19F Hyperpolarization of 15N-3-19F-Pyridine via Signal Amplification by Reversible Exchange
19F Hyperpolarization of 15N-3-19F-Pyridine via Signal Amplification by Reversible Exchange
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DOI：
10.1021/acs.jpcc.8b06654
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发表时间：
2018-10-11
影响因子：
3.7
通讯作者：
Chekmenev, Eduard Y.
中科院分区：
文献类型：
--
作者：
Chukanov, Nikita V.;Salnikov, Oleg G.;Chekmenev, Eduard Y.
本文报道了用锌基盐法合成N-15-3-E-19-吡啶，总收率为35%，N-15同位素纯度为84%。利用超极化研究了N-15-3-E-19-吡啶和N-14-3-F-19-吡啶中在毫特斯拉和微特斯拉磁场下仲氢氢化物质子向F-19核的极化转移机制.我们发现N-15和F-19磁场超极化分布在微特斯拉区域的不匹配，表明自发超极化过程可能直接发生在仲氢衍生的氢化物质子到F-19核，而不需要通过N-15位点进行自旋中继。在SABRE磁场状态（毫特斯拉磁场范围）的情况下，我们发现H-1和F-19超极化的磁场分布非常相似，F-19极化水平显著低于H-1 SABRE极化水平，也低于F-19 SABRE-SHEATH（即，在微特斯拉磁场下获得）极化水平。我们的研究结果支持的假设，在毫特斯拉磁场制度，F-19核超极化的过程是通过质子的基板，因此是非常低效的。这些研究结果对超极化硬件的改进和超极化分子探针的合理设计具有重要意义。
We report synthesis of N-15-3-E-19-pyridine via Zincke salt formation with overall 35% yield and 84% N-15 isotopic purity. Hyperpolarization studies of signal amplification by reversible exchange (SABRE) and SABRE in SHield Enables Alignment Transfer to Heteronuclei (SABRE-SHEATH) were performed to investigate the mechanism of polarization transfer from parahydrogen-derived hydride protons to F-19 nucleus in millitesla and microtesla magnetic field regimes in N-15-3-E-19-pyridine and N-14-3-F-19-pyridine. We found the mismatch between N-15 and F-19 magnetic-field hyperpolarization profiles in the microtesla regime indicating that the spontaneous hyperpolarization process likely happens directly from parahydrogen-derived hydride protons to F-19 nucleus without spin-relaying via N-15 site. In the case of SABRE magnetic-field regime (millitesla magnetic-field range), we found that magnetic-field profiles for H-1 and F-19 hyperpolarization are very similar and F-19 polarization levels are significantly lower than H-1 SABRE polarization levels and lower than F-19 SABRE-SHEATH (i.e., obtained at microtesla magnetic field) polarization levels. Our findings support the hypothesis that in millitesla magnetic-field regime, the process of F-19 nuclei hyperpolarization is relayed via protons of the substrate and therefore is very inefficient. These findings are important in the context of improvement of the hyperpolarization hardware and rational design of the hyperpolarized molecular probes.