A covalent organic framework membrane with highly selective and permeable artificial sodium channels via ion recognition.

Wang, Jing; Zhang, Junwei; Jin, Pengrui; Wen, He; Dai, Ziwen; Tan, Hao; Yuan, Shushan; Yang, Jiakuan et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

Biological sodium channels efficiently discriminate between same-charge ions with similar hydration shells. However, achieving precise ion selectivity and high throughput in artificial ion channel fabrication remains challenging. Here, we investigate angstrom-scale channels in 15-crown-5 (15C5) functionalized COF membranes for fast, selective ion transport. Due to crown ether recognition of sodium ions, channels in DHTA-Hz-15C5 membranes selectively facilitate Na<sup>+</sup> transport, further enhanced by the hydroxyl-enriched COF skeleton. A Na<sup>+</sup>/K<sup>+</sup> selectivity of 58.31 is achieved with 9.33 mmol m<sup>-2</sup> h<sup>-1</sup> permeance, significantly exceeding current membranes and resembling biological channels. Theoretical simulations indicate one-dimensional COF channels facilitate transport, while crown ether recognition makes the Na<sup>+</sup> energy barrier significantly lower than K⁺, enabling ultrahigh selectivity with high Na⁺ permeability. This promotes COFs for efficient single-ion transport and advances crown ether ion selectivity in nano-restricted environments.