Pub Date : 2020-10-01DOI: 10.1016/j.ssnmr.2020.101684
Eugeny Kryukov, Yury Bugoslavsky, Angel Joaquin Perez Linde, Thomas Holubar, Stephen Burgess, David Marlow, Jeremy Good
We propose a fast algorithm to energise a cryogen free magnet to a highly persistent state. A decay rate as low as 0.021 ppm/h can be achieved in less than an hour after reaching the target field. The decay rate drops further to 0.0004 ppm/h in the following 48 h. This procedure can be applied at different values of target field, which makes it feasible to use a single magnet for study of various NMR lines at different fields. The mechanism of establishing a highly stable magnetic field can be understood on the basis of the magnetic properties of the superconducting wire, which were studied using a vibrating sample magnetometer. The results confirm the high quality of the superconducting wire and joints.
{"title":"A method for fast field settling in cryogen-free superconducting magnets for NMR","authors":"Eugeny Kryukov, Yury Bugoslavsky, Angel Joaquin Perez Linde, Thomas Holubar, Stephen Burgess, David Marlow, Jeremy Good","doi":"10.1016/j.ssnmr.2020.101684","DOIUrl":"10.1016/j.ssnmr.2020.101684","url":null,"abstract":"<div><p>We propose a fast algorithm to energise a cryogen free magnet to a highly persistent state. A decay rate as low as 0.021 ppm/h can be achieved in less than an hour after reaching the target field. The decay rate drops further to 0.0004 ppm/h in the following 48 h. This procedure can be applied at different values of target field, which makes it feasible to use a single magnet for study of various NMR lines at different fields. The mechanism of establishing a highly stable magnetic field can be understood on the basis of the magnetic properties<span><span> of the superconducting wire, which were studied using a vibrating sample </span>magnetometer. The results confirm the high quality of the superconducting wire and joints.</span></p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2020.101684","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38427607","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}
Pub Date : 2020-10-01DOI: 10.1016/j.ssnmr.2020.101687
Jan Gerrit Schiffmann , Franziska Emmerling , Inês C.B. Martins , Leo Van Wüllen
We present an approach towards the in situ solid state NMR monitoring of mechanochemical reactions in a ball mill. A miniaturized vibration ball mill is integrated into the measuring coil of a home-built solid state NMR probe, allowing for static solid state NMR measurements during the mechanochemical reaction within the vessel. The setup allows to quantitatively follow the product evolution of a prototypical mechanochemical reaction, the formation of zinc phenylphosphonate from zinc acetate and phenylphosphonic acid. MAS NMR investigations on the final reaction mixture confirmed a reaction yield of 89% in a typical example. Thus, NMR spectroscopy may in the future provide complementary information about reaction mechanisms of mechanochemical reactions and team up with other analytical methods which have been employed to follow reactions in situ, such as Raman spectroscopy or X-ray diffraction.
