Pyridine/Oxadiazole‐Based Helical Foldamer Ion Channels with Exceptionally High K⁺/Na⁺ Selectivity

Abstract

Protein channels are characterized by high transport selectivity, which is essential for maintaining cellular function. Efforts to reproduce such high selectivity over the past four decades have not been very successful. We report a novel series of aromatic foldamer‐based polymeric channels where the backbone is stabilized by differential electrostatic repulsions among heteroatoms helically arrayed along the helical backbone. Nanotubes averaging 2.3 and 2.7 nm in length mediate highly efficient transport of K+ ions as a consequence of hydrophilic electron‐rich hollow cavities that are 3 Å in diameter. Exceptionally high K+ and Na+ selectivity values of 16.3 and 12.6, respectively, are achieved.

Polyhydrazide‐Based Organic Nanotubes as Efficient and Selective Artificial Iodide Channels

“…3.4 nm, Figure 1). Achieving this goal through polymerization has proven to be achallenging task, [11] and can mostly be ascribed to the low reactivity of amines and carboxylic acids,w hich are destined to form covalent bonds but are highly rigidified by intramolecular hydrogen bonds.I nf act, despite availability of diverse types of fully hydrogen-bonded aromatic foldamers [12] reported since the pioneering reports, [13] the hitherto reported longest nanotube with af ully hydrogen-bonded aromatic tubular cavity carries an average of 30 repeating units and ah elical height of 1.4 nm, [11a,14] while partially hydrogen-bonded polymers with am ore flexible backbone could reach 6.1 nm. [11a] In this work, we,f or the first time,r eport successful production of fully hydrogen-bonded, helically folded polymeric foldamers that possess al ong tubular cavity with as much as 14 nm in height, by polymerization of two readily accessible repeating units, A and B (Figure 1).…”

Reversible Ligand‐Gated Ion Channel via Interconversion between Hollow Single Helix and Intertwined Double Helix

“…The cation transport selectivity order of Cs + > Rb + > K + > Na + > Li + can be formulated, which agrees with their ionic diameters. This is further underpinning that the 1D hollow helical tube from 1 is responsible for ion transport (Figure S27) …”

“…This is further underpinning that the 1D hollow helical tube from 1 is responsible for ion transport ( Figure S27). [18] Single channel current traces are one of the most promising methods for providing convincing evidence of biomimetic ion channels. [19] Therefore, a planar lipid bilayer which is made up of 1,2-diphytanoyl-sn-glycero-3-phosphocholine (diPhyPC) was used to perform the conductance measurement experiments.…”

A Synthetic Phospholipid Derivative Mediates Ion Transport Across Lipid Bilayers

“…Therefore, ion transport through membrane is actually a supramolecular function (Fyles, 2007 ). Inspired by the functional sophistication of ion transporters in nature, supramolecular chemists have created a variety of synthetic systems to replicate the transport functions by using small molecules and synthetic compounds (Kim and Sessler, 2015 ; Si et al, 2015 ; Chen et al, 2018a , b , 2020 ; Wu et al, 2018 ; Zhang et al, 2019 ; Zheng et al, 2020 ). It is of biological importance to build artificial ion transporters with desired properties, which will not only help to elucidate the possible mechanism by biological transporters, but also to provide early diagnosis and potential medical applications for the treatment of diseases caused by structural and functional abnormalities (such as “channelopathies”) (Zaydman et al, 2012 ).…”