Abstract The Co(bdp) family has been widely investigated for the adsorption properties of gas molecules such as hydrogen, nitrogen, and methane. In this paper, the structural and mechanical properties of the Co(bdp) family, including Co(bdp), Co(bdp)-p-F2, Co(bdp)-Me2, and Fe(bdp), were studied based on first-principles theory. Using the methane adsorption behaviours of the Co(bdp) family as references, the adsorption properties of the Co(bdp) family were analysed by studying the structural properties. The adsorption properties can be estimated by analysing the accessible porous channel and ligand arrangement of the frameworks. This study can guide the design of flexible organic frameworks for specific adsorption or separation requirements. The effects of mechanical pressure and adsorbate molecules on the structural transition were analysed to reveal the mechanism of the structural transition of Co(bdp) when adsorbing gas molecules. The applied mechanical pressure from 0 to 50 bars will not result in a structural transition. The structural transition from the collapsed phase to the expanded phase induced by adsorbate molecules was simulated by applying expansion strains to the collapsed Co(bdp) phase. An intrinsic barrier of 13.15 eV per unit cell is present in the structural transition of Co(bdp). The energy necessary to overcome the energy barrier can be provided by the adsorbate molecular insertion. The simulation method in the present study is potentially applicable to the structural transition analysis of other flexible metal-organic frameworks.

中文翻译：

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与柔性金属有机骨架 Co(bdp) 的结构和机械性能相关的本征吸附行为

摘要 Co(bdp) 家族已被广泛研究用于气体分子（如氢气、氮气和甲烷）的吸附特性。本文首先研究了 Co(bdp) 家族的结构和力学性能，包括 Co(bdp)、Co(bdp)-p-F2、Co(bdp)-Me2 和 Fe(bdp)。 ——原理理论。以Co(bdp)族的甲烷吸附行为为参考，通过研究结构性质，分析了Co(bdp)族的吸附性能。吸附特性可以通过分析框架的可及多孔通道和配体排列来估计。这项研究可以指导针对特定吸附或分离要求的灵活有机框架的设计。分析了机械压力和吸附物分子对结构转变的影响，以揭示吸附气体分子时 Co(bdp) 结构转变的机制。从 0 到 50 巴施加的机械压力不会导致结构转变。通过对塌陷的 Co(bdp) 相施加膨胀应变来模拟由吸附物分子诱导的从塌陷相到膨胀相的结构转变。Co(bdp) 的结构转变中存在每个晶胞 13.15 eV 的本征势垒。克服能垒所需的能量可以由吸附分子插入提供。本研究中的模拟方法可能适用于其他柔性金属有机骨架的结构转变分析。