Rational design of new in situ reduction of Ni(II) catalytic system for low-cost and large-scale preparation of porous aromatic frameworks

Porous aromatic framework 1 (PAF-1) is an extremely representative nanoporous organic framework owing to its high stability and exceptionally high surface area. Currently, the synthesis of PAF-1 is catalyzed by the Ni(COD)₂/COD/bpy system, suffering from great instability and high cost. Herein, we developed an in situ reduction of the Ni(II) catalytic system to synthesize PAF-1 in low cost and high yield. The active Ni(0) species produced from the NiCl₂/bpy/NaI/Mg catalyst system can effectively catalyze homocoupling of tetrakis(4-bromophenyl)methane at the room temperature to form PAF-1 with high Brunauer–Emmett–Teller (BET)-specific surface area up to 4948 m² g⁻¹ (Langmuir surface area, 6785 m² g⁻¹). The possible halogen exchange and dehalogenation coupling mechanisms for this new catalytic process in PAF's synthesis are discussed in detail. The efficiency and universality of this innovative catalyst system have also been demonstrated in other PAFs' synthesis. This work provides a cheap, facile, and efficient method for scalable synthesis of PAFs and explores their application for high-pressure storage of Xe and Kr.