Artigos de revistas: "Solid NMR"

1

LUO, Qing, e Fumitaka HORII. "Solid-State NMR". Kobunshi 55, n.º 2 (2006): 101–5. http://dx.doi.org/10.1295/kobunshi.55.101.

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Horii, Fumitaka. "High-resolution NMR: Solid-state NMR." Kobunshi 39, n.º 12 (1990): 888–91. http://dx.doi.org/10.1295/kobunshi.39.888.

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3

Harris, Kenneth D. M., Colan E. Hughes, P. Andrew Williams e Gregory R. Edwards-Gau. "`NMR Crystallization': in-situ NMR techniques for time-resolved monitoring of crystallization processes". Acta Crystallographica Section C Structural Chemistry 73, n.º 3 (6 de fevereiro de 2017): 137–48. http://dx.doi.org/10.1107/s2053229616019811.

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Solid-state NMR spectroscopy is a well-established and versatile technique for studying the structural and dynamic properties of solids, and there is considerable potential to exploit the power and versatility of solid-state NMR for in-situ studies of chemical processes. However, a number of technical challenges are associated with adapting this technique for in-situ studies, depending on the process of interest. Recently, an in-situ solid-state NMR strategy for monitoring the evolution of crystallization processes has been developed and has proven to be a promising approach for identifying the sequence of distinct solid forms present as a function of time during crystallization from solution, and for the discovery of new polymorphs. The latest development of this technique, called `CLASSIC' NMR, allows the simultaneous measurement of both liquid-state and solid-state NMR spectra as a function of time, thus yielding complementary information on the evolution of both the liquid phase and the solid phase during crystallization from solution. This article gives an overview of the range of NMR strategies that are currently available for in-situ studies of crystallization processes, with examples of applications that highlight the potential of these strategies to deepen our understanding of crystallization phenomena.

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4

Oschkinat, H. "Bio-Solid State NMR". EPJ Web of Conferences 30 (2012): 03004. http://dx.doi.org/10.1051/epjconf/20123003004.

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5

Griffiths, Jennifer. "Solid-state NMR probes". Analytical Chemistry 80, n.º 5 (março de 2008): 1381–84. http://dx.doi.org/10.1021/ac0860222.

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6

Bai, Shi, Wei Wang e Cecil Dybowski. "Solid State NMR Spectroscopy". Analytical Chemistry 82, n.º 12 (15 de junho de 2010): 4917–24. http://dx.doi.org/10.1021/ac100761m.

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7

Dybowski*, Cecil, e Shi Bai. "Solid-State NMR Spectroscopy". Analytical Chemistry 80, n.º 12 (junho de 2008): 4295–300. http://dx.doi.org/10.1021/ac800573y.

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8

Martineau, Charlotte, Boris Bouchevreau e Francis Taulelle. "NMR crystallography driven structure determination". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 de agosto de 2014): C1517. http://dx.doi.org/10.1107/s2053273314084824.

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Because solid-state nuclear magnetic resonance (ss-NMR) spectroscopy is sensitive to local order and is selective to the nature of the atoms, this technique has emerged as ideally complementary to powder diffraction for structure determination of a wide range of solids. Here, we will illustrate with the example of hybrid solids (aluminophosphates) the role of high-resolution one and two-dimensional solid-state NMR data to drive the search for a structure model from powder diffraction data. Great progresses have been made in the field of ss-NMR in the past few years (higher magnetic field, more robust pulse sequences, etc.) that now allows access to NMR spectra with very high resolution in such compounds [1]. From these NMR data, information about the cations (number, coordination number, etc) and the connectivity between the cation polyhedra are readily available. Such knowledge allows performing a more constraint structure search, thus increasing the chance to obtain a solution [2]. NMR data further provide information about the non-periodic sub-networks in hybrid compounds (water molecules, OH groups, templates...), allowing to draw very detailed pictures of the solids [3].

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9

Kinsey, Robert A. "Solid-State NMR of Elastomers". Rubber Chemistry and Technology 63, n.º 3 (1 de julho de 1990): 407–25. http://dx.doi.org/10.5254/1.3538263.

