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 the reaction of bromomethyl pyrene and tertiary amines with different alkyl chains combined with graphitic carbon nitride (g-CN) through π-π stacking interactions. The new pyrene-based ammonium bromides were investigated both in homogenous phase and heterogeneous phase combining with g-CN for the CO 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-CN and PABs was confirmed by quantum chemical calculations. g-CN/Py-C 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-CN/Py-C and the activation energy was calculated to be 61.5 kJ mol.