Preparation and catalysis of poly(β-cyclodextrin)-stabilized palladium nanoparticles

Abstract

Interests in colloidal dispersions of nanoscopic materials and their application to catalyses have greatly stimulated research on metal nanoparticles. Stabilizers, often used to prevent metal nanoparticles from aggregation, can also promote some special properties of metal nanoparticles. Cyclodextrins (CyD) are known to form inclusion complexes with organic compounds in solution. Palladium nanoparticles can be well stabilized not by CyD, but by poly(β-cyclodextrin) (PCyD). PCyD-stabilized Pd nanoparticles, prepared by refluxing an alcohol/water resolution of palladium acetate in the presence of PCyD, act as highly active catalysts for hydrogenation of olefins. The catalytic activity for 10-undecenoic acid was higher than that for 2-undecenoic acid, suggesting a steric effect on the catalytic activity due to inclusion complex formation of Pd nanoparticle-containing PCyD with the substrates. A similar effect was observed for 4- and 3-vinylbenzoic acids.