{"title":"In-situ reaction monitoring of a mechanochemical ball mill reaction with solid state NMR","authors":"Jan Gerrit Schiffmann , Franziska Emmerling , Inês C.B. Martins , Leo Van Wüllen","doi":"10.1016/j.ssnmr.2020.101687","DOIUrl":"10.1016/j.ssnmr.2020.101687","url":null,"abstract":"<div><p>We present an approach towards the <em>in situ</em><span> solid state NMR<span><span> monitoring of mechanochemical reactions in a ball mill. A miniaturized vibration ball mill is integrated into the measuring coil of a home-built solid state NMR probe, allowing for static solid state NMR measurements during the mechanochemical reaction within the vessel. The setup allows to quantitatively follow the product evolution of a prototypical mechanochemical reaction, the formation of zinc phenylphosphonate from zinc acetate and phenylphosphonic acid. </span>MAS<span> NMR investigations on the final reaction mixture confirmed a reaction yield of 89% in a typical example. Thus, NMR spectroscopy may in the future provide complementary information about reaction mechanisms of mechanochemical reactions and team up with other analytical methods which have been employed to follow reactions </span></span></span><em>in situ</em><span>, such as Raman spectroscopy or X-ray diffraction.</span></p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2020.101687","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38360232","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}
Pub Date : 2020-10-01DOI: 10.1016/j.ssnmr.2020.101685
Zhuoran Wang , Michael P. Hanrahan , Takeshi Kobayashi , Frédéric A. Perras , Yunhua Chen , Frank Engelke , Christian Reiter , Armin Purea , Aaron J. Rossini , Marek Pruski
Dynamic nuclear polarization (DNP) and indirect detection are two commonly applied approaches for enhancing the sensitivity of solid-state NMR spectroscopy. However, their use in tandem has not yet been investigated. With the advent of low-temperature fast magic angle spinning (MAS) probes with 1.3-mm diameter rotors capable of MAS at 40 kHz it becomes feasible to combine these two techniques. In this study, we performed DNP-enhanced 2D indirectly detected heteronuclear correlation (idHETCOR) experiments on 13C, 15N, 113Cd and 89Y nuclei in functionalized mesoporous silica, CdS nanoparticles, and Y2O3 nanoparticles. The sensitivity of the 2D idHETCOR experiments was compared with those of DNP-enhanced directly-detected 1D cross polarization (CP) and 2D HETCOR experiments performed with a standard 3.2-mm rotor. Due to low CP polarization transfer efficiencies and large proton linewidth, the sensitivity gains achieved by indirect detection alone were lower than in conventional (non-DNP) experiments. Nevertheless, despite the smaller sample volume the 2D idHETCOR experiments showed better absolute sensitivities than 2D HETCOR experiments for nuclei with the lowest gyromagnetic ratios. For 89Y, 2D idHETCOR provided 8.2 times better sensitivity than the 1 D89Y-detected CP experiment performed with a 3.2-mm rotor.
{"title":"Combining fast magic angle spinning dynamic nuclear polarization with indirect detection to further enhance the sensitivity of solid-state NMR spectroscopy","authors":"Zhuoran Wang , Michael P. Hanrahan , Takeshi Kobayashi , Frédéric A. Perras , Yunhua Chen , Frank Engelke , Christian Reiter , Armin Purea , Aaron J. Rossini , Marek Pruski","doi":"10.1016/j.ssnmr.2020.101685","DOIUrl":"10.1016/j.ssnmr.2020.101685","url":null,"abstract":"<div><p><span><span><span>Dynamic nuclear polarization (DNP) and indirect detection are two commonly applied approaches for enhancing the sensitivity of solid-state NMR spectroscopy. However, their use in tandem has not yet been investigated. With the advent of low-temperature fast </span>magic angle spinning (MAS) probes with 1.3-mm diameter rotors capable of MAS at 40 kHz it becomes feasible to combine these two techniques. In this study, we performed DNP-enhanced 2D indirectly detected </span>heteronuclear correlation (idHETCOR) experiments on </span><sup>13</sup>C, <sup>15</sup>N, <sup>113</sup>Cd and <sup>89</sup><span>Y nuclei in functionalized mesoporous silica<span>, CdS nanoparticles, and Y</span></span><sub>2</sub>O<sub>3</sub><span><span><span> nanoparticles. The sensitivity of the 2D idHETCOR experiments was compared with those of DNP-enhanced directly-detected 1D cross polarization (CP) and 2D </span>HETCOR experiments performed with a standard 3.2-mm rotor. Due to low CP </span>polarization transfer<span> efficiencies and large proton linewidth, the sensitivity gains achieved by indirect detection alone were lower than in conventional (non-DNP) experiments. Nevertheless, despite the smaller sample volume the 2D idHETCOR experiments showed better absolute sensitivities than 2D HETCOR experiments for nuclei with the lowest gyromagnetic ratios. For </span></span><sup>89</sup>Y, 2D idHETCOR provided 8.2 times better sensitivity than the 1 D<sup>89</sup>Y-detected CP experiment performed with a 3.2-mm rotor.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2020.101685","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38381848","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}
Pub Date : 2020-10-01DOI: 10.1016/j.ssnmr.2020.101686
John E. Kelly , Christine Chrissian , Ruth E. Stark
Many interesting solid-state targets for biological research do not form crystalline structures; these materials include intrinsically disordered proteins, plant biopolymer composites, cell-wall polysaccharides, and soil organic matter. The absence of aligned repeating structural elements and atomic-level rigidity presents hurdles to achieving structural elucidation and obtaining functional insights. We describe strategies for adapting several solid-state NMR methods to determine the molecular structures and compositions of these amorphous biosolids.
