Pub Date : 2022-06-01DOI: 10.1016/j.ssnmr.2022.101794
Renny Mathew , Ivan V. Sergeyev , Fabien Aussenac , Lydia Gkoura , Melanie Rosay , Maria Baias
Solid-state dynamic nuclear polarization enhanced magic angle spinning (DNP-MAS) NMR measurements coupled with density functional theory (DFT) calculations enable the full resonance assignment of a complex pharmaceutical drug molecule without the need for isotopic enrichment. DNP dramatically enhances the NMR signals, thereby making possible previously intractable two-dimensional correlation NMR spectra at natural abundance. Using inputs from DFT calculations, herein we describe a significant improvement to the structure elucidation process for complex organic molecules. Further, we demonstrate that a series of two-dimensional correlation experiments, including 15N–13C TEDOR, 13C–13C INADEQUATE/SARCOSY, 19F–13C HETCOR, and 1H–13C HETCOR, can be obtained at natural isotopic abundance within reasonable experiment times, thus enabling a complete resonance assignment of sitagliptin, a pharmaceutical used for the treatment of type 2 diabetes.
{"title":"Complete resonance assignment of a pharmaceutical drug at natural isotopic abundance from DNP-Enhanced solid-state NMR","authors":"Renny Mathew , Ivan V. Sergeyev , Fabien Aussenac , Lydia Gkoura , Melanie Rosay , Maria Baias","doi":"10.1016/j.ssnmr.2022.101794","DOIUrl":"10.1016/j.ssnmr.2022.101794","url":null,"abstract":"<div><p>Solid-state dynamic nuclear polarization enhanced magic angle spinning (DNP-MAS) NMR measurements coupled with density functional theory (DFT) calculations enable the full resonance assignment of a complex pharmaceutical drug molecule without the need for isotopic enrichment. DNP dramatically enhances the NMR signals, thereby making possible previously intractable two-dimensional correlation NMR spectra at natural abundance. Using inputs from DFT calculations, herein we describe a significant improvement to the structure elucidation process for complex organic molecules. Further, we demonstrate that a series of two-dimensional correlation experiments, including <sup>15</sup>N–<sup>13</sup>C TEDOR, <sup>13</sup>C–<sup>13</sup>C INADEQUATE/SARCOSY, <sup>19</sup>F–<sup>13</sup>C HETCOR, and <sup>1</sup>H–<sup>13</sup>C HETCOR, can be obtained at natural isotopic abundance within reasonable experiment times, thus enabling a complete resonance assignment of sitagliptin, a pharmaceutical used for the treatment of type 2 diabetes.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0926204022000236/pdfft?md5=37edeb9b3fa6812c2fb544dd1320984c&pid=1-s2.0-S0926204022000236-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46931050","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 : 2022-06-01DOI: 10.1016/j.ssnmr.2022.101795
Scott A. Southern , David L. Bryce
Weak hydrogen bonds are important structure-directing elements in supramolecular chemistry and biochemistry. We consider here weak CH⋯O hydrogen bonds in a series of cocrystals of theophylline and caffeine and assess to what extent the CH⋯O distance and angle govern the observed 13C and 1H isotropic chemical shifts. Gauge-including projector-augmented wave density functional theory (GIPAW DFT) calculations consistently predict a decrease in the 13C and 1H magnetic shielding constants upon hydrogen bond formation on the order of 2–5 ppm (13C) and 1–2 ppm (1H). These trends are reproduced using the machine-learning approach implemented in ShiftML. Experimental 13C and 1H chemical shifts obtained for powdered samples using one-dimensional NMR spectroscopy as well as heteronuclear correlation (HETCOR) spectroscopy correlate well with the GIPAW DFT results. However, the experimental 13C NMR response only correlates moderately well with the hydrogen bond length and angle, while the experimental 1H chemical shifts only show very weak correlations to these local structural elements. DFT computations on isolated imidazole-formaldehyde models show that the 13C and 1H chemical shifts generally decrease with the C⋯O distance but show no clear dependence on the CH⋯O angle. These results demonstrate that the 13C and 1H response to weak CH⋯O hydrogen bonding is influenced significantly by additional weak contacts within cocrystal heterodimeric units.
