FOR 2433: Switchable Metal-Organic Frameworks (MOF-Switches)

多孔材料在气相和液相分离、能量储存、催化剂以及光学和化学传感方面发挥着关键作用。金属有机框架（MOF）因其极高的孔隙率和模块可调性而在其他多孔材料中脱颖而出。虽然大多数多孔固体（和M0 F）是刚性的，但近年来发现了一类新颖且独特的可切换M0 F。这些材料仅动态地打开它们的孔，作为对在气体吸收期间与前所未有的逐步晶胞体积变化（超过240%）相关的特征浓度下的气体或液体的存在的响应。这种可切换的M0 F能够通过打开它们的孔来特异性地响应或甚至识别某些类型的分子种类，从而导致物理（即磁性、光密度、体积密度等）的逐步变化。和化学特性（催化活性、反应性）。 此外，它们在不存在相应物质的情况下可逆地关闭它们的孔。在这样的材料中的动态现象的原理理解将代表一个独特的技术基础，用于设计可切换的催化剂，过滤器，阈值传感器，或刺激诱导的药物输送的受体系统与集成的键锁功能。然而，到目前为止，可切换的MOF（也称为门控或呼吸MOF）的发现基本上是偶然的。今天，只有有限数量的这种化合物是已知的，它是不可能合理地预测新的可切换的结构，因为根本的微观结构的原则，负责这样一个高度的灵活性，不理解。对于可切换MOFs在分离，催化或传感方面的技术发展，需要对潜在的结构原理和气固相互作用机制有基本的了解。新的研究单位主要解决了在固态和基本原则的孔隙度切换现象的基本原理。针对理想化的模型材料，网络成分的灵活性程度的作用将研究在一个合作和密切协调的实验和理论方法，以得出一个预测模型的框架灵活性。将建立一个可扩展的物理表征工具，使原位全局散射技术（XRD）和原位局部探针光谱（NMR，EPR，EXAFS）的应用，以分析吸附/解吸过程中的主体/客体相互作用引起的微观结构转变和动力学。只有在一个重点研究单位的跨学科努力可以提供所需的结构，以开发可切换的MOF的预测框架，促进理论家，合成化学家和物理学家的密切合作。

Porous materials play a key role in gas and liquid phase separations, energy storage, as catalysts and for optical and chemical sensing. Metal-Organic Frameworks (MOFs) stand out among other porous materials due to their extremely high porosity and modular tunability. While the majority of porous solids (and MOFs) is rigid, a novel and unique class of switchable MOFs was discovered in recent years. These materials only open their pores dynamically, as a response to the presence of gases or liquids at a characteristic concentration associated with unprecedented, step-wise unit cell volume changes (more than 240 %) during gas uptake. Such switchable MOFs are able to specifically respond or even recognize certain types of molecular species by opening their pores, resulting in a step-wise change of physical (i.e. magnetism, optical density, bulk density, etc.) and chemical characteristics (catalytic activity, reactivity). Moreover, they reversibly close their pores in the absence of the respective species. A principle understanding of the dynamic phenomena in such materials would represent a unique technological basis for the design of switchable catalysts, filters, threshold sensors, or stimulus induced drug delivery by receptor systems with integrated key-lock functionality. However, so far the discovery of switchable MOFs (also named gating, or breathing MOFs) was essentially accidental. Today only a limited number of such compounds are known, and it is impossible to rationally predict new switchable structures, because the underlying microstructural principles, responsible for such a high degree of flexibility, are not understood. For the technological development of switchable MOFs in separation, catalysis, or sensing, a fundamental understanding of the underlying structural principles and gas-solid interaction mechanisms is needed. The new research unit primarily addresses the fundamentals of porosity switching phenomena in the solid state and the underlying principles. Targeting idealized model materials, the role of network constituents on the degree of flexibility will be studied in a collaborative and closely coordinated experimental and theoretical approach in order to derive a predictive model for framework flexibility. Parallelized physical characterization tools will be established enabling the application of in situ global scattering techniques (XRD) and in situ local probe spectroscopies (NMR, EPR, EXAFS) in order to analyze the microscopic structural transformations and dynamics induced by host/guest interactions during adsorption/desorption. Only an interdisciplinary effort in a focused research unit can provide the structure required to develop a predictive framework for switchable MOFs fostering an intense cooperation of theoreticians, synthetic chemists, and physicists.