Shifting the Selectivity of Perethylated Pillar[5]arene through Functionalization toward the Separation of Isomers of Ethyltoluene – A DFT and Molecular Dynamics Study

Isomers of ethyltoluene are widely utilized in various industries owing to their diverse properties. However, separating the meta‐ethyltoluene (MET) and para‐ethyltoluene (PET) isomers from their mixture, often produces during industrial production, poses a significant challenge. Conventional separation methods are ineffective because of the similar properties of isomers, and the process often generates environmentally harmful by‐products. To tackle this challenge, perethylated bromopillar[5]arenes (EBP5) are employed to selectively complex with PET, facilitating isomer separation. This study investigates tuning selectivity by replacing the bromo functionality with carboxylic acid and methoxy groups (ECP5 and EMP5), utilizing density functional theory calculations and molecular dynamics simulations. The complexation energies confirm that EBP5 effectively attracts PET, forming a stable host‐guest complex, while MET exhibits strong stability within the ECP5 and EMP5 environments. The NCI and QTAIM studies reveal the non‐covalent interactions stabilizing the isomers within the host cavities. A 10 ns molecular dynamics simulation verifies the stability and behavior of these complexes and isomers. This findings suggest that functionalized perethylated pillar[5]arenes can selectively separate para/meta isomers, with enhanced functionality and improves encapsulation. This research contributes to the development of selective host molecules for key organic compounds.