Nitrogen-containing polydentate ligand with –NR3+/−PPh3+ moieties chelated Pd(0) nanoparticles functionalized fiber for green catalysis of C–C bond coupling reaction

Abstract

Highly dispersion and small particle size Pd(0) nanoparticles were immobilized into nitrogen-containing polydentate ligand and quaternary ammonium/phosphonium salt bifunctionalized polyacrylonitrile fiber to prepared a novel functionalized fiber catalyst (PAN_NP/QA&PSF-Pd(0)). Some necessary instrumental analysis methods, including inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscope (TEM), etc., were applied to accurately characterize the microscopic physical and chemical properties of PAN_NP/QA&PSF-Pd(0), confirming the structure of the novel fiber catalyst was in accordance with our expected design. Additionally, the Heck reaction was changed as a classic template reaction for evaluating the catalytic activity of prepared fiber catalyst. The result verified that PAN_NP/QA&PSF-Pd(0) can efficiently catalyze the Heck reaction between different halogenated aromatic hydrocarbons and terminal olefins within 6 h under catalyst dosage of 0.02 % and solvent-free condition, and the isolated yields of target products can reach 46–99 %, respectively. Furthermore, PAN_NP/QA&PSF-Pd(0) can also smoothly catalyze Suzuki reaction between different iodized aromatics and arylboric acids, achieving satisfactory yields of 67–99 %. Moreover, PAN_NP/QA&PSF-Pd(0) can be reused 8 times with slight decline in catalytic activity (isolated yield of 91 % and 80 %, respectively), and the average size of Pd(0) nanoparticles only increased from 1.94 nm to 2.98 nm, verifing that the Pd(0) nanoparticles in PAN_NP/QA&PSF-Pd(0) was validly dispersed and stabilized, which makes the fiber catalyst has excellent recyclability. Noteworthily, a reasonable heterogeneous catalytic mechanism was proposed.