13 C Hyperpolarization of Viscous Liquids by Transfer of Solid-Effect 1 H Dynamic Nuclear Polarization at High Magnetic Field.

Dynamic nuclear polarization (DNP) is routinely used as a method for increasing the sensitivity to nuclear magnetic resonance (NMR). Recently, high-field solid-effect DNP in viscous liquids on 1 H nuclei was demonstrated using narrow-line polarizing agents. Here we expand the applicability of DNP in viscous media to 13 C nuclei. To hyperpolarize 13 C nuclei, we combined solid-effect 1 H DNP with a subsequent transfer of the 1 H polarization to 13 C via insensitive nuclei enhanced by polarization transfer (INEPT). We demonstrate this approach using a triarylmethyl radical as a polarizing agent and glycerol- 13 C 3 as an analyte. We achieved 13 C enhancement factors of up to 45 at a magnetic field of 9.4 T and room temperature.