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  4. A Slowly Relaxing Rigid Biradical for Efficient Dynamic Nuclear Polarization Surface-Enhanced NMR Spectroscopy: Expeditious Characterization of Functional Group Manipulation in Hybrid Materials
 
research article

A Slowly Relaxing Rigid Biradical for Efficient Dynamic Nuclear Polarization Surface-Enhanced NMR Spectroscopy: Expeditious Characterization of Functional Group Manipulation in Hybrid Materials

Zagdoun, Alexandre
•
Casano, Gilles
•
Ouari, Olivier
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2012
Journal of the American Chemical Society

A new nitroxide-based biradical having a long electron spin-lattice relaxation time (T-1e) 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 (epsilon) of over 100 at a magnetic field of 9.4 T and sample temperatures of similar to 100 K. The effects of radical concentration on the DNP enhancement factors and on the overall sensitivity enhancements (Sigma(dagger)) are reported. The relatively high DNP efficiency of the biradical is attributed to an increased T-1e, 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 C-13 and N-15 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.

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Type
research article
DOI
10.1021/ja210177v
Web of Science ID

WOS:000301084600066

Author(s)
Zagdoun, Alexandre
Casano, Gilles
Ouari, Olivier
Lapadula, Giuseppe
Rossini, Aaron J.  
Lelli, Moreno
Baffert, Mathieu
Gajan, David
Veyre, Laurent
Maas, Werner E.
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Date Issued

2012

Publisher

AMER CHEMICAL SOC

Published in
Journal of the American Chemical Society
Volume

134

Issue

4

Start page

2284

End page

2291

Editorial or Peer reviewed

REVIEWED

Written at

OTHER

EPFL units
LRM  
Available on Infoscience
January 8, 2015
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/109992
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