Direct Elucidation of the Gas Adsorption Behaviour of Metal-Organic Frameworks (MOFs) by In-situ Single Crystal X-ray Diffraction

金属有机骨架(MOF)构成了受到全球研究关注的最大一组晶体纳米多孔材料，过去20年来发表的约21000篇研究论文中报告的数千种金属有机骨架就是明证。MOF具有巨大的应用潜力，包括气体储存和分离技术，正在作为商业产品销售，用于高度有毒气体的气体储存/释放应用，例如PH3，以及防止水果成熟的控释产品。MOF在吸附氮气、二氧化碳、甲烷、二硫化氢等气体时表现出一系列令人兴奋的气体吸附现象，包括滞后和阶跃和栅极吸附。这些现象往往是由于框架结构的变化而促成的。气体吸附和其他数据已经证明了这些气体吸附现象的存在，计算模型为其作用的结构机理提供了一些预测性的见解。然而，在这些吸附行为中，很少有实验确定的晶体结构，这阻碍了对这些新行为的关键理解。该项目旨在通过实验确定各种工业相关气体在不同温度和压力下的不同负载引发的单晶到单晶转变过程中某些刚性和柔性骨架MOF的气体吸附行为。该项目将涉及合成单晶形式的已知或改性的MOF，表征包括单晶和粉末X射线衍射、扫描电子显微镜、气体吸附测量和其他相关光谱技术。该项目的重点将是使用原位单晶X射线结晶学，使用最先进的单晶X射线衍射仪和毛细管气室(工作温度范围为100-500K，压力范围为0-15bar)来获得气体载气MOF的晶体结构。该项目的成功将使人们能够通过实验确定这些吸附过程的实际机理，这将对学术界和工业界具有极大的吸引力，并通过更多的了解，将使未来多功能纳米多孔材料的改进设计成为可能。

Metal-organic frameworks (MOFs) form the largest group of crystalline nanoporous material that has been receiving global research attention, as evidenced by the several thousand MOFs reported within the ca. 21000 research papers produced over the past 20 years. MOFs have huge potential for a wide variety of applications including gas storage and separation technologies and are being sold as commercial products for gas storage/ release applications of highly toxic gases, for example, PH3, and in a controlled release product that prevents fruit ripening.MOFs exhibit a range of exciting gas adsorption phenomena including hysteresis, and stepped and gated adsorption when gases such as nitrogen, carbon dioxide, methane, hydrogen disulphide are adsorbed. These phenomena are often facilitated by framework structural changes. Gas adsorption and other data have demonstrated the existence of these gas adsorption phenomena and computational modelling has provided some predicative insight into the structural mechanism of their action. However, few experimentally determined crystal structures exist for these materials during these adsorption behaviours which prevent critical comprehension of these novel behaviours.This project aims to determine the gas adsorption behaviour of certain rigid and flexible framework MOFs by experimentally determining the crystal structures of the MOFs during single crystal-to-single crystal transitions instigated by different loadings of a diverse variety of industrially relevant gases at various temperatures and pressures.The project will involve the synthesis of known or modified MOFs in single crystal form, characterisation including single crystal and powder X-ray diffraction, scanning electron microscopy, gas adsorption measurements and other associated spectroscopic techniques. Particular emphasis of the project will be on using in-situ single crystal X-ray crystallography to obtain the crystal structures of gas loaded MOFs using state-of-the art single crystal X-ray diffractometers and a capillary gas cell (operating temperature range 100 - 500 K, pressure range 0 - 15 bar).Success of the project will enable experimental determination of the actual mechanisms for these adsorption processes that will be highly attractive to the academic and industrial communities and, through greater understanding, will enable enhanced design of future multifunctional nanoporous materials.