Palladium metal nanoparticles on organically modified thin hybrid films

Hybrid thin films containing palladium nanoparticles in different concentrations (0.5% and 1%) with and without nanoparticle stabiliser agent [mercaptopropyl trimethoxysilane, MPTMS] were prepared using a sol–gel process. Pd nanoparticles were found to be highly dispersed on the thin films with particles ranging from 7 to 10 nm. The catalytic properties of the thin films supported Pd nanoparticles were investigated in the Heck reaction of iodobenzene and methyl acrylate. Films containing Pd MNP (with and without MPTMS) gave quantitative conversion and complete selectivity to the targeted product (methyl cinnamate) in a short time of reaction (<15 min) under microwave irradiation. While Pd containing films without MPTMS were highly active and reusable after 3 runs, MPTMS containing films were found to be inactive after the first use. Such phenomenon was correlated to the steric hindrance round the Pd MNP due to the adsorption of species on the surface that render the catalysts inactive.