Grenev Ivan V, Shubin Aleksandr A, Solovyeva Marina V, Gordeeva Larisa G
Boreskov Institute of Catalysis, Ac. Lavrentiev av. 5, Novosibirsk 630090, Russia.
Novosibirsk State University, Pirogova str. 1, Novosibirsk 630090, Russia.
Phys Chem Chem Phys. 2021 Sep 29;23(37):21329-21337. doi: 10.1039/d1cp03242a.
Aluminum-based metal-organic framework (MOF) CAU-10-H is a promising candidate for heat transformation and water harvesting applications due to its hydrothermal stability, beneficial step-wise water adsorption isotherm and low toxicity. In this study, the effects of the framework flexibility and structural defects on the mechanism of water sorption in CAU-10-H were studied by grand canonical Monte Carlo (GCMC) methods. It was shown by the simulations that the rigid ideal MOF framework is hydrophobic. The account of the linker "flapping" motion during the simulations made the framework more hydrophilic due to unblocking of hydroxyl groups that are inaccessible to water molecules for the rigid structure model. However, this model cannot predict the experimental pressure, at which the step on the adsorption isotherm is observed. Based on this result, we suggested that the presence of structural defects could increase the MOF hydrophilicity. The investigation of the water adsorption using several models of defective structures demonstrated that even a small number of defects shift the calculated position of the step on the adsorption isotherm towards the experimental values. The results obtained in this study emphasize that the controlled synthesis of defective structures is one of the most efficient methods of regulating the MOF adsorption properties.
基于铝的金属有机框架（MOF）CAU-10-H因其水热稳定性、有利的逐步水吸附等温线和低毒性，是热转换和水收集应用的一个有前景的候选材料。在本研究中，通过巨正则蒙特卡罗（GCMC）方法研究了框架柔性和结构缺陷对CAU-10-H中水吸附机理的影响。模拟结果表明，刚性理想MOF框架是疏水的。模拟过程中考虑连接体的“摆动”运动会使框架更亲水，这是因为对于刚性结构模型，水分子无法接触到的羟基被打开了。然而，该模型无法预测观察到吸附等温线上台阶的实验压力。基于这一结果，我们认为结构缺陷的存在会增加MOF的亲水性。使用几种缺陷结构模型对水吸附的研究表明，即使少量缺陷也会使吸附等温线上台阶的计算位置向实验值偏移。本研究获得的结果强调，缺陷结构的可控合成是调节MOF吸附性能的最有效方法之一。
