| Autor: |
Negroni M; Faculty of Chemistry, Institute of Biological Chemistry, University Vienna, Währinger Straße 38, 1090 Vienna, Austria., Turhan E; Faculty of Chemistry, Institute of Biological Chemistry, University Vienna, Währinger Straße 38, 1090 Vienna, Austria., Kress T; Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, U.K., Ceillier M; Centre de Résonance Magnétique Nucléaire à Très Hauts Champs (UMR 5082) Université de Lyon/CNRS/Université Claude Bernard Lyon 1/ENS de Lyon, 5 Rue de la Doua, 69100 Villeurbanne, France., Jannin S; Centre de Résonance Magnétique Nucléaire à Très Hauts Champs (UMR 5082) Université de Lyon/CNRS/Université Claude Bernard Lyon 1/ENS de Lyon, 5 Rue de la Doua, 69100 Villeurbanne, France., Kurzbach D; Faculty of Chemistry, Institute of Biological Chemistry, University Vienna, Währinger Straße 38, 1090 Vienna, Austria. |
| Abstrakt: |
Nuclear magnetic resonance (NMR) spectroscopy is a key technique for molecular structure determination in solution. However, due to its low sensitivity, many efforts have been made to improve signal strengths and reduce the required substrate amounts. In this regard, dissolution dynamic nuclear polarization (DDNP) is a versatile approach as signal enhancements of over 10 000-fold are achievable. Samples are signal-enhanced ex situ by transferring electronic polarization from radicals to nuclear spins before dissolving and shuttling the boosted sample to an NMR spectrometer for detection. However, the applicability of DDNP suffers from one major drawback, namely, paramagnetic relaxation enhancements (PREs) that critically reduce relaxation times due to the codissolved radicals. PREs are the primary source of polarization losses canceling the signal improvements obtained by DNP. We solve this problem by using potassium nitrosodisulfonate (Frémy's salt) as polarization agent (PA), which provides high nuclear spin polarization and allows for rapid scavenging under mild reducing conditions. We demonstrate the potential of Frémy's salt, (i) showing that both 1 H and 13 C polarization of ∼30% can be achieved and (ii) describing a hybrid sample shuttling system (HySSS) that can be used with any DDNP/NMR combination to remove the PA before NMR detection. This gadget mixes the hyperpolarized solution with a radical scavenger and injects it into an NMR tube, providing, within a few seconds, quantitatively radical-free, highly polarized solutions. The cost efficiency and broad availability of Frémy's salt might facilitate the use of DDNP in many fields of research. |
