Influence of Metal Ions on Metal–Organic Frameworks for Cocatalyst-Free Carbon Dioxide Conversion

Metal–organic frameworks (MOFs) stand out as a preferred category of materials owing to their remarkable tunability and design flexibility for targeted applications. The fixation of carbon dioxide (CO 2 ) into value-added chemicals, such as cyclic carbonates, often requires the use of cocatalysts. Herein, a series of MOFs were synthesized under solvothermal conditions by reacting 2,5-dibromoterephthalic acid (DBTA) with metal ions (M = Mn 2+, Fe 3+, Co 2+, Ni 2+, Cu 2+, Zn 2+ ), termed M-DBTA. The choice of metal ions in M-DBTA plays a pivotal role in tuning structural attributes and catalytic efficiency. The synergistic interplay between CO 2 affinity and acidic sites enhances catalytic performance in the CO 2 conversion into cyclic carbonates at atmospheric pressure, without cocatalysts or solvents. Mn-DBTA and Co-DBTA achieve higher catalytic activity for the formation of 4-(chloromethyl)-1,3-dioxolan-2-one (achieving yields of 85% and 87%, respectively) from the reaction of CO 2 with epichlorohydrin. This superior activity is attributed to the strong CO 2 affinity ( Q st ) of Co-DBTA (47.8–28.9 kJ mol –1 ) and Mn-DBTA (16–28 kJ mol –1 ), along with Lewis acidic sites. The low kinetic barrier further facilitates CO 2 conversion, as supported by thermodynamic parameters. Notably, Co-DBTA shows recyclability, maintaining structural integrity over four cycles. These findings highlight the potential of MOFs for sustainable CO 2 conversion under mild conditions, paving the way for future advancements in catalytic design.