Non-3d metal modulated zinc imidazolate frameworks for CO2 cycloaddition in simulated flue gas under ambient condition

Cycloaddition of CO2 and epoxide into cyclic carbonate is one of the most efficient ways for CO2 conversion with 100% atom-utilization. Metal–organic frameworks are a kind of potential heterogeneous catalysts, however, high temperature, high pressure, and high-purity CO2 are still required for the reaction. Here, we report two new Zn(II) imidazolate frameworks incoporating MoO42– or WO42– units, which can catalyse cycloaddition of CO2 and epichlorohydrin at room temperature and atomospheric pressure, giving 95% yield after 24 h in pure CO2 and 98% yield after 48 h in simulated flue gas (15% CO2 + 85% N2), respectively. For comparison, the analogic Zn(II) imidazolate framework MAF-6 without non-3d metal oxide units showed 71% and 33% yields under the same conditions, respectively. The insightful modulation mechanisms of the MoO42– unit in optimizing the electronic structure of Zn(II) centre, facilitating the rate-determined ring opening process, and minimizing the reaction activation energy, were revealed by X-ray photoelectron spectroscopy, temperature programmed desorption and computational calculations.