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Vosegaard T. Single-crystal NMR spectroscopy. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2021; 123:51-72. [PMID: 34078537 DOI: 10.1016/j.pnmrs.2021.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 01/22/2021] [Accepted: 01/28/2021] [Indexed: 06/12/2023]
Abstract
Single-crystal (SC) NMR spectroscopy is a solid-state NMR method that has been used since the early days of NMR to study the magnitude and orientation of tensorial nuclear spin interactions in solids. This review first presents the field of SC NMR instrumentation, then provides a survey of software for analysis of SC NMR data, and finally it highlights selected applications of SC NMR in various fields of research. The aim of the last part is not to provide a complete review of all SC NMR literature but to provide examples that demonstrate interesting applications of SC NMR.
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Affiliation(s)
- Thomas Vosegaard
- Department of Chemistry and Interdisciplinary Nanoscience Center, Aarhus University, Gustav Wieds Vej 14, DK-8000 Aarhus C, Denmark.
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Aleksis R, Pell AJ. Low-power synchronous helical pulse sequences for large anisotropic interactions in MAS NMR: Double-quantum excitation of 14N. J Chem Phys 2020; 153:244202. [PMID: 33380069 DOI: 10.1063/5.0030604] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We develop a theoretical framework for a class of pulse sequences in the nuclear magnetic resonance (NMR) of rotating solids, which are applicable to nuclear spins with anisotropic interactions substantially larger than the spinning frequency, under conditions where the radiofrequency amplitude is smaller than or comparable to the spinning frequency. The treatment is based on average Hamiltonian theory and allows us to derive pulse sequences with well-defined relationships between the pulse parameters and spinning frequency for exciting specific coherences without the need for any detailed calculations. This framework is applied to the excitation of double-quantum spectra of 14N and is used both to evaluate the existing low-power pulse schemes and to predict the new ones, which we present here. It is shown that these sequences can be designed to be γ-encoded and therefore allow the acquisition of sideband-free spectra. It is also shown how these new double-quantum excitation sequences are incorporated into heteronuclear correlation NMR, such as 1H-14N dipolar double-quantum heteronuclear multiple-quantum correlation spectroscopy. The new experiments are evaluated both with numerical simulations and experiments on glycine and N-acetylvaline, which represent cases with "moderate" and "large" quadrupolar interactions, respectively. The analyzed pulse sequences perform well for the case of a "moderate" quadrupolar interaction, however poorly with a "large" quadrupolar interaction, for which future work on pulse sequence development is necessary.
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Affiliation(s)
- Rihards Aleksis
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Andrew J Pell
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
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Aleksis R, Carvalho JP, Jaworski A, Pell AJ. Artefact-free broadband 2D NMR for separation of quadrupolar and paramagnetic shift interactions. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2019; 101:51-62. [PMID: 31121358 DOI: 10.1016/j.ssnmr.2019.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 04/30/2019] [Accepted: 05/01/2019] [Indexed: 06/09/2023]
Abstract
Two new two-dimensional, broadband, solid-state NMR experiments for separating and correlating the quadrupolar and shift interactions of spin I=1 nuclei in paramagnetic systems are proposed. The new pulse sequences incorporate the short, high-power adiabatic pulses (SHAPs) into the shifting d-echo experiment of Walder et al. [J. Chem. Phys., 142, 014201 (2015)], in two different ways, giving double and quadruple adiabatic shifting d-echo sequences. These new experiments have the advantage over previous methods of both suppressing spectral artefacts due to pulse imperfections, and exhibiting a broader excitation bandwidth. Both experiments are analysed with theoretical calculations and simulations, and are applied experimentally to the 2H NMR of deuterated CuCl2 ⋅2H2O, and two deuterated samples of the ion conductor oxyhydride BaTiO3-xHy prepared using two different methods. For the CuCl2 ⋅2H2O sample, both new methods obtain very high-quality spectra from which the parameters describing the shift and quadrupolar interaction tensors, and their relative orientation, were extracted. The two BaTiO3-xHy samples exhibited different local hydride environments with different tensor parameters. The 2H spectra of these oxyhydrides exhibit inhomogeneous broadening of the 2H shifts, and so whilst the quadrupolar interaction parameters were easily extracted, the measurement of the shift parameters was more complex. However, effective shift parameters were extracted, which combine the effects of both the paramagnetic shift tensor and the inhomogeneous broadening.
