Aqueous Phase Synthesis of Palladium Tripod Nanostructures for Sonogashira Coupling Reactions

Abstract

In this work, palladium tripod nanocrystals have been synthesized by mixing an aqueous solution of cetyltrimethylammonium bromide (CTAB) surfactant, Na(2)PdCl(4), copper acetate, and ascorbic acid at 30 °C for 3 h. Addition of a small amount of copper ion source is critical to the formation of these tripods with a pod length reaching 100 nm. The incorporation of Cu atoms into the Pd tripods has been verified. The entire Pd tripod is single-crystalline with their branches growing along the [111] and [200] directions. Formation of side branches can be observed in some tripods. Triangular nanoplates are initially formed and evolved into the tripod structure in 20-30 min of reaction. Further growth leads to elongation of the pods. The large Pd tripods can serve as active and recyclable catalysts for a broad range of Sonogashira coupling reactions in water using a variety of aromatic halides containing electron-donating and -withdrawing substituents.

Direct Synthesis of Palladium Nanocrystals in Aqueous Solution with Systematic Shape Evolution

“…1,2 They also catalyze hydrogenation and formic acid oxidation reactions. 3−11 A wide variety of Pd nanocrystal morphologies has been prepared including rods, plates, and polyhedra.…”

The facile synthesis of single crystalline palladium arrow-headed tripods and their application in formic acid electro-oxidation

“…[1][2][3][4] Thus, one promising route to develop high-performance metal catalysts is to induce the exposure of specific catalytically active facets of nanocrystals through shape-controlled syntheses. [6][7][8][9][10][11][12] Palladium plays a crucial role in many catalytic applications. 5 Among them, multipod nanocrystals with branched arms naturally have concave regions on the surface and thus have received particular interest.…”

Can Polymorphism be Used to form Branched Metal Nanostructures?

“…Nanomaterials with well‐defined branched structures have attracted numerous interests because of their unique size‐ and shape‐dependent optical, electronic and catalytic properties. For instance, semiconductor tetrapods are pursued for improved performance in optoelectronic devices,1, 2 and catalytic metal tripods are found to be highly active in a range of coupling reactions 3. Nevertheless, the formation of complex, branched nanoparticles of metallic systems is challenging due to the high degree of symmetry in the face centered cubic ( fcc ) crystal structure.…”