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Abstract The versatility of solid state NMR for the characterization of elastomers and elastomer composites has been demonstrated. NMR can be used as an analytical tool for identifying the elastomer(s) present (including the sequence distribution and tacticity), measuring crosslink levels, and monitoring chemical modifications. In addition, with relaxation measurements, NMR provides direct physical insight into the dynamics, and hence the spatial interactions of elastomeric systems. The interfacial regions of heterogeneous systems such as IPNs, filled elastomers, and block copolymers can be probed. A variety of NMR parameters can be correlated with physical properties. Future studies will extend the use of variable temperature and high magnetic field strength measurements, as well as utilize the growing number of two-dimensional experiments. The use of solid state H-l NMR should increase as instrumentation progresses, complementing the heteronuclear work. Solid H-l NMR offers significant sensitivity increases over C-13 NMR, but with decreased resolution. N-15 NMR studies have been recently performed at natural abundance with rigid polymers, and will likely be useful for characterizing elastomers.

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10

Ashbrook, Sharon E., John M. Griffin e Karen E. Johnston. "Recent Advances in Solid-State Nuclear Magnetic Resonance Spectroscopy". Annual Review of Analytical Chemistry 11, n.º 1 (12 de junho de 2018): 485–508. http://dx.doi.org/10.1146/annurev-anchem-061417-125852.

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The sensitivity of nuclear magnetic resonance (NMR) spectroscopy to the local atomic-scale environment offers great potential for the characterization of a diverse range of solid materials. Despite offering more information than its solution-state counterpart, solid-state NMR has not yet achieved a similar level of recognition, owing to the anisotropic interactions that broaden the spectral lines and hinder the extraction of structural information. Here, we describe the methods available to improve the resolution of solid-state NMR spectra and the continuing research in this area. We also highlight areas of exciting new and future development, including recent interest in combining experiment with theoretical calculations, the rise of a range of polarization transfer techniques that provide significant sensitivity enhancements, and the progress of in situ measurements. We demonstrate the detailed information available when studying dynamic and disordered solids and discuss the future applications of solid-state NMR spectroscopy across the chemical sciences.

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11

Harris, Kenneth D. M. "NMR Crystallography as a Vital Tool in Assisting Crystal Structure Determination from Powder XRD Data". Crystals 12, n.º 9 (8 de setembro de 2022): 1277. http://dx.doi.org/10.3390/cryst12091277.

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Powder X-ray diffraction (XRD) and solid-state NMR spectroscopy are complementary techniques for investigating the structural properties of solids, and there are considerable opportunities and advantages to applying these techniques synergistically together in determining the structural properties of crystalline solids. This article provides an overview of the potential to exploit structural information derived from solid-state NMR data to assist and enhance the process of crystal structure determination from powder XRD data, focusing in particular on the structure determination of organic molecular materials.

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12

Hughes, Colan E., P. Andrew Williams, Victoria L. Keast, Vasileios G. Charalampopoulos, Gregory R. Edwards-Gau e Kenneth D. M. Harris. "New in situ solid-state NMR techniques for probing the evolution of crystallization processes: pre-nucleation, nucleation and growth". Faraday Discussions 179 (2015): 115–40. http://dx.doi.org/10.1039/c4fd00215f.

