Methylated b-Cyclodextrin-Capped Ruthenium Nanoparticles: Synthesis Strategies, Characterization, and Application in Hydrogenation Reactions

Abstract : Colloidal suspensions of ruthenium nanoparticles (Ru0 NPs) stabilized by randomly methylated β-cyclodextrins were easily prepared in aqueous solution by two comparative reductive approaches. The first method relies on a one-step hydrogen reduction of ruthenium trichloride as a metal precursor in the presence of cyclodextrins (one-pot method). The second method consists of the chemical reduction of metal salts by NaBH4, followed by the stabilization of ruthenium NPs by post-addition of the methylated β-cyclodextrins (cascade method). The modified β-cyclodextrin-capped ruthenium NPs obtained were characterized using TEM, DLS, and NMR techniques. The highly dispersed colloidal suspensions contain very small particles in the size range of 1-1.4 nm. Their catalytic performances were investigated in terms of activity and selectivity of their biphasic hydrogenation of various substrates (olefins, ketones, and disubstituted arenes) under mild conditions.