A new series of hydrogen-bonded helical aromatic hydrazide oligomers and polymer that bear phenylalanine tripeptide chains have been designed and synthesized. It was revealed that the helical structures could insert into lipid bilayers to form unimolecular channels. The longest oligomeric and polymeric helical channels exhibited an NH4+/K+ selectivity that was higher than that of natural gramicidin A, whereas the transport of a short helical channel for Tl+ could achieve an efficiency as high as that of gramicidin A.