1. Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139 (USA), Fax: (+1)?781‐736‐2538 http://web.mit.edu/fbml/cmr/griffin‐group/index.html;2. Department of Chemistry, Brandeis University, Waltham, MA 02454 (USA);3. CNRS‐UMR 6517, Chemistry, Biology and Free Radicals, University of Aix‐Marseille I and III, Marseille (France);4. LCP CNRS‐UMR 6264, University of Provence, 13397 Marseille Cedex 20 (France);5. Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, 60438 Frankfurt (Germany)
Abstract:
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.
