A Rigid Molecular Triangle as an Ultrafast and Highly Selective Transmembrane Li ⁺ Channel

A central challenge in engineering artificial ion channels is the simultaneous achievement of high ion transport efficiency and high selectivity. In this study, we report a unimolecular Li + channel based on a rigid, C 3 ‐symmetric pyromellitic diimide molecular triangle. The structure features a defined wall height of 2.2 nm and a narrow 4.1 Å pore lined with electron‐rich carbonyl oxygens. Single‐channel measurements reveal ultrafast Li + transport with a conductance of 57.4 pS—2.5 times that of gramicidin A‐mediated K + conductance—alongside the record‐high selectivity ratios of 50.1 for Li + /Na + and 171.4 for Li + /K + . These performance metrics place this system among the most efficient and selective artificial Li + channels reported to date, while establishing a versatile molecular platform for Li + ‐selective membranes and targeted therapeutics.