Article
Dynamic Nuclear Polarization NMR Spectroscopy of Microcrystalline Solids
Journal of the American Chemical Society
(2012)
Abstract
Dynamic nuclear polarization (DNP) solid-state NMR has been applied to powdered microcrystalline solids to obtain sensitivity enhancements on the order of 100. Glucose, sulfathiazole, and paracetamol were impregnated with bis-nitroxide biradical (bis-cyclohexyl-TEMPO-bisketal, bCTbK) solutions of organic solvents. The organic solvents were carefully chosen to be nonsolvents for the compounds, so that DNP-enhanced solid-state NMR spectra of the unaltered solids could be acquired. A theoretical model is presented that illustrates that for externally doped organic solids characterized by long spin–lattice relaxation times (T1(1H) > 200 s), 1H–1H spin diffusion can relay enhanced polarization over micrometer length scales yielding substantial DNP enhancements (ε). ε on the order of 60 are obtained for microcrystalline glucose and sulfathiazole at 9.4 T and with temperatures of ca. 105 K. The large gain in sensitivity enables the rapid acquisition of 13C–13C correlation spectra at natural isotopic abundance. It is anticipated that this will be a general method for enhancing the sensitivity of solid-state NMR experiments of organic solids.
Disciplines
Publication Date
September 11, 2012
DOI
10.1021/ja308135r
Publisher Statement
Reprinted (adapted) with permission from Journal of the American Chemical Society, 134(40); 16899-16908. Doi: 10.1021/ja308135r. Copyright 2012 American Chemical Society.
Citation Information
Aaron J. Rossini, Alexandre Zagdoun, Franziska Hegner, Martin Schwarzwalder, et al.. "Dynamic Nuclear Polarization NMR Spectroscopy of Microcrystalline Solids" Journal of the American Chemical Society Vol. 134 Iss. 40 (2012) p. 16899 - 16908 Available at: http://works.bepress.com/aaron-rossini/19/