Metalated Mesoporous Poly(triphenylphosphine) with Azo Functionality: Efficient Catalysts for CO2 Conversion

Mesoporous poly(triphenylphosphine) with azo functionality (poly(PPh3)-azo) is reported, which was synthesized via oxidative polymerization of P(m-NH2Ph)(3) at ambient conditions. This kind of polymer could strongly coordinate with metal ions (e.g., Ru3+) and could reduce Ag+ in situ to metallic form. The resultant metalated poly(PPh3)-azo (e.g., poly(PPh3)-azo-Ag or -Ru) were discovered to be highly efficient catalysts for CO2 transformation. Poly(PPh3)-azo-Ag showed more than 400 times higher site-time-yield (STY) for the carboxylative cyclization of propargylic alcohols with CO2 at room temperature compared with the best heterogeneous catalyst reported. Poly(PPh3)-azo-Ru also exhibited good activity for the methylation of amines with CO2. It was demonstrated that the high performances of the catalysts originated from the cooperative effects between the polymer and the metal species. In addition, both catalysts showed good stability and easy recyclability, thus demonstrating promising potential for practical utilization for the conversion of CO2 into value-added chemicals.