A flexible linker-based indium frameworks as highly efficient catalysts for carbon dioxide conversion

The chemical fixation of carbon dioxide (CO 2 ) represents a viable strategy to achieve carbon neutrality. However, the conversion of CO 2 is still limited by the lack of efficient heterogeneous catalysts. To address this problem, a flexible linker-based metal-organic frameworks were synthesized using hard Lewis acid indium as metal center (In-MOFs) and their catalytic performance for the CO 2 cycloaddition with epoxides in the absence of solvent and co-catalyst was evaluated. Experimental results revealed that In-MOFs exhibited great catalytic activity (cyclic carbonate yield, 97.2 %) and selectivity (>98 %) for the cycloaddition of CO 2 and epichlorohydrin (ECH) under mild conditions (80 °C for 5 h, 0.1 MPa CO 2 ) due to the strong Lewis acidity of In (III), which significantly lowered energy barrier of epoxide ring opening and the insertion of CO 2 , consequently promoting the CO 2 cycloaddition reaction. These results suggested that the In-MOFs exhibited promising potential as catalysts for the CO 2 chemical fixation and may provide a new approach for the fabrication of MOFs-based catalysts for the CO 2 conversion.