Application of NMR spectroscopy for the investigation of structure-mobility relations in nanoporous host-guest systems in concerted action with IR Micro-Imaging

在KA 953/20-1,2项目的过程中，重点是基于仪器和系统的工作，为新的微成像方法（用红外和干涉显微镜测量瞬态浓度曲线）奠定了基础。它们为探索纳米孔主客体体系的分子动力学提供了新的途径。脉冲场梯度核磁共振扩散测量（PFG NMR）是另一种微观方法，它以双重方式互补。首先，它是在平衡条件下应用的，其次，在温度和压力的变化中（从而在客体负载的变化中），可以覆盖更大的范围（此外，这种变化是用更少的实验努力实现的）。PFG核磁共振和微成像协同应用的潜力将在本项目中有目的地得到利用，以加深我们对纳米多孔材料分子动力学的了解。该提案与C. Chmelik的“微成像用于探索纳米多孔材料中的扩散和反应”的申请同时提交。只有协调使用这两种技术，才能成功地解决所提出的问题。除了PFG核磁共振在特定领域（包括温度、压力和超过电流限制的观察时间的变化）使用的技术和仪器开发之外，工作将集中在以下三个主题上：(i)自扩散（PFG NMR，本项目）和输运扩散（微成像）的联合测量为研究平衡和非平衡条件下输运现象的相互关系提供了前所未有的选择。这是目前空间约束下介观分子体系研究的基本问题之一，应成为第一课题研究的重点。（ii）其次，我们将检查并利用PFG NMR的选项来研究主-客相互作用对宿主结构和客体动力学的影响。这尤其包括在一个大范围内温度变化的选项，在这个范围内，预计特征会发生剧烈变化。为了理解这些过程，甚至可能仅仅是为了检测它们，一个特别广泛的变化是必不可少的。（iii）虽然发现第二个主题中考虑的主客体相互作用会产生一种全新的滞后现象，但介孔材料中的吸附滞后现象已经知道了100多年。然而，这一现象的起源和决定其时间依赖性的内在机制仍然是一个有争议的话题。通过PFG核磁共振和微成像结合应用所获得的信息，我们希望在我们研究计划的第三个主题中，为迄今为止无法获得的实验证据做出贡献。

With the focus on instrument-based and methodical work, in the course of the project KA 953/20-1,2, the background was set for new micro-imaging methods (measurement of transient concentration profiles with IR and interference microscopy). They provide a new approach to the exploration of molecular dynamics in nanoporous host-guest systems. NMR diffusometry with pulsed field gradients (PFG NMR) constitutes another microscopic method, which is complementary in a double fashion. First, it is applied under equilibrium conditions and, second, in the variation of temperature and pressure (and thereby of the guest loading) a much wider range can be covered (moreover, the variation is achieved with much less experimental effort). The potential offered by the concerted application of PFG NMR and Micro-Imaging shall be purposefully employed in this project to deepen our knowledge on molecular dynamics in nanoporous materials. The proposal is submitted in parallel with the application of C. Chmelik on "Micro-Imaging for the exploration of diffusion and reaction in nanoporous materials". A successful approach of the posed questions will be achieved only by the concerted use of both techniques. Besides technical and instrument-based developments for the use of PFG NMR in the particular fields (including the variation of temperature, pressure and observation time above the current limits), the work will be centered on the following three topics: (i) The combined measurement of self-diffusion (PFG NMR, this project) and transport diffusion (Micro-Imaging) establishes unprecedented options for the investigation of the interrelation of transport phenomena under equilibrium and non-equilibrium conditions. This is one of the fundamental questions of current research in the investigation of mesoscopic molecular systems under spatial confinement, which shall be in the focus of the studies within the first topic. (ii) We are, second, going to examine and to exploit the options of PFG NMR to study the impact of host-guest interactions on host structure and guest dynamics. This includes, in particular, the option of temperature variation over a wide range, in which drastic changes in the characteristics are expected. For the understanding of these processes and, possibly, even for their mere detection, a particular wide variation is essential. (iii) While the host-guest interactions considered in the second topic was found to give rise to a completely new type of hysteresis phenomena sorption hysteresis in mesoporous materials is known since over 100 years. However, the origin of this phenomenon and the intrinsic mechanisms determining its time dependence are still a topic of controversial discussion. With the information obtained by the combined application of PFG NMR and Micro-Imaging on the intrinsic dynamics of such systems we hope to contribute, within a third topic of our research plan, with so far inaccessible experimental evidence.