Highly Efficient Fixation of Carbon Dioxide at RT and Atmospheric Pressure Conditions: Influence of Polar Functionality on Selective Capture and Conversion of CO₂

The rapid increase in the concentration of atmospheric carbon dioxide (CO₂) has resulted in undesirable environmental issues. Hence, selective CO₂ capture and utilization as C1 feedstock for the preparation of high-value chemicals and fuels has been considered as a promising step toward mitigating the growing concentration of atmospheric CO₂. In this direction, herein we report rational construction of a Ag­(I)-anchored sulfonate-functionalized UiO-66 MOF named as MOF-SO₃Ag composed of CO₂-philic sulfonate functionality and catalytically active alkynophilic Ag­(I) sites for chemical fixation of carbon dioxide. The MOF-SO₃Ag exhibits selective as well as recyclable adsorption of CO₂ with a high heat of adsorption energy (Q_st) of 37.8 kJ/mol. On the other hand, the analogous MOF, UiO-66 doped with Ag­(I), showed a lower Q_st value of 30 kJ/mol, highlighting the importance of the sulfonate group for stronger interaction with CO₂. Furthermore, the MOF-SO₃Ag acts as an efficient heterogeneous catalyst for cyclic carboxylation of propargylic alcohols to generate α-alkylidene cyclic carbonates in >99% yield at mild conditions of RT and 1 bar CO₂. More importantly, one-pot synthesis of oxazolidinones by a three-component reaction between CO₂, propargylic alcohol, and primary amine has also been achieved using MOF-SO₃Ag catalyst under the mild conditions. The MOF is highly recyclable and retains its superior catalytic activity even after several cycles. To the best of our knowledge, MOF-SO₃Ag is the first example of MOF reported for RT chemical fixation of CO₂ to oxazolidinones by aminolysis of α-alkylidene cyclic carbonates under the environment-friendly mild conditions.