Propane-d(6) Heterogeneously Hyperpolarized by Parahydrogen

[Image: see text] Long-lived spin states of hyperpolarized propane-d(6) gas were demonstrated following pairwise addition of parahydrogen gas to propene-d(6) using heterogeneous parahydrogen-induced polarization (HET-PHIP). Hyperpolarized molecules were synthesized using Rh/TiO(2) solid catalyst with 1.6 nm Rh nanoparticles. Hyperpolarized (P(H) ∼ 1%) propane-d(6) was detected at high magnetic field (9.4 T) spectroscopically and by high-resolution 3D gradient-echo MRI (4.7 T) as the gas flowed through the radiofrequency coil with a spatial and temporal resolution of 0.5 × 0.5 × 0.5 mm(3) and 17.7 s, respectively. Stopped-flow hyperpolarized propane-d(6) gas was also detected at 0.0475 T with an observed nuclear spin polarization of P(H) ∼ 0.1% and a relatively long lifetime with T(1,eff) = 6.0 ± 0.3 s. Importantly, it was shown that the hyperpolarized protons of the deuterated product obtained via pairwise parahydrogen addition could be detected directly at low magnetic field. Importantly, the relatively long low-field T(1,eff) of HP propane-d(6) gas is not susceptible to paramagnetic impurities as tested by exposure to ∼0.2 atm oxygen. This long lifetime and nontoxic nature of propane gas could be useful for bioimaging applications including potentially pulmonary low-field MRI. The feasibility of high-resolution low-field 2D gradient-echo MRI was demonstrated with 0.88 × 0.88 mm(2) spatial and ∼0.7 s temporal resolution, respectively, at 0.0475 T.