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Affiliation(s)
- Rihards Aleksis
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91, Stockholm, Sweden
| | - José P Carvalho
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Aleksander Jaworski
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Andrew J Pell
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91, Stockholm, Sweden.
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Pell AJ, Sanders KJ, Wegner S, Pintacuda G, Grey CP. Low-power broadband solid-state MAS NMR of 14N. J Chem Phys 2018; 146:194202. [PMID: 28527462 DOI: 10.1063/1.4983220] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We propose two broadband pulse schemes for 14N solid-state magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) that achieves (i) complete population inversion and (ii) efficient excitation of the double-quantum spectrum using low-power single-sideband-selective pulses. We give a comprehensive theoretical description of both schemes using a common framework that is based on the jolting-frame formalism of Caravatti et al. [J. Magn. Reson. 55, 88 (1983)]. This formalism is used to determine for the first time that we can obtain complete population inversion of 14N under low-power conditions, which we do here using single-sideband-selective adiabatic pulses. It is then used to predict that double-quantum coherences can be excited using low-power single-sideband-selective pulses. We then proceed to design a new experimental scheme for double-quantum excitation. The final double-quantum excitation pulse scheme is easily incorporated into other NMR experiments, as demonstrated here for double quantum-single quantum 14N correlation spectroscopy, and 1H-14N dipolar heteronuclear multiple-quantum correlation experiments. These pulses and irradiation schemes are evaluated numerically using simulations on single crystals and full powders, as well as experimentally on ammonium oxalate ((NH4)2C2O4) at moderate MAS and glycine at ultra-fast MAS. The performance of these new NMR methods is found to be very high, with population inversion efficiencies of 100% and double-quantum excitation efficiencies of 30%-50%, which are hitherto unprecedented for the low radiofrequency field amplitudes, up to the spinning frequency, that are used here.
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Affiliation(s)
- Andrew J Pell
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Kevin J Sanders
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques (CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon, 69100 Villeurbanne, France
| | | | - Guido Pintacuda
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques (CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon, 69100 Villeurbanne, France
| | - Clare P Grey
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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Avadhut YS, Weber J, Schmedt Auf der Günne J. Accurate determination of chemical shift tensor orientations of single-crystals by solid-state magic angle spinning NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 282:89-103. [PMID: 28797926 DOI: 10.1016/j.jmr.2017.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/11/2017] [Accepted: 06/14/2017] [Indexed: 06/07/2023]
Abstract
An improved implementation of single-crystal magic-angle-spinning (MAS) NMR is presented which gives access to chemical shift tensors both in orientation (relative to the crystal axis system) and principal axis values. For mounting arbitrary crystals inside ordinary MAS rotors, a mounting tool is described which allows to relate the crystal orientation determined by diffraction techniques to the rotor coordinate system. The crystal is finally mounted into a MAS rotor equipped with a special insert which allows a defined reorientation of the single-crystal by 90°. The approach is based on the idea that the dispersive spectra, which are obtained when applying read-pulses at specific rotor-phases, not only yield the size of the eigenvalues but also encode the orientation of the different chemical shift (rank-2) tensors. For this purpose two 2D-data sets with orthogonal crystal orientation are fitted simultaneously. The presented analysis for chemical shift tensors is supported by an analytical formula which allows fast calculation of phase and amplitude of individual spinning side-bands and by a protocol which solves the problem of finding the correct reference phase of the spectrum. Different rotor-synchronized pulse-sequences are introduced for the same reason. Experiments are performed on L-alanine and O-phosphorylethanolamine and the observed errors are analyzed in detail. The experimental data are opposed to DFT-computed chemical shift tensors which have been obtained by the extended embedded ion method.
