Synthesis of a Pyrazole-Based Microporous Organic Polymer for High-Performance CO₂ Capture and Alkyne Carboxylation

The methodology for the transformation of CO2 into high-value chemicals is the Holy Grail of sustainable chemistry [Carter Acc. Chem. Res. 2017, 50, 472−475]. Herein, we report the carboxylation of alkynes with CO2 catalyzed by silver nanoparticles (Ag NPs) supported by a microporous organic polymer (MOP) under mild reaction conditions. A pyrazole-based MOP (MOP-PZ) with abundant NH and N═C groups was prepared by Scholl coupling of 3,5-diphenyl-1H-pyrazole. Silver nanoparticles (Ag NPs) were successfully embedded in MOP-PZ to produce a stable MOP-PZ–Ag hybrid material. The as-prepared MOP-PZ and MOP-PZ–Ag materials could absorb significant concentrations of CO2 of 202 and 183.7 mg g–1, respectively, under 1 bar at 273 K. Multifunctional MOP-PZ–Ag efficiently catalyzed the carboxylation of various terminal alkynes with CO2 to yield propiolic acids under ambient pressure at 50 °C. This heterogeneous catalyst could be recycled five times without significant degradation.