We study the effects of the deuteration of biradical polarizing agents on the efficiency of dynamic nuclear polarization (DNP) via the cross-effect. To this end, we synthesized a series of bTbK and TOTAPol biradicals with systematically increased deuterium substitution. The deuteration increases the radicals' relaxation time, thus contributing to a higher saturation factor and larger DNP enhancement, and reduces the pool of protons within the so-called spin diffusion barrier. Notably, we report that full or partial deuteration leads to improved DNP enhancement factors in standard samples, but also slows down the build-up of hyperpolarization. Improvements in DNP enhancements factors of up to 70% and time savings of up to 38% are obtained upon full deuteration. It is foreseen that this approach may be applied to other DNP polarizing agents thus enabling further sensitivity improvements.
Available at: http://works.bepress.com/aaron_sadow/64/
This article is published as Perras, Frédéric A., Regina R. Reinig, Igor I. Slowing, Aaron D. Sadow, and Marek Pruski. "Effects of biradical deuteration on the performance of DNP: towards better performing polarizing agents." Physical Chemistry Chemical Physics 18, no. 1 (2016): 65-69. DOI: 10.1039/C5CP06505D. Posted with permission.