Crown Ether- and Benzoxazine-Linked Porous Organic Polymers Displaying Enhanced Metal Ion and CO₂ Capture through Solid-State Chemical Transformation

In this paper, we describe dual crown ether (CE)- and benzoxazine (BZ)-linked porous organic polymers (CE-BZPOPs) incorporating pyrene (Py) and tetraphenylethylene (TPE) units, synthesized through a multistep process involving Schiffbase formation, reduction, Mannich condensation, and Sonogashira-Hagihara coupling, with their structures confirmed using Fourier transform infrared and solid-state nuclear magnetic resonance spectroscopy. The presence of both CE and BZ units in POPs has never been explored previously. Here, the BZ units underwent solid-state chemical transformations through thermal ringopening polymerization without a thermal curing agent or any catalyst. The resulting Mannich bridges and phenolic units facilitated CO2 capture, mediated through strong acid/base and/or intermolecular hydrogen bonding interactions; furthermore, the CE units bound strongly with metal ions through specific metal-ligand interactions, suggesting that these CE-BZ-POPs might be useful for wastewater treatment.