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Yamada K, Takahashi M, Tritrakarn T, Okamura T. Field-Stepwise-Swept Solid-State 35Cl NMR and NQR of Trichloroisocyanuric Acid. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.140250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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2
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Hung I, Altenhof AR, Schurko RW, Bryce DL, Han OH, Gan Z. Field-stepped ultra-wideline NMR at up to 36 T: On the inequivalence between field and frequency stepping. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2021; 59:951-960. [PMID: 33373086 PMCID: PMC8239055 DOI: 10.1002/mrc.5128] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/16/2020] [Accepted: 12/23/2020] [Indexed: 06/12/2023]
Abstract
Field-stepped NMR spectroscopy at up to 36 T using the series-connected hybrid (SCH) magnet at the U.S. National High Magnetic Field Laboratory is demonstrated for acquiring ultra-wideline powder spectra of nuclei with very large quadrupolar interactions. Historically, NMR evolved from the continuous-wave (cw) field-swept method in the early days to the pulsed Fourier-transform method in the modern era. Spectra acquired using field sweeping are generally considered to be equivalent to those acquired using the pulsed method. Here, it is shown that field-stepped wideline spectra of half-integer spin quadrupolar nuclei acquired using WURST/CPMG methods can be significantly different from those acquired with the frequency-stepped method commonly used with superconducting magnets. The inequivalence arises from magnetic field-dependent NMR interactions such as the anisotropic chemical shift and second-order quadrupolar interactions; the latter is often the main interaction leading to ultra-wideline powder patterns of half-integer spin quadrupolar nuclei. This inequivalence needs be taken into account to accurately and correctly determine the quadrupolar coupling and chemical shift parameters. A simulation protocol is developed for spectral fitting to facilitate analysis of field-stepped ultra-wideline NMR spectra acquired using powered magnets. A MATLAB program which implements this protocol is available on request.
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Affiliation(s)
- Ivan Hung
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
| | - Adam R Altenhof
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32306, USA
| | - Robert W Schurko
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32306, USA
| | - David L Bryce
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Oc Hee Han
- Western Seoul Center, Korea Basic Science Institute, Seoul, 03759, South Korea
| | - Zhehong Gan
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
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3
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Gan Z. Perspectives on high-field and solid-state NMR methods of quadrupole nuclei. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 306:86-90. [PMID: 31358369 DOI: 10.1016/j.jmr.2019.07.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 05/28/2019] [Accepted: 07/08/2019] [Indexed: 06/10/2023]
Abstract
High magnetic field can dramatically increase the spectral resolution and sensitivity of quadrupole nuclei S > 1/2 by the reduction of the second-order quadrupole broadening. A brief overview and outlook on spectral acquisition, the importance of high magnetic field, inter-nuclei distance measurement, various 2D separation and correlation methods of quadrupole nuclei are presented. The complications and consequences of spin dynamics under rf irradiation for the (2S + 1) level system and level-crossing with the satellite transition frequencies under magic-angle spinning are discussed. There is a scaling down of (S + 1/2) to the efficiency of many experiments in comparison with a spin-1/2 due to the fact that only two central transition spin states out of the (2S + 1) levels contribute to polarization transfer and spin correlation.
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Affiliation(s)
- Zhehong Gan
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA.
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4
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Litvak IM, Griffin A, Paulino J, Mao W, Gor'kov P, Shetty KK, Brey WW. Achieving 1 ppm field homogeneity above 24 T: Application of differential mapping for shimming Keck and the Series Connected Hybrid magnets at the NHMFL. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 301:109-118. [PMID: 30870670 PMCID: PMC6474693 DOI: 10.1016/j.jmr.2019.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 03/01/2019] [Accepted: 03/03/2019] [Indexed: 06/09/2023]
Abstract
Powered resistive and resistive-superconductive hybrid magnets can reach fields higher than superconducting NMR magnets but lack the field homogeneity and temporal stability needed for high resolution NMR. Due to field fluctuations in powered magnets, commercially available mapping systems fail to produce maps of these magnets with sufficient reproducibility, thus hampering attempts to improve homogeneity of the field they generate. Starting with a commercial mapper, we built a mapping system which uses a two-channel (measurement + reference) mapper probe. We used this system to map and then to shim two magnets of Florida Bitter type at the National High Magnetic Field Laboratory in Tallahassee, FL. With a combination of passive (ferromagnetic) and active shims we achieved 2.3 ppm homogeneity in 1 cm diameter spherical volume (dsv) at 25.0 T in the Keck resistive magnet, and 0.9 ppm homogeneity in 1 cm dsv at 23.5, 28.2, and 35.2 T in the series-connected resistive-superconductive hybrid (SCH) magnet.
