Engineered dynamic configuration of nanopores to access enhanced diffusion and selectivity for aliphatic isomers

Molecular diffusion in porous solids (metal-organic and covalent organic frameworks, zeolites) can be regulated by engineering the chemical environment of the nanochannels. Selective chemical interactions between the nanochannel surface and diffusing molecules enable discrimination at the molecular level, a feature critical for the development of high-performance chemical separation membranes. A major challenge, however, is to concurrently achieve rapid molecular diffusion and high selectivity, as these attributes exhibit an intrinsic trade-off. In this communication we introduce a de novo methodology exploring the rotational dynamics of the nanochannel chemical components and realize simultaneous enhancement of both diffusion and selectivity for aliphatic chemical isomers (branched hexanes). The methodology utilizes crystalline metal-organic framework thin film architecture akin to membrane structures, supported by a comprehensive experimental and simulation framework to achieve the dual objectives effectively.