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.