Biomimetic NaK Channel Membrane Enabled by a Crown Ether‐Coordinated Metal–Organic Framework

Abstract Biological NaK channels integrate exquisite ion selectivity with dynamic gating to regulate life processes, yet achieving such multifunctionality in synthetic channels has remained a formidable challenge. Here, we present a metal–organic framework (MOF) channel membrane that combines two complementary ion‐conduction motifs: carboxyl groups from UiO‐66‐COOH and carboxybenzo‐15‐crown‐5 (15C5‐COOH), assembled in a one‐step coordination strategy. This hybrid architecture recapitulates essential NaK channel functions, offering both ultrahigh ion selectivity and controllable gating. The membrane enables highly selective conduction of monovalent cations while effectively excluding Mg 2+ , yielding M + /Mg 2+ selectivity above 10 2 . Under mixed‐ion conditions, it achieves unprecedented Na⁺/K⁺ selectivity exceeding 10 3 , far surpassing reported artificial ion channels. Remarkably, Mg 2+ ions dynamically gate Na⁺ and K⁺ transport with sustainable on–off ratios around 30. These outstanding performances arise from the synergistic interplay of crown ether and carboxyl groups confined within subnanometer MOF pores. This work establishes a versatile strategy for designing multifunctional artificial ion channels, opening avenues toward advanced ionic devices for artificial cells and biomedical technologies.