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Banerjee S, Chaykina D, Stigter R, Colombi G, Eijt SWH, Dam B, de Wijs GA, Kentgens APM. Exploring Multi-Anion Chemistry in Yttrium Oxyhydrides: Solid-State NMR Studies and DFT Calculations. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:14303-14316. [PMID: 37529664 PMCID: PMC10388355 DOI: 10.1021/acs.jpcc.3c02680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 06/30/2023] [Indexed: 08/03/2023]
Abstract
Rare earth oxyhydrides REOxH(3-2x), with RE = Y, Sc, or Gd and a cationic FCC lattice, are reversibly photochromic in nature. It is known that structural details and anion (O2-:H-) composition dictate the efficiency of the photochromic behavior. The mechanism behind the photochromism is, however, not yet understood. In this study, we use 1H, 2H, 17O, and 89Y solid-state NMR spectroscopy and density functional theory (DFT) calculations to study the various yttrium, hydrogen, and oxygen local environments, anion oxidation states, and hydride ion dynamics. DFT models of YOxH(3-2x) with both anion-ordered and anion-disordered sublattices are constructed for a range of compositions and show a good correlation with the experimental NMR parameters. Two-dimensional 17O-1H and 89Y-1H NMR correlation experiments reveal heterogeneities in the samples, which appear to consist of hydride-rich (x ≈ 0.25) and hydride-poor domains (x ≈ 1) rather than a single composition with homogeneous anion mixing. The compositional variation (as indicated by the different x values in YOxH(3-2x)) is determined by comparing static 1H NMR line widths with calculated 1H-1H dipolar couplings of yttrium oxyhydride models. The 1D 17O MAS spectrum demonstrates the presence of a small percentage of hydroxide (OH-) ions. DFT modeling indicates a reaction between the protons of hydroxides and hydrides to form molecular hydrogen (H+ + H- → H2). 1H MAS NMR indicates the presence of a mobile component that, based on this finding, is attributed to trapped molecular H2 in the lattice.
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Affiliation(s)
- Shrestha Banerjee
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, NL-6525 AJ Nijmegen, The Netherlands
| | - Diana Chaykina
- Materials
for Energy Conversion and Storage, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands
| | - Rens Stigter
- Fundamental
Aspects of Materials and Energy, Department of Radiation Science and
Technology, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, NL-2629 JB Delft, The Netherlands
| | - Giorgio Colombi
- Materials
for Energy Conversion and Storage, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands
| | - Stephan W. H. Eijt
- Fundamental
Aspects of Materials and Energy, Department of Radiation Science and
Technology, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, NL-2629 JB Delft, The Netherlands
| | - Bernard Dam
- Materials
for Energy Conversion and Storage, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands
| | - Gilles A. de Wijs
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, NL-6525 AJ Nijmegen, The Netherlands
| | - Arno P. M. Kentgens
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, NL-6525 AJ Nijmegen, The Netherlands
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Welton C, Raval P, Trébosc J, Reddy GNM. Chemical exchange of labile protons by deuterium enables selective detection of pharmaceuticals in solid formulations. Chem Commun (Camb) 2022; 58:11551-11554. [PMID: 36165029 DOI: 10.1039/d2cc04585k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chemically assisted swapping of labile protons by deuterons is presented for amino acids, polysaccharides, pharmaceutical compounds, and their solid formulations. Solid-state packing interactions in these compounds are elucidated by 1H-2H isotope correlation NMR spectroscopy (iCOSY). A minuscule concentration of dopamine, 5 wt% or ∼100 μg, in a solid formulation can be detected by 2H NMR at 28.2 T (1H, 1200 MHz) in under a minute.
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Affiliation(s)
- Claire Welton
- University of Lille, CNRS, Centrale Lille Institut, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, F-59000, Lille, France.
| | - Parth Raval
- University of Lille, CNRS, Centrale Lille Institut, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, F-59000, Lille, France.
| | - Julien Trébosc
- University of Lille, CNRS, INRAE, Centrale Lille, Univ. Artois, FR 2638 - IMEC - Institut Michel-Eugène Chevreul, F-59000, Lille, France
| | - G N Manjunatha Reddy
- University of Lille, CNRS, Centrale Lille Institut, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, F-59000, Lille, France.
