Aromatic Foldamers with Tunable Pore Sizes Synthesized via Suzuki Coupling for Mass Transport

π-Conjugated polymers (CPs) have garnered significant attention due to their versatile applications in optoelectronics, energy storage, sensing, and biomedicine. However, research on bioinspired folded architectures and their functional development remains limited, primarily due to the lack of suitable coupling strategies. In this study, we report the synthesis of a novel class of helical polymer nanotubes constructed via a scalable and highly homogeneous Suzuki-Miyaura cross-coupling polymerization. The helical conformation of the nanotube backbone is stabilized by electrostatic repulsion between heteroatoms distributed along the helical axis or intramolecular hydrogen-bonding interactions. The helical tubular structure of these polymers has been unambiguously confirmed by atomic force microscopy (AFM), single-crystal X-ray diffraction, circular dichroism (CD) spectroscopy, and theoretical calculations. The resulting helical polymer nanotubes exhibit an average length of ~5 nm, featuring a hydrophilic, electron-rich interior lumen and hydrophobic alkyl side chains on the exterior. This unique architecture enables the nanotubes to spontaneously insert into the lipid bilayers, demonstrating distinct transmembrane transport behaviors that are highly dependent on pore size. While larger pores facilitate glucose permeation, narrower channels with precisely positioned coordination sites enable selective K⁺ transport. Systematic investigation of K⁺ transport properties through vesicle-based kinetic assays and symmetric/asymmetric bilayer lipid membrane (BLM) experiments revealed exceptional K⁺ selectivity. Remarkably, the F3 system achieved a K⁺/Na⁺ selectivity ratio of 26.8 in asymmetric BLM measurements. This work not only establishes a new paradigm for aromatic helical polymers, but also elucidates the critical role of coordination site density in governing K⁺ selectivity. These findings provide a strategic blueprint for the rational design of artificial K⁺-specific nanopores and pave the way for their potential biomedical applications, including therapeutic interventions for channelopathy-related diseases.