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Experimental aspects of ^(14)N overtone RESPDOR solid-state nmr spectroscopy under MAS beyond 60 kHz

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Magnetic Resonance Letters 2024年第1期4卷 40-49页

作者： Yutaro Ogaeri Yusuke Nishiyama JEOL Ltd. AkishimaTokyo196-8558Japan

Nitrogen-14(^(14)N)overtone(OT)spectroscopy under fast magic angle spinning(MAS)conditions(>60 kHz)has emerged as a powerful technique for observing correlations and distances between ^(14)N and ^(1)H,owing to the absence of the first-order quadrupolar broad*** addition,^(14)N^(OT) allows selective manipulation of ^(14)N nuclei for each *** extensive theoretical and experimental studies,the spin dynamics of ^(14)N^(OT) remains under *** this study,we conducted experimental investigations to assess the spin dynamics of ^(14)N^(OT) using the rotational-echo saturation-pulse double-resonance(RESPDOR)sequence,which monitors population transfer induced by a^(14)N^(OT) *** ^(14)N^(OT) spin dynamics is well represented by a model of a two-energy-level *** spin-1/2,the maximum excitation efficiency of ^(14)N^(OT) coherences of powdered solids,denoted by p,depends on the radiofrequency field(rf-field)strength due to orientation dependence of effective nutation fields even when pulse lengths are *** is also found that the p factor,contributing to the ^(14)N^(OT) spin dynamics,is nearly independent of the B0 ***,the filtering efficiency of RESPDOR experiments exhibits negligible dependence on B0 when the ^(14)N^(OT) pulse length is *** study also identifies the optimal experimental conditions for ^(14)N^(OT)/^(1)H RESPDOR correlation experiments.

关键词： ^(14)N Overtone RESPDOR ^(14)N/^(1)H correlation solid-state nmr Fast MAS

Structural analysis of silk using solid-state nmr

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Magnetic Resonance Letters 2024年第3期4卷 19-34页

作者： Tetsuo Asakura Department of Biotechnology Tokyo University of Agriculture and TechnologyKoganeiTokyo184-8588Japan

Silkworms and spiders are capable of generating fibers that are both highly durable and elastic in a short span of time,using a silk solution stored within their bodies at room temperature and normal atmospheric *** dragline silk fiber,which is essentially a spider's lifeline,surpasses the strength of a steel wire of equivalent ***,humans have yet to replicate this process to produce fibers with similar high strength and elasticity in an eco-friendly ***,it is of utmost importance to thoroughly comprehend the extraordinary structure and fibrillation mechanism of silk,and leverage this understanding in the manufacturing of high-strength,high-elasticity *** review will delve into the recent progress in comprehending the structure of silks derived from silkworms and spiders,emphasizing the distinctive attributes of solidstate nmr.

关键词： Silk Bombyx mori Spider solid-state nmr Structure

solid-state nmr spectroscopy at ultrahigh resolution for structural and dynamical studies of MOFs

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Magnetic Resonance Letters 2023年第2期3卷 175-186,I0005页

作者： Qing Wang Min Peng Cong-Cong Liang Jing Tan Sophia Zhang Yue-Biao Zhang Haiming Liu School of Physical Science and Technology ShanghaiTech UniversityShanghai201210China Maling Middle School SuqianJiangsu223800China Washington University in St.Louis St.LouisMO63130USA

