Sulphonated “Click” Dendrimer‐Stabilized Palladium Nanoparticles as Highly Efficient Catalysts for Olefin Hydrogenation and Suzuki Coupling Reactions Under Ambient Conditions in Aqueous Media

Abstract

Water-soluble 1,2,3-triazolyl dendrimers were synthesized by "click chemistry" and used to stabilize palladium nanoparticles (PdNPs). These new "click" dendrimer-stabilized nanoparticles (DSN) are highly stable to air and moisture and are catalytically active for olefin hydrogenation and Suzuki coupling reaction, in aqueous media, under ambient conditions using a low amount of palladium (0.01 mol% Pd). Kinetic studies show high catalytic efficiency and high stability for the new "click" DSN in both reactions. The complexation of potassium tetrachloropalladate (K 2 PdCl 4 ) to the triazole ligands present in the dendritic structures was monitored by UV/vis and, after reduction, the nanoparticles were characterized by transmission electron microscopy (TEM).

The Redox Functions of Metallodendrimers

“…In fact the triazolyl-Fc termini allowed redox recognition of both oxo-anions and transition-metal cations with positive dendritic effects [99,100]. Binding of transition-metal cations by the triazolyl ligand was also especially fruitful, because further reduction of the triazole-coordinated transition-metal cations led to the formation of catalytically active metal NPs [101][102][103]. Remarkably, this new strategy of metallodendrimer design and synthesis could be extended to several other redox-active redox groups such as biferrocene [104], cobalticenium [105], [FeCp(arene)] ?…”

Tailored Nanoparticles for Clean Technology–Achieving Size and Shape Control

“…The simple chemical methods, such as deposition-precipitation (DP) [65], ion exchange, and impregnation [66], aim to control the growth of nanoparticles on various supports via reduction/decomposition of simple precursors such as metal salts or organometallic compounds [67]. Improved control can be achieved via the immobilization of premade metal ion-containing templates (such as dendrimers [68]) onto supports, followed by careful reduction/decomposition to form well-defined nanoparticles [69][70][71][72][73][74][75][76][77]. Interestingly, dendrimers could be used both to deliver precise metal nanoparticles onto supports in fabrication of the heterogeneous catalysts, yet could also act as unsupported, homogeneous catalysts [71].…”

Water Soluble Starch Stabilized Palladium Nanoparticle: Efficient Catalyst for Miyaura‐Suzuki Coupling Reaction

“…6 Most recently, palladium nanoparticles attracted much attention in Miyaura-Suzuki reation. Air-stable and highly active dendritic phosphine oxide-stabilized palladium nanoparticles, 7 sulphonated "click" dendrimer-stabilized palladium nanoparticles, 8 palladium nanoparticles stabilized by star-shaped heavily fluorous compounds, 9 palladium nanoparticles on polysaccharide-derived mesoporous materials, 10 palladium nanoclusters supported on propylurea-modified siliceous mesocellular foam, 11 palladium nanoparticles supported on alumina-based oxides as heterogeneous catalysts, 12 Pd nanoparticles on carbon nanotube microparticles, 13 Pd nanoparticles immobilized on pH-responsive and chelating nanospheres 14 and in situ-generated palladium nanoparticles free of ligand 15 highly efficiently catalyzed aryl halides (X＝Br, I) with aryl and alkylboronic acids in good to excellent yields. Palladium nanoparticles supported on polyaniline nanofibers as a semi-heterogeneous catalyst, 16 in situ generated palladium nanoparticles from PEG-400/Pd(OAc) 2 , 17 homogeneous nanosize palladium catalysts with a ligand of phosphine with a TPPh moiety, 18 in situ generated palladium nanoparticles in PEG-400 under aerobic conditions 19 and Pd on surface-modified NiFe 2 O 4 nanoparticles 20 highly efficiently promoted coupling reaction of aryl chlorides with arylboronic acids in good to excellent yields.…”