{"title":"To what extent do bond length and angle govern the 13C and 1H NMR response to weak CH⋯O hydrogen bonds? A case study of caffeine and theophylline cocrystals","authors":"Scott A. Southern , David L. Bryce","doi":"10.1016/j.ssnmr.2022.101795","DOIUrl":"10.1016/j.ssnmr.2022.101795","url":null,"abstract":"<div><p><span><span>Weak hydrogen bonds<span> are important structure-directing elements in supramolecular chemistry and biochemistry. We consider here weak CH⋯O hydrogen bonds in a series of cocrystals of </span></span>theophylline and caffeine and assess to what extent the CH⋯O distance and angle govern the observed </span><sup>13</sup>C and <sup>1</sup>H isotropic chemical shifts. Gauge-including projector-augmented wave density functional theory (GIPAW DFT) calculations consistently predict a decrease in the <sup>13</sup>C and <sup>1</sup><span>H magnetic shielding constants upon hydrogen bond formation on the order of 2–5 ppm (</span><sup>13</sup>C) and 1–2 ppm (<sup>1</sup>H). These trends are reproduced using the machine-learning approach implemented in ShiftML. Experimental <sup>13</sup>C and <sup>1</sup><span><span>H chemical shifts obtained for powdered samples using one-dimensional NMR spectroscopy as well as </span>heteronuclear correlation (HETCOR) spectroscopy correlate well with the GIPAW DFT results. However, the experimental </span><sup>13</sup>C NMR response only correlates moderately well with the hydrogen bond length and angle, while the experimental <sup>1</sup>H chemical shifts only show very weak correlations to these local structural elements. DFT computations on isolated imidazole-formaldehyde models show that the <sup>13</sup>C and <sup>1</sup>H chemical shifts generally decrease with the C⋯O distance but show no clear dependence on the CH⋯O angle. These results demonstrate that the <sup>13</sup>C and <sup>1</sup>H response to weak CH⋯O hydrogen bonding is influenced significantly by additional weak contacts within cocrystal heterodimeric units.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48434460","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 : 2022-04-01DOI: 10.1016/j.ssnmr.2022.101784
Alexander E. Khudozhitkov , Sergei S. Arzumanov , Daniil I. Kolokolov , Alexander G. Stepanov
UiO-66 (Zr) is a metal-organic framework (MOF) known for its thermal and chemical stability and wide range of adsorption-based applications. This MOF exhibits high separation selectivity for butane isomers. It has been earlier inferred that the separation performance of the material depends on the hydroxylation state of the zirconia cluster. In this contribution, we apply 2H solid-state NMR to characterize the dynamics of both the MOF organic framework itself and butane isomers in hydroxylated and dehydroxylated forms of UiO-66. It is established that the rate of π-flipping and the amplitude of the phenylene ring plane librations in the framework are higher for the dehydroxylated form. Self-diffusion coefficients of butane isomers have been estimated for both forms of UiO-66. The diffusivity is higher for n-butane in the dehydroxylated form, whereas the diffusion of isobutane is not affected by the presence of OH groups in the zirconia cluster of the MOF. Higher diffusivity of n-butane in dehydroxylated form is accounted for by the larger effective diameter of the window between the adjacent cages in this form, which arises from faster rotation and larger amplitude of framework linker libration. This rationalizes the higher efficiency of the dehydroxylated form of UiO-66(Zr) material for butane isomers separation.
