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 Ca^2 +, which is nearly two orders of magnitude higher than the biological one, and 1128 against Mg^2 +. 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.

Significance: Strong electrophilicity usually goes hand in hand with positive charge. In contrast, most negative ions behave like nucleophiles. Here we challenge this conventional wisdom by introducing an apparently counterintuitive idea that anions can, under well-defined circumstances, behave as superelectrophiles and even show superior binding strength and kinetic product stabilization in comparison with typical superelectrophilic cations. Emanating from the most stable gas-phase dianion [B₁₂(CN)₁₂]²⁻, synthesized here, we generate its superelectrophilic fragment anion [B₁₂(CN)₁₁]⁻, which binds Ar covalently at room temperature. This opens up additional directions for activation of inert compounds and elements.