Highly selective removal of heterocyclic impurities from toluene by nonporous adaptive crystals of perethylated pillar[6]arene

The removal of heterocyclic impurities from toluene in the petrochemical industry is necessary but challenging. Herein, we provide a convenient and environmentally-friendly adsorptive separation strategy using nonporous adaptive crystals of perethylated pillar[6]arene (EtP6). These crystals show a highly selective preference for heterocyclic compounds, and are capable of selectively adsorbing them from a mixture of toluene and heterocyclic compounds, ultimately improving the purity of toluene from 96.78% to 99.00%. Single crystal structures indicate that the selectivity derives from the differences in the structural stability of guest-loaded EtP6 crystals.