Highly efficient ion sieving through angstrom-scale channels embedded with supramolecular coordination complexes

Artificial channels that mimic biological systems are of significant interest, but their fabrication remains challenging. Here, we prepare the well-defined platinum(II)-based supramolecular coordination complexes (SCCs) 1 via the directional bonding of SCCs. These are attached to the inner walls of a solid polyethylene terephthalate channel having a bullet-like morphology based on self-assembled interfacial growth. The resulting channels allow the rapid transport of monovalent metal ions (K+, Na+, and Li+) from tip to base while inhibiting the migration of divalent ions (Mg2+ and Ca2+). These channels efficiently separate monovalent from divalent metal ions on this basis, with an ultrahigh K+/Mg2+ selectivity ratio of 1,015.5. Theoretical simulations demonstrate that this selectivity results from the high dehydration energy of the divalent ions and their strong interactions with porphyrin groups on the SCCs. The present work is expected to assist in the future design of functionalized ion channels and efficient separation membrane materials.