Selective Separation of Phenanthrene from Aromatic Isomer Mixtures by a Water-Soluble Azobenzene-Based Macrocycle

Selective separation of phenanthrene (PHE) from aromatic isomer mixtures is a big challenge in industry. In this work, a light-responsive water-soluble azobenzene-based macrocycle 1is synthesized and an aqueous solution of E,E-1is employed to separate PHE from anthracene via a solid–liquid extraction method under ambient conditions. After five extraction cycles, the average purity for PHE is about 91.1% and macrocycle 1can be reused at least five times without obvious reduction of separation performance for PHE. This work not only comprises a new and clean way to separate PHE by taking advantage of a macrocyclic host but also promotes the application of host–guest chemistry.