Synthesis, Characterization, and Catalytic Applications of a Palladium-Nanoparticle-Cored Dendrimer

Abstract

A palladium-nanoparticle-cored G-3 dendrimer, characterized by TEM, TGA, absorption, and IR spectroscopies, has approximately 300 Pd atoms in the metallic core and an average diameter of 2.0 nm, to which are attached fourteen G-3 dendrons. Nearly 90% of the metal nanoparticle surface is unpassivated and available for catalysis. The dendrons inhibit metal agglomeration without adversely affecting chemical reactivity. Thus, preliminary investigations have shown that Pd-G-3 can efficiently catalyze Heck and Suzuki reactions.

Recent Advances in the Liquid‐Phase Synthesis of Metal Nanostructures with Controlled Shape and Size for Catalysis

“…Ex situ prepared stabilized colloidal Pd (6,(134)(135)(136)(137) and Ru (138) nanoparticles have gained considerable attention due to their high activity and recyclability. Pd equidimensional nanoparticles of mean sizes from 1.7 to 3.7 nm stabilized by PVP were used as a catalytic probe to study structure sensitivity of Heck coupling of p-bromobenzaldehyde with butyl acrylate (25).…”

Dendronization: A Useful Synthetic Strategy to Prepare Multifunctional Materials

“…The third type of nanostructures comprises nanoparticle-cored dendrimers [153] (NCDs, Figure 16(c)), which are core-shell dendritic nanomaterials formed by an inorganic nanoparticle (the core) located at the center of the structure and dendrons (the shell) attached to the core. The core can consist of different inorganic nanoparticles such as metallic (e.g., Au [20,36,[153][154][155][156][157][158][159][160][161][162][163][164][165][166][167][168][169][170][171][172], Pd [173][174][175], Pt [176]), metallic oxide (e.g., iron oxides) [177][178][179][180][181] or semiconductor (quantum dots, e.g., CdS, CdSe) [182] clusters. The inorganic core is functionalized with dendrons, in a radial way by specific interactions.…”

“…These moieties are able to specifically interact and self-assembly onto the NP surface (Figure 17(a)) [154,156,161,[165][166][167][168]170,171]. Note that it is also possible to use dendrimers having a core moiety which self-assembles onto the surface in such a way as to leave individual dendrons functionalizing the NP, for example disulfide-cored dendrimers functionalizing gold NPs [36,153,155,163,173]. The disadvantage of this method relies on the large excess of dendritic ligands required for the synthesis of these nanomaterials [184].…”

“…To date, NCDs having a Fréchet-type dendritic shell have been widely explored. For example, Gopidas et al [173] synthesized Pd NPs functionalized with a G3 dendritic disulfide. These NCDs present the dual requirements for its use in catalysis: high exposed metallic surface (ca.…”

Palladium Nanoscale Catalysts in Ionic Liquids: Coupling and Hydrogenation Reactions

“…Today, rather few works have been published using Pd-NPs in ILs as catalyst in this reaction. (Pathak et al, 2000;Ramarao et al, 2002;Gopidas et al, 2003;Narayanan & ElSayed, 2003;Pittelkow et al, 2003;Kim et al, 2004;Liu et al, 2004;Fernandez et al, 2007;Durand et al, 2008) For example, Calo and Nacci reported on Pd-NPs in tetraalkylammonium ILs, starting from Pd(OAc) 2 in the presence of TBAA at 90 °C, which were used as precursor for the coupling of aryl halides (Scheme 5; entry 6, Table 1 Interestingly, with tetrabutylammonium hydroxide as base, the catalytic efficiency increased significantly, thus, the reaction was performed even under milder conditions. This can be explained by the elevated concentration of tetraalkylammonium in water, contributing through partitioning equilibrium, keeping the concentration of the cations in the IL constant.…”