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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Distance Measurements by Dipolar Recoupling Two-Dimensional Solid-State NMR
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Distance Measurements by Dipolar Recoupling Two-Dimensional Solid-State NMR

机译：通过偶极耦合二维固态NMR进行距离测量

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摘要

We present a two-dimensional NMR technique for the measurement of dipolar couplings in polycrystalline solids. This experiment is fully transverse and used a windowless dipolar recoupling pulse sequence (DRAWS, described in Gregory, D. M.; et al. Chem, Phys. Lett. 1995, 246, 654-663) to effect coherence transfer. Direct, internuclear coherence transfer produces negative cross-peaks in the 2D spectrum. Cross-peak development and experimental requirements for obtaining distances from the two-dimensional solid-state NMR spectra of two- and three-spin systems are discussed, and demonstrations are shown for thymidine-2,4-~(13)C_2 and L-alanine-~(13)C_3. Internuclear distances are derived by comparison of experimental cross-peak buildup curves with numerical simulations. In the three-spin system, indirect coherence-transfer mechanisms prohibit the interpretation of buildup curves as due to isolated spin pair interactions and limit the accuracy of some distance measurements. This 2D technique can also be used for spectral assignment, as demonstrated by an application to L-arginine·HCl-U-~(13)C,~(15)N.
机译：我们提出了一种二维NMR技术，用于测量多晶固体中的偶极耦合。该实验是完全横向的，并且使用无窗偶极子再耦合脉冲序列（DRAWS，描述于Gregory，D.M .;等人，Chem，Phys.Lett.1995，246，654-663）来实现相干转移。直接的核间相干转移会在2D光谱中产生负的交叉峰。讨论了从两旋和三旋系统的二维固态NMR谱图获取距离的跨峰发展和实验要求，并展示了对胸苷-2,4-〜（13）C_2和L-丙氨酸-〜（13）C_3。核间距离是通过比较实验的峰间累积曲线与数值模拟得出的。在三自旋系统中，间接相干传递机制由于孤立的自旋对相互作用而禁止解释累积曲线，并限制了一些距离测量的准确性。如在L-精氨酸·HCl-U-〜（13）C，〜（15）N上的应用所证明的，该2D技术也可以用于光谱分配。

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