Molecular Ion Fishers as Highly Active and Exceptionally Selective K⁺ Transporters

We report here a unique ion-fishing mechanism as an alternative to conventional carrier or channel mechanisms for mediating highly efficient and exceptionally selective transmembrane K⁺ flux. The molecular framework, underlying the fishing mechanism and comprising a fishing rod, a fishing line and a fishing bait/hook, is simple yet modularly modifiable. This feature enables rapid construction of a series of molecular ion fishers with distinctively different ion transport patterns. While more efficient ion transports are generally achieved by using 18-crown-6 as the fishing bait/hook, ion transport selectivity (K⁺/Na⁺) critically depends on the length of the fishing line, with the most selective MF6-C14 exhibiting exceptionally high selectivity (K⁺/Na⁺ = 18) and high activity ( EC₅₀ = 1.1 mol % relative to lipid).