Source data for Nature manuscript 2025-03-06652C

Nanoporous anion-conducting membranes (ACMs) have gained considerable interest for their potential to reduce resistance in electrochemical devices1-4. Current pore-forming methods, such as backbone engineering through polymers of intrinsic microporosity5,6 or covalent/metal-organic frameworks7,8, 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. Crucially, the dynamic host-guest interactions allow the pore structure to fluctuate on picosecond and angstrom scales. This transient environment supports low-friction hydroxide migration via 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.