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Affiliation(s)
- Ilya M Litvak
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA.
| | - Adrian Griffin
- Oxford NMR Magnets Ltd, Hexagon House, Avenue 4, Station Lane, Witney, Oxon OX28 4BN, United Kingdom
| | - Joana Paulino
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA
| | - Wenping Mao
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA
| | - Peter Gor'kov
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA
| | - Kiran K Shetty
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA
| | - William W Brey
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA
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5
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Gan Z, Hung I, Wang X, Paulino J, Wu G, Litvak IM, Gor'kov PL, Brey WW, Lendi P, Schiano JL, Bird MD, Dixon IR, Toth J, Boebinger GS, Cross TA. NMR spectroscopy up to 35.2T using a series-connected hybrid magnet. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 284:125-136. [PMID: 28890288 PMCID: PMC5675800 DOI: 10.1016/j.jmr.2017.08.007] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 08/15/2017] [Accepted: 08/17/2017] [Indexed: 05/05/2023]
Abstract
The National High Magnetic Field Laboratory has brought to field a Series-Connected Hybrid magnet for NMR spectroscopy. As a DC powered magnet it can be operated at fields up to 36.1T. The series connection between a superconducting outsert and a resistive insert dramatically minimizes the high frequency fluctuations of the magnetic field typically observed in purely resistive magnets. Current-density-grading among various resistive coils was used for improved field homogeneity. The 48mm magnet bore and 42mm outer diameter of the probes leaves limited space for conventional shims and consequently a combination of resistive and ferromagnetic shims are used. Field maps corrected for field instabilities were obtained and shimming achieved better than 1ppm homogeneity over a cylindrical volume of 1cm diameter and height. The magnetic field is regulated within 0.2ppm using an external 7Li lock sample doped with paramagnetic MnCl2. The improved field homogeneity and field regulation using a modified AVANCE NEO console enables NMR spectroscopy at 1H frequencies of 1.0, 1.2 and 1.5GHz. NMR at 1.5GHz reflects a 50% increase in field strength above the highest superconducting magnets currently available. Three NMR probes have been constructed each equipped with an external lock rf coil for field regulation. Initial NMR results obtained from the SCH magnet using these probes illustrate the very exciting potential of ultra-high magnetic fields.
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Affiliation(s)
- Zhehong Gan
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States
| | - Ivan Hung
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States
| | - Xiaoling Wang
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States
| | - Joana Paulino
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States; Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, United States; Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, United States
| | - Gang Wu
- Department of Chemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Ilya M Litvak
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States
| | - Peter L Gor'kov
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States
| | - William W Brey
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States
| | - Pietro Lendi
- Bruker BioSpin AG, 26, Industriestrasse Fällanden, 8117, Switzerland
| | - Jeffrey L Schiano
- School of Electrical Engineering and Computer Science, Penn State University, University Park, PA 16802, United States
| | - Mark D Bird
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States
| | - Iain R Dixon
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States
| | - Jack Toth
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States
| | - Gregory S Boebinger
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States; Department of Physics, Florida State University, Tallahassee, FL 32306, United States
| | - Timothy A Cross
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States; Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, United States; Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, United States.
