Generating and sustaining long-lived spin states in 15N,15N′-azobenzene
Generating and sustaining long-lived spin states in 15N,15N′-azobenzene
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DOI：
10.1038/s41598-019-56734-y
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发表时间：
2019-12-27
影响因子：
4.6
通讯作者：
Yurkovskaya, Alexandra V.
中科院分区：
文献类型：
--
作者：
Sheberstov, Kirill F.;Vieth, Hans-Martin;Yurkovskaya, Alexandra V.
长寿命自旋态 (LLS) 在维持非热自旋有序以及通过核磁共振 (NMR) 光谱研究各种慢过程方面具有广阔的前景。这种应用特别感兴趣的是含有几乎等效磁核的分子，即使在高磁场下也具有 LLS。在这项工作中，我们报告了反式-N-15,N-15'-偶氮苯的 LLS。 N-15 自旋对的单线态表现出长寿命的特征。我们解决了生成和检测这种 LLS 的挑战性问题，并通过将更高的质子磁化强度转换为 N-15 单线态自旋顺序来进一步增加 LLS 数量。就这种自旋顺序的寿命而言，已经测试了各种方案来维持 LLS。在 16.4T 下，寿命达到了 17 分钟，该值比 N-15 在该磁场中的纵向弛豫时间长约 250 倍。我们相信，这种延长的弛豫时间，以及偶氮苯的光致变色特性，在光照射下会改变构象，并且可以通过使用仲氢进行超极化，有望用于设计具有光可切换长寿命超极化的新实验。
Long-Lived spin States (LLSs) hold a great promise for sustaining non-thermal spin order and investigating various slow processes by Nuclear Magnetic Resonance (NMR) spectroscopy. Of special interest for such application are molecules containing nearly equivalent magnetic nuclei, which possess LLSs even at high magnetic fields. In this work, we report an LLS in trans-N-15,N-15'-azobenzene. The singlet state of the N-15 spin pair exhibits a long-lived character. We solve the challenging problem of generating and detecting this LLS and further increase the LLS population by converting the much higher magnetization of protons into the N-15 singlet spin order. As far as the longevity of this spin order is concerned, various schemes have been tested for sustaining the LLS. Lifetimes of 17 minutes have been achieved at 16.4T, a value about 250 times longer than the longitudinal relaxation time of N-15 in this magnetic field. We believe that such extended relaxation times, along with the photochromic properties of azobenzene, which changes conformation upon light irradiation and can be hyperpolarized by using parahydrogen, are promising for designing new experiments with photo-switchable long-lived hyperpolarization.