A zinc porphyrin polymer as efficient bifunctional catalyst for conversion of CO2 to cyclic carbonates

The design and synthesis of efficient heterogeneous catalysts for catalytic conversion of CO2 are an important challenge. The novel zinc porphyrin polymer reported herein, [ZnPy+CPP-BTA]I-, is synthesized from trans-A(2)B(2) porphyrin precursor 5,15-(4-carboxyphenyl)-10,20-(pyridyl)-porphyrin (PyCPP) and 1,2,4,5-benzenetetramine tetrahydrochloride (BTA), employing a sequential post-synthetic methylation and metalation strategy. The newly synthesized zinc porphyrin polymer was well characterized by Fourier transform infrared spectroscopy (FT-IR), Ultraviolet-visible spectroscopy (UV-vis), scanning electron microscope (SEM), transmission electron microscope (TEM), thermal gravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). As bifunctional heterogeneous catalyst incorporated zinc porphyrin and nucleophile I-, [ZnPy+CPP-BTA]I- shows good catalytic activity and recyclability for the cycloaddition reactions of epoxides and CO2 under lower CO2 initial pressure and cocatalyst-free conditions.