Rational Design of [¹³C,D₁₄]Tert-butylbenzene as a Scaffold Structure for Designing Long-lived Hyperpolarized ¹³C Probes

Dynamic nuclear polarization (DNP) is a technique to polarize the nuclear spin population. As a result of the hyperpolarization, the NMR sensitivity of the nuclei in molecules can be dramatically enhanced. Recent application of the hyperpolarization technique has led to advances in biochemical and molecular studies. A major problem is the short lifetime of the polarized nuclear spin state. Generally, in solution, the polarized nuclear spin state decays to a thermal spin equilibrium, resulting in loss of the enhanced NMR signal. This decay is correlated directly with the spin-lattice relaxation time T₁. Here we report [¹³C,D₁₄]tert-butylbenzene as a new scaffold structure for designing hyperpolarized ¹³C probes. Thanks to the minimized spin-lattice relaxation (T₁) pathways, its water-soluble derivative showed a remarkably long ¹³C T₁ value and long retention of the hyperpolarized spin state.