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3
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de Oliveira M, Herr K, Brodrecht M, Haro-Mares NB, Wissel T, Klimavicius V, Breitzke H, Gutmann T, Buntkowsky G. Solvent-free dynamic nuclear polarization enhancements in organically modified mesoporous silica. Phys Chem Chem Phys 2021; 23:12559-12568. [PMID: 34027938 DOI: 10.1039/d1cp00985k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
High-field dynamic nuclear polarization is a powerful tool for the structural characterization of species on the surface of porous materials or nanoparticles. For these studies the main source of polarization are radical-containing solutions which are added by post-synthesis impregnation of the sample. Although this strategy is very efficient for a wide variety of materials, the presence of the solvent may influence the chemistry of functional species of interest. Here we address the development of a comprehensive strategy for solvent-free DNP enhanced NMR characterization of functional (target) species on the surface of mesoporous silica (SBA-15). The strategy includes the partial functionalization of the silica surface with Carboxy-Proxyl nitroxide radicals and target Fmoc-Glycine functional groups. As a proof of principle, we have observed for the first time DNP signal enhancements, using the solvent-free approach, for 13C{1H} CPMAS signals corresponding to organic functionalities on the silica surface. DNP enhancements of up to 3.4 were observed for 13C{1H} CPMAS, corresponding to an experimental time save of about 12 times. This observation opens the possibility for the DNP-NMR study of surface functional groups without the need of a solvent, allowing, for example, the characterization of catalytic reactions occurring on the surface of mesoporous systems of interest. For 29Si with direct polarization NMR, up to 8-fold DNP enhancements were obtained. This 29Si signal enhancement is considerably higher than the obtained with similar approaches reported in literature. Finally, from DNP enhancement profiles we conclude that cross-effect is probably the dominant polarization transfer mechanism.
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Affiliation(s)
- Marcos de Oliveira
- Institut für Physikalische Chemie, Technische Universität Darmstadt, 64287 Darmstadt, Germany. and São Carlos Institute of Physics, University of São Paulo, PO Box 369, 13560-970, São Carlos, SP, Brazil.
| | - Kevin Herr
- Institut für Physikalische Chemie, Technische Universität Darmstadt, 64287 Darmstadt, Germany.
| | - Martin Brodrecht
- Institut für Physikalische Chemie, Technische Universität Darmstadt, 64287 Darmstadt, Germany.
| | - Nadia B Haro-Mares
- Institut für Physikalische Chemie, Technische Universität Darmstadt, 64287 Darmstadt, Germany.
| | - Till Wissel
- Institut für Physikalische Chemie, Technische Universität Darmstadt, 64287 Darmstadt, Germany.
| | - Vytautas Klimavicius
- Institut für Physikalische Chemie, Technische Universität Darmstadt, 64287 Darmstadt, Germany. and Institute of Chemical Physics, Vilnius University, Sauletekio av. 3, LT-10257 Vilnius, Lithuania
| | - Hergen Breitzke
- Institut für Physikalische Chemie, Technische Universität Darmstadt, 64287 Darmstadt, Germany.
| | - Torsten Gutmann
- Institut für Physikalische Chemie, Technische Universität Darmstadt, 64287 Darmstadt, Germany.
| | - Gerd Buntkowsky
- Institut für Physikalische Chemie, Technische Universität Darmstadt, 64287 Darmstadt, Germany.
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Gouilleux B, Meddour A, Lesot P. 2 H QUOSY 2D-NMR Experiments in Weakly Aligning Systems: From the Conventional to the Ultrafast Approach. Chemphyschem 2020; 21:1548-1563. [PMID: 32633460 DOI: 10.1002/cphc.202000336] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 06/03/2020] [Indexed: 11/08/2022]
Abstract
We describe three anisotropic ultrafast (UF) QUadrupolar Ordered SpectroscopY (QUOSY) 2D-NMR experiments (referred to as ADUF 2D NMR spectroscopy) designed for recording the 2 H homonuclear 2D spectra of weakly aligned (deuterated) solutes in sub-second experiment times. These new ADUF 2D experiments derive from the Q-COSY, Q-resolved and Q-DQ 2D pulse sequences (J. Am. Chem. Soc. 1999, 121, 5249) and allow the correlation between the two components of each quadrupolar doublet, and then their assignment on the basis of 2 H chemical shifts. The UF 2D pulse sequences are analyzed by using the Cartesian spin-operator formalism for spin I=1 nuclei with a small quadrupolar moment. The optimal experimental/practical conditions as well as the resolution, sensitivity and quantification issues of these ADUF 2D experiments are discussed on comparison to their conventional 2D counterparts and their analytical potentialities. Illustrative ADUF 2D experiments using deuterated achiral/prochiral/chiral solutes in poly-γ-benzyl-L-glutamate based chiral liquid crystals are presented, as well as the first examples of natural abundance deuterium (ANADUF) 2D spectrum using 14.1 T magnetic field and a basic gradient unit (53 G.cm-1 ) in oriented solvents.
