This study shows that polymer nanogels (well-defined cross-linked nanoparticles behaving as highly hydrated unimolecular objects) are suitable capping agents for palladium nanoparticle catalyst systems. In spite of the structurally complex nature of the catalysts, it was possible to go from acrylate-based monomers to ready-to-use and recyclable catalysts in only two-steps. First, nanogels were synthesized by activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) method with sequential addition of monomers. Then, in the second step, palladium acetate was reduced to obtain ready-to-use catalysts (ca. 25 nm nanogel structures containing ca. 7 nm palladium nanoparticles). The catalytic activity was confirmed in p -nitrophenol (Nip) reduction and Suzuki cross-coupling reactions. The observed rate constants (kobs) for Nip reduction were in the range of 0.8-10.0 × 10-2 s-1 depending on the polymeric capping agent structure, with the highest value being found for nanogel-based systems. These composite catalysts also mediated the cross-coupling Suzuki reaction providing the expected products in quantitative yields under relatively mild conditions after 4 h at 50 ºC. The simplicity of catalyst preparation protocol that ensures excellent activity and the low concentration of polymer applied during the synthesis are a step forward in terms of environmental and economic prospects.

Neste trabalho foi desenvolvido um método eficiente para a síntese de selenetos de diorganoíla e β-seleno aminas empregando Zn, quantidades catalíticas de ZnO nanoestruturado e líquidos iônicos (LI) como solventes recicláveis. Este sistema ZnO/LI apresentou alta eficiência nesta transformação, levando à formação dos produtos desejados em bons rendimentos.

We have developed an efficient method for the synthesis of diorganyl selenides and β-seleno amines using Zn, catalytic amounts of ZnO nanopowder, as a catalyst and ionic liquid as a recyclable solvent. This ZnO/ionic liquid system shows high efficiency in catalyzing these transformations with the formation of the desired products in high yields.