A new dynamic nuclear polarization (DNP) mechanism has been discovered involving methyl rotation to mediate an Overhauser effect (OE).
The low sensitivity of NMR spectroscopy limits its application in the characterization of interfacial structure. DNP is the solution but its efficiency at very high fields is low. The discovery of methyl-driven OE DNP will enable the design of highly-efficient polarizing agents with good performance at high fields.
- The methyl functionalization of a Blatter’s radical triggers its ability to perform OE DNP.
- Deuteration of the methyl group quenches the 1H OE but enables 2H OE DNP, confirming the assignment of the mechanism.
- DFT and spin dynamics calculations are used to rationalize the effect.
Perras, F. A.; Flesariu, D. F.; Southern, S. A.; Nicolaides, C.; Bazak, J. D.; Washton, N. M.; Trypiniotis, T.; Constantinides, C. P.; Koutentis, P. A. J. "Methyl-Driven Overhauser Dynamic Nuclear Polarization." Phys. Chem. Lett. 2022, 13, 4000-4006.