The main spectroscopic problems in studying amorphous structures by NMR are over/under-sampling of the spin signals and spectral complexity. These problems arise in part because amorphous biosolids typically contain a mix of rigid and mobile domains, making it difficult to select a single experiment or set of acquisition conditions that fairly represents all nuclear spins in a carbon-based organic sample. These issues can be addressed by running hybrid experiments, such as using direct excitation alongside cross polarization-based methods, to develop a more holistic picture of the macromolecular system. In situations of spectral crowding or overlap, the structural elucidation strategy can be further assisted by coupling 13C spins to nuclei such as 15N, filtering out portions of the spectrum, highlighting individual moieties of interest, and adding a second or third spectral dimension to an NMR experiment in order to spread out the resonances and link them pairwise through space or through bonds. We discuss practical aspects and illustrations from the recent literature for 1D experiments that use cross or direct polarization and both homo- and heteronuclear 2D and 3D solid-state NMR experiments.
{"title":"Tailoring NMR experiments for structural characterization of amorphous biological solids: A practical guide","authors":"John E. Kelly , Christine Chrissian , Ruth E. Stark","doi":"10.1016/j.ssnmr.2020.101686","DOIUrl":"10.1016/j.ssnmr.2020.101686","url":null,"abstract":"<div><p><span>Many interesting solid-state targets for biological research do not form crystalline structures; these materials include intrinsically disordered proteins, plant biopolymer<span> composites, cell-wall polysaccharides, and </span></span>soil organic matter<span><span>. The absence of aligned repeating structural elements and atomic-level rigidity presents hurdles to achieving structural elucidation and obtaining functional insights. We describe strategies for adapting several solid-state NMR methods to determine the molecular structures and compositions of these </span>amorphous biosolids.</span></p><p>The main spectroscopic problems in studying amorphous structures by NMR are over/under-sampling of the spin signals and spectral complexity. These problems arise in part because amorphous biosolids typically contain a mix of rigid and mobile domains, making it difficult to select a single experiment or set of acquisition conditions that fairly represents all nuclear spins in a carbon-based organic sample. These issues can be addressed by running hybrid experiments, such as using direct excitation alongside cross polarization-based methods, to develop a more holistic picture of the macromolecular system. In situations of spectral crowding or overlap, the structural elucidation strategy can be further assisted by coupling <sup>13</sup>C spins to nuclei such as <sup>15</sup>N, filtering out portions of the spectrum, highlighting individual moieties of interest, and adding a second or third spectral dimension to an NMR experiment in order to spread out the resonances and link them pairwise through space or through bonds. We discuss practical aspects and illustrations from the recent literature for 1D experiments that use cross or direct polarization and both homo- and heteronuclear 2D and 3D solid-state NMR experiments.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2020.101686","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38353990","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}
Experimental and theoretical investigations of indium-115 electric-field-gradient (EFG) tensors of indium(III) oxide, In2O3, have been presented. Field-stepwise-swept QCPMG solid-state 115In NMR experiments are carried out at T = 120 K, observed at 52.695 MHz, and in the range of external magnetic fields between 4.0 and 6.5 T. The spectral simulations yield the quadrupolar coupling constant, CQ value, of 183(2) MHz and the asymmetry parameter, ηQ, of 0.05(5), for In(1), and that of 126(2) MHz and ηQ of 0.86(5) for In(2). Quantum chemical calculations are carried out to provide 115In EFG tensor orientations with respect to the molecular structure. A relationship between operative frequencies and variable ranges of external magnetic fields is briefly discussed for field-swept solid-state 115In NMR.
