posted on 2020-03-17, 16:35authored byXinru Sheng, Errui Li, Yujuan Zhou, Run Zhao, Weijie Zhu, Feihe Huang
Two
monochloropyridine isomers, 2-chloropyridine (2-CP) and
3-chloropyridine (3-CP), are in need of a more
effective separation method besides rectification. Herein we offer
a facile and energy-saving adsorptive separation strategy using nonporous
adaptive crystals of perethylated pillar[5]arene (EtP5), perethylated pillar[6]arene (EtP6), perbromoethylated
pillar[5]arene (BrP5), and perbromoethylated pillar[6]arene
(BrP6), which possess different cavity sizes and substituents
and have never been employed in the separation of single-substituted
heterocyclic aromatic compounds. BrP6 crystals show a
marked preference for 2-CP in the equimolar mixture of 2-CP and 3-CP, affording it with 96.4% purity.
Single crystal diffraction experiments demonstrate that BrP6 has stronger host–guest interactions with 2-CP than 3-CP. The cycling experiments demonstrate that BrP6 crystals can be used at least five times without losing
their adsorption selectivity or capacity.