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Dynamic Nuclear Polarization with a Rigid Biradical


  • We thank Sandrine Lambert for technical assistance, and Galia Debelouchina, Albert Smith, Alexander Barnes, and Jean-Pierre Finet for many stimulating discussions. This research was supported by the National Institutes of Health through grants EB002804, EB002026, EB009866, EB001965, and EB001035, and by the EU-Design Study Bio-DNP in Framework 6. T.M. acknowledges receipt of a postdoctoral fellowship from the Deutsche Forschungsgemeinschaft. Y.M. acknowledges partial financial support from the Naito Foundation.


A new polarizing agent with superior performance in dynamic nuclear polarization experiments is introduced, and utilizes two TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) moieties connected through a rigid spiro tether (see structure). The observed NMR signal intensities were enhanced by a factor of 1.4 compared to those of TOTAPOL, a previously described TEMPO-based biradical with a flexible tether.

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