Biomimetic approach for highly selective artificial water channels based on tubular Pillar[5]Arene dimers

Nature provides answers for efficient transport of water by using Aquaporins AQPs as the translocation relays. Artificial Water Channels biomimicking natural AQPs, can be used for both selective and fast transport of water. Here, we use complementary synthetic methods, X-ray structural data, transport assays to quantify the transport performances of peralkyl-carboxylate-pillar[5]arenes dimers in bilayer membranes. They are able to transport ~107 water molecules/channel/second, within one order of magnitude of AQPs' rates, rejecting Na+ and K+ cations. The dimers have an tubular structure, superposing larger pillar[5]arene pores of 5 A diameter with narrowest twisted carboxy-phenyl pores of 2.8 A diameter. This exceptional channel biomimetic platform, with variable pore dimensions within the same structure, offers size restriction reminiscent to natural proteins. It allows water molecules to selectively transit and prevent bigger hydrated cations to pass through the 2.8 A pore. Molecular simulations probe that dimeric or multimeric honeycomb aggregates are stable in the membrane and form water pathways through the bilayer. Over time, a significant shift of the upper vs. lower layer of occurs initiating new unexpected water permeation events through novel toroidal pores. Altogether, uncovering the interplay between supramolecular construction and transport performances, the novel PAD channels described here are critical to accelerate the systematic discovery for artificial water channels for water desalting.