Cobalt-Cluster-Based Metal–Organic-Framework-Catalyzed Carboxylative Cyclization of Propargylic Amines with CO2 from Flue Gas

Abstract

The fixation of carbon dioxide (CO₂) directly from flue gas into valuable chemicals like 2-oxazolidinones is of great significance for economic and environmental benefits, which is typically catalyzed by noble-metal catalysts and under harsh conditions. Herein, a novel 2-fold interpenetrated framework {[Co₃(μ₂-O)(TCA)₂(HDPTA)₂]·2H₂O·2DMF}_n [Co(II)-based metal–organic framework (Co-MOF)] containing [Co₃] clusters and highly dense amino groups (−NH₂) dispersed in the channel was prepared, exhibiting high solvent/pH stability and CO₂ adsorption capacity (24.9 cm³·g^–1). Catalytic experiments demonstrated that Co-MOF could catalyze the carboxylative cyclization of propargylic amines to generate 2-oxazolidinones with yields of up to 98% under mild conditions with CO₂ directly from flue gas. In addition, Co-MOF retained its structure and catalytic activity after five-cycle catalytic experiments, showing the promising practical application. Density functional theory (DFT) calculation suggested that the [Co₃] centers in the MOF activated the C≡C of propargylic amines with much more binding energy than Co(NO₃)₂, partly accounting for the high catalytic activity of Co-MOF. This work demonstrates the first Co-based MOF material that is highly efficient for carboxylative cyclization of propargylic amines with flue gas as the CO₂ source, inspiring further rational design of porous catalysts for efficient CO₂ utilization.