Fluctuation-driven mass-selective transport in dynamic nanopores

Abstract

Abstract Precise molecular separation is essential in nanotechnology. However, static designs based on pore size and host-guest interactions often fail for species with nearly identical properties. To overcome this, we elucidate how nanopore dynamics govern transport and separation by establishing a general, predictive framework. We demonstrate that diffusion in a fluctuating periodic potential is maximized at an optimal fluctuation rate. Critically, this rate depends on molecular mass, translating subtle mass differences into significant kinetic disparities. By integrating this framework with quantum-chemical energy landscapes for archetypal soft porous crystals, we identify two factors governing selectivity: the magnitude of energy-barrier fluctuations and the alignment between nanopore dynamics and the energy-fluctuation rate that maximizes selectivity. These results establish nanopore dynamics as a key design dimension for controlling separation by tuning structural dynamics via ligand substitution or external fields, providing a theoretical foundation for the rational design of separation materials.