Levien, Marcel, Maik Reinhard, Markus Hiller, Igor Tkach, Marina Bennati, and Tomas Orlando. “Spin Density Localization and Accessibility of Organic Radicals Affect Liquid-State DNP Efficiency.” Physical Chemistry Chemical Physics 23, no. 8 (2021): 4480–85.
https://doi.org/10.1039/D0CP05796G.
We report a large variation in liquid DNP performance of up to a factor of about five in coupling factor among organic radicals commonly used as polarizing agents. A comparative study of 1H and 13C DNP in model systems shows the impact of the spin density distribution and accessibility of the radical site by the target molecule.