Source: School of Chemistry
Written by: School of Chemistry
Edited by: Wang Dongmei

Transmembrane ion transport is of tremendous importance in physiology, its malfunction usually leads to serious body disorders. A lot of artificial ion channels or carriers were developed by scientists to study the mechanism and mimic the translocation of ions across lipid bilayer.  
 

Writing in the journal Angewandte Chemie, chemists from LIFM (Lehn Institute of Functional Materials) have designed a series of small molecules based on small macrocycle 15-crown-5 to facilitate alkali cation transport with exceptional selectivity and activity. 

One of the compound 3, is selective as carrier for Na⁺at low concentration. Meanwhile, at high concentration, this compound could self-assemble into channel which is selectively responsive for K⁺cations. Unlike 3, compound 4, 5, 6 bearing more rigid benzo-15-crown-5 moieties all favor K⁺over Na⁺. 

Furthermore, all of the active crown ethers have shown an electrogenic transport mechanism which means their transport rates follow as M⁺>H⁺, confirmed by HPTS assay coupled with protonophore FCCP. 

 Fig 1. (left) Schematic representation of self-assembled channel inside lipid bilayer; (right) two membrane transport mechanisms by crown ethers with or without protonophores
 

This study suggests that simple macrocyclic scaffolds hold significant promise for the development of innovative artificial ionophores biomimicking the functions of natural ones. 

For detailed information, please read the recently published paper “Structure - Driven Selection of Adaptive Transmembrane Na⁺Carriers or K⁺Channels” in Angewandte Chemie, international edition, doi: 10.1002/anie.201802570.
 

Link to the article: https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201802570