Synthesis of Isocyanurate-Imidazolium-Derived Flexible Ionic Porous Organic Polymers for CO₂ Fixation

The flexible ionic porous organic polymers (iPOPs) usually exhibit inferior porosity due to the intermolecular packing caused by the charge interaction. In this work, we report a series of isocyanurate-imidazolium-derived flexible iPOPs (IC-IM-1, IC-IM-2, and IC-IM-3) synthesized via the Heck cross-coupling reaction of the tri(4-ethenylbenzene)isocyanurate (IC) with the substituted imidazolium salts (IM-1, IM-2, and IM-3). Among these three iPOPs, IC-IM-3, synthesized from IC and imidazolium salts with sterically bulky substituents (IM-3), exhibits the highest Brunauer–Emmett–Teller specific surface area (375.0 m2 g–1), CO2 adsorption capacity [39.2 cm3 g–1 (273 K) and 23.2 cm3 g–1 (298 K)], and catalytic activity (up to 99% yield with 99% selectivity) for the epoxide-CO2 cycloaddition. Density functional theory calculations reveal that the synergistic adsorption of CO2 by the IC and IM-3 moieties in adjacent layers favors CO2 fixation. Besides, a possible reaction mechanism is proposed based on the experimental results and theoretical calculations.