Selective Gradient Separation of Aminophenol Isomers by Cucurbit[6]Uril

Abstract

Separation of aminophenol isomers from their mixture is dominantly crucial in chemical industries. Herein, the selective adsorption of Para-Aminophenol (PAP), Meta-Aminophenol (MAP) and Ortho-Aminophenol (OAP) has been executed by using cucurbit[6]uril (Q[6]). The Q[6] has adsorbed PAP and MAP from aminophenol isomers mixture with remarkably high selectivity, resulting in the separation of PAP from 1:1:1 v/v/v PAP:MAP:OAP mixture at 25℃, and yielding in a single adsorption cycle PAP with the purity of > 96.70%. Again, Q[6] has been utilized to isolate MAP from 1:1 v/v MAP:OAP mixture at 60 ℃, yielding in a single adsorption cycle MAP and OAP with >94.16% and 91.46% purities, respectively. Single-crystal structures, powder X-ray diffraction patterns, and molecular simulations have suggested that such selectivity has not only originated from guest-induced structural changes in Q[6], but also has been attributed to the simple cavity/ pore size effect. The isolated PAP and MAP and Q[6] can be quickly resolved in organic solvents and recovered, suggesting reusability of the as-synthesized material towards selective isolation of isomers for multiple cycles without any significant loss in performance.

Keywords: Cucurbit[6]uril, Separation, aminophenol isomers, host-guest complex, Supramolecular Chemistry