as maximize the signal-to-noise ratio in order to detect small intensity signals directly linked to vacancies. Virtual Crystal Approximation (VCA) calculations performed with WIEN2K helped to interpret the NMR spectra. For Te-based crystalline conducting samples the best experimental results were obtained using 3.2 ​mm thin wall rotors with diluted samples 40 ​vol% GeTe-60 ​vol% SiO₂<span>. In addition to the WURST-CPMG technique, high resolution spectra using MAS<span> as implemented in the pj-MAT technique allowed us to identify the distributions of chemical shift parameters in the high intensity contribution of the 1D spectra. The NMR spectra recorded on the samples showed that an addition of Tellurium in the stoichiometric Ge</span></span>₅₀Te₅₀ sample leads to an important broadening of the spectrum together with a shift of the lines. According to VCA calculations it could be attributed to a distribution of concentrations of germanium vacancies in the sample and it would appear that Knight Shift but also Chemical Shift could contribute in similar proportion to the NMR line position when metavalent bonding is invoked.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"115 ","pages":"Article 101751"},"PeriodicalIF":3.2,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2021.101751","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39280602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accurate fragment-based 51-V chemical shift predictions in molecular crystals","authors":"Amanda Mathews,&nbsp;Joshua D. Hartman","doi":"10.1016/j.ssnmr.2021.101733","DOIUrl":"10.1016/j.ssnmr.2021.101733","url":null,"abstract":"<div><p><span>Nuclear magnetic resonance (NMR) spectroscopy plays a crucial role in determining molecular structure for complex biological and pharmaceutical compounds. NMR investigations are increasingly reliant on computation for mapping spectral features to chemical structures. Here we benchmark the accuracy of fragment-based </span>⁵¹<span>V chemical shielding tensor calculations using a training set comprised of 10 biologically and pharmaceutically relevant oxovanadium complexes. Using our self-consistent reproduction of the Madelung potential (SCRMP) electrostatic embedding model, we demonstrate comparable performance between fragment methods and computationally demanding cluster-based techniques. Specifically, fragment methods employing hybrid density functionals are capable of reproducing the experimental </span>⁵¹V isotropic chemical shifts with a training set rms error of <span><math><mrow><mo>~</mo></mrow></math></span><span>9 ​ppm, representing a 20% improvement over traditional plane wave techniques. We provide training set-derived linear regression models for mapping the absolute shieldings obtained from computation to the experimentally determined chemical shifts using four common density functionals; PBE0, B3LYP, PBE, and BLYP. Finally, we establish the utility of fragment methods and the reported regression parameters examining four oxovanadium structures excluded from the training set including the tetracoordinate oxovanadium silicate </span><span><math><mrow><msub><mrow><mo>(</mo><mrow><mi>P</mi><msub><mi>h</mi><mn>3</mn></msub><mi>S</mi><mi>i</mi><mi>O</mi></mrow><mo>)</mo></mrow><mn>3</mn></msub><mi>V</mi><mi>O</mi></mrow></math></span>, VO¹⁵NGlySalbz which contains redox-active ligands, and the solid-state form of the common ⁵¹V NMR reference compound <span><math><mrow><mi>V</mi><mi>O</mi><mi>C</mi><msub><mi>l</mi><mn>3</mn></msub></mrow></math></span>.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"114 ","pages":"Article 101733"},"PeriodicalIF":3.2,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2021.101733","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38989309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of the chemical shift tensor anisotropy and asymmetry of strongly dipolar coupled protons under fast MAS","authors":"Takeshi Kobayashi ,&nbsp;Frédéric A. Perras ,&nbsp;Yusuke Nishiyama","doi":"10.1016/j.ssnmr.2021.101743","DOIUrl":"10.1016/j.ssnmr.2021.101743","url":null,"abstract":"<div><p><span><span><span>Orientationally-dependent interactions such as dipolar coupling, quadrupolar coupling, and </span>chemical shift anisotropy (CSA) contain a wealth of spatial information that can be used to elucidate </span>molecular conformations and dynamics. To determine the sign of the chemical shift tensor anisotropy parameter (</span><em>δ</em>_aniso), both the |<em>m</em>| ​= ​1 and |<em>m</em>| ​= ​2 components of the CSA need to be symmetry allowed, while the recoupling of the |<em>m</em>| ​= ​1 term is accompanied with the reintroduction of homonuclear dipolar coupling components. Therefore, previously suggested sequences which solely recouple the |<em>m</em>| ​= ​2 term cannot determine the sign a ¹H's <em>δ</em>_aniso in a densely-coupled network. In this study, we demonstrate the CSA recoupling of strongly dipolar coupled ¹H spins using the <span><math><mrow><mi>C</mi><msubsup><mi>n</mi><mi>n</mi><mn>1</mn></msubsup><mrow><mo>(</mo><mrow><msub><mn>90</mn><mn>0</mn></msub><msub><mn>360</mn><mn>180</mn></msub><msub><mn>540</mn><mn>0</mn></msub><msub><mn>360</mn><mn>180</mn></msub><msub><mn>90</mn><mn>0</mn></msub></mrow><mo>)</mo></mrow></mrow></math></span> sequence. This pulse scheme recouples both the |<em>m</em>| ​= ​1 and |<em>m</em>| ​= ​2 CSA terms but the scaling factors for the homonuclear dipolar coupling terms are zeroed. Consequently, the sequence is sensitive to the sign of <em>δ</em>_aniso<span> but is not influenced by homonuclear dipolar interactions.</span></p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"114 ","pages":"Article 101743"},"PeriodicalIF":3.2,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2021.101743","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39253050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Efficient symmetry-based γ-encoded DQ recoupling sequences for suppression of t1-noise in solid-state NMR spectroscopy at fast MAS","authors":"Yusuke Nishiyama ,&nbsp;Vipin Agarwal ,&nbsp;Rongchun Zhang","doi":"10.1016/j.ssnmr.2021.101734","DOIUrl":"https://doi.org/10.1016/j.ssnmr.2021.101734","url":null,"abstract":"<div><p><span>Solid-state NMR spectroscopy has played a significant role in elucidating the structure and dynamics of materials and biological solids at a molecular level for decades. In particular, the </span>¹H double-quantum/single-quantum (DQ/SQ) chemical shift correlation experiment is widely used for probing the proximity of protons, rendering it a powerful tool for elucidating the hydrogen-bonding interactions and molecular packing of various complex molecular systems. Two factors, namely, the DQ filtering efficiency and <em>t</em>₁-noise, dictate the quality of the 2D ¹H DQ/SQ spectra. Experimentally different recoupling sequences show varied DQ filtering efficiencies and <em>t</em>₁-noise. Herein, after a systematic search of symmetry-based DQ recoupling sequences, we report that the symmetry-based γ-encoded <span><math><mrow><mi>R</mi><msubsup><mi>N</mi><mi>n</mi><mi>ν</mi></msubsup></mrow></math></span> sequences show superior performance to other DQ recoupling sequences, which not only have a higher DQ recoupling efficiency but can also significantly reduce <em>t</em>₁-noise. The origin of <em>t</em>₁-noise is further discussed in detail via extensive numerical simulations. We envisage that such γ-encoded <span><math><mrow><mi>R</mi><msubsup><mi>N</mi><mi>n</mi><mi>ν</mi></msubsup></mrow></math></span> sequences are superior candidates for DQ recoupling in proton-based solid-state NMR spectroscopy due to its capability of efficiently exciting DQ coherences and suppressing <em>t</em>₁-noise.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"114 ","pages":"Article 101734"},"PeriodicalIF":3.2,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2021.101734","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72249281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}