Complex-bearing Metal-Organic Frameworks: Snapshots of Reactions

精确确定分子结构的能力是化学的核心。通常，了解分子的结构可以对该分子的性质和反应性提供宝贵的见解。然而，许多反应进行得如此之快，以至于使用常规方法来确定分子的三维结构，特别是短寿命的中间体，即使不是不可能的，也可能是巨大的挑战。多年来，单晶X射线衍射提供了确定分子结构的主要方法，但该技术受到对单晶，没有或几乎没有缺陷的晶体的要求的限制。并不总是能够获得某些分子种类的单晶，例如，如果化合物是高反应性的，以少量生产，或者根本不采用单晶所需的良好有序排列。我们将使用金属有机框架（MOFs），这种框架结构提供分子构建块的有序结构排列，作为捕获和支持能够进行后续反应的金属络合物的平台-所有这些都在结晶相中。可以制备这样的系统，使得金属络合物（包括模拟催化过程中使用的化合物的系统）位于框架的支柱上，并且位于允许将试剂运输到反应性金属位点的通道旁边。然后，负载的络合物可以进行反应而不损失框架的整体结晶度，从而可以确定产物的结构。由于反应性位点被保护不受嵌入框架结构的其他分子的影响，因此可以控制将哪些分子引入反应性框架支撑的复合物中并防止反应性位点聚集在一起。通过这种方式，可以有效地将活性物质捕获在框架内，从而可以确定它们的结构。这个项目将开发这种策略，为我们提供一种方法来拍摄分子反应的“快照”。

The ability to precisely determine molecular structure lies at the heart of chemistry. Often, understanding the structure of a molecule gives invaluable insight into the properties and reactivity of that molecule. However, many reactions proceed so rapidly that the determination of the three-dimensional structure of a molecule, particularly short-lived intermediates, can be enormously challenging if not impossible using conventional approaches. For many years single crystal X-ray diffraction has provided the primary methodology for determining molecular structure, but the technique is limited by the requirement for a single crystal, a crystal without, or nearly without, flaws. It is not always possible to obtain a single crystal of some molecular species, for example if a compound is highly reactive, produced in small quantities or simply does not adopt the well-ordered arrangements required for single crystals. This proposal seeks to address these issues.We will use metal-organic frameworks (MOFs), framework structures that provide ordered structural arrangements of molecular building-blocks, as a platform for trapping and supporting metal complexes that are able to undergo subsequent reactions - all in a crystalline phase. It is possible to prepare such systems such that metal complexes, including systems that mimic compounds used in catalytic processes, sit upon the struts of the framework and are positioned next to channels that allow transport of reagents to the reactive metal site. The supported complexes can then undergo reactions without losing the overall crystallinity of the framework, allowing determination of the structure of the products. As the reactive site is protected from other molecules, embedded with the framework structure, it is possible to control which molecules are introduced to the reactive framework-supported complex and to preclude reactive sites coming together. In this way it is possible to effectively trap reactive species within the framework, allowing determination of their structures. This project will develop this strategy providing us with a method to take 'snapshots' of molecular reactions.