A Molecular Staircase Built from Hydrazide-Linked Pyridines as an Artificial Proton Channel

Artificial proton channels exhibiting high selectivity remain largely unexplored, with only two such systems recently reported. Inspired by the DNA duplex's iconic helical structure, we present here a novel strategy for designing a molecular-scale staircase configuration. The resulting molecular staircase (MS), predominantly linear in shape, consists of pyridine units linked by hydrazide groups, with backbone rigidity enhanced by intramolecular H-bonding. This MS incorporates up to five proton-transporting motifs, demonstrating remarkable efficacy as a proton-conducting channel within lipid bilayer membranes. Our findings indicate that the MS exhibits high proton transport activity (EC₅₀ of 0.31 mol%, relative to lipids) and significant selectivity for protons, with selectivity values of 160.3 for K⁺, 90.5 for Na⁺, and 3.5 for Cl^⁻. These results underscore the potential of the MS and its variants as a highly selective and efficient proton channel, advancing the field of artificial ion transport systems.