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Dynamic Nuclear Polarization with Vanadium(IV) Metal Centers
Chem ( IF 23.5 ) Pub Date : 2020-11-12 , DOI: 10.1016/j.chempr.2020.10.021
Sheetal Kumar Jain , Chung-Jui Yu , Christopher Blake Wilson , Tarnuma Tabassum , Danna E. Freedman , Songi Han

Dynamic nuclear polarization (DNP) harnesses the large polarization of electron spins to dramatically increase nuclear magnetic resonance (NMR) sensitivity. This study expands the scope of DNP beyond its traditional focus on hyperpolarizing the solvent network using exogenous polarizing agents (PAs). We introduce 1H DNP with endogenous V4+ centers positioned in a set of vanadyl complexes with tunable V4+-1H distances. We traced the polarization transfer from V4+ to 1H spins, specifically differentiating between direct V4+-1Hs polarization transfer and the 1H spin-diffusion-mediated bulk solvent 1H polarization buildup and illuminated the effect of the V4+-1H distance on these processes. These results deepen our understanding of polarization pathways and expand the catalog of PAs to broad-line transition metals. This study establishes crucial first steps toward employing strategically positioned endogenous paramagnetic metal centers for DNP and the conceptual framework of hyperfine DNP spectroscopy that merges both spatial and chemical diagnosis of target nuclear spins.



中文翻译:

钒(IV)金属中心的动态核极化

动态核极化(DNP)利用电子自旋的大极化来显着提高核磁共振(NMR)灵敏度。这项研究扩大了DNP的范围,使其超越了传统上对使用外源偏振剂(PAs)超极化溶剂网络的关注。我们引进1 ^ h DNP与内源性V 4+定位在一组氧钒配合物可调的V中心4+ - 1 ^ h的距离。我们跟踪从V极化转移4+1个ħ旋转时,直接V的特异性分化4+ - 1个HS极化转移和1个ħ自旋扩散介导的散装溶剂1和H偏振累积和照明的V的效果4+ - 1个这些过程ħ距离。这些结果加深了我们对极化途径的理解,并将PA的类别扩展到宽线过渡金属。这项研究建立了关键的第一步,即将战略定位的内生顺磁性金属中心用于DNP以及结合目标核自旋的空间和化学诊断的超精细DNP光谱学的概念框架。

更新日期:2020-11-12
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