Isostructural MFM-300(Sc) and MFM-300(In): Adsorption Behavior to Determine Their Differences

Abstract

and MFM-300(In) are isostructural materials that experimentally exhibit similar benzene adsorption properties with a higher capture value for MFM-300(Sc). This difference is explained in this report with a theoretical study. Intermolecular interactions are analyzed with the electron density functional theory, using Quantum Theory of Atoms in Molecules (QTAIM) and Non-Covalent Interactions index (NCI). Theoretical results indicate the establishment of two interactions between the benzene molecule and two μ 2 -OH groups from MFM-300(In). Meanwhile, in MFM-300(Sc), there is only one interaction between a benzene molecule and the μ 2 -OH group. According to the NCI and QTAIM, this additional C−H•••O contact is with a neighbor μ 2 -OH from MFM-300(In). Therefore, MFM-300(In) shows two occupied μ 2 -OH groups. These μ 2 -OH groups are also less directed to the center of the pore. In combination with a higher BET (Brunauer, Emmett, and Teller) surface area, this inactivates the adsorption sites, affording a higher benzene uptake for MFM-300(Sc). We present an interesting explanation of adsorption behavior beyond experimentally available parameters such as surface area or pore volume, focusing on different molecular interactions. In this investigation, experiments and theory together explain the similarities and differences of these isostructural materials.

Computational tools to study non-covalent interactions and confinement effects in chemical systems

“…Another example of chemical confined systems is with Metal-Organic Structures (MOF). These systems have many atoms, and the adsorption of some molecules inside the MOFs is one of the main applications of these materials [71][72][73][74][75][76][77][78][79] In these systems, the characterization of the MOF-guest interactions is relevant. For example, the interaction of CO molecule with the MOF named InOF-1 was characterized by using the GPUAM code.…”

MFM-300(Sc): a chemically stable Sc(iii)-based MOF material for multiple applications

“…Vargas et al , 125 studied the adsorption capacity of benzene on MFM-300(Sc) and MFM-300(In) with adsorption isotherms from 0 to 0.85 P / P 0 at 298 K, obtaining 4.8 mmol g −1 of capture for MFM-300(Sc), which was slightly higher than that for MFM-300(In) of 3.5 mmol g −1 . DFT simulations indicated that the benzene molecule forms stable interactions in both MOFs, Bz@MFM-300(M), with formation energies of −84.09 kJ mol −1 for MFM-300(Sc) and −97.07 kJ mol −1 for MFM-300(In).…”