Highly Selective Artificial Cholesteryl Crown Ether K+‐Channels

The bacterial KcsA channel conducts K⁺ cations at high rates while excluding Na⁺ cations. Herein, we report an artificial ion‐channel formed by H‐bonded stacks of crown‐ethers, where K⁺ cation conduction is highly preferred to Na⁺ cations. The macrocycles aligned along the central pore surround the K⁺ cations in a similar manner to the water around the hydrated cation, compensating for the energetic cost of their dehydration. In contrast, the Na⁺ cation does not fit the macrocyclic binding sites, so its dehydration is not completely compensated. The present highly K⁺‐selective macrocyclic channel may be regarded as a biomimetic of the KcsA channel.