A covalently anchored Pd(II)-Schiff base complex over a modified surface of mesoporous silica SBA-16: An efficient and reusable catalyst for the Heck-Mizoroki coupling reaction in water

A new heterogeneous palladium catalyst was prepared by covalent anchoring of a palladium-(II)-Schiff base complex onto the mesoporous cage-like material SBA-16. Several instrumental techniques such as Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray analysis (EDX), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), N-2 adsorption-desorption isotherms, UV-vis spectroscopy, and elemental analysis were carried out to characterize the structure and composition of the catalyst. This catalyst displayed excellent activity for the Heck-Mizoroki reaction of various aryl halides and alkenes in water as a green solvent. It was found that the solid catalyst could be easily recovered by simple filtration and reused six times without a significant loss of catalytic activity. In addition, Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), N-2 adsorption-desorption isotherms, and high resolution transmission electron microscopy (HRTEM) techniques were used to prove the stability of the reused catalyst.