A general strategy towards efficient hyperpolarization in high-field magnetic resonance using mixed-valence compounds

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Dynamic nuclear polarization (DNP) is a powerful method that greatly enhances signal intensities in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) enabling unprecedented applications in life and material science. The ultimate scientific goal is to expand the use of DNP to ultra-high magnetic fields where optimal spectral resolution and sensitivity are integrated. While considerable progress has been made in constructing DNP-NMR instruments operating at ultra-high magnetic fields, designing polarizing agents that optimally perform under such conditions has thus far been challenging. The investigation of new radicals that allow for significant DNP enhancements in high fields is therefore urgently needed. Recently, the so called Overhauser effect has become an interesting focus to overcome these challenges. Firstly, in contrast to previous expectations, the effect was demonstrated to occur in glassy insulating matrices which would be required for practical applications in NMR/MRI. Secondly, the effect was shown to scale favorably with static magnetic field strength.Here I propose to systematically and broadly investigate the Overhauser effect in insulating solids by combination of experimental and theoretical techniques. Previously, I have examined the BDPA radical by ab initio methods. My findings put this radical into a larger group of mixed-valence compounds, also known as Jahn-Teller systems. In preliminary calculations, I have identified several new molecules that have properties similar to the studied radical. Some of the molecules were synthesized, and have experimentally demonstrated Overhauser effect DNP in insulating matrix . These results set the stage for optimization of their molecular properties including the electron transfer rate, charge, and the surrounding solvent with the goal to develop a novel class of powerful DNP agents that optimally perform at ultra-high magnetic fields.