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

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.