Artificial sodium-selective ionic device based on crown-ether crystals with subnanometer pores

Abstract

Biological sodium channels ferry sodium ions across the lipid membrane while rejecting potassium ions and other metal ions. Realizing such ion selectivity in an artificial solid-state ionic device will enable new separation technologies but remains highly challenging. In this work, we report an artificial sodium-selective ionic device, built on synthesized porous crown-ether crystals which consist of densely packed 0.26-nm-wide pores. The Na+ selectivity of the artificial sodium-selective ionic device reached 15 against K + , which is comparable to the biological counterpart, 523 against Ca2 + , which is nearly two orders of magnitude higher than the biological one, and 1128 against Mg2 + . The selectivity may arise from the size effect and molecular recognition effect. This work may contribute to the understanding of the structure-performance relationship of ion selective nanopores.

Angstrom-scale ion channels towards single-ion selectivity

“…Very recently, a perfect selectivity was observed for Na + over K + in the ionophore. 229 As for another example, crown-ether-based porous crystals with tubular subnanometer pores were reported, 132 showing a favorable transport of Na + over other metal ions, such as K + , Ca 2+ , and Mg 2+ (Fig. 14C).…”

“…Angstrom-sized ion channel devices/membranes were also fabricated by confined growth of zinc nitrate hydroxide and DA18C6-nitrate crystals into single glass nanopores, 132 growth of covalent organic framework membranes on nanoporous supports, 133 and liquid-crystalline nanostructured membranes. 134 Solid confinement conversion methods were developed to fabricate functional and angstrom-porous PSS@CuBTC 135 and DNA@-ZIF-8 136 (Fig.…”

“…So far, artificial Na + channels have been fabricated by macrocyclic antibiotic monensin, 226 cucurbituril (CB [5]), 210 calix [4]arene, 227 and crown ethers. 132,228 For example, a CB [5]-assembled channel 210 exhibited a Na + selectivity over K + . An amphiphilic calix [4]arene in the 1,3alternate conformation with pendant polyether substituents was assembled in lipid bilayers.…”

Biomimetic Nanochannels: From Fabrication Principles to Theoretical Insights

“…Very recently, Gao et al reported sodium-selective transport in crown-ether crystals based nanochannels, the separation ratio of Na + /K + can reach 15. [75] Other success examples include reversible-tuned nanofluidic diode based on interactions between the hydrophobic 1-(4-aminophenyl)-2,2,2-trifluoro-ethanone (APTE) molecules and carbonate ions, [76] fluoride-responsive nanochannels modified by 4-aminophenylboronic acid (APBA) (Figure 5b), [77] dopamine (DOPA)-modified funnel-shaped nanochannels for iron(III) detection with high sensitivity, [78] and 4-amino benzamidoxime (ABX) functionalized nanochannels for detection (Figure 5c) and removal of uranyl ions, etc. [79] Another aminoethyl-benzo-12-crown-4 (BC12C4NH 2 ) modified nanochannels can act as lithium-selective receptor device with high selectivity.…”

A New Strategy for Highly Efficient Separation between Monovalent Cations by Applying Opposite‐Oriented Pressure and Electric Fields

“…[9] To compete with their biological counterparts in selective ionic transport, many artificial ionic nanochannels/nanopores have been developed. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] Despite various exciting progresses, their selectivity between ions with the same charge and similar size is still low. [3] Although the record of the mono/divalent ion selectivity reaches more than 10 3 for metal-organic framework-based sub-nanochannels (MOFSNCs), [11] the selectivity between alkali metal ions is less than 10 for most of the artificial nanostructures such as synthetic ion channels called metal-organic polyhedral (MOP), [12] MOFSNCs, [11,13] single graphene nanopores, [14] carbon nanotubes (CNTs), [15] MXenes, [16] and graphene-based 2D materials.…”