Abstract.
Dynamic nuclear polarization (DNP) is a potent method to enhance the sensitivity of nuclear magnetic resonance (NMR) signals. In a recent implementation of DNP, samples are polarized at low temperature in a glassy state followed by dissolution with hot solvent and transfer to an NMR magnet (J.H. Ardenkjaer-Larsen, B. Fridlund, A. Gram, G. Hansson, L. Hansson, M.H. Lerche, R. Servin, M. Thaning, K. Golman: Proc. Natl. Acad. Sci. USA 100, 10158, 2003). Although enormous polarizations in the order of tens of thousands were reported, such enhancements were only obtained for very few molecules. Here we have polarized a range of small molecules in order to identify determinants of polarizability. The key factors include functional groups which allow for a good contact to the radical and substances with long longitudinal relaxation times T 1. We also observe that methyl groups play a particularly interesting role in 13C-DNP-NMR spectra taken at low temperature.
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Authors' address: Ulrich L. Günther, Henry Wellcome Building for Biomolecular NMR Spectroscopy, CR UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom
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Emwas, AH., Saunders, M., Ludwig, C. et al. Determinants for Optimal Enhancement in Ex Situ DNP Experiments. Appl Magn Reson 34, 483–494 (2008). https://doi.org/10.1007/s00723-008-0120-x
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DOI: https://doi.org/10.1007/s00723-008-0120-x