Complex-bearing Metal-Organic Frameworks: Snapshots of Reactions

点击翻译按钮获取中文摘要

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.