A new heterogeneous host-guest catalytic system as an eco-friendly approach for the synthesis of cyclic carbonates from CO2 and epoxides

Two strategies have been explored towards the heterogenization of a host-guest catalytic system where either cavitand host [3iPO] or quaternary ammonium catalysts are grafted on silica supports. The bis-propargyl substituted triphosphonate cavitand [3iPO] was clicked onto an azido functionalized ultra-large pore SBA-15 type silica (UL-SBA-15). Ammonium hybrid materials were produced by grafting a propyltrimethylammonium chloride silane precursor onto silicas of varying porosities and textural properties (UL-SBA-15, SBA-15 and SiO2). Extensive characterization of each material is presented (XRD, N-2 sorption, TGA, solid state NMR, elemental analyses, FT-IR). The effect of heterogenization was investigated in the coupling of CO2 with styrene oxide and was compared to all-soluble cavitand/ammonium homogeneous analogs.