{"title":"Field-stepwise-swept QCPMG solid-state 115In NMR of indium oxide","authors":"Kazuhiko Yamada , Takumi Yamaguchi , Ryutaro Ohashi , Shinobu Ohki , Kenzo Deguchi , Kenjiro Hashi , Atsushi Goto , Tadashi Shimizu","doi":"10.1016/j.ssnmr.2020.101688","DOIUrl":"10.1016/j.ssnmr.2020.101688","url":null,"abstract":"<div><p>Experimental and theoretical investigations of indium-115 electric-field-gradient (EFG) tensors of indium(III) oxide, In<sub>2</sub>O<sub>3</sub>, have been presented. Field-stepwise-swept QCPMG solid-state <sup>115</sup>In NMR experiments are carried out at <em>T</em><span> = 120 K, observed at 52.695 MHz, and in the range of external magnetic fields between 4.0 and 6.5 T. The spectral simulations yield the quadrupolar coupling constant, </span><em>C</em><sub>Q</sub> value, of 183(2) MHz and the asymmetry parameter, η<sub>Q</sub>, of 0.05(5), for In(1), and that of 126(2) MHz and η<sub>Q</sub><span> of 0.86(5) for In(2). Quantum chemical calculations are carried out to provide </span><sup>115</sup>In EFG tensor orientations with respect to the molecular structure. A relationship between operative frequencies and variable ranges of external magnetic fields is briefly discussed for field-swept solid-state <sup>115</sup>In NMR.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2020.101688","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38397379","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}
Pub Date : 2020-08-01DOI: 10.1016/j.ssnmr.2020.101665
Petra Rovó
This review describes two rotating-frame () relaxation dispersion methods, namely the Bloch-McConnell Relaxation Dispersion and the Near-rotary Resonance Relaxation Dispersion, which enable the study of microsecond time-scale conformational fluctuations in the solid state using magic-angle-spinning nuclear magnetic resonance spectroscopy. The goal is to provide the reader with key ideas, experimental descriptions, and practical considerations associated with measurements that are needed for analyzing relaxation dispersion and quantifying conformational exchange. While the focus is on protein motion, many presented concepts can be equally well adapted to study the microsecond time-scale dynamics of other bio- (e.g. lipids, polysaccharides, nucleic acids), organic (e.g. pharmaceutical compounds), or inorganic molecules (e.g., metal organic frameworks). This article summarizes the essential contributions made by recent theoretical and experimental solid-state NMR studies to our understanding of protein motion. Here we discuss recent advances in fast MAS applications that enable the observation and atomic level characterization of sparsely populated conformational states which are otherwise inaccessible for other experimental methods. Such high-energy states are often associated with protein functions such as molecular recognition, ligand binding, or enzymatic catalysis, as well as with disease-related properties such as misfolding and amyloid formation.
