Construction and sorption properties of pyrene-based porous aromatic frameworks

We report here pyrene-based fluorescent porous aromatic frameworks (PAF-19 and PAF-20), which are constructed by a quadrilateral building unit 1,3,6,8-tetrabromopyrene (TBrPy) with linkers 1,4-diethynylbenzene and 1,3,5-triethynylbenzene via Sonogashira-Hagihara coupling reaction, respectively. TG analysis shows that PAF-19 and PAF-20 are thermally stable up to 350 °C in air condition. Both materials also exhibit high chemical stability and cannot dissolve or decompose in any common organic solvents. N₂ sorption results reveal that the BET surface areas of PAF-19 and PAF-20 are 250 m² g^-1 and 702 m² g ^-1, respectively. They also display relatively high sorption abilities for hydrogen and carbon dioxide. H₂O sorption measurements demonstrate that the skeletons of PAF-19 and PAF-20 are highly hydrophobic. Interestingly, PAF-19 and PAF-20 exhibit excellent sorption abilities to organic chemical pollutants at the saturated vapor pressure and room temperature. PAF-20 can adsorb large amounts of methanol and benzene, with values of 609 mg g^-1 and 1038 mg g^-1, respectively. The good performances of PAF-19 and PAF-20 with high sorption selectivity promise their potential application for eliminating environmental pollutants in presence of H ₂O.