Calix[4]pyrrole-Crosslinked Porous Polymeric Networks for the Removal of Micropollutants from Water

Abstract

Calix[4]pyrrole-based porous organic polymers (P1–P3) for removing organic micropollutants from water were prepared. A bowl-shaped α,α,α,α-tetraalkynyl calix[4]pyrrole and diketopyrrolopyrrole monomer were crosslinked via Sonogashira coupling to produce a 3D network polymer, P1. P1 proved too hydrophobic for use as an adsorbent and was converted to the corresponding neutral polymer P2 (containing carboxylic acid groups) and its anionic derivative P3 (containing carboxylate anion groups). Anionic P3 outperformed P2 in screening studies involving a variety of model organic micropollutants of different charge, hydrophilicity and functionality. P3 proved particularly effective for cationic micropollutants. The theoretical maximum adsorption capacity (qmax,e) of P3 reached 454 mg g−1 for the dye methylene blue, 344 mg g−1 for the pesticide paraquat, and 495 mg g−1 for diquat. These uptake values are significantly higher than those of most synthetic adsorbent materials reported to date.