Complex-bearing Metal-Organic Frameworks: Snapshots of Reactions

精确测定分子结构的能力是化学的核心。通常，了解一个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，以至于确定分子的三维结构，特别是短寿命中间体，即使不是不可能使用传统方法，也是极具挑战性的。多年来，单晶x射线衍射提供了确定分子结构的主要方法，但该技术受到单晶、无缺陷或几乎无缺陷晶体要求的限制。获得某些分子种类的单晶并不总是可能的，例如，如果一种化合物是高活性的，少量生产的，或者只是没有采用单晶所需的有序排列。本提案旨在解决这些问题。我们将使用金属有机框架（mof），框架结构提供分子构建块的有序结构安排，作为捕获和支持金属配合物的平台，这些配合物能够进行后续反应-所有反应都在结晶相中。可以制备这样的系统，使得金属配合物，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，并位于允许将试剂运输到活性金属位点的通道旁边。然后，支撑的配合物可以在不失去框架的整体结晶度的情况下进行反应，从而可以确定产物的结构。由于与框架结构嵌入的反应性位点不受其他分子的影响，因此可以控制哪些分子被引入到反应性框架支持的复合物中，并防止反应性位点聚集在一起。通过这种方式，可以有效地在框架内捕获活性物质，从而确定它们的结构。这个项目将发展这一策略，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.