Dynamic nuclear polarization with a rigid biradical

Angew Chem Int Ed Engl. 2009;48(27):4996-5000. doi: 10.1002/anie.200805940.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cyclic N-Oxides / chemistry*
  • Electron Spin Resonance Spectroscopy
  • Free Radicals / chemistry
  • Magnetic Resonance Spectroscopy
  • Spiro Compounds / chemistry*


  • Cyclic N-Oxides
  • Free Radicals
  • Spiro Compounds
  • bis-TEMPO-bisketal