A Novel Porphyrin-Palladium(0) Functionalized Polyacrylonitrile Fiber as Highly Efficient and Recyclable Heterogeneous Catalyst for the Heck Reaction

Abstract

A novel tetra(4-pyridyl)porphyrin-chelated palladium(0) nanoparticles functionalized polyacrylonitrile fiber (PANTPPF-Pd(0)) was prepared for the first time. Some necessary methods including Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), etc. were used to verify the micro structure and properties of PANTPPF-Pd(0). Furthermore, with the Heck reaction chosen as a model reaction to determine the catalytic activity of PANTPPF-Pd(0), the experiment results shows that PANTPPF-Pd(0) can efficiently catalyze the Heck reaction with high yields (47-99%) in extensive substrate scope (35 examples) under non-solvent condition. Noteworthily, the average size of Pd(0) nanoparticles observed by transmission electron microscopy (TEM) slightly increased from 2.32 nm to 2.59nm after recycled 9 times achieving an 80% isolated yield of Heck reaction catalyzed by PANTPPF-Pd(0), which proves that the PANTPPF-Pd(0) can maintain satisfactory recyclability. Finally, based on the π-π stacking interactions and dipolar-dipolar interaction between porphyrin moieties in PANTPPF-Pd(0) and substrates, a novel heterogeneous “capture-catalyze” mechanisms was proposed.

Keywords: heterogeneous catalyst, green catalysis, porphyrin ligand