G. Collins, C. ODywer, J.D. Holmes
University College Cork and Tyndall National Institute, Ireland
pp. 79 - 82
Keywords: palladium, nanoparticle, surface functionalization, Suzuki reaction
The Suzuki-Miyaura reaction is a highly utilised reaction for aryl-aryl bond formation in organic synthesis due it is versatility. The motivation for the application of heterogeneous catalysts in these systems is the easy recovery and potential recyclability of the catalyst. In this study, the effect of surface chemistry and functionalization on the catalytic performance is assessed. Capping ligands commonly used in colloidal synthesis such as oleylamine, dodecanethiol, propylene glycol and polyvinylpyrrolidone (PVP) are compared with commercial Pd on carbon catalysts. The catalysts are analyzed pre- and post-reaction with transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The presence of capping ligands is found to have a positive or negative effect on the catalytic performance depending on the chemistry of the functional group. The capping ligands further impacts on the recyclability of the catalyst. Changes in the nanoparticle surface chemistry and morphology during the reaction are key deactivation pathways. The presence of capping ligands, in particular PVP, was observed to give excellent stability to colloidal catalysts, preventing significant nanoparticle aggregation and facilitating excellent reusability. Overall, a complex interplay between surface chemistry and stability under the reaction conditions influence catalytic performance and recyclability.