Crown-Ether-Based Artificial K+ Selective Ionic Filter.

In this study, we have successfully synthesized bis (cholesterol-dibenzo-18-crown-6-ether)-pillar[5]arene compound 1 through a click reaction, which could spontaneously insert into lipid bilayers to form ion channel due to the membrane anchor cholesterol group and show significant transport activity of K⁺ superior to Na⁺, with a permeability ratio of K⁺/Na⁺ equal to 4.58. Compound 1 two crown ether modules act as selective filters similar to natural K⁺ channel, which are determined to 1 : 2 binding stoichiometry to K⁺ by Job's plot and NMR titration. This structurally unambiguously unimolecule artificial channel provides ideas for constructing highly K⁺/Na⁺ selective molecular filters.