Molecules, Vol. 29, Pages 1697: On the Diffusion of Ionic Liquids in ILs@ZIF-8 Composite Materials: A Density Functional Theory Study

Molecules, Vol. 29, Pages 1697: On the Diffusion of Ionic Liquids in ILs@ZIF-8 Composite Materials: A Density Functional Theory Study
Molecules doi: 10.3390/molecules29081697
Authors:
Longlong Liu
Kun Jiang
Qingjun Chen
Lei Liu

Recently, composite materials consisting of ionic liquids (ILs) and metal–organic frameworks (MOFs) have attracted a great deal of attention due to their fantastic properties. Many theoretical studies have been performed on their special structures and gas separation applications. Yet, the mechanism for the diffusion of ILs inside MOF channels still remains unclear. Here, the DFT calculations (e.g., rigid and relaxed potential energy surface, PES, scan) together with frontier orbital analysis, natural charge analysis, and energy decomposition analysis were performed to investigate the diffusion behavior of a typical IL, [C4mim][PF6], into the ZIF-8 SOD cage. The PES profiles indicate that it is quite difficult for the cation [C4min]+ to diffuse into the cage of ZIF-8 through the pristine pores because of the large imidazole steric hindrance, which results in a large energy barrier of ca. 40 kcal·mol−1 at the least. Interestingly, the PES reveals that a successful diffusion could be obtained by thermal contributions, which enlarge the pore size through swing effects at higher temperatures. For example, both [C4mim]+ and [PF6]− could easily diffuse through the channel of the ZIF-8 SOD...

Source: Molecules - April 9, 2024 Category: Chemistry Authors: Longlong Liu Kun Jiang Qingjun Chen Lei Liu Tags: Article Source Type: research