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Affiliation(s)
- Yamini S Avadhut
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Catalysis Resource Center, Egerlandstrasse 3, D-91058 Erlangen, Germany; Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstraβe 5-13 (D), D-81377 München, Germany
| | - Johannes Weber
- Universität Siegen, Department Chemie und Biologie, Adolf-Reichweinstraβe, D-57068 Siegen, Germany; Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstraβe 5-13 (D), D-81377 München, Germany
| | - Jörn Schmedt Auf der Günne
- Universität Siegen, Department Chemie und Biologie, Adolf-Reichweinstraβe, D-57068 Siegen, Germany; Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstraβe 5-13 (D), D-81377 München, Germany.
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Vinding MS, Kessler TO, Vosegaard T. A simple low-cost single-crystal NMR setup. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 269:120-127. [PMID: 27295612 DOI: 10.1016/j.jmr.2016.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 05/31/2016] [Accepted: 06/06/2016] [Indexed: 06/06/2023]
Abstract
A low-cost single-crystal NMR kit is presented along with a web-based post-processing software. The kit consists of a piezo-crystal motor and a goniometer for the crystal, both embedded in a standard wide-bore NMR probe with a 3D printed scaffold. The NMR pulse program controls the angle setting automatically, and the post-processing software incorporates a range of orientation-angle discrepancies present in the kit and other single-crystal setups. Results with a NaNO3 single-crystal show a high degree of reproducibility and excellent agreement with previous findings for the anisotropic quadrupolar interaction.
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Affiliation(s)
- Mads S Vinding
- Center for Ultrahigh-Field NMR Spectroscopy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus, Denmark; Department of Chemistry, Aarhus University, DK-8000 Aarhus, Denmark
| | - Tommy O Kessler
- Department of Chemistry, Aarhus University, DK-8000 Aarhus, Denmark
| | - Thomas Vosegaard
- Center for Ultrahigh-Field NMR Spectroscopy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus, Denmark; Department of Chemistry, Aarhus University, DK-8000 Aarhus, Denmark.
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Shen M, Trébosc J, Lafon O, Gan Z, Pourpoint F, Hu B, Chen Q, Amoureux JP. Solid-state NMR indirect detection of nuclei experiencing large anisotropic interactions using spinning sideband-selective pulses. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 72:104-117. [PMID: 26411981 DOI: 10.1016/j.ssnmr.2015.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 09/04/2015] [Accepted: 09/04/2015] [Indexed: 06/05/2023]
Abstract
Under Magic-Angle Spinning (MAS), a long radio-frequency (rf) pulse applied on resonance achieves the selective excitation of the center-band of a wide NMR spectrum. We show herein that these rf pulses can be applied on the indirect channel of Hetero-nuclear Multiple-Quantum Correlation (HMQC) sequences, which facilitate the indirect detection via spin-1/2 isotopes of nuclei exhibiting wide spectra. Numerical simulations show that this indirect excitation method is applicable to spin-1/2 nuclei experiencing a large chemical shift anisotropy, as well as to spin-1 isotopes subject to a large quadrupole interaction, such as (14)N. The performances of the long pulses are analyzed by the numerical simulations of scalar-mediated HMQC (J-HMQC) experiments indirectly detecting spin-1/2 or spin-1 nuclei, as well as by dipolar-mediated HMQC (D-HMQC) experiments achieving indirect detection of (14)N nuclei via (1)H in crystalline γ-glycine and N-acetyl-valine samples at a MAS frequency of 60kHz. We show on these solids that for the acquisition of D-HMQC spectra between (1)H and (14)N nuclei, the efficiency of selective moderate excitation with long-pulses at the (14)N Larmor frequency, ν0((14)N), is comparable to those with strong excitation pulses at ν0((14)N) or 2ν0((14)N) frequencies, given the rf field delivered by common solid-state NMR probes. Furthermore, the D-HMQC experiments also demonstrate that the use of long pulses does not produce significant spectral distortions along the (14)N dimension. In summary, the use of center-band selective weak pulses is advantageous for HMQC experiments achieving the indirect detection of wide spectra since it (i) requires a moderate rf field, (ii) can be easily optimized, (iii) displays a high robustness to CSAs, offsets, rf-field inhomogeneities, and fluctuations in MAS frequency, and (iv) is little dependent on the quadrupolar coupling constant.
