An artificial sodium-selective subnanochannel

J Lu and GP Jiang and HC Zhang and BB Qian and HJ Zhu and QF Gu and Y Yan and JZ Liu and BD Freeman and L Jiang and HT Wang, SCIENCE ADVANCES, 9, eabq1369 (2023).

DOI: 10.1126/sciadv.abq1369

Single-ion selectivity with high precision has long been pursued for fundamental bioinspired engineering and applications such as in ion separation and energy conversion. However, it remains a challenge to develop arti-ficial ion channels to achieve single-ion selectivity comparable to their biological analogs, especially for high Na+/K+ selectivity. Here, we report an artificial sodium channel by subnanoconfinement of 4 '-aminobenzo-15-crown-5 ethers (15C5s) into similar to 6-angstrom-sized metal-organic framework subnanochannel (MOFSNC). The resulting 15C5-MOFSNC shows an unprecedented Na+/K+ selectivity of tens to 10(2) and Na+/Li+ selectivity of 103 under multicomponent permeation conditions, comparable to biological sodium channels. A co-ion-responsive single-file transport mechanism in 15C-MOFSNC is proposed for the preferential transport of Na+ over K+ due to the synergetic effects of size exclusion, charge selectivity, local hydrophobicity, and preferential binding with functional groups. This study provides an alternative strategy for developing potential single- ion selective chan-nels and membranes for many applications.

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