EBSI Team | NMR Methodology
Table of contents
Past team members: Tangi Jezequel, Valentin Joubert, Evelyne Baguet, Kévin Bayle, Ugo Bussy, Elsa Caytan, Flore Legrand, Eve Tenailleau, Christophe Thibaudeau.
This project is on-going as it is a permanent objective of the team from the beginnings. Isotopic 13C-NMR at natural abundance requires highly precise measurements (a few per mil), that have already been achieved by one-dimensional 13C acquisitions thank to an original 1H-decoupling scheme. However it is quite time consuming, even for a relatively simple molecular structure. Using optimized adiabatic multipulse sequences (1D or 2D) a dramatic reduction is gained in the experimental time without deterioration in short time or long time stability. This approach permits to envisage for the first time 15N PSIA by NMR.
Until now, the specific compositions calculation required measurement of the global 13C composition (δ13Cg) by mass spectrometry. In a radical new approach, we have shown that an internal isotopic chemical reference can be used instead. The strategy uses 1H NMR to quantify molar concentrations in the NMR tube. Thus, the sample preparation protocol is greatly simplified, bypassing the previous requirement for precise purity and mass determination. The key to accurate results is suppressing the effect of radiation damping in 1H NMR which produces signal distortion and alters quantification.
The interest of oxygen isotopes content is of interest. No PSIA information are available on organic molecules. We currently working on 17O NMR to evaluate its capability.References:
Supported by: National Council for Scientific research and University of Nantes
Past team members: Shrikant Kunjir, Boris Gouilleux, Maxime Tharaud
Collaborations (past and present): Fabrice Besacier and Virginie Ladroue (INPS Lyon), Paul Bowyer (Magritek USA), Ernesto Danieli and Juan Perlo (Magritek Germany), Myriam Malet-Martino (Univ. Toulouse),
High-field NMR has been constantly improving with superconducting magnets and cold probes, but it is associated with high purchase and operating costs and the need for dedicated staff. In the last few years, a new generation of transportable and cryogen-free low-field spectrometers has emerged as a promising alternative. These permanent magnets have reached a recognized analytical potential with stable and homogeneous static magnetic fields.
However, those spectrometers operating at 1H resonance frequencies between 40 and 80 MHz involve a loss of analytical performance. In addition to the low sensitivity, the reduction of the spectral resolution leads to overcrowded spectra with huge signal overlaps, especially in the case of complex mixtures. Moreover, ubiquitous second order couplings make identification and quantification very difficult.
Thanks to the pulse sequence programming capabilities of benchtop spectrometers and to their instrumental improvement with a gradient coil, advanced high-field NMR methods have been successfully implemented to improve their analytical capabilities. Among them, we are particularly exploring spatially-encoded experiments such as ultrafast 2D NMR and pure-shift experiments. We have also demonstrated the potential of benchtop NMR DOSY to investigate complex mixtures. Gradient coils have also enabled the implementation of modern solvent suppression schemes. Applications to reaction and process monitoring are currently explored. Key references:
Supported by Région Pays de la Loire (Paris scientifiques RésoNantes and AMER-METAL), CNRS (Projets interdisciplinarité RMN-(ME)2-TAL and Emergence ARES-TATION), and the French national research agency (ANR DEVIL_INSID).
Past team members: Tangi Jézéquel, Bertrand Plainchont, Boris Gouilleux, Adrien Le Guennec, Meerakhan Pathan, Laetitia Rouger
Collaboration (past and present): Stefano Caldarelli (Aix-Marseille Université), Philippe Lesot (ICMMO Orsay), Hassan Oulyadi (Rouen), Patricia Sepulcri (Sanofi Pasteur), Stanislav Sokolenko (Univ. Dalhousie), Christina Thiele (TU Darmstadt)
Measuring the accurate concentration of analytes in chemical or biochemical mixtures is, together with the identification of these components, one of the main goals of analytical chemistry. Nuclear Magnetic Resonance (NMR) is a widely used quantitative approach, known for its high reproducibility and robustness.
However, 1D proton NMR suffers from large overlap between peaks that restrains its quantitative use, particularly when complex mixtures are studied. In order to overcome these drawbacks, we are developing new quantitative 2D NMR approaches, since multidimensional NMR offers a better discrimination between resonances in complex samples with overlapped peaks.
Still, conventional 2D NMR experiments are affected by long experiment durations that, beyond timetable constraints, limit their use for quantitative analysis (since long experiments are highly sensitive to spectrometer instabilities) or for studying fast processes (kinetics, dynamics, etc.). For this reason, we focus on developing fast and precise 2D NMR experiments and we apply them to a variety of quantitative studies. A large part of our projects concerns the development of quantitative methods based on the ultrafast 2D NMR methodology, which makes it possible to record 2D NMR spectra in a fraction of a second to a few minutes.
Supported by: ERC (CoG SUMMIT 814747), ANR (QUANTUM and T-ERC SUMMIT), IUF, industrial funding
Current team members:Bertrand Plainchont, Benoît Charrier, Elodie Lesquin, Estelle Martineau, Jean-Nicolas Dumez*, Patrick Giraudeau* Past team members: Bertrand Plainchon, Elodie Lesquin
Collaborations (past and present): Geoffrey Bodenhausen (ENS Paris), Catherine Deborde and Annick Moing (INRA Bordeaux), Lucio Frydman (Weizmann Institute, Rehovot), Sami Jannin (Univ. Lyon)
Hyperpolarization methods can boost the sensitivity of NMR by several orders of magnitude. In particular, dissolution dynamic nuclear polarization (D-DNP) can yield sensitivity improvements by 4 to 5 orders of magnitude in liquid-state NMR. While D-DNP has been widely applied to in vivo situations, its application to analytical chemistry, and in particular to the analysis of complex mixtures, remains limited. We are exploring the potential of D-DNP in this context, with the aim of evaluating D-DNP for “omics” applications (metabolomics, fluxomics and isotopomics).
