Cocrystalline matrices for hyperpolarization at room temperature using photoexcited electrons

We propose using cocrystals as effective polarization matrices for triplet dynamic nuclear polarization (DNP) at room temperature. The polari-zation source can be uniformly doped into cocrystals formed through acid–acid, amide–amide, and acid–amide synthons. The dense-packing crystal structures, facilitated by multiple hydrogen bonding and – interactions, result in extended T1 relaxation times, enabling efficient polarization diffusion within the crystals. Our study demonstrates the successful polarization of a DNP-magnetic resonance imaging molecular probe, such as urea, within a cocrystal matrix at room temperature using triplet-DNP.