Natural-Abundance Solid-State 2H NMR Spectroscopy at High Magnetic Field

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• 作者：Abil E. Aliev ; Sam E. Mann ; Dinu Iuga ; Colan E. Hughes ; Kenneth D. M. Harris
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：June 9, 2011
• 年：2011
• 卷：115
• 期：22
• 页码：5568-5578
• 全文大小：993K
• 年卷期：v.115,no.22(June 9, 2011)
• ISSN：1520-5215

文摘

High-resolution solid-state ²H NMR spectroscopy provides a method for measuring ¹H NMR chemical shifts in solids and is advantageous over the direct measurement of high-resolution solid-state ¹H NMR spectra, as it requires only the application of routine magic angle sample spinning (MAS) and routine ¹H decoupling methods, in contrast to the requirement for complex pulse sequences for homonuclear ¹H decoupling and ultrafast MAS in the case of high-resolution solid-state ¹H NMR. However, a significant obstacle to the routine application of high-resolution solid-state ²H NMR is the very low natural abundance of ²H, with the consequent problem of inherently low sensitivity. Here, we explore the feasibility of measuring ²H MAS NMR spectra of various solids with natural isotopic abundances at high magnetic field (850 MHz), focusing on samples of amino acids, peptides, collagen, and various organic solids. The results show that high-resolution solid-state ²H NMR can be used successfully to measure isotropic ¹H chemical shifts in favorable cases, particularly for mobile functional groups, such as methyl and 鈭扤⁺H₃ groups, and in some cases phenyl groups. Furthermore, we demonstrate that routine ²H MAS NMR measurements can be exploited for assessing the relative dynamics of different functional groups in a molecule and for assessing whole-molecule motions in the solid state. The magnitude and field-dependence of second-order shifts due to the ²H quadrupole interaction are also investigated, on the basis of analysis of simulated and experimental ¹H and ²H MAS NMR spectra of fully deuterated and selectively deuterated samples of the 伪 polymorph of glycine at two different magnetic field strengths.