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Pressure-induced phase transition of isoreticular MOFs: Mechanical instability due to ligand buckling
Microporous and Mesoporous Materials ( IF 5.2 ) Pub Date : 2020-11-18 , DOI: 10.1016/j.micromeso.2020.110765
Penghua Ying , Jin Zhang , Zheng Zhong

Since MOFs are often upon varied pressures in gas adsorption/desorption process, understanding the mechanical stability of these ultraporous frameworks becomes extremely crucial. In this paper, taking the isoreticular DUT material as an example, the relation between the mechanical stability of isoreticular MOFs and their ligands is investigated by real-time molecular dynamics simulations as well as three state of art computational approaches including Born stability criteria, anisotropy in elastic moduli and pressure-versus-volume equations. It is found that the global instability of DUT materials is driven by the local buckling of their ligand backbones. Inspired by this finding, we develop here a mechanical model based on three parameters including the topology constant, the elastic modulus of ligand and the ligand length. Through comparing to the results extracted from computational methods, it is found that our mechanical model is reliable in describing the critical transition pressure of various isoreticular MOF materials such as DUT and IRMOF materials. The mechanical model developed here not only provides a design criterion for isoreticular MOF crystals to modify their rigid/flexible properties, but also can be utilized to give a quick prediction of the critical transition pressure of isoreticular MOFs.



中文翻译:

等压MOF的压力诱导相变:配体屈曲引起的机械不稳定性

由于MOF在气体吸附/解吸过程中通常处于变化的压力下,因此了解这些超多孔骨架的机械稳定性变得至关重要。本文以等网状DUT材料为例,通过实时分子动力学模拟以及三种先进的计算方法,包括玻恩稳定性判据,各向异性和各向异性,研究了等网状MOF及其配体的机械稳定性之间的关系。弹性模量和压力对体积方程。发现DUT材料的整体不稳定性是由其配体主链的局部屈曲驱动的。受此发现启发,我们在此基于三个参数开发了一个机械模型,包括拓扑常数,配体的弹性模量和配体长度。通过与从计算方法中提取的结果进行比较,发现我们的力学模型在描述各种等网状MOF材料(例如DUT和IRMOF材料)的临界转变压力方面是可靠的。此处开发的力学模型不仅为等网状MOF晶体提供了设计标准,以修改其刚性/柔韧性,而且还可以用于快速预测等网状MOF的临界转变压力。

更新日期:2020-11-18
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