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Affiliation(s)
- Boris Gouilleux
- Université Paris-Saclay, ICMMO, UMR CNRS 8182, RMN en Milieu Orienté, Bât. 410, 15, rue du Doyen Georges Poitou, UFR d'Orsay, 91405, Orsay cedex, France
| | - Abdelkrim Meddour
- Université Paris-Saclay, ICMMO, UMR CNRS 8182, RMN en Milieu Orienté, Bât. 410, 15, rue du Doyen Georges Poitou, UFR d'Orsay, 91405, Orsay cedex, France
| | - Philippe Lesot
- Université Paris-Saclay, ICMMO, UMR CNRS 8182, RMN en Milieu Orienté, Bât. 410, 15, rue du Doyen Georges Poitou, UFR d'Orsay, 91405, Orsay cedex, France
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Lesot P, Aroulanda C, Berdagué P, Meddour A, Merlet D, Farjon J, Giraud N, Lafon O. Multinuclear NMR in polypeptide liquid crystals: Three fertile decades of methodological developments and analytical challenges. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2020; 116:85-154. [PMID: 32130960 DOI: 10.1016/j.pnmrs.2019.10.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 10/24/2019] [Indexed: 06/10/2023]
Abstract
NMR spectroscopy of oriented samples makes accessible residual anisotropic intramolecular NMR interactions, such as chemical shift anisotropy (RCSA), dipolar coupling (RDC), and quadrupolar coupling (RQC), while preserving high spectral resolution. In addition, in a chiral aligned environment, enantiomers of chiral molecules or enantiopic elements of prochiral compounds adopt different average orientations on the NMR timescale, and hence produce distinct NMR spectra or signals. NMR spectroscopy in chiral aligned media is a powerful analytical tool, and notably provides unique information on (pro)chirality analysis, natural isotopic fractionation, stereochemistry, as well as molecular conformation and configuration. Significant progress has been made in this area over the three last decades, particularly using polypeptide-based chiral liquid crystals (CLCs) made of organic solutions of helically chiral polymers (as PBLG) in organic solvents. This review presents an overview of NMR in polymeric LCs. In particular, we describe the theoretical tools and the major NMR methods that have been developed and applied to study (pro)chiral molecules dissolved in such oriented solvents. We also discuss the representative applications illustrating the analytical potential of this original NMR tool. This overview article is dedicated to thirty years of original contributions to the development of NMR spectroscopy in polypeptide-based chiral liquid crystals.
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Affiliation(s)
- Philippe Lesot
- Université Paris Sud/Université Paris-Saclay, UMR CNRS 8182, Institut de Chimie Moléculaire et des Matériaux d'Orsay, ICMMO, Equipe RMN en Milieu Orienté, Bât. 410, 15 rue du Doyen Georges Poitou, F-91405 Orsay cedex, France; Centre National de la Recherche Scientifique (CNRS), France.
| | - Christie Aroulanda
- Université Paris Sud/Université Paris-Saclay, UMR CNRS 8182, Institut de Chimie Moléculaire et des Matériaux d'Orsay, ICMMO, Equipe RMN en Milieu Orienté, Bât. 410, 15 rue du Doyen Georges Poitou, F-91405 Orsay cedex, France
| | - Philippe Berdagué
- Université Paris Sud/Université Paris-Saclay, UMR CNRS 8182, Institut de Chimie Moléculaire et des Matériaux d'Orsay, ICMMO, Equipe RMN en Milieu Orienté, Bât. 410, 15 rue du Doyen Georges Poitou, F-91405 Orsay cedex, France
| | - Abdelkrim Meddour
- Université Paris Sud/Université Paris-Saclay, UMR CNRS 8182, Institut de Chimie Moléculaire et des Matériaux d'Orsay, ICMMO, Equipe RMN en Milieu Orienté, Bât. 410, 15 rue du Doyen Georges Poitou, F-91405 Orsay cedex, France
| | - Denis Merlet
- Université Paris Sud/Université Paris-Saclay, UMR CNRS 8182, Institut de Chimie Moléculaire et des Matériaux d'Orsay, ICMMO, Equipe RMN en Milieu Orienté, Bât. 410, 15 rue du Doyen Georges Poitou, F-91405 Orsay cedex, France
| | - Jonathan Farjon
- Centre National de la Recherche Scientifique (CNRS), France; Faculté des Sciences et Techniques de Nantes, UMR CNRS 6230, Chimie et Interdisciplinarité, Synthèse, Analyse, Modélisation, CEISAM, Equipe EBSI, BP 92208, 2 rue de la Houssinière, F-44322 Nantes cedex 3, France
| | - Nicolas Giraud
- Université Paris Descartes, Sorbonne Paris Cité, UMR CNRS 8601, Laboratory of Pharmacological and Toxicological Chemistry and Biochemistry, LPTCB, 45 rue des Saints Pères, F-75006 Paris, France
| | - Olivier Lafon
- Universite de Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR CNRS 8181, Unité de Catalyse et Chimie du Solide, UCCS, F-59000 Lille, France; Institut Universitaire de France (IUF), France
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6
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Rankin AGM, Trébosc J, Pourpoint F, Amoureux JP, Lafon O. Recent developments in MAS DNP-NMR of materials. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2019; 101:116-143. [PMID: 31189121 DOI: 10.1016/j.ssnmr.2019.05.009] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/21/2019] [Accepted: 05/21/2019] [Indexed: 05/03/2023]
Abstract
Solid-state NMR spectroscopy is a powerful technique for the characterization of the atomic-level structure and dynamics of materials. Nevertheless, the use of this technique is often limited by its lack of sensitivity, which can prevent the observation of surfaces, defects or insensitive isotopes. Dynamic Nuclear Polarization (DNP) has been shown to improve by one to three orders of magnitude the sensitivity of NMR experiments on materials under Magic-Angle Spinning (MAS), at static magnetic field B0 ≥ 5 T, conditions allowing for the acquisition of high-resolution spectra. The field of DNP-NMR spectroscopy of materials has undergone a rapid development in the last ten years, spurred notably by the availability of commercial DNP-NMR systems. We provide here an in-depth overview of MAS DNP-NMR studies of materials at high B0 field. After a historical perspective of DNP of materials, we describe the DNP transfers under MAS, the transport of polarization by spin diffusion and the various contributions to the overall sensitivity of DNP-NMR experiments. We discuss the design of tailored polarizing agents and the sample preparation in the case of materials. We present the DNP-NMR hardware and the influence of key experimental parameters, such as microwave power, magnetic field, temperature and MAS frequency. We give an overview of the isotopes that have been detected by this technique, and the NMR methods that have been combined with DNP. Finally, we show how MAS DNP-NMR has been applied to gain new insights into the structure of organic, hybrid and inorganic materials with applications in fields, such as health, energy, catalysis, optoelectronics etc.