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6
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Pecher O, Halat DM, Lee J, Liu Z, Griffith KJ, Braun M, Grey CP. Enhanced efficiency of solid-state NMR investigations of energy materials using an external automatic tuning/matching (eATM) robot. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 275:127-136. [PMID: 28064071 DOI: 10.1016/j.jmr.2016.12.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 12/16/2016] [Accepted: 12/19/2016] [Indexed: 06/06/2023]
Abstract
We have developed and explored an external automatic tuning/matching (eATM) robot that can be attached to commercial and/or home-built magic angle spinning (MAS) or static nuclear magnetic resonance (NMR) probeheads. Complete synchronization and automation with Bruker and Tecmag spectrometers is ensured via transistor-transistor-logic (TTL) signals. The eATM robot enables an automated "on-the-fly" re-calibration of the radio frequency (rf) carrier frequency, which is beneficial whenever tuning/matching of the resonance circuit is required, e.g. variable temperature (VT) NMR, spin-echo mapping (variable offset cumulative spectroscopy, VOCS) and/or in situ NMR experiments of batteries. This allows a significant increase in efficiency for NMR experiments outside regular working hours (e.g. overnight) and, furthermore, enables measurements of quadrupolar nuclei which would not be possible in reasonable timeframes due to excessively large spectral widths. Additionally, different tuning/matching capacitor (and/or coil) settings for desired frequencies (e.g.7Li and 31P at 117 and 122MHz, respectively, at 7.05 T) can be saved and made directly accessible before automatic tuning/matching, thus enabling automated measurements of multiple nuclei for one sample with no manual adjustment required by the user. We have applied this new eATM approach in static and MAS spin-echo mapping NMR experiments in different magnetic fields on four energy storage materials, namely: (1) paramagnetic 7Li and 31P MAS NMR (without manual recalibration) of the Li-ion battery cathode material LiFePO4; (2) paramagnetic 17O VT-NMR of the solid oxide fuel cell cathode material La2NiO4+δ; (3) broadband 93Nb static NMR of the Li-ion battery material BNb2O5; and (4) broadband static 127I NMR of a potential Li-air battery product LiIO3. In each case, insight into local atomic structure and dynamics arises primarily from the highly broadened (1-25MHz) NMR lineshapes that the eATM robot is uniquely suited to collect. These new developments in automation of NMR experiments are likely to advance the application of in and ex situ NMR investigations to an ever-increasing range of energy storage materials and systems.
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Affiliation(s)
- Oliver Pecher
- University of Cambridge, Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK
| | - David M Halat
- University of Cambridge, Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK
| | - Jeongjae Lee
- University of Cambridge, Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK
| | - Zigeng Liu
- University of Cambridge, Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK
| | - Kent J Griffith
- University of Cambridge, Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK
| | - Marco Braun
- NMR Service GmbH, Blumenstr. 70, 99092 Erfurt, Germany
| | - Clare P Grey
- University of Cambridge, Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK.
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7
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Tijssen KCH, Blaakmeer ESM, Kentgens APM. Solid-state NMR studies of Ziegler-Natta and metallocene catalysts. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 68-69:37-56. [PMID: 25957882 DOI: 10.1016/j.ssnmr.2015.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 03/30/2015] [Accepted: 04/02/2015] [Indexed: 06/04/2023]
Abstract
Ziegler-Natta catalysts are the workhorses of polyolefin production. However, although they have been used and intensively studied for half a century, there is still no comprehensive picture of their mechanistic operation. New techniques are needed to gain more insight in these catalysts. Solid-state NMR has reached a high level of sophistication over the last few decades and holds great promise for providing a deeper insight in Ziegler-Natta catalysis. This review outlines the possibilities for solid-state NMR to characterize the different components and interactions in Ziegler-Natta and metallocene catalysts. An overview is given of some of the expected mechanisms and the resulting polymer microstructure and other characteristics. In the second part of this review we present studies that have used solid-state NMR to investigate the composition of Ziegler-Natta and metallocene catalysts or the interactions between their components.
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Affiliation(s)
- Koen C H Tijssen
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, Nijmegen, The Netherlands.
| | - E S Merijn Blaakmeer
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, Nijmegen, The Netherlands.
| | - Arno P M Kentgens
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, Nijmegen, The Netherlands.
