Endohedral gas adsorption by cucurbit[7]uril: a theoretical study

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Computational Chemistry

Background:

• Cucurbit[7]uril (CB[7]) is a macrocyclic host molecule with potential applications in molecular recognition and separation.
• Selective gas adsorption is crucial for environmental remediation and industrial processes, such as flue gas treatment.

Purpose of the Study:

• To investigate the adsorption selectivity of cucurbit[7]uril (CB[7]) for a diverse range of small gas molecules.
• To elucidate the underlying interactions governing the selective adsorption of sulfur dioxide (SO2) by CB[7].

Main Methods:

• Density Functional Theory (DFT) based computational study.
• Calculation of non-covalent interaction (NCI) indices.
• Energy Decomposition Analysis (EDA) to analyze binding interactions.

Main Results:

• CB[7] exhibits significantly higher selectivity for adsorbing SO2 compared to 13 other tested molecules, including hydrocarbons, halogens, nitrogen oxides, and carbon oxides.
• Dispersion forces are the dominant contributor to the stabilization of all studied complexes.
• Electrostatic interactions play a considerable role, particularly in the selective binding of SO2 within the CB[7] cavity.

Conclusions:

• The computational study confirms the high selectivity of CB[7] for SO2 adsorption.
• The combined effects of dispersion and electrostatic interactions are responsible for the observed selectivity, making CB[7] a potential candidate for SO2 separation from flue gas.