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Affiliation(s)
- Andrew G M Rankin
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181, UCCS, Unité de Catalyse et Chimie du Solide, F-59000, Lille, France
| | - Julien Trébosc
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181, UCCS, Unité de Catalyse et Chimie du Solide, F-59000, Lille, France; Univ. Lille, CNRS-FR2638, Fédération Chevreul, F-59000 Lille, France
| | - Frédérique Pourpoint
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181, UCCS, Unité de Catalyse et Chimie du Solide, F-59000, Lille, France
| | - Jean-Paul Amoureux
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181, UCCS, Unité de Catalyse et Chimie du Solide, F-59000, Lille, France; Bruker Biospin, 34 rue de l'industrie, F-67166, Wissembourg, France
| | - Olivier Lafon
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181, UCCS, Unité de Catalyse et Chimie du Solide, F-59000, Lille, France; Institut Universitaire de France, 1 rue Descartes, F-75231, Paris, France.
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7
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Zhao L, Pinon AC, Emsley L, Rossini AJ. DNP-enhanced solid-state NMR spectroscopy of active pharmaceutical ingredients. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:583-609. [PMID: 29193278 DOI: 10.1002/mrc.4688] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 11/15/2017] [Accepted: 11/19/2017] [Indexed: 06/07/2023]
Abstract
Solid-state NMR spectroscopy has become a valuable tool for the characterization of both pure and formulated active pharmaceutical ingredients (APIs). However, NMR generally suffers from poor sensitivity that often restricts NMR experiments to nuclei with favorable properties, concentrated samples, and acquisition of one-dimensional (1D) NMR spectra. Here, we review how dynamic nuclear polarization (DNP) can be applied to routinely enhance the sensitivity of solid-state NMR experiments by one to two orders of magnitude for both pure and formulated APIs. Sample preparation protocols for relayed DNP experiments and experiments on directly doped APIs are detailed. Numerical spin diffusion models illustrate the dependence of relayed DNP enhancements on the relaxation properties and particle size of the solids and can be used for particle size determination when the other factors are known. We then describe the advanced solid-state NMR experiments that have been enabled by DNP and how they provide unique insight into the molecular and macroscopic structure of APIs. For example, with large sensitivity gains provided by DNP, natural isotopic abundance, 13 C-13 C double-quantum single-quantum homonuclear correlation NMR spectra of pure APIs can be routinely acquired. DNP also enables solid-state NMR experiments with unreceptive quadrupolar nuclei such as 2 H, 14 N, and 35 Cl that are commonly found in APIs. Applications of DNP-enhanced solid-state NMR spectroscopy for the molecular level characterization of low API load formulations such as commercial tablets and amorphous solid dispersions are described. Future perspectives for DNP-enhanced solid-state NMR experiments on APIs are briefly discussed.
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Affiliation(s)
- Li Zhao
- Department of Chemistry, Iowa State University, Ames, IA, USA
- US DOE Ames Laboratory, Ames, IA, USA
| | - Arthur C Pinon
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Aaron J Rossini
- Department of Chemistry, Iowa State University, Ames, IA, USA
- US DOE Ames Laboratory, Ames, IA, USA
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8
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Li W, Wang Q, Xu J, Aussenac F, Qi G, Zhao X, Gao P, Wang C, Deng F. Probing the surface of γ-Al 2O 3 by oxygen-17 dynamic nuclear polarization enhanced solid-state NMR spectroscopy. Phys Chem Chem Phys 2018; 20:17218-17225. [PMID: 29900471 DOI: 10.1039/c8cp03132k] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
γ-Al2O3 is an important catalyst and catalyst support of industrial interest. Its acid/base characteristics are correlated to the surface structure, which has always been an issue of concern. In this work, the complex (sub-)surface oxygen species on surface-selectively labelled γ-Al2O3 were probed by 17O dynamic nuclear polarization surface-enhanced NMR spectroscopy (DNP-SENS). Direct 17O MAS and indirect 1H-17O cross-polarization (CP)/MAS DNP experiments enable observation of the (sub-)surface bare oxygen species and hydroxyl groups. In particular, a two-dimensional (2D) 17O 3QMAS DNP spectrum was for the first time achieved for γ-Al2O3, in which two O(Al)4 and one O(Al)3 bare oxygen species were identified. The 17O isotropic chemical shifts (δcs) vary from 56.7 to 81.0 ppm and the quadrupolar coupling constants (CQ) range from 0.6 to 2.5 MHz for the three oxygen species. The coordinatively unsaturated O(Al)3 species is characterized by a higher field chemical shift (56.7 ppm) and the largest CQ value (2.5 MHz) among these oxygen sites. 2D 1H → 17O HETCOR DNP experiments allow us to discriminate three bridging (Aln)-μ2-OH and two terminal (Aln)-μ1-OH hydroxyl groups. The structural features of the bare oxygen species and hydroxyl groups are similar for the γ-Al2O3 samples isotopically labelled by 17O2 gas or H217O. The results presented here show that the combination of surface-selective labelling and DNP-SENS is an effective approach for characterizing oxides with complex surface species.
