Adsorption-Induced Structural Transition of ZIF-8: A Combined Experimental and Simulation Study
Adsorption-Induced Structural Transition of ZIF-8: A Combined Experimental and Simulation Study
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DOI：
10.1021/jp500931g
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发表时间：
2014-04
影响因子：
3.7
通讯作者：
Hideki Tanaka;Shuji Ohsaki;Shotaro Hiraide;Daigo Yamamoto;Satoshi Watanabe;M. Miyahara
中科院分区：
文献类型：
--
作者：
Hideki Tanaka;Shuji Ohsaki;Shotaro Hiraide;Daigo Yamamoto;Satoshi Watanabe;M. Miyahara
沸石咪唑酸框架-8 （ZIF-8）具有“开门”框架，具有狭窄的孔径，通过客体吸附使2-甲基咪唑酸（MeIM）连接剂重定向而打开。本研究旨在利用自由能分析来深入了解由MeIM连接体重定向引起的吸附诱导结构转变的机制。我们将低温下的氩吸附实验与大正则蒙特卡罗模拟相结合，确定了MeIM连接器旋转角（θIM）和气体压力随自由能分布的函数。我们还估计了系统的能量涨落，这对讨论从亚稳态的结构转变至关重要。自由能分析的结果，例如，在91 K时，得出以下结论：随着气体压力的增加，MeIM连接体在θIM = 10.5°处逐渐重新定向，随后发生自发的结构过渡。
Zeolitic imidazolate framework-8 (ZIF-8) has a “gate-opening” framework with narrow pore apertures that swing open by reorientation of 2-methylimidazolate (MeIM) linkers enforced by guest adsorption. The present study aimed to employ free energy analysis to provide insight into the mechanism of the adsorption-induced structural transition that results from the reorientation of the MeIM linkers. We combined experimental Ar adsorption at cryogenic temperatures with grand canonical Monte Carlo simulations to determine the free energy profiles as functions of the rotational angle of the MeIM linker (θIM) and bulk gas pressure. We also estimated the energy fluctuation of the system, which is crucial to discussing the structural transition from a metastable state. The results from the free energy analysis, for example, at 91 K, suggest the following conclusions: A gradual reorientation of the MeIM linkers up to θIM = 10.5° occurs with increasing gas pressure that is followed by a spontaneous structural transiti...