CAJ | 학술논문

金属-有机骨架材料（metal-organic frameworks，MOFs）的纳微结构可根据特定需求进行功能化调控，有望成为良好的工业催化材料。由于溶剂环境可对其界面微环境及催化性能产生较大影响，因此研究溶剂化效应对于MOF材料的影响具有重要的意义。以Cu-BTC和MOP-15两种典型MOF材料作为研究对象，采用密度泛函理论与COSMO溶剂模型相结合的方法，考察了溶剂效应对材料几何结构与电子稳定性的影响，并研究了不同溶剂对其Lewis酸性的影响。结果表明，溶剂环境可以使材料中的电子从不饱和配位金属处转移到有机配体上，进而使材料具有更强的 Lewis 酸性，并且电负性较大有机配体构成的 MOF 材料，受溶剂效应的影响更加显著。本工作将有助于深入理解溶剂化对调控MOF材料液相催化活性的影响。
금속-유궤골가재료（metal-organic frameworks，MOFs）적납미결구가근거특정수구진행공능화조공，유망성위량호적공업최화재료。유우용제배경가대기계면미배경급최화성능산생교대영향，인차연구용제화효응대우MOF재료적영향구유중요적의의。이Cu-BTC화MOP-15량충전형MOF재료작위연구대상，채용밀도범함이론여COSMO용제모형상결합적방법，고찰료용제효응대재료궤하결구여전자은정성적영향，병연구료불동용제대기Lewis산성적영향。결과표명，용제배경가이사재료중적전자종불포화배위금속처전이도유궤배체상，진이사재료구유경강적 Lewis 산성，병차전부성교대유궤배체구성적 MOF 재료，수용제효응적영향경가현저。본공작장유조우심입리해용제화대조공MOF재료액상최화활성적영향。
The nanoporous structures of metal-organic frameworks (MOFs) can be functionally regulated according to specific targets of interest, and thus such types of solids can be considered as promising industrial catalytic materials. Since interface microenvironments and catalytic properties of MOFs might be affected by the solvents, it is necessary to study the influence of solvent effects on their catalytic activities. Although MOFs with coordinatively unsaturated metal sites (CUMs) have shown promising applications in liquid-phase catalysis, the related solvent effects on the Lewis acid catalytic performance of these CUMs are seldom investigated. In this work, density functional theory calculations were conducted to investigate the solvent effects on the properties of the Lewis acid sites in two typical MOFs, Cu-BTC and MOP-15, where the COSMO (conductor-like solvent model) was used to mimic the dielectric response of the solvent environments. Different relative dielectric constants were considered, including in vacuum, toluene, ethyl acetate, 1, 2-dichloroethane and acetonitrile. Using CO as the probe molecule, the solvent effects were examined by exploring the geometry parameters, the Mulliken charges, and the vibrational frequency as well as the adsorption energy of CO molecule around those CUMs. The strengths of Lewis acid sites could be enhanced with the increase of the dielectric constant. Further, the solvent effects became more evident in CUMs when the organic linkers had higher electronegativity. These observations provide fundamental insights into the regulation of the liquid-phase catalytic activity of MOFs using specific solvents.