论文标题
通过DNP和电子解耦观测附近的核上的核和MOF
Observing Nearby Nuclei on Paramagnetic Trityls and MOFs via DNP and Electron Decoupling
论文作者
论文摘要
动态核极化（DNP）是一种NMR灵敏度增强技术，可介导从未配对电子到NMR活性核的极化转移。尽管它成功地阐明了有关生物学和无机材料的重要结构信息，但详细的极化转移途径从电子到附近的电子，然后是大量溶剂核，最后是利益 - 雷因素的分子，不清楚。特别是，顺磁两极化剂中的核在将增强的NMR极化转移到更遥远的核中起着重要作用。尽管它们的重要性，但由于敏感性不佳，对这些核的直接观察是具有挑战性的。在这里，我们表明联合DNP和电子解耦方法可以促进这些核的直接NMR检测。我们通过在Trityl自由基上以0.35 t和80 K的电子去耦，通过电子与80 k耦合，在NMR强度上取得了约80％的提高。此外，我们使用电子去耦$ε$ 〜90 $ 〜90 $ 〜90 $ 〜11％，使用电子与磁磁性金属有机框架，己氧基二苯镁（MGHOTP MOF）上的NMR强度提高了11％。
Dynamic nuclear polarization (DNP) is an NMR sensitivity enhancement technique that mediates polarization transfer from unpaired electrons to NMR-active nuclei. Despite its success in elucidating important structural information on biological and inorganic materials, the detailed polarization-transfer pathway-from the electrons to the nearby and then the bulk solvent nuclei, and finally to the molecules of interest-remains unclear. In particular, the nuclei in the paramagnetic polarizing agent play significant roles in relaying the enhanced NMR polarizations to more remote nuclei. Despite their importance, the direct NMR observation of these nuclei is challenging because of poor sensitivity. Here, we show that a combined DNP and electron decoupling approach can facilitate direct NMR detection of these nuclei. We achieved an ~80 % improvement in NMR intensity via electron decoupling at 0.35 T and 80 K on trityl radicals. Moreover, we recorded a DNP enhancement factor of $ε$ ~ 90 and ~11 % higher NMR intensity using electron decoupling on a paramagnetic metal-organic framework, magnesium hexaoxytriphenylene (MgHOTP MOF).