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Affiliation(s)
- Wenzheng Li
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China.
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Ashbrook SE, Griffin JM, Johnston KE. Recent Advances in Solid-State Nuclear Magnetic Resonance Spectroscopy. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2018; 11:485-508. [PMID: 29324182 DOI: 10.1146/annurev-anchem-061417-125852] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
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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Affiliation(s)
- Sharon E Ashbrook
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom;
| | - John M Griffin
- Department of Chemistry and Materials Science Institute, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Karen E Johnston
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom
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10
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Lilly Thankamony AS, Wittmann JJ, Kaushik M, Corzilius B. Dynamic nuclear polarization for sensitivity enhancement in modern solid-state NMR. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2017; 102-103:120-195. [PMID: 29157490 DOI: 10.1016/j.pnmrs.2017.06.002] [Citation(s) in RCA: 273] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/03/2017] [Accepted: 06/08/2017] [Indexed: 05/03/2023]
Abstract
The field of dynamic nuclear polarization has undergone tremendous developments and diversification since its inception more than 6 decades ago. In this review we provide an in-depth overview of the relevant topics involved in DNP-enhanced MAS NMR spectroscopy. This includes the theoretical description of DNP mechanisms as well as of the polarization transfer pathways that can lead to a uniform or selective spreading of polarization between nuclear spins. Furthermore, we cover historical and state-of-the art aspects of dedicated instrumentation, polarizing agents, and optimization techniques for efficient MAS DNP. Finally, we present an extensive overview on applications in the fields of structural biology and materials science, which underlines that MAS DNP has moved far beyond the proof-of-concept stage and has become an important tool for research in these fields.
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Affiliation(s)
- Aany Sofia Lilly Thankamony
- Institute of Physical and Theoretical Chemistry, Institute of Biophysical Chemistry, and Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue-Str. 7-9, 60438 Frankfurt, Germany
| | - Johannes J Wittmann
- Institute of Physical and Theoretical Chemistry, Institute of Biophysical Chemistry, and Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue-Str. 7-9, 60438 Frankfurt, Germany
| | - Monu Kaushik
- Institute of Physical and Theoretical Chemistry, Institute of Biophysical Chemistry, and Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue-Str. 7-9, 60438 Frankfurt, Germany
| | - Björn Corzilius
- Institute of Physical and Theoretical Chemistry, Institute of Biophysical Chemistry, and Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue-Str. 7-9, 60438 Frankfurt, Germany.
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11
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Socha O, Hodgkinson P, Widdifield CM, Yates JR, Dračínský M. Exploring Systematic Discrepancies in DFT Calculations of Chlorine Nuclear Quadrupole Couplings. J Phys Chem A 2017; 121:4103-4113. [PMID: 28475331 DOI: 10.1021/acs.jpca.7b02810] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Previous studies have revealed significant discrepancies between density functional theory (DFT)-calculated and experimental nuclear quadrupolar coupling constants (CQ) for chlorine atoms, particularly in ionic solids. Various aspects of the computations are systematically investigated here, including the choice of the DFT functional, basis set convergence, and geometry optimization protocol. The effects of fast (fs) time-scale dynamics are probed using molecular dynamics (MD) and nuclear quantum effects (NQEs) are considered using path-integral MD calculations. It is shown that the functional choice is the most important factor related to improving the accuracy of the quadrupolar coupling calculations, and that functionals beyond the generalized gradient approximation (GGA) level, such as hybrid and meta-GGA functionals, are required for good correlations with experiment. The influence of molecular dynamics and NQEs is less important than the functional choice in the studied systems. A method which involves scaling the calculated quadrupolar coupling constant is proposed here; its application leads to good agreement with experimental data.
