Bis-15-crown-5-ether-pillar[5]arene K+-Responsive Channels.

An artificial selective K+ channel is formed from the supramolecular organization on bis(benzo-15-crown-5- ether-ureido)-pillar[5]arene compound. This channel achieves a selectivity of SK+/Na+ = 5 for an initial transport rate of kK+ = 3.2 × 10-3 s-1. The cation-file diffusion occurs via selective macrocyclic-filters anchored on inactive supporting pillar[5]arene relays. The sandwich-type binding geometry of the K+ cation by two 15-crown-5 moieties sites is a key feature influencing channel efficiency.