New paradigms for NMR of organic solids

有机固体核磁共振的新范例

• 批准号: EP/H023291/1
• 负责人: Paul Hodgkinson
• 金额: $ 56.47万
• 依托单位: Durham University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FH023291%2F1
• 关键词: New; paradigms; NMR; organic; solids

Nuclear Magnetic Resonance (NMR) spectroscopy is a vital analytical tool across science. NMR is most usually applied to substances dissolved in solution since this considerably simplifies the interpretation of the results (spectra) that are obtained; molecular motion averages out interactions, such as the dipolar (through space magnetic) interaction between the magnetic nuclei. However, in many applications, particularly in materials chemistry and biology, it is impossible or inappropriate to apply NMR to samples in solutions and it is necessary to work with solid samples. This creates particular difficulties for studies using hydrogen (1H) NMR which is otherwise the most widely used form of NMR (including in medical imaging applications). Typical organic (carbon-containing) molecules contain high densities of hydrogen nuclei. Although an advantage in terms of the strength of the NMR signal, the multiple magnetic (dipolar) interactions between the hydrogen nuclei cause the NMR signal to decay quickly and broaden the NMR lines into uninformative broad features. This problem has traditionally been tackled in a couple of ways. Firstly by spinning the sample (magic-angle spinning), but unfeasibly high spinning rates would be required to completely remove the dipolar interactions. Secondly using radio-frequency irradiation to average out the dipolar interactions, but this can be technically complex and the results are very susceptible to experimental deficiencies. Since the line-broadening involves the interactions of multiple nuclear spins it has been difficult to model computationally and to investigate mathematically. As a result, progress in improving 1H NMR spectra in solids has been rather fitful.This project will tackle this bottle-neck for the development of solid-state NMR. Firstly by putting together a consortium of international research groups with complementary expertise (experimental, computational and theoretical) and equipment (including NMR spectrometers operating at some of the highest magnetic fields available worldwide) we will be able to tackle the problem simultaneously and systematically from different directions. Secondly, recent advances in spectrometer hardware, simulation and NMR theory mean that the individual tools are in place to make concerted progress. Finally we will be focussing on one parameter, the decay rate of the magnetisation, which is the key limiting factor. Previous work has addressed final NMR spectra, but since these are affected by a number of additional factors, this has tended to confuse the underlying issues. The large discrepancies between simulations and current experiments suggest that potentially major improvements are possible.Finding routes to producing high-quality NMR spectra of hydrogen-containing organic solids in a routine fashion will have a major impact on the practice of solid-state NMR. Some experiments which are currently impractical due to the length of time they would take will become practical and narrowing the NMR lines will allow new, finer spectral detail to be measured, such as weak interactions across hydrogen bonds connecting different components of crystal structures. As a result this proposal is being supported by a wide range of scientists, varying from users of solid-state NMR to manufacturers of pharmaceutics to suppliers of NMR equipment.

核磁共振波谱是一种跨科学的重要分析工具。核磁共振最常用于溶解在溶液中的物质，因为这大大简化了对所获得的结果(光谱)的解释；分子运动平均了相互作用，例如磁核之间的偶极(通过空间磁)相互作用。然而，在许多应用中，特别是在材料化学和生物学中，不可能或不适合将核磁共振应用于溶液中的样品，而必须对固体样品进行研究。这给使用氢(1H)核磁共振的研究带来了特别的困难，否则，氢(1H)核磁共振是最广泛使用的核磁共振形式(包括在医学成像应用中)。典型的有机(含碳)分子含有高密度的氢核。虽然就核磁共振信号的强度而言是一个优势，但氢核之间的多重磁(偶极)相互作用导致核磁共振信号迅速衰减，并将核磁共振谱线展宽为没有信息的广泛特征。这个问题传统上是通过几种方式解决的。首先通过旋转样品(魔角旋转)，但需要极高的旋转速度才能完全消除偶极相互作用。其次，使用射频辐射来平均偶极相互作用，但这可能是技术复杂的，结果非常容易受到实验缺陷的影响。由于谱线展宽涉及多个核自旋的相互作用，因此很难对其进行计算建模和数学研究。因此，改善固体核磁共振氢谱的进展相当适中。本项目将解决固体核磁共振发展的这一瓶颈。首先，通过建立一个具有互补专业知识(实验、计算和理论)和设备(包括在世界上一些最高磁场下运行的核磁共振光谱仪)的国际研究小组联盟，我们将能够从不同的方向同时和系统地解决这一问题。其次，光谱仪硬件、模拟和核磁共振理论方面的最新进展意味着单个工具已经到位，可以共同取得进展。最后，我们将集中讨论一个参数，即磁化的衰减率，这是关键的限制因素。以前的工作已经解决了最终的核磁共振谱，但由于这些谱受到许多额外因素的影响，这往往会混淆根本问题。模拟和当前实验之间的巨大差异表明，潜在的重大改进是可能的。找到以常规方式产生高质量含氢有机固体的核磁共振谱的方法将对固体核磁共振的实践产生重大影响。一些由于时间长而目前不切实际的实验将变得实用，缩小核磁共振谱线将允许测量新的、更精细的光谱细节，例如连接晶体结构不同成分的氢键之间的弱相互作用。因此，这一提议得到了广泛的科学家的支持，从固态核磁共振的用户到制药制造商再到核磁共振设备的供应商。

项目成果

Unexpected effects of third-order cross-terms in heteronuclear spin systems under simultaneous radio-frequency irradiation and magic-angle spinning NMR.

同时射频辐射和魔角旋转核磁共振下异核自旋系统中三阶交叉项的意外效应。

• DOI: 10.1063/1.3684879
• 发表时间: 2012
• 期刊: The Journal of chemical physics
• 作者: Tatton AS

Rationalising Heteronuclear Decoupling in Refocussing Applications of Solid-State NMR Spectroscopy.

• DOI: 10.1002/cphc.201601003
• 发表时间: 2017-02-17
• 期刊: Chemphyschem : a European journal of chemical physics and physical chemistry
• 作者: Frantsuzov I;Vasa SK;Ernst M;Brown SP;Zorin V;Kentgens AP;Hodgkinson P
• 通讯作者: Hodgkinson P

Simulating spin dynamics in organic solids under heteronuclear decoupling

模拟异核解耦下有机固体的自旋动力学

• DOI: 10.3929/ethz-b-000104622
• 发表时间: 2015
• 作者: Frantsuzov, Ilya