1.D.270.  The Hydrazide-linked Pyridine-Artificial Proton Channel (HP-APC) Family  

Artificial proton channels exhibiting high selectivity are largely unexplored. Inspired by the DNA duplex's iconic helical structure, Xu et al. 2025 presented 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 (Xu et al. 2025).

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