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Affiliation(s)
- Ondřej Socha
- Institute of Organic Chemistry and Biochemistry , Flemingovo nám. 2, 16610, Prague, Czech Republic
| | - Paul Hodgkinson
- Department of Chemistry, Durham University , South Road, DH1 3LE, Durham, U.K
| | - Cory M Widdifield
- Department of Chemistry, Durham University , South Road, DH1 3LE, Durham, U.K
| | - Jonathan R Yates
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, U.K
| | - Martin Dračínský
- Institute of Organic Chemistry and Biochemistry , Flemingovo nám. 2, 16610, Prague, Czech Republic
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12
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Lee D, Chaudhari SR, De Paëpe G. Solvent signal suppression for high-resolution MAS-DNP. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 278:60-66. [PMID: 28365491 DOI: 10.1016/j.jmr.2017.03.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/13/2017] [Accepted: 03/20/2017] [Indexed: 06/07/2023]
Abstract
Dynamic nuclear polarization (DNP) has become a powerful tool to substantially increase the sensitivity of high-field magic angle spinning (MAS) solid-state NMR experiments. The addition of dissolved hyperpolarizing agents usually results in the presence of solvent signals that can overlap and obscure those of interest from the analyte. Here, two methods are proposed to suppress DNP solvent signals: a Forced Echo Dephasing experiment (FEDex) and TRAnsfer of Populations in DOuble Resonance Echo Dephasing (TRAPDORED) NMR. These methods reintroduce a heteronuclear dipolar interaction that is specific to the solvent, thereby forcing a dephasing of recoupled solvent spins and leaving acquired NMR spectra free of associated resonance overlap with the analyte. The potency of these methods is demonstrated on sample types common to MAS-DNP experiments, namely a frozen solution (of l-proline) and a powdered solid (progesterone), both containing deuterated glycerol as a DNP solvent. The proposed methods are efficient, simple to implement, compatible with other NMR experiments, and extendable past spectral editing for just DNP solvents. The sensitivity gains from MAS-DNP in conjunction with FEDex or TRAPDORED then permits rapid and uninterrupted sample analysis.
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Affiliation(s)
- Daniel Lee
- Univ. Grenoble Alpes, INAC, F-38000 Grenoble, France; CEA, INAC, F-38000 Grenoble, France
| | - Sachin R Chaudhari
- Univ. Grenoble Alpes, INAC, F-38000 Grenoble, France; CEA, INAC, F-38000 Grenoble, France
| | - Gaël De Paëpe
- Univ. Grenoble Alpes, INAC, F-38000 Grenoble, France; CEA, INAC, F-38000 Grenoble, France.
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13
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Chaudhari SR, Griffin JM, Broch K, Lesage A, Lemaur V, Dudenko D, Olivier Y, Sirringhaus H, Emsley L, Grey CP. Donor-acceptor stacking arrangements in bulk and thin-film high-mobility conjugated polymers characterized using molecular modelling and MAS and surface-enhanced solid-state NMR spectroscopy. Chem Sci 2017; 8:3126-3136. [PMID: 28507688 PMCID: PMC5413886 DOI: 10.1039/c7sc00053g] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 02/11/2017] [Indexed: 11/21/2022] Open
Abstract
Conjugated polymers show promising properties as cheap, sustainable and solution-processable semiconductors. A key challenge in the development of these materials is to determine the polymer chain structure, conformation and packing in both the bulk polymer and in thin films typically used in devices. However, many characterisation techniques are unable to provide atomic-level structural information owing to the presence of disorder. Here, we use molecular modelling, magic-angle spinning (MAS) and dynamic nuclear polarisation surface-enhanced NMR spectroscopy (DNP SENS) to characterise the polymer backbone group conformations and packing arrangement in the high-mobility donor-acceptor copolymer diketopyrrolo-pyrrole-dithienylthieno[3,2-b]thiophene (DPP-DTT). Using conventional 1H and 13C solid-state MAS NMR coupled with density functional theory calculations and molecular dynamics simulations, we find that the bulk polymer adopts a highly planar backbone conformation with a laterally-shifted donor-on-acceptor stacking arrangement. DNP SENS enables acquisition of 13C NMR data for polymer films, where sensitivity is limiting owing to small sample volumes. The DNP signal enhancement enables a two-dimensional 1H-13C HETCOR spectrum to be recorded for a drop-cast polymer film, and a 13C CPMAS NMR spectrum to be recorded for a spin-coated thin-film with a thickness of only 400 nm. The results show that the same planar backbone structure and intermolecular stacking arrangement is preserved in the films following solution processing and annealing, thereby rationalizing the favourable device properties of DPP-DTT, and providing a protocol for the study of other thin film materials.
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Affiliation(s)
- Sachin R Chaudhari
- Institut des Sciences Analytiques , Centre de RMN à Très Hauts Champs , Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) , 69100 Villeurbanne , France
| | - John M Griffin
- Department of Chemistry , Lancaster University , Lancaster LA1 4YB , UK .
