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

Confinement is a very common phenomenon in chemistry, for example, when molecules are located inside cavities. In these conditions, the electronic structure of atoms and molecules is modified. These changes could be mapped through the interaction with other molecules since non-covalent interactions between molecules are also influenced by confinement. In this work we address both topics, non-covalent interactions, and confined systems, using quantum chemistry tools with new software, emphasizing the importance of analyzing both fields simultaneously.

SO2 Capture at Low Pressure in a Prototypical MIL-53 Aluminum MOF Family: The Influence of Pore Expansion

Not only is excellent performance in SO2 capture by porous materials (uptake above 17 mmol g-1) relevant, but also finding a correlation between the architecture changes into a family and their SO2 adsorption is very useful. In this contribution, we studied the SO2 adsorption behavior (at very low pressure) of an Al(III)-MOF family that shares the pore architecture of MIL-53. The results indicate an inversely proportional trend for the SO2 capture and pore expansion, since by increasing the length of the channel pore, the SO2 uptake gradually decreases. In addition, this trend is clearly observed in the heat of adsorption, which describes the interaction between the SO2 molecule and the μ-OH functional group. These finding are supported by experimental analysis and computational studies.

SO2 Capture by Two Aluminum-Based MOFs: Rigid-like MIL-53(Al)-TDC versus Breathing MIL-53(Al)-BDC

Metal-organic frameworks MIL-53(Al)-TDC and MIL-53(Al)-BDC were explored in the SO₂ adsorption process. MIL-53(Al)-TDC was shown to behave as a rigid-like material upon SO₂ adsorption. On the other hand, MIL-53(Al)-BDC exhibits guest-induced flexibility of the framework with the presence of multiple steps in the SO₂ adsorption isotherm that was related through molecular simulations to the existence of three different pore opening phases narrow pore, intermediate pore, and large pore. Both materials proved to be exceptional candidates for SO₂ capture, even under wet conditions, with excellent SO₂ adsorption, good cycling, chemical stability, and easy regeneration. Further, we propose MIL-53(Al)-TDC and MIL-53(A)-BDC of potential interest for SO₂ sensing and SO₂ storage/transportation, respectively.