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The application of in situ techniques for investigating crystallization processes promises to yield significant new insights into fundamental aspects of crystallization science. With this motivation, we recently developed a new in situ solid-state NMR technique that exploits the ability of NMR to selectively detect the solid phase in heterogeneous solid–liquid systems (of the type that exist during crystallization from solution), with the liquid phase “invisible” to the measurement. As a consequence, the technique allows the first solid particles produced during crystallization to be observed and identified, and allows the evolution of different solid phases (e.g., polymorphs) present during the crystallization process to be monitored as a function of time. This in situ solid-state NMR strategy has been demonstrated to be a powerful approach for establishing the sequence of solid phases produced during crystallization and for the discovery of new polymorphs. The most recent advance of the in situ NMR methodology has been the development of a strategy (named “CLASSIC NMR”) that allows both solid-state NMR and liquid-state NMR spectra to be measured (essentially simultaneously) during the crystallization process, yielding information on the complementary changes that occur in both the solid and liquid phases as a function of time. In this article, we present new results that highlight the application of our in situ NMR techniques to successfully unravel different aspects of crystallization processes, focusing on: (i) the application of a CLASSIC NMR approach to monitor competitive inclusion processes in solid urea inclusion compounds, (ii) exploiting liquid-state NMR to gain insights into co-crystal formation between benzoic acid and pentafluorobenzoic acid, and (iii) applications of in situ solid-state NMR for the discovery of new solid forms of trimethylphosphine oxide and l-phenylalanine. Finally, the article discusses a number of important fundamental issues relating to practical aspects, the interpretation of results and the future scope of these techniques, including: (i) an assessment of the smallest size of solid particle that can be detected in in situ solid-state NMR studies of crystallization, (ii) an appraisal of whether the rapid sample spinning required by the NMR measurement technique may actually influence or perturb the crystallization behaviour, and (iii) a discussion of factors that influence the sensitivity and time-resolution of in situ solid-state NMR experiments.

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13

Siminovitch, David J. "Solid-state NMR studies of proteins: the view from static 2H NMR experiments". Biochemistry and Cell Biology 76, n.º 2-3 (1 de maio de 1998): 411–22. http://dx.doi.org/10.1139/o98-054.

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The application of solid-state 2H NMR spectroscopy to the study of protein and peptide structure and dynamics is reviewed. The advantages of solid-state NMR for the study of proteins are considered, and the particular advantages of solid-state 2H NMR are summarized. Examples of work on the integral membrane protein bacteriorhodopsin, and the membrane peptide gramicidin, are used to highlight the major achievements of the 2H NMR technique. These examples demonstrate that through the use of oriented samples, it is possible to obtain both structural and dynamic information simultaneously.Key words: solid-state NMR, 2H NMR, membrane peptides, membrane proteins, oriented bilayers.

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14

Facey, Glenn A., Terrence J. Connolly, Corinne Bensimon e Tony Durst. "A solid state NMR and X-ray crystallographic investigation of dynamic disorder in solid tetrahydronaphthalene derivatives". Canadian Journal of Chemistry 74, n.º 10 (1 de outubro de 1996): 1844–51. http://dx.doi.org/10.1139/v96-206.

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The solid state disorder of two tetrahydronaphthalene derivatives, N-methyl-N-methoxy-5,6,7,8-tetrahydro-1-naphthamide and 5,6,7,8-tetrahydro-1-naphthoic acid, was studied by solid state NMR and single crystal X-ray diffraction. The X-ray crystal structure of N-methyl-N-methoxy-5,6,7,8-tetrahydro-1-naphthamide was obtained at 123 K. It indicated the presence of two distinct molecular conformations. Solid state 13C CP/MAS NMR data using the dipolar dephasing technique revealed that the two conformations of the molecule are dynamically disordered, while solid state 2H NMR data, collected on a specifically deuterated analog, were used to determine the populations of each conformation as well as an apparent activation energy. Solid state NMR experiments were also used to show that 5,6,7,8-tetrahydro-1-naphthoic acid possesses the same type of dynamic disorder. Key words: deuterium NMR, solid state NMR, dynamic disorder. X-ray, tetrahydronaphthalene derivatives

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15

Wu, Gang. "Recent developments in solid-state nuclear magnetic resonance of quadrupolar nuclei and applications to biological systems". Biochemistry and Cell Biology 76, n.º 2-3 (1 de maio de 1998): 429–42. http://dx.doi.org/10.1139/o98-045.

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Recent advances in nuclear magnetic resonance (NMR) methodology and improvements in high-field NMR instrumentation have generated a new wave of research interests in the application of solid-state NMR to the study of quadrupolar nuclei. These developments now permit increasingly complex biological systems to be probed by quadrupolar NMR. In this review I describe a few recent developments in NMR studies of quadrupolar nuclei and demonstrate the potential of solid-state quadrupolar NMR in the study of biological systems. In particular, I discuss the application of solid-state NMR of 17O, 67Zn, 59Co, 23Na, and 39K nuclei with a prognosis for future work.Key words: nuclear magnetic resonance, quadrupole, solid state, biological system.