{"title":"Butane isomers mobility and framework dynamics in UiO-66 (Zr) MOF: Impact of the hydroxyl groups in zirconia cluster","authors":"Alexander E. Khudozhitkov , Sergei S. Arzumanov , Daniil I. Kolokolov , Alexander G. Stepanov","doi":"10.1016/j.ssnmr.2022.101784","DOIUrl":"10.1016/j.ssnmr.2022.101784","url":null,"abstract":"<div><p><span>UiO-66 (Zr) is a metal-organic framework (MOF) known for its thermal and chemical stability and wide range of adsorption-based applications. This MOF exhibits high separation selectivity for butane isomers. It has been earlier inferred that the separation performance of the material depends on the hydroxylation state of the zirconia cluster. In this contribution, we apply </span><sup>2</sup>H solid-state NMR to characterize the dynamics of both the MOF organic framework itself and butane isomers in hydroxylated and dehydroxylated forms of UiO-66. It is established that the rate of π-flipping and the amplitude of the phenylene ring plane librations in the framework are higher for the dehydroxylated form. Self-diffusion coefficients of butane isomers have been estimated for both forms of UiO-66. The diffusivity is higher for <em>n</em><span>-butane in the dehydroxylated form, whereas the diffusion of isobutane is not affected by the presence of OH groups in the zirconia cluster of the MOF. Higher diffusivity of </span><em>n</em>-butane in dehydroxylated form is accounted for by the larger effective diameter of the window between the adjacent cages in this form, which arises from faster rotation and larger amplitude of framework linker libration. This rationalizes the higher efficiency of the dehydroxylated form of UiO-66(Zr) material for butane isomers separation.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45870397","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 : 2022-04-01DOI: 10.1016/j.ssnmr.2022.101783
Marcin Skotnicki , Paul Hodgkinson
Irbesartan (IRB) is an antihypertensive drug which exhibits the rare phenomenon of desmotropy; its 1H- and 2H- tetrazole tautomers can be isolated as distinct crystalline forms. The crystalline forms of IRB are poorly soluble, hence the amorphous form is potentially of interest for its faster dissolution rate. The tautomeric form and the nature of hydrogen bonding in amorphous IRB are unknown. In this study, crystalline form A and amorphous form of irbesartan were studied using 13C, 15N and 1H solid-state NMR. Variable-temperature 13C SSMNR studies showed alkyl chain disorder in the crystalline form of IRB, which may explain the conflicting literature crystal structures of form A (the marketed form). 15N NMR indicates that the amorphous material contains an approximately 2:1 ratio of 1H- and 2H-tetrazole tautomers. Static 1H SSNMR and relaxation time measurements confirmed different molecular mobilities of the samples and provided molecular-level insight into the nature of the glass transition. SSNMR is shown to be a powerful technique to investigate the solid state of disordered active pharmaceutical ingredients.
{"title":"Characterization of crystalline and amorphous forms of irbesartan by multi-nuclear solid-state NMR","authors":"Marcin Skotnicki , Paul Hodgkinson","doi":"10.1016/j.ssnmr.2022.101783","DOIUrl":"10.1016/j.ssnmr.2022.101783","url":null,"abstract":"<div><p><span>Irbesartan (IRB) is an antihypertensive drug which exhibits the rare phenomenon of desmotropy; its 1</span><em>H</em>- and 2<em>H</em><span><span>- tetrazole </span>tautomers<span> can be isolated as distinct crystalline forms. The crystalline forms of IRB are poorly soluble, hence the amorphous<span> form is potentially of interest for its faster dissolution rate. The tautomeric form and the nature of hydrogen bonding in amorphous IRB are unknown. In this study, crystalline form A and amorphous form of irbesartan were studied using </span></span></span><sup>13</sup>C, <sup>15</sup>N and <sup>1</sup>H solid-state NMR. Variable-temperature <sup>13</sup>C SSMNR studies showed alkyl chain disorder in the crystalline form of IRB, which may explain the conflicting literature crystal structures of form A (the marketed form). <sup>15</sup>N NMR indicates that the amorphous material contains an approximately 2:1 ratio of 1<em>H</em>- and 2<em>H</em>-tetrazole tautomers. Static <sup>1</sup><span>H SSNMR and relaxation time measurements confirmed different molecular mobilities of the samples and provided molecular-level insight into the nature of the glass transition. SSNMR is shown to be a powerful technique to investigate the solid state of disordered active pharmaceutical ingredients.</span></p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49176733","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}
Fast magic-angle spinning (≥60 kHz) technique has enabled the acquisition of high-resolution 1H NMR spectra of solid materials. However, the spectral interpretation is still difficult because the 1H peaks are overlapped due to the narrow chemical shift range and broad linewidths. An additional 13C or 14N or 1H dimension possibly addresses the issues of overlapped proton resonances, but it leads to the elongated experimental time. Herein, we introduce a single-channel 1H experiment to separate the overlapped 1H peak and identify its spatially proximal 1H–1H correlations. This sequence combines selective excitation, selective 1H–1H polarization transfer by selective recoupling of protons (SERP), and broadband 1H recoupling by back-to-back (BABA) recoupling sequences. The concept for 1H separation is based on (i) the selective excitation of a well-resolved 1H peak and (ii) the selective dipolar polarization transfer from this isolated 1H peak to one of the 1H peaks in the overlapped/poor resolution region by SERP and (iii) the detection of 1H–1H correlations from these two 1H peaks to other neighboring 1Hs by BABA. We demonstrated the applicability of this approach to identify overlapped peaks on two molecules, β-L-aspartyl-l-alanine and Pioglitazone.HCl. The sequence allows the clear observation of 1H–1H correlations from an overlapped 1H peak without an additional heteronuclear dimension and ensures efficient polarization transfers that leads to twelve fold reduction in experimental time compared to 14N edited experiments. The limitation and the conditions of applicability for this approach are discussed in detail.
