Rigid Molecular Triangle as a Biomimetic Ultrafast and Highly Selective Transmembrane Li+ Channel

A central challenge in the engineering of artificial ion channels lies in the simultaneous realization of high ion transport efficiency with high selectivity. Herein, we present a novel unimolecular Li+ channel formed by a rigid, C3-symmetric pyromellitic diimide molecular triangle. The structure features a well-defined wall height of 2.2 nm and a narrow pore of 4.1 Å decorated with the electron-rich carbonyl oxygens, providing a functional mimic of biological selectivity filters. Single channel electrophysiology measurements reveal molecular triangle-mediated ultrafast Li+ transport with a conductance of 76.2 pS, alongside exceptional selectivity ratios of 23.1 for Li+/Na+ and a record-high 265.2 for Li+/K+. These outstanding metrics position it among the most efficient and selective artificial Li+ channels reported to date, while establishing a versatile molecular platform for developing Li+-selective membranes and targeted therapeutics.