Predicting frequency dependent cross-relaxation rates from Molecular Dynamics simulations to provide a basis for a reliable interpretation of experimental NOE data

通过分子动力学模拟预测频率相关的交叉弛豫率，为实验 NOE 数据的可靠解释提供基础

• 批准号: 187094384
• 负责人: Dr. Dietmar Paschek
• 金额: --
• 依托单位: Abteilung Physikalische Chemie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/187094384?language=en
• 关键词: Predicting; frequency; dependent; cross; relaxation

There is still a large degree of uncertainty about the detailed structure and dynamics of ionic liquids (ILs). In particular, how those liquids are organized at the molecular level in terms of intermolecular atom-atom contacts. It has been argued that specific intermolecular interactions matter, and thus might be employed for tuning properties of ILs. To resolve those issues, it is essential to have a profound understanding of the detailed intermolecular structure and dynamics of ILs. Exploiting the Nuclear Overhauser Effect to the fullest could be instrumental in providing such a structural and dynamical picture for those molecular details. However, the situation for a neat ionic liquids is substantially different than for example for the case of large globular proteins. In ILs the conformational diversity is large, the lifetimes of encounter-configurations are typically short, and nonidealities in translatoric diffusion and reorientational dynamics have to be taken into account. Moreover, the specific nanoscale structure of ILs, imposed by the alternating cation/anion charge pattern has to be considered. Diffusion based formulae, developed for simple liquids, cannot be assumed to be adequate. We propose to use molecular dynamics simulations of realistic all atom models of imidazolium based ionic liquids with different counter ions, to fully characterize the frequency dependent cross-relaxation phenomena for particular meaningful spin-combinations. Temperature variation will be used to better characterize and dissect the influence of the structural and dynamical aspects of the intra- and inter-molecular relaxation processes. Moreover, the addition of molecules, such as chloroform, will be used to study the possible preferential interactions of those additives with anions or cations. Our aim is to lay a reliable foundation for the interpretation of experimentally determined NOEs carried out by our collaborator Ralf Giernoth within the SPP. In addition, the simulations will also help to suggest and design future NMR experiments of e.g.varying isotopic composition to verify and test the simulation results.

离子液体的详细结构和动力学仍然存在很大程度的不确定性。特别是，这些液体如何在分子水平上组织在分子间原子-原子接触方面。有人认为，特定的分子间相互作用的问题，因此可能会被用于调谐性能的离子液体。为了解决这些问题，有必要有一个详细的分子间的结构和动力学的离子液体的深刻理解。充分利用核奥弗豪泽效应可能有助于为这些分子细节提供这样的结构和动力学图像。然而，纯离子液体的情况与例如大球状蛋白质的情况基本上不同。在离子液体中的构象多样性是大的，的生命周期的构象是典型的短，在translatoric扩散和重取向动力学的非理想性必须考虑。此外，必须考虑由交替的阳离子/阴离子电荷模式施加的IL的特定纳米级结构。不能假定为简单液体开发的基于扩散的公式是适当的。我们建议使用分子动力学模拟的咪唑基离子液体与不同的反离子的现实的所有原子模型，充分表征的频率相关的交叉弛豫现象，特别是有意义的自旋组合。温度变化将用于更好地表征和剖析分子内和分子间弛豫过程的结构和动力学方面的影响。此外，添加分子，如氯仿，将用于研究这些添加剂与阴离子或阳离子的可能的优先相互作用。我们的目标是为我们的合作者Ralf Giernoth在SPP内进行的实验确定的NOE的解释奠定可靠的基础。此外，模拟还将有助于建议和设计未来的NMR实验，例如改变同位素组成，以验证和测试模拟结果。