A polyhedral oligomeric silsesquioxane-based catalyst for the efficient synthesis of cyclic carbonates

Polyhedral oligomeric silsesquioxane functionalized with imidazolium chloride peripheries (POSS-Imi) was successfully synthesized through a novel synthesis protocol. The solid was extensively characterized via H-1 NMR, C-13 NMR and IR spectroscopy as well as combustion chemical analysis, mass spectrometry and transmission electron microscopy. Moreover, an in-depth investigation through Si-29 NMR was performed. POSS-Imi was used for the first time as a catalyst for the conversion of CO2 and epoxides into cyclic carbonates with excellent results in terms of both yield and selectivity. The catalyst displayed improved catalytic performance with respect to unsupported 1-butyl-3-methylimidazolium chloride. The enhanced activity was ascribed to the proximity effect generated by the increased local concentration of imidazolium species surrounding the inorganic silsesquioxane core.