Pyrene-based ammonium bromides combined with g-CN for the synergistically enhanced fixation reaction of CO and epoxides

A new type of pyrene-based ammonium bromides (PABs) was synthesized via the reaction of bromomethyl pyrene and tertiary amines with different alkyl chains combined with graphitic carbon nitride (g-C 3 N 4 ) through π-π stacking interactions. The new pyrene-based ammonium bromides were investigated both in homogenous phase and heterogeneous phase combining with g-C 3 N 4 for the CO 2 fixation reaction of epoxides under mild conditions. Obviously, the combination was proved to be an efficient system for the conversion of epoxides. The interaction between g-C 3 N 4 and PABs was confirmed by quantum chemical calculations. g-C 3 N 4 /Py-C 12 exhibited an excellent yield of cyclic carbonates (above 93%) at 80 °C, atmospheric pressure and solvent-free conditions. A preliminary kinetic study was performed using g-C 3 N 4 /Py-C 12 and the activation energy was calculated to be 61.5 kJ mol −1 . The synergistic interaction of g-C 3 N 4 and PABs plays an important role in the CO 2 fixation reaction with epoxides.