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16

Alonso, Bruno, e Claire Marichal. "Solid-state NMR studies of micelle-templated mesoporous solids". Chem. Soc. Rev. 42, n.º 9 (2013): 3808–20. http://dx.doi.org/10.1039/c2cs35368g.

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17

Ash, Jason T., e Philip J. Grandinetti. "Solid-state NMR characterization of69Ga and71Ga in crystalline solids". Magnetic Resonance in Chemistry 44, n.º 9 (2006): 823–31. http://dx.doi.org/10.1002/mrc.1841.

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18

Himmelsbach, D. S., F. E. Barton e D. E. Akin. "Comparison of Responses of 13C NMR and NIR Diffuse Reflectance Spectroscopies to Changes in Particle Size and Order in Cellulose". Applied Spectroscopy 40, n.º 7 (setembro de 1986): 1054–58. http://dx.doi.org/10.1366/0003702864508133.

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High-resolution solid-state 13C NMR and NIR diffuse reflectance spectra were obtained on microcrystalline and “noncrystalline” celluloses. Particle sizes and relative crystallinity were confirmed by scanning electron microscopy and MIR transmission spectroscopy, respectively. The results showed that NMR is more sensitive to order changes and less sensitive to particle size. NIR reflectance, on the other hand, is very sensitive to particle size changes and essentially insensitive to differences in order.

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19

Massiot, D. "Techniques of solid-state NMR". EPJ Web of Conferences 30 (2012): 02002. http://dx.doi.org/10.1051/epjconf/20123002002.

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20

Spiess, H. W. "NMR Methods for Solid Polymers". Annual Review of Materials Science 21, n.º 1 (agosto de 1991): 131–58. http://dx.doi.org/10.1146/annurev.ms.21.080191.001023.

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21

Andrew, E. R., e B. Peplinska. "NMR study of solid cholesterol". Molecular Physics 70, n.º 3 (20 de junho de 1990): 505–12. http://dx.doi.org/10.1080/00268979000101151.

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22

SAITÔ, HAZIME. "High-resolution Solid-state NMR". Sen'i Gakkaishi 44, n.º 6 (1988): P219—P223. http://dx.doi.org/10.2115/fiber.44.6_p219.

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23

ASAKURA, TETSUO. "Fibers and Solid State NMR". Sen'i Gakkaishi 50, n.º 1 (1994): P3—P4. http://dx.doi.org/10.2115/fiber.50.p3.

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24

Bellot, P. V., A. Trokiner, Yu Zhdanov e A. Yakubovskii. "43Ca NMR in solid state". Journal de Chimie Physique et de Physico-Chimie Biologique 95, n.º 2 (fevereiro de 1998): 280–88. http://dx.doi.org/10.1051/jcp:1998133.

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25

Drechsler, Alison, e Frances Separovic. "Solid-state NMR Structure Determination". IUBMB Life (International Union of Biochemistry and Molecular Biology: Life) 55, n.º 9 (1 de setembro de 2003): 515–23. http://dx.doi.org/10.1080/15216540310001622740.

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26

Dybowski, Cecil, e Guenther Neue. "Solid state 207Pb NMR spectroscopy". Progress in Nuclear Magnetic Resonance Spectroscopy 41, n.º 3-4 (dezembro de 2002): 153–70. http://dx.doi.org/10.1016/s0079-6565(02)00005-5.

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27

Demko, Bryan A., e Roderick E. Wasylishen. "Solid-state selenium-77 NMR". Progress in Nuclear Magnetic Resonance Spectroscopy 54, n.º 3-4 (abril de 2009): 208–38. http://dx.doi.org/10.1016/j.pnmrs.2008.10.002.