{"title":"Recent advances in solid-state relaxation dispersion techniques","authors":"Petra Rovó","doi":"10.1016/j.ssnmr.2020.101665","DOIUrl":"10.1016/j.ssnmr.2020.101665","url":null,"abstract":"<div><p>This review describes two rotating-frame (<span><math><mrow><msub><mi>R</mi><mrow><mn>1</mn><mi>ρ</mi></mrow></msub></mrow></math></span>) relaxation dispersion methods, namely the Bloch-McConnell Relaxation Dispersion and the Near-rotary Resonance Relaxation Dispersion, which enable the study of microsecond time-scale conformational fluctuations in the solid state using magic-angle-spinning nuclear magnetic resonance spectroscopy. The goal is to provide the reader with key ideas, experimental descriptions, and practical considerations associated with <span><math><mrow><msub><mi>R</mi><mrow><mn>1</mn><mi>ρ</mi></mrow></msub></mrow></math></span><span><span> measurements that are needed for analyzing relaxation dispersion and quantifying conformational exchange. While the focus is on protein motion<span>, many presented concepts can be equally well adapted to study the microsecond time-scale dynamics of other bio- (e.g. lipids, polysaccharides, nucleic acids), organic (e.g. pharmaceutical compounds), or inorganic molecules (e.g., metal organic frameworks). This article summarizes the essential contributions made by recent theoretical and experimental solid-state NMR studies to our understanding of protein motion. Here we discuss recent advances in fast </span></span>MAS<span> applications that enable the observation and atomic level characterization of sparsely populated conformational states which are otherwise inaccessible for other experimental methods. Such high-energy states are often associated with protein functions such as molecular recognition, ligand binding, or enzymatic catalysis, as well as with disease-related properties such as misfolding and amyloid formation.</span></span></p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2020.101665","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38081014","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}
Pub Date : 2020-08-01DOI: 10.1016/j.ssnmr.2020.101676
Marta Marín-Luna , Rosa M. Claramunt , Concepción López , Marta Pérez-Torralba , Dionisia Sanz , Felipe Reviriego , Ibon Alkorta , José Elguero
Theoretical simulation of NMR parameters in compounds bearing heavy atoms generally requires the application of relativistic corrections. We report herein the theoretical characterization of 13C and 15N CPMAS NMR of known bromo-derivative crystals by using both the GIPAW and the combined GIAO-ZORA-SO approximation methods. Several statistical analyses were performed to compare both approaches, with non-relativistic GIPAW method being more useful to predict the 13C and 15N chemical shifts. The problem of applying GIPAW to crystal structures showing static or dynamic crystalline disorder of the special class resulting in half-protons will be discussed in detail.
{"title":"A GIPAW versus GIAO-ZORA-SO study of 13C and 15N CPMAS NMR chemical shifts of aromatic and heterocyclic bromo derivatives","authors":"Marta Marín-Luna , Rosa M. Claramunt , Concepción López , Marta Pérez-Torralba , Dionisia Sanz , Felipe Reviriego , Ibon Alkorta , José Elguero","doi":"10.1016/j.ssnmr.2020.101676","DOIUrl":"10.1016/j.ssnmr.2020.101676","url":null,"abstract":"<div><p>Theoretical simulation of NMR parameters in compounds bearing heavy atoms generally requires the application of relativistic corrections. We report herein the theoretical characterization of <sup>13</sup>C and <sup>15</sup>N CPMAS NMR of known bromo-derivative crystals by using both the GIPAW and the combined GIAO-ZORA-SO approximation methods. Several statistical analyses were performed to compare both approaches, with non-relativistic GIPAW method being more useful to predict the <sup>13</sup>C and <sup>15</sup>N chemical shifts. The problem of applying GIPAW to crystal structures showing static or dynamic crystalline disorder of the special class resulting in half-protons will be discussed in detail.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2020.101676","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38138488","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}
Pub Date : 2020-08-01DOI: 10.1016/j.ssnmr.2020.101662
Emily K. Corlett , Helen Blade , Leslie P. Hughes , Philip J. Sidebottom , David Walker , Richard I. Walton , Steven P. Brown
An NMR crystallography analysis is presented for four solid-state structures of pyridine fumarates and their cocrystals, using crystal structures deposited in the Cambridge Crystallographic Data Centre, CCDC. Experimental one-dimensional one-pulse 1H and 13C cross-polarisation (CP) magic-angle spinning (MAS) nuclear magnetic resonance (NMR) and two-dimensional 14N–1H heteronuclear multiple-quantum coherence MAS NMR spectra are compared with gauge-including projector augmented wave (GIPAW) calculations of the 1H and 13C chemical shifts and the 14N shifts that additionally depend on the quadrupolar interaction. Considering the high ppm (>10 ppm) 1H resonances, while there is good agreement (within 0.4 ppm) between experiment and GIPAW calculation for the hydrogen-bonded NH moieties, the hydrogen-bonded fumaric acid OH resonances are 1.2–1.9 ppm higher in GIPAW calculation as compared to experiment. For the cocrystals of a salt and a salt formed by 2-amino-5-methylpyridinium and 2-amino-6-methylpyridinium ions, a large discrepancy of 4.2 and 5.9 ppm between experiment and GIPAW calculation is observed for the quaternary ring carbon 13C resonance that is directly bonded to two nitrogens (in the ring and in the amino group). By comparison, there is excellent agreement (within 0.2 ppm) for the quaternary ring carbon 13C resonance directly bonded to the ring nitrogen for the salt and cocrystal of a salt formed by 2,6-lutidinium and 2,5-lutidinium, respectively.