To characterize the structure and dynamics of metal--organic frameworks(MOFs)indepth at the molecular level,it is necessary to pursue high-resolution solid-state magic angle spinning(MAS)nuclear magnetic resonance(nmr)*** resolution is usually affected by the quality of materials and various experimental conditions,of which magic angle(MA)accuracy is a crucial *** current industrial criteria for MA calibration based on the common standard of KBr were found insufficient in guaranteeing optimal resolution MAS nmr for highly ordered *** drive towards higher-resolution MAS nmr spectroscopy,we propose_a calibration protocol for more accurate MA with a higher-precision criterion based on 79Br MAS nmr of KBr,where the linewidth ratio of the fifth-order spinning sideband to the central band of KBr should be less than *** a result,ultrahigh-resolution 13C cross-polarization(CP)MAS nmr of MOF-5 is achieved with minimal linewidths as low as 4 Hz,and therefore MOF-5 can be used as a new standard convenient for verifying MA accuracy and also optimizing 13c CP *** high-precision MA under variable temperature(VT)was found challenging on certain commercial MAS nmr probes,as was systematically investigated by VT nmr using KBr and ***,ultrahigh-resolution MAS nmr spectroscopy with stable MA under VT is employed to reveal fine structures and linker dynamics of a series of Zn-based MOFs with highly regulated *** ultrahigh-resolution nmr methodcan be generally applied to study a broad range of MOFs and other materials.

关键词： solid-state nmr Ultrahigh resolution MOFs Structure and dynamics Magic angle calibration

solid-state nmr studies of sulfonated SBA-15 and the synergistic catalysis of fructose into 5-hydroxymethylfurfural with dimethyl sulfoxide

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Magnetic Resonance Letters 2022年第1期2卷 38-47,I0003页

作者： Xin Li Wanling Shen Han Sun College of Chemistry and Chemical Engineering Henan University of TechnologyZhengzhou450001China

Sulfonic acid functionalized mesoporous SBA-15 was prepared using the grafting *** structure and acid properties were comprehensively characterized using multi-nuclear and quantitative probe molecule solid-state nmr(SSnmr),together with powder X-ray diffraction(XRD),scanning electron microscope(SEM),transmission electron microscopy(TEM),N2 adsorption-desorption *** catalytic performance in the conversion of fructose to 5-hydroxymethylfurfural(HMF)in dimethyl sulfoxide(DMSO)was *** dosage,reaction time,reaction temperature and solvent effect have been investigated.A high yield of HMF up to 93%was obtained at a relatively low temperature of 373 K for 180 *** Brønsted acid of SBA-15_SO3H together with the solvent DMSO was found to synergistically catalyze the *** catalyst preserved most of its activity after five times reuse and the catalytic activity can be recovered by H2O2 process.

关键词： solid acid solid-state nmr Molecular sieve Heterogeneous catalysis Biomass

Recent advances in solid-state nmr of zeolite catalysts

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National Science Review 2022年第9期9卷 79-101页

作者： Weiyu Wang Jun Xu Feng Deng National Center for Magnetic Resonance in Wuhan State Key Laboratory of Magnetic Resonance and Atomic and Molecular PhysicsWuhan Institute of Physics and MathematicsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of Sciences University of Chinese Academy of Sciences

Zeolites are important inorganic crystalline microporous materials with a broad range of applications in the areas of catalysis, ion exchange, and adsorption/separations. solid-state nuclear magnetic resonance(nmr) spectroscopy has proven to be a powerful tool in the study of zeolites and relevant catalytic reactions because of its advantage in providing atomic-level insights into molecular structure and dynamic behavior. In this review, we provide a brief discussion on the recent progress in exploring framework structures, catalytically active sites and intermolecular interactions in zeolites and metal-containing ones by using various solid-state nmr methods. Advances in the mechanistic understanding of zeolite-catalysed reactions including methanol and ethanol conversions are presented as selected examples. Finally, we discuss the prospect of the solid-state nmr technique for its application in zeolites.