We recently demonstrated that D-DNP assisted by cross-polarization can provide major sensitivity enhancements in plant and breast cancer cell extracts at natural 13C abundance. Promising applications arise from the combination of D-DNP with ultrafast 2D NMR, whose single-scan character makes it ideally suited to record 2D NMR spectra of mixtures following D-DNP. In addition, we have shown that the repeatability of D-DNP is perfectly suitable to metabolomics studies. Several projects were recently initiated to evaluate the potential of D-DNP for such applications, and a D-DNP equipment will be installed at CEISAM at the end of 2019.
Supported by: ERC (CoG SUMMIT 814747), ANR (T-ERC SUMMIT), IUF, PRC CNRS-MOST
Current team members: Achine Marchand, Rituraj Mishra, Corentin Jacquemmoz, Patrick Giraudeau and Jean-Nicolas Dumez* Past team members: Ludmilla Guduff, Ghanem Hamdoun
Collaborations (past and present): Daniel Abergel (ENS, Paris), Mohammed Boujtita (Univ. Nantes), Luiz Keng Queiroz and Antonio Gilberto Ferreira (Univ. Sao Carlos), Lucio Frydman (Weizmann Institute), Vincent Gandon (Université Paris-Saclay), Gaspard Huber (CEA, Saclay), Sami Jannin (Université de Lyon), Dennis Kurzbach (University of Vienna), Géraldine Masson (ICSN, Univ. Paris-Saclay)
Solution mixtures that evolve in time encompass a broad range of samples and applications, such as the monitoring of organic and catalytic chemical reactions or the sensitive detection of components in hyperpolarized samples. Multidimensional (ND) NMR spectroscopy can provide extensive information on static solution mixtures, but classic ND experiments typically require several minutes or more, and are often not robust against sample evolution during the measurement.
We develop fast multidimensional NMR methods that are compatible with the analysis of time-evolving samples, with three complementary objectives: i/ reducing the duration needed to collect a complete ND data set (using notably single-scan “ultrafast” 2D NMR; ii/ optimising the frequency with which a time-evolving system can be sampled (with polarisation saving methods and original hardware); iii/ making each measurement more robust against sources of errors, such as convection of flow. The resulting methods open new perspective for mechanistic studies in chemical synthesis and metabolomics applications.
Supported by: Agence Nationale de la Recherche (JCJC SENSOR) Région Ile-de-France (DIM Analytics), Région Pays de la Loire (Connect Talent), CNRS, Israeli MoST, IUF, and European Research Council (STG DINAMIX)
Current team members: Achille Marchand, Rituraj Mishra, Corentin Jacquemmoz, Patrick Giraudeau,* and Jean-Nicolas Dumez*
Past team members: Bertrand Plainchont, Ludmilla Guduff, Maria Grazia Concilio, Laetitia Rouger, Boris Gouilleux, Adrien Le Guennec, Marion André
Collaborations (past and present): Damien Jeannerat (Université de Genève), Ilya Kuprov (University of Southampton), Vincent Sarou-Kanian and Franck Fayon (CNRS Orléans)
The potential of NMR spectroscopy can be greatly enhanced by introducing concepts and methods that exploit spatial (in addition to spectral) dimensions, often building on magnetic resonance imaging (MRI) knowledge and tools. Spatial parallelisation strategies notably yield 2D NMR spectra in a single-scan, and provide a powerful route to the acquisition of ultrahigh resolution 1H spectra. We develop novel strategies for the spatial encoding of NMR interactions and other physical properties, such as translational diffusion coefficients.
These developments jointly rely on the experimental, theoretical and numerical characterisation of the underlying spin dynamics. Specifically, we develop pulse sequence elements for spatial encoding (SPEN) (of, e.g., multiple-quantum coherences or diffusion coefficients), and integrate them into accelerated multidimensional experiments, with the goals of broadening the range of systems that can be analysed, and increasing the information content of ND NMR spectra. These basic ingredients are then used in all of our mixture analysis projects.
Supported by: Agence Nationale de la Recherche (JCJC SENSOR, Tremplin ERC SUMMIT), Région Pays de la Loire (Connect Talent), IUF, and European Research Council (STG DINAMIX, CoG SUMMIT)
Collaborations: Fabien Ferrage (ENS, Paris), Malcolm Levitt (University of Southampton)
While the fundamental theoretical framework of nuclear spin relaxation in solution is well established, peculiar and useful properties are still being discovered in multi-spin systems, based on a subtle role of the symmetry of molecular structure and motion and of spin interactions. We contribute to the theoretical and numerical analysis of several relaxation phenomena that have recently been observed in a variety of multi-spin systems.
One example is the existence of long-lived nuclear spin states in fast rotating methyl groups, which may be used as a ubiquitous carrier of nuclear spin hyperpolarisation. Another example is the complex relaxation dynamics that are central to the analysis of high-resolution relaxometry and two-field NMR, methods that opens a novel window onto biomolecular dynamics.
Supported by: CNRS, Royal Society