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8
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Lucier BEG, Johnston KE, Xu W, Hanson JC, Senanayake SD, Yao S, Bourassa MW, Srebro M, Autschbach J, Schurko RW. Unravelling the Structure of Magnus’ Pink Salt. J Am Chem Soc 2014; 136:1333-51. [DOI: 10.1021/ja4076277] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bryan E. G. Lucier
- Department
of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada N9B 3P4
| | - Karen E. Johnston
- Department
of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada N9B 3P4
| | - Wenqian Xu
- Department
of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Jonathan C. Hanson
- Department
of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Sanjaya D. Senanayake
- Department
of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Siyu Yao
- Center for Computational Science & Engineering, and PKU Green Chemistry Centre, Peking University, Beijing 100871, China
| | - Megan W. Bourassa
- Department
of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Monika Srebro
- Department
of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000, United States
- Department
of Theoretical Chemistry, Faculty of Chemistry, Jagiellonian University, 30-060 Krakow, Poland
| | - Jochen Autschbach
- Department
of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000, United States
| | - Robert W. Schurko
- Department
of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada N9B 3P4
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9
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Masoom H, Courtier-Murias D, Farooq H, Soong R, Simpson MJ, Maas W, Kumar R, Monette M, Stronks H, Simpson AJ. Rapid estimation of nuclear magnetic resonance experiment time in low-concentration environmental samples. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2013; 32:129-136. [PMID: 23065696 DOI: 10.1002/etc.2028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 07/28/2012] [Accepted: 08/23/2012] [Indexed: 06/01/2023]
Abstract
Nuclear magnetic resonance (NMR) spectroscopy is an essential tool for studying environmental samples but is often hindered by low sensitivity, especially for the direct detection of nuclei such as(13) C. In very heterogeneous samples with NMR nuclei at low abundance, such as soils, sediments, and air particulates, it can take days to acquire a conventional(13) C spectrum. The present study describes a prescreening method that permits the rapid prediction of experimental run time in natural samples. The approach focuses the NMR chemical shift dispersion into a single spike, and, even in samples with extremely low carbon content, the spike can be observed in two to three minutes, or less. The intensity of the spike is directly proportional to the total concentration of nuclei of interest in the sample. Consequently, the spike intensity can be used as a powerful prescreening method that answers two key questions: (1) Will this sample produce a conventional NMR spectrum? (2) How much instrument time is required to record a spectrum with a specific signal-to-noise (S/N) ratio? The approach identifies samples to avoid (or pretreat) and permits additional NMR experiments to be performed on samples producing high-quality NMR data. Applications in solid- and liquid-state(13) C NMR are demonstrated, and it is shown that the technique is applicable to a range of nuclei.
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Affiliation(s)
- Hussain Masoom
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada
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10
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Perras FA, Bryce DL. Direct Investigation of Covalently Bound Chlorine in Organic Compounds by Solid-State35Cl NMR Spectroscopy and Exact Spectral Line-Shape Simulations. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201200728] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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11
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Perras FA, Bryce DL. Direct investigation of covalently bound chlorine in organic compounds by solid-state 35Cl NMR spectroscopy and exact spectral line-shape simulations. Angew Chem Int Ed Engl 2012; 51:4227-30. [PMID: 22419499 PMCID: PMC3430411 DOI: 10.1002/anie.201200728] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Indexed: 11/11/2022]
Affiliation(s)
- Frédéric A Perras
- Department of Chemistry and CCRI, University of Ottawa, 10 Marie Curie Private, Ottawa, Ontario, Canada
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12
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Wu G, Zhu J. NMR studies of alkali metal ions in organic and biological solids. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2012; 61:1-70. [PMID: 22340207 DOI: 10.1016/j.pnmrs.2011.06.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2010] [Accepted: 05/31/2011] [Indexed: 05/31/2023]
Affiliation(s)
- Gang Wu
- Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario, Canada.
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13
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Rossini AJ, Zagdoun A, Lelli M, Gajan D, Rascón F, Rosay M, Maas WE, Copéret C, Lesage A, Emsley L. One hundred fold overall sensitivity enhancements for Silicon-29 NMR spectroscopy of surfaces by dynamic nuclear polarization with CPMG acquisition. Chem Sci 2012. [DOI: 10.1039/c1sc00550b] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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14
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Widdifield CM, Bryce DL. A multinuclear solid-state magnetic resonance and GIPAW DFT study of anhydrous calcium chloride and its hydrates. CAN J CHEM 2011. [DOI: 10.1139/v11-009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The group 2 metal halides and corresponding metal halide hydrates serve as useful model systems for understanding the relationship between the electric field gradient (EFG) and chemical shift (CS) tensors at the halogen nuclei and the local molecular and electronic structure. Here, we present a 35/37Cl and 43Ca solid-state nuclear magnetic resonance (SSNMR) study of CaCl2. The 35Cl nuclear quadrupole coupling constant, 8.82(8) MHz, and the isotropic chlorine CS, 105(8) ppm (with respect to dilute NaCl(aq)), are different from the values reported previously for this compound, as well as those reported for CaCl2·2H2O. Chlorine-35 SSNMR spectra are also presented for CaCl2·6H2O, and when taken in concert, the SSNMR observations for CaCl2, CaCl2·2H2O, and CaCl2·6H2O clearly demonstrate the sensitivity of the chlorine EFG and CS tensors to the local symmetry and to changes in the hydration state. For example, the value of δiso decreases with increasing hydration. Gauge-including projector-augmented wave (GIPAW) density functional theory (DFT) calculations are used to substantiate the experimental SSNMR findings, to rule out the presence of other hydrates in our samples, to refine the hydrogen positions in CaCl2·2H2O, and to explore the isostructural relationship between CaCl2 and CaBr2. Finally, the 43Ca CS tensor span is measured to be 31(5) ppm for anhydrous CaCl2, which represents only the fifth CS tensor span measurement for calcium.
