CF3-Incorporated Tetrazole-Based Cu(II)-Organic Framework for Catalytic Transformation of Flue Gas CO2 under Ambient Conditions

Abstract

Efficient carboxylative cyclization of propargylic amines with CO2 is of great significance for the synthesis of value-added oxazolidinones and the sustainable utilization of carbon resources. However, this transformation is generally limited by the use of noble-metal catalysts, high temperatures, and high-purity CO2 feedstocks. To address these challenges, we constructed a novel tetrazole-based Cu(II) metal−organic framework (MOF), Cu-CF3, via an in situ ligand synthesis strategy. The resulting Cu-CF3 features exposed CF3 functional sites, accessible Lewis acidic Cu centers, and excellent structural stability. Notably, Cu-CF3 catalyzes the carboxylative cyclization of a broad range of propargylic amines with pure CO2 under ambient conditions, affording the corresponding oxazolidinones in good to high yields. More importantly, simulated flue-gas CO2 containing 13% CO2 can also be directly employed under ambient conditions, affording the products in moderate to high yields. The catalyst can be readily recovered and reused for 10 consecutive runs without obvious loss of catalytic activity or structural integrity. Mechanistic investigations reveal that the Lewis acidic Cu sites facilitate substrate activation, whereas the exposed CF3 groups enrich CO2 molecules in the vicinity of the catalytic centers, thereby promoting the cyclization process. This work provides an attractive structural design strategy for constructing MOF catalysts that integrate exposed CO2-enriching functional sites with open Lewis acidic centers, enabling efficient carboxylative cyclization under ambient conditions using low-concentration CO2 sources.