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

Abstract

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 (Qst) of 37.8 kJ/mol. On the other hand, the analogous MOF, UiO-66 doped with Ag(I), showed a lower Qst 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 environmentfriendly mild conditions.