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28

Ramanathan, K. V. "Developments in solid-state NMR". Resonance 20, n.º 11 (novembro de 2015): 1040–52. http://dx.doi.org/10.1007/s12045-015-0272-6.

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29

Terao, Takehiko. "Solid-state NMR in Japan". TrAC Trends in Analytical Chemistry 10, n.º 7 (agosto de 1991): 222–25. http://dx.doi.org/10.1016/0165-9936(91)83009-2.

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30

W.S.B. "Solid state NMR for chemists". Journal of Magnetic Resonance (1969) 80, n.º 3 (dezembro de 1988): 564–65. http://dx.doi.org/10.1016/0022-2364(88)90259-4.

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31

SMITH, M. E. "ChemInform Abstract: Solid State NMR". ChemInform 29, n.º 45 (19 de junho de 2010): no. http://dx.doi.org/10.1002/chin.199845330.

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32

HENRICHS, P. M., e J. M. HEWITT. "ChemInform Abstract: Solid-State NMR". ChemInform 22, n.º 28 (23 de agosto de 2010): no. http://dx.doi.org/10.1002/chin.199128319.

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HARRIS, K. D. M. "ChemInform Abstract: Solid State NMR". ChemInform 26, n.º 19 (18 de agosto de 2010): no. http://dx.doi.org/10.1002/chin.199519295.

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34

ANDERSON, M. W. "ChemInform Abstract: Solid State NMR". ChemInform 27, n.º 33 (5 de agosto de 2010): no. http://dx.doi.org/10.1002/chin.199633336.

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GROOMBRIDGE, C. J. "ChemInform Abstract: Solid State NMR". ChemInform 22, n.º 50 (22 de agosto de 2010): no. http://dx.doi.org/10.1002/chin.199150364.

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36

Smith, M. E. "ChemInform Abstract: Solid State NMR". ChemInform 30, n.º 42 (13 de junho de 2010): no. http://dx.doi.org/10.1002/chin.199942327.

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GROOMBRIDGE, C. J. "ChemInform Abstract: Solid State NMR". ChemInform 23, n.º 38 (21 de agosto de 2010): no. http://dx.doi.org/10.1002/chin.199238344.

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38

SMITH, M. E. "ChemInform Abstract: Solid State NMR". ChemInform 28, n.º 46 (3 de agosto de 2010): no. http://dx.doi.org/10.1002/chin.199746340.

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39

AGGER, J. R., e M. W. ANDERSON. "ChemInform Abstract: Solid-State NMR". ChemInform 27, n.º 51 (4 de agosto de 2010): no. http://dx.doi.org/10.1002/chin.199651352.

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40

deAzevedo, Eduardo R., Tito J. Bonagamba e Klaus Schmidt-Rohr. "Pure-Exchange Solid-State NMR". Journal of Magnetic Resonance 142, n.º 1 (janeiro de 2000): 86–96. http://dx.doi.org/10.1006/jmre.1999.1918.

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41

Smith, M. E. "ChemInform Abstract: Solid State NMR". ChemInform 31, n.º 38 (19 de setembro de 2000): no. http://dx.doi.org/10.1002/chin.200038295.

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42

Johann, Christof, Sebastian Wegner, Gerhard Althoff e Jochem Struppe. "Automation in solid state NMR". Journal of Magnetic Resonance 355 (outubro de 2023): 107554. http://dx.doi.org/10.1016/j.jmr.2023.107554.

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43

Bastow, T. J. "Materials Characterisation by Nuclear Quadrupole Interaction". Zeitschrift für Naturforschung A 49, n.º 1-2 (1 de fevereiro de 1994): 320–28. http://dx.doi.org/10.1515/zna-1994-1-247.

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Abstract The power of solid state NMR to characterise solids by determining the nuclear quadrupole coupling of the constituent nuclei is demonstrated for a number of com pounds of current interest in a materials science laboratory. Recent results are presented for the nuclei 17O , 23Na, 27Al, 39K, 71Ga, 91Zr, 93Nb, and 139La. These were derived using a variety of FT NMR techniques including static, magic angle spinning and frequency stepped spin echo NMR spectroscopy.