{"title":"Separating an overlapped 1H peak and identifying its 1H-1H correlations with the use of single-channel 1H solid-state NMR at fast MAS","authors":"Nghia Tuan Duong , Vipin Agarwal , Yusuke Nishiyama","doi":"10.1016/j.ssnmr.2022.101774","DOIUrl":"10.1016/j.ssnmr.2022.101774","url":null,"abstract":"<div><p>Fast magic-angle spinning (≥60 kHz) technique has enabled the acquisition of high-resolution <sup>1</sup>H NMR spectra of solid materials. However, the spectral interpretation is still difficult because the <sup>1</sup><span>H peaks are overlapped due to the narrow chemical shift range and broad linewidths. An additional </span><sup>13</sup>C or <sup>14</sup>N or <sup>1</sup>H dimension possibly addresses the issues of overlapped proton resonances, but it leads to the elongated experimental time. Herein, we introduce a single-channel <sup>1</sup>H experiment to separate the overlapped <sup>1</sup>H peak and identify its spatially proximal <sup>1</sup>H–<sup>1</sup><span>H correlations. This sequence combines selective excitation, selective </span><sup>1</sup>H–<sup>1</sup><span>H polarization transfer by selective recoupling of protons (SERP), and broadband </span><sup>1</sup>H recoupling by back-to-back (BABA) recoupling sequences. The concept for <sup>1</sup>H separation is based on (i) the selective excitation of a well-resolved <sup>1</sup>H peak and (ii) the selective dipolar polarization transfer from this isolated <sup>1</sup>H peak to one of the <sup>1</sup>H peaks in the overlapped/poor resolution region by SERP and (iii) the detection of <sup>1</sup>H–<sup>1</sup>H correlations from these two <sup>1</sup>H peaks to other neighboring <sup>1</sup>Hs by BABA. We demonstrated the applicability of this approach to identify overlapped peaks on two molecules, β-L-aspartyl-<span>l</span><span>-alanine and Pioglitazone.HCl. The sequence allows the clear observation of </span><sup>1</sup>H–<sup>1</sup>H correlations from an overlapped <sup>1</sup>H peak without an additional heteronuclear dimension and ensures efficient polarization transfers that leads to twelve fold reduction in experimental time compared to <sup>14</sup>N edited experiments. The limitation and the conditions of applicability for this approach are discussed in detail.</p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39837922","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 : 2022-02-01DOI: 10.1016/j.ssnmr.2022.101773
Andrea Simion , Mihai Vasilescu , Claudiu Filip , Milica Todea , Marieta Mureșan-Pop , Simion Simon
Atomic-scale description of surfaces and interfaces in core-shell aluminosilicate materials is not fully elucidated, partially due to their amorphous character and complex mechanisms that govern their properties. In this paper, new insights into nanostructured core-shell aluminosilicates have been demonstrated, by using different solid-state NMR methods, i.e 29Si, 29Si cross-polarization (CP), 27Al, 27Al triple-quantum (3Q), and 1H–27Al heteronuclear correlation (HETCOR) MAS NMR. For this purpose, nanostructured silica core-alumina shell microspheres, undoped and doped with gadolinium ions respectively, obtained by a chemical synthesis based on the Stöber method for the silica core and electrostatic attraction for developing the alumina shell were studied. As a result, a new alumino-silicate layer formation was proved at the interface between silica core, where aluminum diffuses, on small scale, in the silica network, and alumina shell, where silicon ions migrate, on a larger scale, in the alumina network, leading to a stable core-shell structure. Moreover, this process is accompanied by significant local structural changes in the transition zone, particularly at the aluminum neighborhood, which is quite well understood now, with the power of solid-state NMR spectroscopy.