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Affiliation(s)
- Cory M. Widdifield
- Department of Chemistry and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie Private, Ottawa, ON K1N 6N5, Canada
| | - David L. Bryce
- Department of Chemistry and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie Private, Ottawa, ON K1N 6N5, Canada
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15
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Xu J, Zhu P, Gan Z, Sahar N, Tecklenburg M, Morris MD, Kohn DH, Ramamoorthy A. Natural-abundance 43Ca solid-state NMR spectroscopy of bone. J Am Chem Soc 2010; 132:11504-9. [PMID: 20681578 DOI: 10.1021/ja101961x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Structural information about the coordination environment of calcium present in bone is highly valuable in understanding the role of calcium in bone formation, biomineralization, and bone diseases like osteoporosis. While a high-resolution structural study on bone has been considered to be extremely challenging, NMR studies on model compounds and bone minerals have provided valuable insight into the structure of bone. Particularly, the recent demonstration of (43)Ca solid-state NMR experiments on model compounds is an important advance in this field. However, application of (43)Ca NMR is hampered due to the low natural-abundance and poor sensitivity of (43)Ca. In this study, we report the first demonstration of natural-abundance (43)Ca magic angle spinning (MAS) NMR experiments on bone, using powdered bovine cortical bone samples. (43)Ca NMR spectra of bovine cortical bone are analyzed by comparing to the natural-abundance (43)Ca NMR spectra of model compounds including hydroxyapatite and carbonated apatite. While (43)Ca NMR spectra of hydroxyapatite and carbonated apatite are very similar, they significantly differ from those of cortical bone. Raman spectroscopy shows that the calcium environment in bone is more similar to carbonated apatite than hydroxyapatite. A close analysis of (43)Ca NMR spectra reveals that the chemical shift frequencies of cortical bone and 10% carbonated apatite are similar but the quadrupole coupling constant of cortical bone is larger than that measured for model compounds. In addition, our results suggest that an increase in the carbonate concentration decreases the observed (43)Ca chemical shift frequency. A comparison of experimentally obtained (43)Ca MAS spectra with simulations reveal a 3:4 mol ratio of Ca-I/Ca-II sites in carbonated apatite and a 2.3:3 mol ratio for hydroxyapatite. 2D triple-quantum (43)Ca MAS experiments performed on a mixture of carbonated apatite and the bone protein osteocalcin reveal the presence of protein-bound and free calcium sites, which is in agreement with a model developed from X-ray crystal structure of the protein.
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Affiliation(s)
- Jiadi Xu
- Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, USA
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16
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Widdifield CM, Bryce DL. Solid-State 127I NMR and GIPAW DFT Study of Metal Iodides and Their Hydrates: Structure, Symmetry, and Higher-Order Quadrupole-Induced Effects. J Phys Chem A 2010; 114:10810-23. [DOI: 10.1021/jp108237x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Cory M. Widdifield
- Department of Chemistry and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie Pvt., Ottawa, Ontario, Canada
| | - David L. Bryce
- Department of Chemistry and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie Pvt., Ottawa, Ontario, Canada
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17
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Hung I, Gan Z. On the practical aspects of recording wideline QCPMG NMR spectra. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 204:256-265. [PMID: 20359918 DOI: 10.1016/j.jmr.2010.03.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Revised: 03/02/2010] [Accepted: 03/02/2010] [Indexed: 05/29/2023]
Abstract
The practical aspects of applying CPMG for acquisition of wideline powder patterns are examined. It is shown that most distortions/modulations of spikelet spectra can be traced to the incoherent signal averaging from multiple coherence transfer pathways. A strategy for minimizing these distortions/modulations is described. Also, a few interesting observations regarding the implementation of the wideline WURST-QCPMG experiment are presented, namely the accumulation of second-order signal phase and the effects of varying the sweep rate and rf field of chirp pulses.
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Affiliation(s)
- Ivan Hung
- Center of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA
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