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Foran, Gabrielle, Nina Verdier, David Lepage, Cédric Malveau, Nicolas Dupré e Mickaël Dollé. "Use of Solid-State NMR Spectroscopy for the Characterization of Molecular Structure and Dynamics in Solid Polymer and Hybrid Electrolytes". Polymers 13, n.º 8 (8 de abril de 2021): 1207. http://dx.doi.org/10.3390/polym13081207.

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Solid-state NMR spectroscopy is an established experimental technique which is used for the characterization of structural and dynamic properties of materials in their native state. Many types of solid-state NMR experiments have been used to characterize both lithium-based and sodium-based solid polymer and polymer–ceramic hybrid electrolyte materials. This review describes several solid-state NMR experiments that are commonly employed in the analysis of these systems: pulse field gradient NMR, electrophoretic NMR, variable temperature T1 relaxation, T2 relaxation and linewidth analysis, exchange spectroscopy, cross polarization, Rotational Echo Double Resonance, and isotope enrichment. In this review, each technique is introduced with a short description of the pulse sequence, and examples of experiments that have been performed in real solid-state polymer and/or hybrid electrolyte systems are provided. The results and conclusions of these experiments are discussed to inform readers of the strengths and weaknesses of each technique when applied to polymer and hybrid electrolyte systems. It is anticipated that this review may be used to aid in the selection of solid-state NMR experiments for the analysis of these systems.

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Ahlbrecht, Hubertus, Jürgen Harbach, Hans-Otto Kalinowski, Andreas Lang e Günther Maier. "Solid-State13C-NMR-Spectroscopy, 3. – Solid-State13C-NMR-Spectroscopic Investigations of α-(Dimethylamino)-benzyllithium Complexes". Chemische Berichte 130, n.º 6 (junho de 1997): 683–86. http://dx.doi.org/10.1002/cber.19971300603.

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46

Clarkson, David, Xi Qin e Horst Meyer. "Pulsed NMR studies in solid D2. I. Solid echo". Journal of Low Temperature Physics 91, n.º 3-4 (maio de 1993): 119–51. http://dx.doi.org/10.1007/bf00120845.

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47

Koenig, Jack L. "Spectroscopic Characterization of the Molecular Structure of Elastomeric Networks". Rubber Chemistry and Technology 73, n.º 3 (1 de julho de 2000): 385–404. http://dx.doi.org/10.5254/1.3547598.

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Abstract In vulcanization, chemical crosslinks are formed across elastomeric polymer chains improving both the strength and elastic properties of the rubber. An understanding of the formation, structure, and stability of vulcanizates is therefore very important. Solid-state NMR and NMR imaging have been effective methods to study many different aspects of vulcanization. In solid-state NMR, several peaks appear in the C-13 spectrum of vulcanized rubber. Through model studies, NMR analysis, and chemical shift additivity calculations, these peaks were assigned to their respective vulcanizate structures. Once this assignment was made, the concentration of each vulcanizate structure formed could be followed with time under a variety of different conditions. In unaccelerated sulfur vulcanization of natural rubber (NR) and polybutadiene rubber (BR), many inefficient (cyclic or intramolecular) structures were formed as compared to intermolecular crosslinks. In accelerated NR and BR sulfur vulcanization, NMR was used to study vulcanizate concentration dependence on (a) type of formulation (efficient, semi-efficient, or conventional), (b) type of accelerator, (c) extent of cure, and (d) different concentration of ingredients (sulfur, activator, etc.). Solid-state NMR was also used to study different parameters in butyl rubber and to identify elastomers in binary blends of chloroprene rubber (CR) and NR, CR and chlorosulfonated polyethylene (CSM), NR and CSM, and styrene—butadiene rubber (SBR) and acrylonitrile—butadiene rubber (NBR) as well as the tertiary blend of NR/SBR/BR. In several studies, the effect of filler (carbon black or silica) on vulcanization was studied. Additionally, the thermo-oxidative degradation of sulfur vulcanizates in NR with heating time and temperature was observed using NMR. NMR imaging has been useful in the determination of internal inhomogeneities arising from inadequate mixing, gradients in crosslinking chemistry, filler distribution, blends, and coagents.

