posted on 2020-03-31, 15:43authored byYujuan Zhou, Kecheng Jie, Run Zhao, Errui Li, Feihe Huang
Removal
of trace chlorobutane (CB) isomers is highly desired to
produce high grade 1-chlorobutane (1-CB) and 2-chlorobutane (2-CB).
Here, we report that nonporous adaptive crystals (NACs) of perethylated
pillar[5]arene (EtP5) and pillar[6]arene (EtP6) effectively remove
trace CB isomers. EtP5 NACs can remove trace 1-CB (2%) from 2-CB to
improve its purity from 98.0% to 99.9%, while EtP6 NACs can remove
trace 2-CB from 1-CB to improve its purity from 98.0% to 99.9%. The
adsorption of trace CB isomers results in the formation of new CB-loaded
crystal structures, whose thermostability is higher than their corresponding
isomer-loaded structures. This determines the selectivity of NACs
toward the trace CB isomers. Reversible transformations between nonporous
guest-free and guest-loaded structures make EtP5 and EtP6 highly recyclable.