Bouquet-shaped crown ether

A covalent pore required for bilayers must be approximately 40 A long and contain a polar core for ion transit and a non-polar exterior for membrane interaction. Oligopeptides with high helical content, polymeric crown ether and bouquet -shaped crown ethers have been reported. The only such... 

Functional artificial ion channels have been reported which illustrate the general criteria. The most obvious course is to prepare oligopeptides with hi helical content (S). Other reported systems are bas on cyclo xtrin (6), polymeric crown ethers (7), and "bouquet" shaped crown ether and cyclodextrin motifs (8). One of the most active systems is a simple tris-crown ether derivative repented by Gokel for the transport of sodium ions(9). All of these systems envisage a uni- or bi-molecular transmembrane structure, similar to the gramicidin structurd paradigm. 

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