Cucurbituril-based anion-conducting membranes with supramolecular nanopores.

Abstract

Nanoporous anion-conducting membranes have gained considerable interest for their potential to reduce resistance in electrochemical devices^1-4. Current pore-forming methods, such as backbone engineering through polymers of intrinsic microporosity^5,6 or covalent organic and metal-organic frameworks^7,8, however, suffer from limited structural control, mechanical fragility or demanding synthesis. Here we establish a supramolecular strategy that overcomes these limitations by constructing uniform, dynamic nanopores. Co-assembly of the rigid macrocyclic host cucurbit[7]uril with the cationic polymer guest quaternized poly(piperidinium-terphenyl) yields a robust network of nanometre-scale channels while simultaneously enhancing mechanical and chemical stability. The dynamic host-guest interactions allow the pore structure to fluctuate on picosecond and angstrom scales. This transient environment supports low-friction hydroxide migration through a Grotthuss mechanism, producing a marked enhancement in ionic conductivity. This bottom-up design principle provides a versatile new tool for molecularly engineering transport pathways and promises to advance electrochemical reactors with respect to energy efficiency, operational stability and the production of high-purity products.