Gas-Phase NMR of Hyperpolarized Propane with 1H-to-13C Polarization Transfer by PH-INEPT
Gas-Phase NMR of Hyperpolarized Propane with 1H-to-13C Polarization Transfer by PH-INEPT
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DOI：
10.1007/s00723-021-01377-4
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发表时间：
2021-07-14
影响因子：
1
通讯作者：
Koptyug, Igor, V
中科院分区：
文献类型：
--
作者：
Burueva, Dudari B.;Kozinenko, Vitaly P.;Koptyug, Igor, V
在这项工作中，我们证明了转移仲氢衍生的H-1极化的C-13核在气相中使用PH-INEPT为基础的脉冲序列的可能性。在7.05 T磁场下，以1wt%Rh/TiO_2为催化剂，丙烯（天然C-13丰度）与仲氢加氢制得超极化H-1核丙烷。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%。通过数值计算，确定了PH-INEPT和PH-INEPT +序列的最佳脉冲间延迟，并考虑了丙烷的全自旋系统，该系统包括8个质子和1个C-13核。优化的PH-INEPT极化转移序列的应用导致[1-C-13]丙烷的甲基和[2-C-13]丙烷的亚甲基的C-13极化值分别为0.07 +/- 0.01%和0.030 +/- 0.006%。[1-C-13]丙烷和[2-C-13]丙烷的C-13偏振值对PH-INEPT序列的脉冲间延迟τ（1）的实验依赖性与模拟结果吻合得很好。使用PH-INEPT +序列得到的C-13极化比通过PH-INEPT的低约2.5倍，这也与数值计算一致。
In this work we demonstrate the possibility to transfer parahydrogen-derived H-1 polarization to C-13 nuclei in the gas phase using PH-INEPT-based pulse sequences. The propane with hyperpolarized H-1 nuclei was produced via hydrogenation of propylene (at natural C-13 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 C-13 nucleus. The application of the optimized PH-INEPT polarization transfer sequence resulted in the C-13 polarization values of 0.07 +/- 0.01% and 0.030 +/- 0.006% for the methyl group of [1-C-13]propane and the methylene group of [2-C-13]propane, respectively. The experimental dependence of the C-13 polarization values for [1-C-13] propane and [2-C-13]propane on the inter-pulse delay tau(1) of the PH-INEPT sequence is in a good agreement with the simulation. The resulting C-13 polarization using PH-INEPT + sequence is similar to 2.5 times lower than that via PH-INEPT, which is also consistent with the numerical calculations.