In this work we demonstrate the possibility to transfer parahydrogen-derived ¹H polarization to ¹³C nuclei in the gas phase using PH-INEPT-based pulse sequences. The propane with hyperpolarized ¹H nuclei was produced via hydrogenation of propylene (at natural ¹³C abundance) with parahydrogen over the heterogeneous 1 wt% Rh/TiO₂ catalyst at 7.05 T magnetic field of a NMR spectrometer. The apparent proton polarization was estimated as 1.8 ± 0.4%, taking into account the polarization losses caused by spin relaxation. The optimal inter-pulse delays for both the PH-INEPT and the PH-INEPT + sequences were determined via the numerical calculations considering the full spin system of propane which includes eight protons and one ¹³C nucleus. The application of the optimized PH-INEPT polarization transfer sequence resulted in the ¹³C polarization values of 0.07 ± 0.01% and 0.030 ± 0.006% for the methyl group of [1-¹³C]propane and the methylene group of [2-¹³C]propane, respectively. The experimental dependence of the ¹³C polarization values for [1-¹³C]propane and [2-¹³C]propane on the inter-pulse delay τ₁ of the PH-INEPT sequence is in a good agreement with the simulation. The resulting ¹³C polarization using PH-INEPT + sequence is ~ 2.5 times lower than that via PH-INEPT, which is also consistent with the numerical calculations.

在这项工作中，我们证明了使用基于 PH-INEPT 的脉冲序列将副氢衍生的¹ H 极化转移到气相中的¹³ C 核的可能性。具有超极化¹ H 核的丙烷是通过丙烯（在天然¹³ C 丰度下）与仲氢在异质 1 wt% Rh/TiO ₂上氢化生产的核磁共振波谱仪在 7.05 T 磁场下的催化剂。考虑到自旋弛豫引起的极化损失，表观质子极化估计为 1.8 ± 0.4%。PH-INEPT 和 PH-INEPT + 序列的最佳脉冲间延迟是通过数值计算确定的，考虑到丙烷的完整自旋系统，包括八个质子和一个¹³ C 核。优化的PH-INEPT极化转移序列的应用导致[1- ¹³ C]丙烷的甲基和[2- ¹³ C的亚甲基的¹³ C极化值分别为0.07±0.01%和0.030±0.006% ]丙烷，分别。¹³的实验依赖性[1- ¹³ C]丙烷和[2- ¹³ C]丙烷在PH-INEPT序列的脉冲间延迟τ ₁上的C极化值与模拟非常一致。使用 PH-INEPT + 序列产生的¹³ C 极化比通过 PH-INEPT产生的¹³ C 极化低约 2.5 倍，这也与数值计算一致。