{"title":"Investigating discrepancies between experimental solid-state NMR and GIPAW calculation: NC–N 13C and OH⋯O 1H chemical shifts in pyridinium fumarates and their cocrystals","authors":"Emily K. Corlett , Helen Blade , Leslie P. Hughes , Philip J. Sidebottom , David Walker , Richard I. Walton , Steven P. Brown","doi":"10.1016/j.ssnmr.2020.101662","DOIUrl":"10.1016/j.ssnmr.2020.101662","url":null,"abstract":"<div><p>An NMR crystallography analysis is presented for four solid-state structures of pyridine fumarates and their cocrystals, using crystal structures deposited in the Cambridge Crystallographic Data Centre, CCDC. Experimental one-dimensional one-pulse <sup>1</sup>H and <sup>13</sup>C cross-polarisation (CP) magic-angle spinning (MAS) nuclear magnetic resonance (NMR) and two-dimensional <sup>14</sup>N–<sup>1</sup>H heteronuclear multiple-quantum coherence MAS NMR spectra are compared with gauge-including projector augmented wave (GIPAW) calculations of the <sup>1</sup>H and <sup>13</sup>C chemical shifts and the <sup>14</sup>N shifts that additionally depend on the quadrupolar interaction. Considering the high ppm (>10 ppm) <sup>1</sup>H resonances, while there is good agreement (within 0.4 ppm) between experiment and GIPAW calculation for the hydrogen-bonded NH moieties, the hydrogen-bonded fumaric acid OH resonances are 1.2–1.9 ppm higher in GIPAW calculation as compared to experiment. For the cocrystals of a salt and a salt formed by 2-amino-5-methylpyridinium and 2-amino-6-methylpyridinium ions, a large discrepancy of 4.2 and 5.9 ppm between experiment and GIPAW calculation is observed for the quaternary ring carbon <sup>13</sup>C resonance that is directly bonded to two nitrogens (in the ring and in the amino group). By comparison, there is excellent agreement (within 0.2 ppm) for the quaternary ring carbon <sup>13</sup>C resonance directly bonded to the ring nitrogen for the salt and cocrystal of a salt formed by 2,6-lutidinium and 2,5-lutidinium, respectively.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2020.101662","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38089000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-08-01DOI: 10.1016/j.ssnmr.2020.101675
Wancheng Zhao, Liyanage D. Fernando, Alex Kirui, Fabien Deligey, Tuo Wang
{"title":"Corrigendum to “Solid-state NMR of plant and fungal cell walls: A critical reviewˮ [Solid State Nucl. Magn. Reson. 107 (2020) 101660]","authors":"Wancheng Zhao, Liyanage D. Fernando, Alex Kirui, Fabien Deligey, Tuo Wang","doi":"10.1016/j.ssnmr.2020.101675","DOIUrl":"10.1016/j.ssnmr.2020.101675","url":null,"abstract":"","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2020.101675","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37970928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-08-01DOI: 10.1016/j.ssnmr.2020.101668
Akiko Sasaki , Yu Tsutsumi , Jean-Paul Amoureux