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Duffy, Stephen J., e Gary W. vanLoon. "Investigations of aluminum hydroxyphosphates and activated sludge by 27Al and 31P MAS NMR". Canadian Journal of Chemistry 73, n.º 10 (1 de outubro de 1995): 1645–59. http://dx.doi.org/10.1139/v95-204.

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High-resolution solid-state 27Al and 31P MAS NMR has been used to investigate the nature of aluminium- and phosphorus-containing solids formed during wastewater treatment. Although difficult to characterize by conventional techniques, these amorphous solids can be characterized by MAS NMR, providing information about their short-range ordering. In the present study, most of the solids were precipitated under conditions of high alkalinity, similar to those encountered during wastewater treatment. The ageing time of the aluminum hydroxide prior to the addition of phosphate (t1), the ageing time of the aluminum hydroxyphosphates after the addition of phosphate (t2), and the phosphorus to aluminum molar ratio were controlled while the effects of changing the parameters were examined. It was found that the aluminum MAS NMR chemical shift was related to the amount of phosphate present in the solid, which in turn was related to t1, t2, and the P:Al molar ratio. The results also lend support to the hypothesis that phosphate removal occurs through an adsorption process onto amorphous aluminum hydroxide, rather than through direct precipitation of aluminum phosphate. The increased understanding of aluminum and phosphate chemistry and the species formed during wastewater treatment will be useful in optimizing wastewater treatment processes. Keywords: aluminum, phosphate, NMR, activated sludge, wastewater treatment.

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49

Clemente, Joyce S., Edward G. Gregorich, André J. Simpson, Rajeev Kumar, Denis Courtier-Murias e Myrna J. Simpson. "Comparison of nuclear magnetic resonance methods for the analysis of organic matter composition from soil density and particle fractions". Environmental Chemistry 9, n.º 1 (2012): 97. http://dx.doi.org/10.1071/en11096.

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Environmental contextThe association of specific organic matter (OM) compounds with clay mineral surfaces is believed to protect these compounds from degradation and thus result in long-term protection in soil. The molecular-level composition of soil OM associated with soil fractions was measured and compared using solid-state 13C nuclear magnetic resonance (NMR) and solution-state 1H NMR methods. Combining these methods allowed more detailed characterisation of OM associated with different soil fractions and will improve the understanding of OM dynamics in soil. AbstractOrganic matter (OM) associated with fine soil fractions is hypothesised to be protected from complete biodegradation by soil microbes. It is therefore important to understand the structure and stage of decomposition of OM associated with various soil fractions. Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy has been used extensively to investigate the OM composition of soils and soil fractions. Solution-state 1H NMR spectroscopy has not been used as much but is an emerging tool for analysing soil OM because 1H NMR spectra are often better resolved and provide information that complements the structural information obtained from solid-state 13C NMR experiments. This study compares one-dimensional solution-state 1H NMR and solid-state 13C NMR methods for assessing the degradation and composition of OM in three different soils, and their light and clay-size fractions. The alkyl/O-alkyl degradation parameter was consistent across all NMR methods and showed that OM associated with clay-size fractions were at more advanced stages of degradation as compared to that in light density soil fractions. Solution-state 1H and diffusion edited (DE) 1H NMR results showed the presence of high concentrations of microbial-derived peptidoglycan and peptide side-chains in clay-sized fractions. Lignin was also identified in clay-sized fractions using solid-state 13C and solution-state 1H NMR techniques. The combination of solid-state 13C and solution-state 1H NMR methods provides a more detailed analysis of OM composition and thereby facilitates a better understanding of the fate and preservation of OM in soil.

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Thiagarajan-Rosenkranz, Pallavi, Adrian W. Draney e Justin L. Lorieau. "Hybrid NMR: A Union of Solution- and Solid-State NMR". Journal of the American Chemical Society 139, n.º 13 (23 de março de 2017): 4715–23. http://dx.doi.org/10.1021/jacs.6b11402.

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