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , UK
| | - Katharina Broch
- Optoelectronics Group , Cavendish Laboratory , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , UK
| | - Anne Lesage
- Institut des Sciences Analytiques , Centre de RMN à Très Hauts Champs , Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) , 69100 Villeurbanne , France
| | - Vincent Lemaur
- Laboratory for Chemistry of Novel Materials , Center for Innovation and Research in Materials and Polymers (CIRMAP) , Université de Mons (UMons) , 20 Place du Parc , 7000 Mons , Belgium
| | - Dmytro Dudenko
- Laboratory for Chemistry of Novel Materials , Center for Innovation and Research in Materials and Polymers (CIRMAP) , Université de Mons (UMons) , 20 Place du Parc , 7000 Mons , Belgium
| | - Yoann Olivier
- Laboratory for Chemistry of Novel Materials , Center for Innovation and Research in Materials and Polymers (CIRMAP) , Université de Mons (UMons) , 20 Place du Parc , 7000 Mons , Belgium
| | - Henning Sirringhaus
- Optoelectronics Group , Cavendish Laboratory , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , UK
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland
| | - Clare P Grey
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , UK
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14
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Wi S, Schurko R, Frydman L. 1H–2H cross-polarization NMR in fast spinning solids by adiabatic sweeps. J Chem Phys 2017; 146:104201. [DOI: 10.1063/1.4976980] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- Sungsool Wi
- National High Magnetic Field Laboratory, Tallahassee, Florida 32304, USA
| | - Robert Schurko
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor N9B 3P4, Ontario, Canada
| | - Lucio Frydman
- National High Magnetic Field Laboratory, Tallahassee, Florida 32304, USA
- Department of Chemical Physics, Weizmann Institute of Sciences, Rehovot 76100, Israel
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15
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Chaudhari SR, Berruyer P, Gajan D, Reiter C, Engelke F, Silverio DL, Copéret C, Lelli M, Lesage A, Emsley L. Dynamic nuclear polarization at 40 kHz magic angle spinning. Phys Chem Chem Phys 2016; 18:10616-22. [PMID: 27035630 PMCID: PMC5048395 DOI: 10.1039/c6cp00839a] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 03/11/2016] [Indexed: 01/07/2023]
Abstract
DNP-enhanced solid-state NMR spectroscopy under magic angle spinning (MAS) is rapidly developing into a powerful analytical tool to investigate the structure of a wide range of solid materials, because it provides unsurpassed sensitivity gains. Most developments and applications of DNP MAS NMR were so far reported at moderate spinning frequencies (up to 14 kHz using 3.2 mm rotors). Here, using a 1.3 mm MAS DNP probe operating at 18.8 T and ∼100 K, we show that signal amplification factors can be increased by up to a factor two when using smaller volume rotors as compared to 3.2 mm rotors, and report enhancements of around 60 over a range of sample spinning rates from 10 to 40 kHz. Spinning at 40 kHz is also shown to increase (29)Si coherence lifetimes by a factor three as compared to 10 kHz, substantially increasing sensitivity in CPMG type experiments. The contribution of quenching effects to the overall sensitivity gain at very fast MAS is evaluated, and applications are reported on a functionalised mesostructured organic-inorganic material.
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Affiliation(s)
- Sachin R. Chaudhari
- Institut de Sciences Analytiques , Centre de RMN à Très Hauts Champs , Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) , France .
| | - Pierrick Berruyer
- Institut de Sciences Analytiques , Centre de RMN à Très Hauts Champs , Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) , France .
| | - David Gajan
- Institut de Sciences Analytiques , Centre de RMN à Très Hauts Champs , Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) , France .
| | | | | | - Daniel L. Silverio
- ETH Zürich , Department of Chemistry , Vladimir Prelog Weg 1-5 , CH-8093 Zürich , Switzerland
| | - Christophe Copéret
- ETH Zürich , Department of Chemistry , Vladimir Prelog Weg 1-5 , CH-8093 Zürich , Switzerland
| | - Moreno Lelli
- University of Florence , Chemistry Department , Magnetic Resonance Center , 50019 Sesto Fiorentino (FI) , Italy
| | - Anne Lesage
- Institut de Sciences Analytiques , Centre de RMN à Très Hauts Champs , Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) , France .
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland .
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16
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Hirsh DA, Rossini AJ, Emsley L, Schurko RW. 35Cl dynamic nuclear polarization solid-state NMR of active pharmaceutical ingredients. Phys Chem Chem Phys 2016; 18:25893-25904. [DOI: 10.1039/c6cp04353d] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In this work, we show how to obtain efficient dynamic nuclear polarization (DNP) enhanced 35Cl solid-state NMR (SSNMR) spectra at 9.4 T and demonstrate how they can be used to characterize the molecular-level structure of hydrochloride salts of active pharmaceutical ingredients (APIs) in both bulk and low wt% API dosage forms.