核壳铝硅酸盐材料表面和界面的原子尺度描述尚未完全阐明,部分原因是它们的无定形特征和控制其性质的复杂机制。本文通过不同的固体核磁共振方法,即29Si, 29Si交叉极化(CP), 27Al, 27Al三量子(3Q)和1H-27Al异核相关(hetor) MAS NMR,展示了对纳米结构核壳铝硅酸盐的新见解。为此,研究了基于Stöber法制备二氧化硅核和静电吸引形成氧化铝壳的化学合成方法,分别制备了未掺杂和掺杂钆离子的纳米二氧化硅核-氧化铝壳微球。结果表明,在二氧化硅核和氧化铝壳之间的界面处形成了新的铝-硅酸盐层,铝在二氧化硅网络中小规模扩散,而硅离子在氧化铝网络中大规模迁移,导致了稳定的核-壳结构。此外,这一过程伴随着过渡区显著的局部结构变化,特别是在铝邻域,这一点现在已经很好地理解了,借助固态核磁共振光谱的力量。
{"title":"Structural characterization of interfaces in silica core-alumina shell microspheres by solid-state NMR spectroscopy","authors":"Andrea Simion , Mihai Vasilescu , Claudiu Filip , Milica Todea , Marieta Mureșan-Pop , Simion Simon","doi":"10.1016/j.ssnmr.2022.101773","DOIUrl":"10.1016/j.ssnmr.2022.101773","url":null,"abstract":"<div><p><span><span>Atomic-scale description of surfaces and interfaces in core-shell aluminosilicate materials is not fully elucidated, partially due to their </span>amorphous character and complex mechanisms that govern their properties. In this paper, new insights into nanostructured core-shell aluminosilicates have been demonstrated, by using different solid-state NMR methods, i.e </span><sup>29</sup>Si, <sup>29</sup>Si cross-polarization (CP), <sup>27</sup>Al, <sup>27</sup>Al triple-quantum (3Q), and <sup>1</sup>H–<sup>27</sup><span><span><span>Al heteronuclear correlation (HETCOR) </span>MAS<span> NMR. For this purpose, nanostructured silica<span><span> core-alumina shell microspheres, undoped and doped with </span>gadolinium<span> ions respectively, obtained by a chemical synthesis based on the Stöber method for the silica core and electrostatic attraction for developing the alumina shell were studied. As a result, a new alumino-silicate layer formation was proved at the interface between silica core, where </span></span></span></span>aluminum<span> diffuses, on small scale, in the silica network, and alumina shell, where silicon ions migrate, on a larger scale, in the alumina network, leading to a stable core-shell structure. Moreover, this process is accompanied by significant local structural changes in the transition zone, particularly at the aluminum neighborhood, which is quite well understood now, with the power of solid-state NMR spectroscopy.</span></span></p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39927776","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 : 2022-02-01DOI: 10.1016/j.ssnmr.2022.101772
Caiyan He , Shenhui Li , Yuqing Xiao , Jun Xu , Feng Deng
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 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.