关键词： solid-state nmr zeolites characterization active sites reaction mechanism

Moisture-Induced Non-Equilibrium Phase Segregation in Triple Cation Mixed Halide Perovskite Monitored by In Situ Characterization Techniques and solid-state nmr

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Energy & Environmental Materials 2023年第2期6卷 185-194页

作者： Mohammad Ali Akhavan Kazemi Nicolas Folastre Parth Raval Michel Sliwa Jean Marie Vianney Nsanzimana Sema Golonu Arnaud Demortiere Jean Rousset Olivier Lafon Laurent Delevoye G.N.Manjunatha Reddy Frédéric Sauvage Laboratoire de Réactivité et Chimie des solides(LRCS) UMR CNRS 7314-Institut de Chimie de Picardie FR 3085Université de Picardie Jules Verne33 rue Saint LeuAmiens Cedex FR-80039France CNRS Centrale LilleUMR 8181UCCSUnitéde Catalyse et Chimie du SolideUniversité de LilleUniversitéd’ArtoisLille F-59000France UMR 8516-LASIRE-Laboratoire de Spectroscopie pour les Interactions la Réactivité et l’EnvironnementCNRSUniversitéde LilleLille F-59000France EDF R&D EDF LabBoulevard Gaspard MongePalaiseau 91120France

Environmental stability is a major bottleneck of perovskite solar *** a handful of studies are investigating the effect of moisture on the structural degradation of the *** mostly rely on ex situ experiments and on completely degraded samples,which restrict the assessment on initial and final *** combining in situ X-ray diffraction under controlled 85%relative humidity,and live observations of the water-induced degradation using liquid-cell transmission electron microscopy,we reveal two competitive degradation paths leading on one hand to the decomposition of state-of-theart mixed cation/anion(Cs_(0.05)(MA_(0.17)FA_(0.83))_(0.95)Pb(Br_(0.17)I_(0.83))_(3)(CsMAFA)into PbI_(2) through a dissolution/recrystallization mechanism and,on the other hand,to a non-equilibrium phase segregation leading to CsPb_(2)Br_(5) and a Cesium-poor/iodide-rich Cs_(0.05)-x(MA_(0.17)FA_(0.83))_(0.95)Pb(Br_(0.17-2y)I_(0.83)+2y)_(3) *** degradation mechanism is corroborated at atomic-scale resolution through solid-state ^(1)H and ^(133)Cs nmr *** to moisture leads to a film containing important heterogeneities in terms of morphology,photoluminescence intensities,and *** results provide new insights and consensus that complex perovskite compositions,though very performant as champion devices,are comparatively metastable,a trait that limits the chances to achieve long-term stability.

关键词： liquid-cell transmission electron microscopy moisture degradation perovskite stability phase segregation solid-state nmr

Deciphering the potassium storage phase conversion mechanism of phosphorus by combined solid-state nmr spectroscopy and density functional theory calculations

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Journal of Energy Chemistry 2023年第4期79卷 45-53页

作者： Huixin Chen Lingyi Meng Hongjun Yue Chengxin Peng Qiaobao Zhang Guiming Zhong Ding Chen state Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082HunanChina CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002FujianChina Laboratory of Advanced Spectro-electrochemistry and Li-ion Batteries Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth MaterialsHaixi InstitutesChinese Academy of SciencesXiamen 361021FujianChina Department of Materials Science and Engineering College of MaterialsXiamen UniversityXiamen 361005FujianChina School of Materials Science and Chemistry University of Shanghai for Science and TechnologyShanghai 200093China

Phosphorus is the potential anode material for emerging potassium-ion batteries(PIBs)owing to the highest specific capacity and relatively low operation ***,the reversible delivered capacities of phosphorus-based anodes,in reality,are far from the theoretical capacity corresponding to the formation of K3P ***,their underlying potassium storage mechanisms remain poorly *** address this issue,for the first time,we perform high-resolution solid-state31P nmr combined with XRD measurements,and density functional theory calculations to yield a systemic quantitative understanding of(de)potassiation reaction mechanism of phosphorus *** explicitly reveal a previously unknown asymmetrical nanocrystalline-to-amorphous transition process via rP←→(K_(3)P_(11),K_(3)P_(7),beta-K_(4)P_(6))←→(alpha-K4P6)←→(K_(1-x)P,KP,K_(4-x)P3,K_(1+x)P)←→(amorphous K4P3,amorphous K3P)that are proceed along with the electrochemical potassiation/depotassiation ***,the corresponding KP alloys intermediates,such as the amorphous phases of K_(4)P_(3),K_(3)P,and the nonstoichiometric phases of“K_(1-x)P”,“K_(1+x)P”,“K_(4-x)P_(3)”are experimentally detected,which indicating various complicated K-P alloy species are coexisted and evolved with the sluggish electrochemical reaction kinetics,resulting in lower capacity of phosphorus-based *** findings offer some insights into the specific multi-phase evolution mechanism of alloying anodes that may be generally involved in conversion-type electrode materials for PIBs.

