Many unique adsorption properties of metal–organic frameworks (MOFs) have been revealed by diffraction crystallography, visualizing their vacant and guest-loaded crystal structures at the molecular scale. However, it has been challenging to see the spatial distribution of the adsorption behaviors throughout a single MOF particle in a transient equilibrium state. Here, we report three-dimensional (3D) visualization of molecular adsorption behaviors in a single crystalline particle of a MOF by in situ X-ray absorption fine structure spectroscopy combined with computed tomography for the first time. The 3D maps of water-coordinated Co sites in a 100 μm-scale MOF-74-Co crystal were obtained with 1 μm spatial resolution under several water vapor pressures. Through the visualization of the water vapor adsorption process, 3D spectroimaging revealed the mechanism and spatial heterogeneity of guest adsorption inside a single particle of a crystalline MOF.

中文翻译：

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金属有机框架单晶颗粒吸附分布的三维可视化

衍射晶体学揭示了金属有机框架（MOF）的许多独特的吸附特性，在分子尺度上可视化其空位和客体负载的晶体结构。然而，观察处于瞬态平衡状态的单个 MOF 颗粒的吸附行为的空间分布一直是一项挑战。在这里，我们首次通过原位X 射线吸收精细结构光谱与计算机断层扫描相结合，对 MOF 单晶颗粒中的分子吸附行为进行三维 (3D) 可视化。 100 μm 级 MOF-74-Co 晶体中水配位 Co 位点的 3D 图是在几种水蒸气压力下以 1 μm 空间分辨率获得的。通过水蒸气吸附过程的可视化，3D 光谱成像揭示了晶体 MOF 单个颗粒内部客体吸附的机制和空间异质性。