Hydrothermal Breakdown of Flexible Metal-Organic Frameworks: A Study by First-Principles Molecular Dynamics
Hydrothermal Breakdown of Flexible Metal-Organic Frameworks: A Study by First-Principles Molecular Dynamics
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DOI：
10.1021/acs.jpclett.5b01926
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发表时间：
2015-11-05
影响因子：
5.7
通讯作者：
Fuchs, Alain H.
中科院分区：
文献类型：
--
作者：
Haigis, Volker;Coudert, Francois-Xavier;Fuchs, Alain H.
柔性金属有机框架，也称为软多孔晶体，已经被提出用于大量的技术应用，因为它们通过结构和性质的大变化来响应小的外部刺激，例如客体分子的吸附和温度或压力的变化。虽然这种行为在传感和驱动等应用中非常理想，但它们的极端灵活性也可能与稳定性降低同义。特别地，它们在工业环境中的性能受到在高温下和在水存在下缺乏稳定性的限制。在这里，我们使用第一性原理分子动力学来研究软多孔晶体的水热击穿。聚焦于材料MIL-53（Ga），我们表明，该结构的弱点是金属中心和有机连接体之间的键，并阐明水降低击穿活化自由能的机制。这使我们能够提出具有增加的热和水稳定性的MOFs的合成策略。
Flexible metal-organic frameworks, also known as soft porous crystals, have been proposed for a vast number of technological applications, because they respond by large changes in structure and properties to small external stimuli, such as adsorption of guest molecules and changes in temperature or pressure. While this behavior is highly desirable in applications such as sensing and actuation, their extreme flexibility can also be synonymous with decreased stability. In particular, their performance in industrial environments is limited by a lack of stability at elevated temperatures and in the presence of water. Here, we use first-principles molecular dynamics to study the hydrothermal breakdown of soft porous crystals. Focusing on the material MIL-53(Ga), we show that the weak point of the structure is the bond between the metal center and the organic linker and elucidate the mechanism by which water lowers the activation free energy for the breakdown. This allows us to propose strategies for the synthesis of MOFs with increased heat and water stability.