关键词： Red phosphorus Phase conversion solid-state nmr Potassium ion batteries

Mechanistic Insight into Ethanol Dehydration over SAPO-34 Zeolite by solid-state nmr Spectroscopy

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Chemical Research in Chinese Universities 2022年第1期38卷 155-160页

作者： ZHOU Xue WANG Chao CHU Yueying WANG Qiang XU Jun DENG Feng National Centre for Magnetic Resonance in Wuhan State Key Laboratory of Magnetic Resonance and Atomic and Molecular PhysicsWuhan Institute of Physics and MathematicsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071P.R.China

The reaction mechanism of ethanol dehydration over SAPO-34 zeolite is investigated by using solid-state nmr spectroscopy. SAPO-34 zeolites with different Si contents are prepared and their acidities are characterized by nmr experiments. The higher content of stronger Brønsted acid sites is correlated to the higher Si content. The adsorption of ethanol on the Brønsted acid sites in SAPO-34 leads to the formation of frustrated Lewis pairs(FLPs). Surface ethoxy species is observed by the dehydration of the FLP sites at room temperature, which can be further converted into ethene products. The decomposing of diethyl ether over Brønsted acid sites is responsible for the formation of ethoxy species at higher reaction temperatures. Triethyloxonium ions are formed in the reaction. A plausible reaction mechanism is proposed for the dehydration of ethanol over SAPO-34.

关键词： Ethanol dehydration SAPO-34 Intermediate Reaction mechanism solid-state nmr

On the use of cross polarization in solid-state nmr:1 H spinlock versus adiabatic demagnetization in the rotating frame

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Magnetic Resonance Letters 2022年第3期2卷 147-158页

作者： Yuchen Li Shengyu Zhang Ze Wu Xinhua Peng Riqiang Fu CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences University of Science and Technology of ChinaHefei230026China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei230026China Hefei National Laboratory Hefei230088China National High Magnetic Field Laboratory 1800 East Paul Dirac DriveTallahasseeFL32310USA

Cross polarization(CP)is a widely used solid-state nuclear magnetic resonance(nmr)technique for enhancing the polarization of dilute S spins from much larger polarization of abundant I spins such as 1 *** achieve such a polarization transfer,the I spin should either be spin-locked or be converted to the dipolar ordered state through adiabatic demagnetization in the rotating *** this work,we analyze the spin dynamics of the Hartmann-Hahn CP(HHCP)utilizing the 1 H spin-locking,and the dipolar-order CP(DOCP)having the 1 H adiabatic *** further propose an adiabatic demagnetization CP(ADCP)where a constant radio-frequency pulse is applied on the S spin while 1 H is adiabatically *** analyses indicate that ADCP utilizes the adiabatic passage to effectively achieve the polarization transfer from the 1 H to S *** addition,the dipolar ordered state generated during the 1 H demagnetization process could also be converted into the observable S polarization through DOCP,further enhancing the polarized *** is shown by both static and magic-angle-spinning(MAS)nmr experiments that ADCP has dramatically broadened the CP matching condition over the other CP *** samples have been used to demonstrate the polarization transfer efficiency of this newly proposed ADCP scheme.

关键词： Cross polarization Spin-lock in rotating frame Adiabatic demagnetization Spin dynamics Dipolar ordered state solid-state nmr