Systematic Evaluation of Polarizing Agents for Dynamic Nuclear Polarization Enhanced NMR
Abstract
Abstract Dynamic nuclear polarization (DNP) can significantly enhance the sensitivity of nuclear magnetic resonance (NMR) spectroscopy, via the transfer of polarization from unpaired electrons to nuclei. As a result, there is considerable interest in improving DNP efficiency, particularly through the development of new polarizing agents (PAs). Here, a series of 32 PAs, including 26 dinitroxide and 6 hetero biradicals, of which 11 are introduced for the first time, were evaluated for their performance in DNP NMR experiments at magnetic field strengths of 9.4 T, 14.1 T, and 21.1 T. The PAs that are soluble in aqueous media were compared for different proton concentrations. A detailed comparison of the enhancement factors, polarization build‐up times, contribution factors, and the resulting overall sensitivity factors is provided. We find that the class of narrow‐line‐broad‐line biradicals not only yield the best performance at high field (21.1 T and 14.1 T) but remain among the best at intermediate fields (9.4 T). Specifically, SNAPol‐1 and HyTEK2 are consistently among the best performing radicals at any field. Among the dinitroxides, notably at 9.4 T, the AsymPol‐POK and M‐TinyPol families stand out in proton‐dense aqueous matrices, and a newly developed dinitroxide, NaphPolCbo, is found to provide the best overall sensitivity factor in organic solvent.
Article Details
Authors (19)
Ran Wei
Institut des Sciences et Ingénierie Chimiques
Gilles Casano
Aix Marseille Univ., CNRS, Institut de Chimie Radicalaire (UMR 7273), Av. Esc. Normandie Niemen, 13013 Marseille, France
Yuxuan Zhang
College of Chemistry
Ivanska M. Gierbolini‐Colón
National High Magnetic Field Laboratory Florida State University Tallahassee FL 32301 USA
Yu Rao
Institut des Sciences et Ingénierie Chimiques
Shubha S. Gunaga
National High Magnetic Field Laboratory
Faith J. Scott
National High Magnetic Field Laboratory
Jiaxin Zhou
Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Science, Frontiers Science Center for New Organic Matter, College of Chemistry
Satyaki Chatterjee
Department of Chemistry, Science Institute, University of Iceland
Sanyog Kumari
Department of Chemistry University of Iceland Science Institute Reykjavik 107 Iceland
Hakim Karoui
Aix‐Marseille Univ., CNRS Institut de Chimie Radicalaire UMR 7273 Marseille 13013 France
Mang Huang
Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics, School of Pharmacy Tianjin Medical University Tianjin 300070 P.R. China
Snorri Th. Sigurdsson
Science Institute, University of Iceland, Dunhaga 5, Reykjavik 107, Iceland
Gaël De Paëpe
Univ. Grenoble Alpes, CEA, CNRS, IRIG, MEM
Yangping Liu
Frederic Mentink‐Vigier
National High Magnetic Field Laboratory Florida State University Tallahassee FL USA
Amrit Venkatesh
Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL)
Olivier Ouari
Aix Marseille Univ., CNRS, Institut de Chimie Radicalaire (UMR 7273), Av. Esc. Normandie Niemen, 13013 Marseille, France
Lyndon Emsley
Laboratory of Magnetic Resonance, Institut des Sciences et Ingénierie Chimiques