NMR spectroscopy in an oriented medium (also called “anisotropic” NMR) makes it possible to record high-resolution NMR spectra whose frequencies are governed by anisotropic NMR interactions (zero-averaged interactions in liquids). Their analysis provides many key molecular information (stereochemistry, isotopy, dynamics, …), and makes it possible to determine the orientation of the solutes with respect to the magnetic field B0. The efficient extraction of these spectral data generally requires the use of two-dimensional (2D) NMR experiments whose total acquisition times can exceed several hours.
Recently, Philippe Lesot from the Molecular Chemistry and Materials Institute of Orsay (ICMMO, UMR 8182) and Olivier Lafon from the Lille NMR platform from INFRANALYTICS have written a chapter on the rapid recording of 2D NMR spectra in an oriented medium in the book " Fast 2D Solution-state NMR published by the Royal Society of Chemistry.
This chapter presents the specific challenges associated with fast and ultrafast 2D NMR experiments in oriented media and describes the different approaches developed to date to reduce the duration of these experiments. Non-uniform sampling, recycling time optimization and spatial encoding are discussed. The gain in sensitivity offered by non-uniform sampling is particularly useful for the detection of monodeuterated isotopomers in natural abundance (1,5 ´ 10−2 %) of aligned molecules, while spatial encoding combined with chiral oriented media opens innovative perspectives for tracking , chemical reactions involving enantiomers (racemization).
figure 1. Rapid acquisition of NMR spectra 2H of small organic molecules in chiral liquid crystals using either non-uniform sampling (left) or spatial encoding (right).
Reference:
P. Lesot, O. Lafon, Combining Fast 2D NMR Methods and Oriented Media. In Fast 2D Solution-State NMR: Concepts and Applications; Co-editors: Jean-Nicolas Dumez and Patrick Giraudeau, The Royal Society of Chemistry, 2023.
https://doi.org/10.1039/BK9781839168062-00441.
Contact :
Philippe Lesot
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+33 (0)1 69 15 47 59
Paris-Saclay University, UMR CNRS 8182, Molecular Chemistry and Materials Institute of Orsay, ICMMO, NMR Team in Oriented Medium, BPC Site (HM1), 17–19 Avenue des Sciences, 91400 Orsay, France
Olivier Lafon
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+33 (0)3 74 95 13 12
University of Lille, CNRS, Centrale Lille, Artois University, UMR CNRS 8181, Solid State Chemistry and Catalysis Unit, UCCS, F-59000 Lille, France