This is a very interesting article describing the preparation of a sample for DNP by co-milling the analyte with the polarizing substrate. For a long time it was thought that just mechanically mixing the polarizing agent with the analyte will not result in a sample that is useful for DNP because the radical has to be mixed at an atomic level. Clearly this article demonstrate that this is not necessary. This will open up DNP to be used with a complete class of new materials.
Elisei, E., et al., Dynamic nuclear polarization of a glassy matrix prepared by solid state mechanochemical amorphization of crystalline substances. Chemical Communications, 2015. 51(11): p. 2080-2083.
A mechanochemical \”solvent-free\” route is presented for the preparation of solid samples ready to be employed in the Dynamic Nuclear Polarization (DNP). 1H-DNP build-up curves at 3.46 T as a function of temperature and radical concentration show steady state nuclear polarization of 10% (0.5% TEMPO concentration at 1.75 K).