Executive Summary : | Chemical transformations of carbon dioxide have gained significant interest due to their affordability and sustainability as a sustainable carbon source. CO2, the main greenhouse gas, is increasing in the atmosphere, leading to global warming. The conversion, storage, and capture of CO2 has become a crucial area of research. Extensive research is ongoing to use carbon dioxide for the synthesis of chemicals like cyclic carbonate and polycarbonates. Transition metal complexes containing organic ligands, commonly salen type complexes, are used as tools for chemical fixation of CO2 to cyclic carbonates and polycarbonates. For cyclic carbonates/polycarbonates synthesis, epoxides are commonly used as a chemical feedstock. The reaction of epoxide with CO2 proceeds through critical steps: coordination, ring-opening reaction, and insertion. However, coordination and ring-opening reactions become difficult due to electron-rich ligands, requiring a co-catalyst (typically tetrabutylammonium iodide). The efficiency of the catalyst is poor at higher temperatures. A π-acceptor iminopyridyl moiety containing imidazole-phenolate complex is planned to stabilize complexes in lower oxidation states and stabilize complexes at higher oxidation states. This catalyst system is expected to work in a milder reaction condition. Bi-functional catalysts D and E are also proposed for CO2 conversion. First, designed ligands and their 3d-transition metal complexes will be synthesized and characterized, followed by exploration for chemical conversion of CO2 with epoxide to result in cyclic organic carbonate and polycarbonates. |