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Affiliation(s)
- David A. Hirsh
- Department of Chemistry and Biochemistry
- University of Windsor
- Windsor
- Canada
| | - Aaron J. Rossini
- Department of Chemistry
- Iowa State University
- Ames
- USA
- US DOE Ames Laboratory
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques
- Ecole Polytechnique Fédérale de Lausanne (EPFL)
- Lausanne
- Switzerland
| | - Robert W. Schurko
- Department of Chemistry and Biochemistry
- University of Windsor
- Windsor
- Canada
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17
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Lelli M, Chaudhari SR, Gajan D, Casano G, Rossini AJ, Ouari O, Tordo P, Lesage A, Emsley L. Solid-State Dynamic Nuclear Polarization at 9.4 and 18.8 T from 100 K to Room Temperature. J Am Chem Soc 2015; 137:14558-61. [PMID: 26555676 PMCID: PMC4671100 DOI: 10.1021/jacs.5b08423] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Efficient dynamic nuclear polarization
(DNP) in solids, which enables
very high sensitivity NMR experiments, is currently limited to temperatures
of around 100 K and below. Here we show how by choosing an adequate
solvent, 1H cross effect DNP enhancements of over 80 can
be obtained at 240 K. To achieve this we use the biradical TEKPol
dissolved in a glassy phase of ortho-terphenyl (OTP).
We study the solvent DNP enhancement of both TEKPol and BDPA in OTP
in the range from 100 to 300 K at 9.4 and 18.8 T. Surprisingly, we
find that the DNP enhancement decreases only relatively slowly for
temperatures below the glass transition of OTP (Tg = 243 K), and 1H enhancements around 15–20
at ambient temperature can be observed. We use this to monitor molecular
dynamic transitions in the pharmaceutically relevant solids Ambroxol
and Ibuprofen.
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Affiliation(s)
- Moreno Lelli
- Institut de Sciences Analytiques, Centre de RMN à Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) , 69100 Villeurbanne, France
| | - Sachin R Chaudhari
- Institut de Sciences Analytiques, Centre de RMN à Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) , 69100 Villeurbanne, France
| | - David Gajan
- Institut de Sciences Analytiques, Centre de RMN à Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) , 69100 Villeurbanne, France
| | - Gilles Casano
- Aix-Marseille Université, CNRS, ICR UMR 7273 , 13397 Marseille, France
| | - Aaron J Rossini
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Olivier Ouari
- Aix-Marseille Université, CNRS, ICR UMR 7273 , 13397 Marseille, France
| | - Paul Tordo
- Aix-Marseille Université, CNRS, ICR UMR 7273 , 13397 Marseille, France
| | - Anne Lesage
- Institut de Sciences Analytiques, Centre de RMN à Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) , 69100 Villeurbanne, France
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
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18
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Pinon A, Rossini AJ, Widdifield CM, Gajan D, Emsley L. Polymorphs of Theophylline Characterized by DNP Enhanced Solid-State NMR. Mol Pharm 2015; 12:4146-53. [PMID: 26393368 PMCID: PMC4699642 DOI: 10.1021/acs.molpharmaceut.5b00610] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 09/15/2015] [Accepted: 09/22/2015] [Indexed: 11/29/2022]
Abstract
We show how dynamic nuclear polarization (DNP) enhanced solid-state NMR spectroscopy can be used to characterize polymorphs and solvates of organic solids. We applied DNP to three polymorphs and one hydrated form of the asthma drug molecule theophylline. For some forms of theophylline, sample grinding and impregnation with the radical-containing solution, which are necessary to prepare the samples for DNP, were found to induce polymorphic transitions or desolvation between some forms. We present protocols for sample preparation for solid-state magic-angle spinning (MAS) DNP experiments that avoid the polymorphic phase transitions in theophylline. These protocols include cryogrinding, grinding under inert atmosphere, and the appropriate choice of the impregnating liquid. By applying these procedures, we subsequently demonstrate that two-dimensional correlation experiments, such as (1)H-(13)C and (1)H-(15)N HETCOR or (13)C-(13)C INADEQUATE, can be obtained at natural isotopic abundance in reasonable times, thus enabling more advanced structural characterization of polymorphs.
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Affiliation(s)
- Arthur
C. Pinon
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
- Institut
de Sciences Analytiques (CNRS/ENS de Lyon/UCB-Lyon 1), Centre de RMN
à Très Hauts Champs, Université
de Lyon, 69100 Villeurbanne, France
| | - Aaron J. Rossini
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
- Institut
de Sciences Analytiques (CNRS/ENS de Lyon/UCB-Lyon 1), Centre de RMN
à Très Hauts Champs, Université
de Lyon, 69100 Villeurbanne, France
| | - Cory M. Widdifield
- Institut
de Sciences Analytiques (CNRS/ENS de Lyon/UCB-Lyon 1), Centre de RMN
à Très Hauts Champs, Université
de Lyon, 69100 Villeurbanne, France
| | - David Gajan
- Institut
de Sciences Analytiques (CNRS/ENS de Lyon/UCB-Lyon 1), Centre de RMN
à Très Hauts Champs, Université
de Lyon, 69100 Villeurbanne, France
| | - Lyndon Emsley
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
- Institut
de Sciences Analytiques (CNRS/ENS de Lyon/UCB-Lyon 1), Centre de RMN
à Très Hauts Champs, Université
de Lyon, 69100 Villeurbanne, France
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