Cr(iii)-salophen catalysts: efficient single-component and binary systems for sustainable CO₂/cyclohexene oxide...

Area of Science:

• Catalysis
• Polymer Chemistry
• Green Chemistry

Background:

• Rising carbon dioxide (CO2) emissions drive the greenhouse effect.
• CO2 utilization offers a strategy for climate change mitigation.
• Catalytic conversion of CO2 with epoxides to polycarbonates is a promising route.

Purpose of the Study:

• To synthesize and evaluate novel Co(iii) and Cr(iii) salophen-type complexes as catalysts.
• To investigate the copolymerization of cyclohexene oxide (CHO) with CO2 for poly(cyclohexene)carbonate (PCHC) production.
• To optimize catalytic performance through variation of reaction conditions and co-ligands.

Main Methods:

• Synthesis of nine Co(iii) and Cr(iii) salophen-type complexes (Cat1-Cat9).
• Catalytic testing in copolymerization of CHO with CO2 under varying conditions (temperature, pressure, solvent, co-ligand).
• Characterization of the resulting PCHC polymer, including tacticity and crystallinity.

Main Results:

• Cat5 exhibited the highest selectivity in initial screening.
• The Cat5:DMAP binary system achieved the best catalytic performance.
• Production of a semi-crystalline PCHC copolymer with a high degree of isotacticity was achieved.

Conclusions:

• Novel salophen-type Co(iii) and Cr(iii) complexes are effective catalysts for CO2 utilization.
• The Cat5:DMAP system represents an optimized approach for PCHC synthesis.
• This work contributes to the development of sustainable chemical production methods using CO2.