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A Slowly Relaxing Rigid Biradical for Efficient Dynamic Nuclear Polarization Surface-Enhanced NMR Spectroscopy: Expeditious Characterization of Functional Group Manipulation in Hybrid Materials
Journal of the American Chemical Society (2012)
  • Alexandre Zagdoun, Université de Lyon
  • Gilles Casano, Aix-Marseille Université
  • Olivier Ouari, Aix-Marseille Université
  • Giuseppe Lapadula, ETH Zürich
  • Aaron J. Rossini, Université de Lyon
  • Moreno Lelli, Université de Lyon
  • Mathieu Baffert, Institut de Chimie de Lyon
  • David Gajan, ETH Zürich
  • Laurent Veyre, Institut de Chimie de Lyon
  • Werner E. Maas, Bruker BioSpin Corporation
  • Melanie Rosay, Bruker BioSpin Corporation
  • Ralph T. Weber, Bruker BioSpin Corporation
  • Chloe Thieuleux, Institut de Chimie de Lyon
  • Christophe Coperet, ETH Zürich
  • Anne Lesage, University of Lyon
  • Paul Tordo, Aix-Marseille Université
  • Lyndon Emsley, University of Lyon
Abstract
A new nitroxide-based biradical having a long electron spin–lattice relaxation time (T1e) has been developed as an exogenous polarization source for DNP solid-state NMR experiments. The performance of this new biradical is demonstrated on hybrid silica-based mesostructured materials impregnated with 1,1,2,2-tetrachloroethane radical containing solutions, as well as in frozen bulk solutions, yielding DNP enhancement factors (ε) of over 100 at a magnetic field of 9.4 T and sample temperatures of ∼100 K. The effects of radical concentration on the DNP enhancement factors and on the overall sensitivity enhancements (Σ) are reported. The relatively high DNP efficiency of the biradical is attributed to an increased T1e, which enables more effective saturation of the electron resonance. This new biradical is shown to outperform the polarizing agents used so far in DNP surface-enhanced NMR spectroscopy of materials, yielding a 113-fold increase in overall sensitivity for silicon-29 CPMAS spectra as compared to conventional NMR experiments at room temperature. This results in a reduction in experimental times by a factor >12 700, making the acquisition of 13C and 15N one- and two-dimensional NMR spectra at natural isotopic abundance rapid (hours). It has been used here to monitor a series of chemical reactions carried out on the surface functionalities of a hybrid organic–silica material.
Publication Date
December 19, 2012
DOI
10.1021/ja210177v
Publisher Statement
Reprinted (adapted) with permission from Journal of the American Chemical Society,134 94); 2284-2291. Doi: 10.1021/ja210177v. Copyright 2012 American Chemical Society.
Citation Information
Alexandre Zagdoun, Gilles Casano, Olivier Ouari, Giuseppe Lapadula, et al.. "A Slowly Relaxing Rigid Biradical for Efficient Dynamic Nuclear Polarization Surface-Enhanced NMR Spectroscopy: Expeditious Characterization of Functional Group Manipulation in Hybrid Materials" Journal of the American Chemical Society Vol. 134 Iss. 4 (2012) p. 2284 - 2291
Available at: http://works.bepress.com/aaron-rossini/21/