Bisimidazole-functionalized manganese porphyrin promoted cycloaddition of epoxides and CO2 under atmospheric pressure

Three bisimidazole-modified manganese porphyrin complexes have been synthesized and applied as bi-functional catalysts for the chemical conversion of epoxides and atmospheric CO2 into cyclic carbonates without any co-catalysts and solvents. Imidazole-modified alkoxyl chains at different porphyrin positions modulate the distance between the imidazole group and the manganese center of the porphyrin, thus considerably affecting their catalytic properties. Catalyst E-m6 shows the best catalytic performance un-der optimal conditions. Foundational kinetic study results catalyzed by E-o6, E-m6 and E-p6 show the apparent activation energies E-a(E-m6) value is the lowest, only 41.7 kJ/mol, revealing its relative position of imidazole group and porphyrin manganese center is the most appropriate.(C) 2023 Elsevier B.V. All rights reserved.