Targeted synthesis of a porous aromatic framework with a high adsorption capacity for organic molecules

Abstract

Tetrakis(4-bromophenyl)methane (TBPM) as a tetrahedral unit and a diboronic acid as a linker were selected to couple the phenyl rings into a porous aromatic framework, PAF-11. PAF-11 was polymerized via a Suzuki coupling reaction. A TG analysis showed that PAF-11 is thermally stable up to 400 °C in air. PAF-11 also has a high chemical stability and cannot be dissolved or decomposed in common solvents or concentrated hydrochloric acid. A N₂ sorption measurement on activated PAF-11 revealed a surface area of 952 m² g⁻¹ in the Langmuir model. PAF-11 also shows a considerable adsorption capacity for H₂. Interestingly, PAF-11 is a highly hydrophobic material but with a high methanol uptake (654 mg g⁻¹ at saturated vapour pressure and room temperature). PAF-11 also exhibits high adsorption abilities for small aromatic molecules such as benzene and toluene (874 and 780 mg g⁻¹, respectively, at saturated vapour pressure and room temperature) due to its aromatic framework. This ability of PAF-11 could be very useful to eliminate harmful small aromatic molecules produced by industry.