Ultrahydrophobic Porous Molecular Sieves for Benzene Separation from Azeotropic Mixtures

We report an ultrahydrophobic biphenyl-extended pillar[6]arene with an extended cavity and enhanced fluorine content, allowing for extremely selective benzene separation from challenging azeotropic mixtures. The material selectively adsorbed trace amounts of benzene from cyclohexane and methanol with selectivities of 13 and 499, respectively. Benzene separation from methanol yields a record-high selectivity and purity of 99.80%, which is among the highest reported to date. Structural and adsorption studies show that a persistent porous macrocycle preferentially binds benzene within both intrinsic and extrinsic cavities via strong solid-state interactions. These findings show that adaptable macrocyclic molecular sieves can compete with extended frameworks for energy-efficient and sustainable hydrocarbon separations.