In solid-state NMR, multiple-quantum MAS (MQMAS) and satellite-transition MAS (STMAS) experiments are well-established techniques to obtain high-resolution spectra of half-integer quadrupolar nuclei. In 2004 and 2005, a soft-pulse-added-mixing (SPAM) concept was introduced by Gan and Amoureux to enhance the S/N ratio of MQMAS and STMAS experiments. Despite their robustness and simplicity, SPAM approaches have not yet been widely applied. Here, we further exploit SPAM concepts for sensitivity enhancement upon acquisition of two-dimensional MQMAS and STMAS spectra and also establish a general procedure upon implementation of SPAM-MQMAS and SPAM-STMAS NMR. Its effectiveness and ease in experimental setup are demonstrated using simulations and experiments performed on I = 3/2 (23Na, 87Rb), 5/2 (27Al, 85Rb) and 9/2 (93Nb) nuclei with a variety of quadrupolar coupling constants (CQ). Compared to the conventional z-filter methods, sensitivity enhancements in between 2 and 4 are achievable with SPAM. We recommend to use SPAM with a ratio of 4:1 for the number of echoes and antiechoes to safely maximize the sensitivity and resolution simultaneously. In addition, a comparison of the experimental approaches is made in the context of SPAM-MQMAS and SPAM-STMAS NMR with respect to repetition delay and spinning frequency, aiming to discuss the precautions upon making a judicious choice of high-resolution NMR methods of half-integer quadrupolar nuclei.
{"title":"Accelerating high-resolution NMR of half-integer quadrupolar nuclei in solids: SPAM-MQMAS and SPAM-STMAS","authors":"Akiko Sasaki , Yu Tsutsumi , Jean-Paul Amoureux","doi":"10.1016/j.ssnmr.2020.101668","DOIUrl":"10.1016/j.ssnmr.2020.101668","url":null,"abstract":"<div><p><span><span>In solid-state NMR, multiple-quantum MAS (MQMAS) and satellite-transition MAS (STMAS) experiments are well-established techniques to obtain high-resolution spectra of half-integer quadrupolar nuclei. In 2004 and 2005, a soft-pulse-added-mixing (SPAM) concept was introduced by Gan and Amoureux to enhance the S/N ratio of </span>MQMAS and STMAS experiments. Despite their robustness and simplicity, SPAM approaches have not yet been widely applied. Here, we further exploit SPAM concepts for sensitivity enhancement upon acquisition of two-dimensional MQMAS and STMAS spectra and also establish a general procedure upon implementation of SPAM-MQMAS and SPAM-STMAS NMR. Its effectiveness and ease in experimental setup are demonstrated using simulations and experiments performed on I = 3/2 (</span><sup>23</sup>Na, <sup>87</sup>Rb), 5/2 (<sup>27</sup>Al, <sup>85</sup>Rb) and 9/2 (<sup>93</sup>Nb) nuclei with a variety of quadrupolar coupling constants (C<sub>Q</sub>). Compared to the conventional z-filter methods, sensitivity enhancements in between 2 and 4 are achievable with SPAM. We recommend to use SPAM with a ratio of 4:1 for the number of echoes and antiechoes to safely maximize the sensitivity and resolution simultaneously. In addition, a comparison of the experimental approaches is made in the context of SPAM-MQMAS and SPAM-STMAS NMR with respect to repetition delay and spinning frequency, aiming to discuss the precautions upon making a judicious choice of high-resolution NMR methods of half-integer quadrupolar nuclei.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.ssnmr.2020.101668","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38135834","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}