A Porphyrin-Based Porous rtl Metal-Organic Framework as an Efficient Catalyst for the Cycloaddition of CO2 to Epoxides.

A porous rtl metal-organic framework (MOF) [Mn₅L(H₂O)₆⋅(DMA)₂]⋅5DMA⋅4C₂H₅OH ( 1⋅Mn) (H₁₀L=5,10,15,20-tetra(4-(3,5-dicarboxylphenoxy)phenyl)porphyrin; DMA= N, N′-dimethylacetamide) was synthesized by employing a new porphyrin-based octacarboxylic acid ligand. 1⋅Mn exhibits high Mn^II density in the porous framework, providing it great Lewis-acid heterogeneous catalytic capability for the cycloaddition of CO₂ with epoxides. Strikingly, 1⋅Mn features excellent catalytic activity to the cycloaddition of CO₂ to epoxides, with a remarkable initial turnover frequency 400 per mole of catalyst per hour at 20 atm. As-synthesized 1⋅Mn also exhibits size selectivity to different epoxide substrates on account of their steric hindrance. The high catalytic activity, size selectivity, and stability toward the epoxides on catalytic cycloaddition of CO₂ make 1⋅Mn a promising heterogeneous catalyst for fixation and utilization of CO₂. [ABSTRACT FROM AUTHOR]