A click grafted cobalt complex on chloromethyl polystyrene for the catalytic cycloaddition reaction of CO₂ with epoxides

The increasing amount of CO₂ in the atmosphere has a great impact on all living systems. Therefore, society and researchers are paying enormous attention to the control, storage, and utilization of this greenhouse gas. Preparing valuable cyclic carbonates from epoxides and CO₂ has attracted significant attention due to its 100% atom economy. Here, chloromethyl polystyrene (CMPS) containing -CH₂Cl functional groups was used as a support for immobilizing a cobalt-based complex for catalyzing the reaction of CO₂ and epoxides. Functionalization of -CH₂Cl with propargyl alcohol through the nucleophilic attack of oxygen groups on -CH₂Cl motifs produced alkyne-functionalized-PS for the subsequent alkyne-azide click reaction. On the other hand, an azide-containing part was obtained by preparing the [Co(bpy)₂(N₃)₂] complex, which was subjected to a click reaction with alkyne functionalized-PS to achieve the final catalyst. The synthesized catalyst played an efficient catalytic role in the CO₂/epichlorohydrin cycloaddition reaction without using any co-catalyst, halide, or solvent (conversion of 100% at 130 °C and 4 h). This catalyst also has great performance in the presence of various epoxides.