Institute for Materials and Processes, School of Engineering, The University of Edinburgh, United Kingdom.
J Am Chem Soc. 2011 Jun 15;133(23):8900-2. doi: 10.1021/ja202154j. Epub 2011 May 19.
ZIF-8 is a zeolitic imidazole-based metal-organic framework with large cavities interconnected by narrow windows. Because the small size of the windows, it allows in principle for molecular sieving of gases such as H(2) and CH(4). However, the unexpected adsorption of large molecules on ZIF-8 suggests the existence of structural flexibility. ZIF-8 flexibility is explored in this work combining different experimental techniques with molecular simulation. We show that the ZIF-8 structure is modified by gas adsorption uptake in the same way as it is at a very high pressure (i.e., 14,700 bar) due to a swing effect in the imidazolate linkers, giving access to the porosity. Tuning the flexibility, and so the opening of the small windows, has a further impact on the design of advanced molecular sieving membrane materials for gas separation, adjusting the access of fluids to the porous network.
ZIF-8 是一种沸石咪唑酯骨架的金属有机骨架，具有由窄窗口相互连接的大空腔。由于窗口较小，原则上允许对 H(2)和 CH(4)等气体进行分子筛筛选。然而，ZIF-8 对大分子的意外吸附表明其存在结构灵活性。本工作结合不同的实验技术和分子模拟探索了 ZIF-8 的灵活性。我们表明，ZIF-8 结构通过气体吸附吸收而发生变化，与由于咪唑酯连接体的摆动效应而在非常高的压力（即 14700 巴）下发生的变化相同，从而使孔隙率得以实现。调节灵活性，也就是小窗口的开度，对气体分离用先进的分子筛膜材料的设计有进一步的影响，可调节流体进入多孔网络的通道。