{"title":"Application of solid-state NMR techniques for structural characterization of metal-organic frameworks","authors":"Caiyan He , Shenhui Li , Yuqing Xiao , Jun Xu , 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":null,"pages":null},"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}
Pub Date : 2022-02-01DOI: 10.1016/j.ssnmr.2021.101763
Shira Haber, Michal Leskes
The increasing need for portable and large-scale energy storage systems requires development of new, long lasting and highly efficient battery systems. Solid state NMR spectroscopy has emerged as an excellent method for characterizing battery materials. Yet, it is limited when it comes to probing thin interfacial layers which play a central role in the performance and lifetime of battery cells. Here we review how Dynamic Nuclear Polarization (DNP) can lift the sensitivity limitation and enable detection of the electrode-electrolyte interface, as well as the bulk of some electrode and electrolyte systems. We describe the current challenges from the point of view of materials development; considering how the unique electronic, magnetic and chemical properties differentiate battery materials from other applications of DNP in materials science. We review the current applications of exogenous and endogenous DNP from radicals, conduction electrons and paramagnetic metal ions. Finally, we provide our perspective on the opportunities and directions where battery materials can benefit from current DNP methodologies as well as project on future developments that will enable NMR investigation of battery materials with sensitivity and selectivity under ambient conditions.
{"title":"Dynamic Nuclear Polarization in battery materials","authors":"Shira Haber, Michal Leskes","doi":"10.1016/j.ssnmr.2021.101763","DOIUrl":"10.1016/j.ssnmr.2021.101763","url":null,"abstract":"<div><p><span>The increasing need for portable and large-scale energy storage systems requires development of new, long lasting and highly efficient battery systems. </span>Solid state NMR<span><span> spectroscopy has emerged as an excellent method for characterizing battery materials. Yet, it is limited when it comes to probing thin interfacial layers which play a central role in the performance and lifetime of battery cells. Here we review how Dynamic Nuclear Polarization<span> (DNP) can lift the sensitivity limitation and enable detection of the electrode-electrolyte interface, as well as the bulk of some electrode and electrolyte systems. We describe the current challenges from the point of view of materials development; considering how the unique electronic, magnetic and chemical properties differentiate battery materials from other applications of DNP in materials science. We review the current applications of exogenous and endogenous DNP from radicals, conduction electrons and paramagnetic </span></span>metal ions. Finally, we provide our perspective on the opportunities and directions where battery materials can benefit from current DNP methodologies as well as project on future developments that will enable NMR investigation of battery materials with sensitivity and selectivity under ambient conditions.</span></p></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39712628","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 : 2022-02-01DOI: 10.1016/j.ssnmr.2021.101771
S. Chandra Shekar , Wancheng Zhao , Thomas K. Weldeghiorghis, Tuo Wang
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 NMR signal, 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.
{"title":"Effect of cross polarization radiofrequency phases on signal phase","authors":"S. Chandra Shekar , Wancheng Zhao , Thomas K. Weldeghiorghis, 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":null,"pages":null},"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}
Pub Date : 2022-02-01DOI: 10.1016/j.ssnmr.2022.101775
Otto E.O. Zeman, Thomas Bräuniger
Single crystals of the compound []Cl4 ⋅ 2H2O were studied by 45Sc-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 B0 = 17.6 T showed strong second-order effects due to the comparatively large coupling constant of χ = |14.613 ± 0.006| MHz, with an associated asymmetry parameter of ηQ = 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 δ11 = (5.6 ± 0.9) ppm, δ22 = (12.4 ± 0.9) ppm, and δ33 = (38.5 ± 0.9) ppm. In spectra acquired at a lower magnetic field of B0 = 9.4 T, third-order effects could be detected, and similarly quantified using analytical expressions.
{"title":"Quantifying the quadrupolar interaction by 45Sc-NMR spectroscopy of single crystals","authors":"Otto E.O. Zeman, 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>]Cl<sub>4</sub> ⋅ 2H<sub>2</sub>O were studied by <sup>45</sup><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><sub>0</sub> = 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><sub><em>Q</em></sub> = 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><sub>11</sub> = (5.6 ± 0.9) ppm, <em>δ</em><sub>22</sub> = (12.4 ± 0.9) ppm, and <em>δ</em><sub>33</sub> = (38.5 ± 0.9) ppm. In spectra acquired at a lower magnetic field of <em>B</em><sub>0</sub> = 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":null,"pages":null},"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}