Artificial K ⁺ Channels Formed by Pillararene-Cyclodextrin Hybrid Molecules: Tuning Cation Selectivity and Generating Membrane Potential

A class of artificial K ⁺ channels formed by pillararene-cyclodextrin hybrid molecules have been designed and synthesized. These channels efficiently inserted into lipid bilayers and displayed high selectivity for K ⁺ over Na ⁺ in fluorescence and electrophysiological experiments. The cation transport selectivity of the artificial channels is tunable by varying the length of the linkers between pillararene and cyclodexrin. The shortest channel showed specific transmembrane transport preference for K ⁺ over all alkali metal ions (selective sequence: K ⁺ > Cs ⁺ > Rb ⁺ > Na ⁺ > Li ⁺ ), and is rarely observed for artificial K ⁺ channels. The high selectivity of this artificial channel for K ⁺ over Na ⁺ ensures specific transmembrane translocation of K ⁺ , and generated stable membrane potential across lipid bilayers.