Diamine-modified porous indium frameworks with crystalline porous materials(CPM)-5 structure for carbon dioxide fixation under co-catalyst and solvent free conditions

In the presentwork,functional diamine groups into indium frameworks to synthesize cyclic carbonates from CO_(2)and epoxides with efficient catalytic activity in the absence of cocatalyst and solvent are reported for the first time.Crystalline porous materials(CPM)-5 modified with 1,2-phenylene diamine and ethylene diamine(CPM-5-PhDA and CPM-5-EDA),were prepared using a post-synthetic modification(PSM)method.The properties of the modified CPM-5 were characterized by powder X-ray diffraction(PXRD),Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),N2-adsorption,scanning electron microscopy(SEM),CO_(2)adsorption,and temperature programmed desorption TPD methods.The presence of diamine groups as basic sites and indium Lewis acid sites in the framework structure were desirable for high catalytic activity.For a given catalyst weight,CPM-5-PhDA was the best candidate to appear with great catalytic activity and selectivity for the cycloaddition reaction at 100°C and1MPa CO_(2)under co-catalyst and solvent free conditions.CPM-5-PhDA alsowas found to afford large and bulky epoxides.The catalyst can be easily separated and reused five times without any decline in activity.