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Affiliation(s)
- Ming Shen
- UCCS, CNRS, UMR 8181, University of Lille, Villeneuve d'Ascq 59652, France; Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
| | - Julien Trébosc
- UCCS, CNRS, UMR 8181, University of Lille, Villeneuve d'Ascq 59652, France
| | - Olivier Lafon
- UCCS, CNRS, UMR 8181, University of Lille, Villeneuve d'Ascq 59652, France.
| | - Zhehong Gan
- Center of Interdisciplinary Magnetic Resonance, NHMFL, Tallahassee, FL 32310, USA
| | | | - Bingwen Hu
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
| | - Qun Chen
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
| | - Jean-Paul Amoureux
- UCCS, CNRS, UMR 8181, University of Lille, Villeneuve d'Ascq 59652, France; Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China.
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Pell AJ, Pintacuda G. Broadband solid-state MAS NMR of paramagnetic systems. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2015; 84-85:33-72. [PMID: 25669740 DOI: 10.1016/j.pnmrs.2014.12.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 12/15/2014] [Indexed: 06/04/2023]
Abstract
The combination of new magnet and probe technology with increasingly sophisticated pulse sequences has resulted in an increase in the number of applications of solid-state nuclear magnetic resonance (NMR) spectroscopy to paramagnetic materials and biomolecules. The interaction between the paramagnetic metal ions and the NMR-active nuclei often yields crucial structural or electronic information about the system. In particular the application of magic-angle spinning (MAS) has been shown to be crucial to obtaining resolution that is sufficiently high for studying complex systems. However such systems are generally extremely difficult to study as the shifts and shift anisotropies resulting from the same paramagnetic interaction broaden the spectrum beyond excitation and detection, and the paramagnetic relaxation enhancement (PRE) shortens the lifetimes of the excited signals considerably. One specific area that has therefore been receiving significant attention in recent years, and for which great improvements have been seen, is the development of broadband NMR sequences. The development of new excitation and inversion sequences for paramagnetic systems under MAS has often made the difference between the spectrum being unobtainable, and a complete NMR study being possible. However the development of the new sequences must explicitly take account of the modulation of the anisotropic shift interactions due to the sample rotation, with the resulting spin dynamics often being complicated considerably. The NMR sequences can either be helped or hindered by MAS, with the efficiency of some pulse schemes being destroyed, and others being greatly enhanced. This review describes the pulse sequences that have recently been proposed for broadband excitation, inversion, and refocussing of the signal components of paramagnetic systems. In doing so we define exactly what is meant by "broadband" under spinning conditions, and what the perfect pulse scheme should deliver. We also give a unified description of the spin dynamics under MAS which highlights the strengths and weaknesses of the various schemes, and which can be used as guidance for future research in this area. All the reviewed pulse schemes are evaluated both with simulations and experimental data obtained on the battery material LiFe(0.5)Mn(0.5)PO(4) which is typical of the complexity of the paramagnetic systems that are currently under study.
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Affiliation(s)
- Andrew J Pell
- Centre de RMN à Très Hauts Champs, Université de Lyon, Institute of Analytical Sciences UMR 5280 (CNRS/CNRS, Ecole Normale Supérieure de Lyon/Lyon, Université Claude Bernard Lyon 1), 5 rue de la Doua, 69100 Villeurbanne, France.
| | - Guido Pintacuda
- Centre de RMN à Très Hauts Champs, Université de Lyon, Institute of Analytical Sciences UMR 5280 (CNRS/CNRS, Ecole Normale Supérieure de Lyon/Lyon, Université Claude Bernard Lyon 1), 5 rue de la Doua, 69100 Villeurbanne, France.
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Pell AJ, Clément RJ, Grey CP, Emsley L, Pintacuda G. Frequency-stepped acquisition in nuclear magnetic resonance spectroscopy under magic angle spinning. J Chem Phys 2013; 138:114201. [DOI: 10.1063/1.4795001] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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