Rational Construction of a Responsive Azo-Functionalized Porous Organic Framework for CO₂ Sorption

An azo-functionalized porous organic framework (denoted as JJU-1) was synthesized via FeCl₃-promoted oxidative coupling polymerization. By virtue of a porous skeleton and a light/heat responsive azo functional group, this task-specific JJU-1 displays a reversible stimuli-responsive adsorption property triggered by UV irradiation and heat treatment. The initial Brunauer-Emmet-Teller (BET) surface area of this porous material is 467 m² g^-1. The CO₂ sorption isotherms exhibit a slight decrease after UV irradiation because of the trans to cis conversion of the azo functional skeleton. It is worth mentioning that the responsive CO₂ adsorption performance can be recycled for three cycles via alternating external stimuli, confirming the excellently reversible switchability of trans-to-cis isomerization and controllable CO₂ adsorption.