Construction and adsorption properties of porous aromatic frameworks via AlCl3-triggered coupling polymerization

Currently, synthesis of most porous organic frameworks (POFs) requires noble metals as the main catalyst. Herein we report a low-cost and straightforward synthetic strategy to develop porous aromatic frameworks (PAFs). With AlCl3 as the catalyst, the Scholl coupling reaction could occur between the phenyl rings of aromatic compounds. Using 3-dimensional monomers, such as triphenylamine, tetraphenylmethane, tetraphenylsilane, and tetraphenylgermane, we successfully obtained a series of PAFs with moderate Brunauer–Emmett–Teller (BET) surface areas ranging from 515 m2 g−1 to 1119 m2 g−1. Among the obtained PAF materials, PAF-41 exhibited the best CH4 and CO2 sorption capacity with CH4 (1.04 mmol g−1) and CO2 (3.52 mmol g−1) at 273 K. In addition, PAF-43 demonstrated its comparably high isosteric heat of adsorption at 34.8 kJ mol−1 for CO2 and 29.7 kJ mol−1 for CH4. It is also worth mentioning that the developed approach also overcomes typical flaws of some classic PAFs, such as high cost and complexity of precursor preparation.