Synthesis, Characterization, Reactivity, and Electrochemistry of Palladium Monolayer Protected Clusters

Gross, Stephen M.; Murray, Royce W.

doi:10.1021/la0010525

Cited by 164 publications

(213 citation statements)

References 69 publications

Supporting

Mentioning

183

Contrasting

Unclassified

Order By: Relevance

“…[1][2][3] Most reports of MPCs focus on Au, 1-3 but Pd MPCs have also been reported in the literature with sizes ranging from 2.3 to 6.5 nm. [15][16][17][18] The approach we describe is fundamentally different from these methods, because nanoparticle formation relies on preloading a welldefined molecular template rather than on less easily controlled nucleation and growth phenomena. Consequently, the size and size distribution of the resulting MPCs can be tightly controlled without need for purification.…”

mentioning

confidence: 99%

Extraction of Monodisperse Palladium Nanoparticles from Dendrimer Templates

2003

View full text Add to dashboard Cite

We report that size-monodisperse Pd nanoparticles can be extracted intact from dendrimer templates using n-alkanethiols. This is a significant discovery for several reasons. First, it demonstrates that nanometer-scale materials prepared within a molecular template can be removed, leaving both the replica and template undamaged. Second, it provides a straightforward approach for preparing highly monodisperse metallic and bimetallic monolayer-protected clusters (MPCs) 1-3 without need for subsequent purification. Third, it demonstrates that multiple, fairly complex operations, including formation of covalent bonds, electron-transfer, molecular transport, heterogeneous self-assembly, and nanoparticle transport, can all be executed within the interior of a 4.5-nm dendrimer. These points are demonstrated here by templating the formation of ∼1.7-nm Pd nanoparticles within poly(amidoamine) (PAMAM) dendrimers, [4][5][6][7][8] and then extracting the Pd into a toluene phase while leaving the dendrimer in the aqueous phase (Scheme 1).Dendrimer-encapsulated nanoparticles (DENs) 4-7 are prepared in a two-step process. First, metal ions are sequestered within the dendrimer, and then the ions are chemically reduced. Because the synthesis relies on a dendrimeric template, the resulting metal nanoparticle (the replica) can be quite monodisperse in size. Among the desirable characteristics of DENs are that they can be solubilized in nearly any solvent, 4 they are catalytically active, 6-8 the dendrimer itself can be used to lend functionality to the nanoparticle composite, 7 and recently it has been shown that very small DENs can be highly luminescent. 9 There have been two prior reports of ligand adsorption to Au DENs, in one case a thiol 10 and in the other a disulfide, 11 but there was no evidence for extraction of the nanoparticle in either case.There are several other approaches for preparing metal nanoparticles in the <2-nm size range. For example, MPCs are commonly prepared by mixing a metal salt, a chemical reducing agent, and a surfactant 2,12 (often an n-alkanethiol). The reductant initiates particle growth, which is eventually quenched by adsorption of the surfactant. MPCs can also be synthesized by postsynthesis ligand-exchange reactions starting with polymer-stabilized clusters. 13 MPCs have many desirable attributes: they can be repeatedly isolated from and redissolved in common organic solvents without irreversible aggregation or decomposition, 14 their surface can be functionalized with a vast range of modifiers, and they can be linked to polymers, biomolecules, and monolithic surfaces. 1-3 Most reports of MPCs focus on Au, 1-3 but Pd MPCs have also been reported in the literature with sizes ranging from 2.3 to 6.5 nm. [15][16][17][18] The approach we describe is fundamentally different from these methods, because nanoparticle formation relies on preloading a welldefined molecular template rather than on less easily controlled nucleation and growth phenomena. Consequently, the size and size distribution of the re...

show abstract

mentioning

confidence: 99%

Extraction of Monodisperse Palladium Nanoparticles from Dendrimer Templates

2003

View full text Add to dashboard Cite

show abstract

“…[36][37][38][39][40][41][42] Mayer and co-workers have studied extensively the stabilizing polymer on the reduction of an aqueous suspension of Ag, Au, Pt, or Pd ions by KBH 4 . [43][44][45][46] They investigated cationic polyelectrolytes, polyacids, non-ionic polymers, and block copolymers.…”

Section: Synthesis Of Metal Nanoparticlesmentioning

confidence: 99%

“…17 In particular, their high surface area-to-volume ratio and size- in the application of these materials is the control of the size, shape, composition, and stability of the nanoparticles, 28,[116][117][118][119][120] which can be accomplished through synthesis and functionalization of the nanoparticles with organic stabilizers such as polymers, [24][25][26][27] dendrimers, [28][29][30][31][32] surfactants, [33][34][35] or ligands. [36][37][38][39][40][41][42] In 1994, Brust and co-workers reported, for the first time, an easy and reproducible synthesis for the preparation of Au NPs stabilized with self-assembled monolayers of dodecanethiolate ligands. 52 These roughly spherical particles have a core of metallic atoms surrounded by an organic monolayer.…”

Section: Introductionmentioning

confidence: 99%

“…Alkanethiolate-protected Au NPs are highly stable, can be stored as solid, solvent-free powders, and characterized by the same analytical techniques used for the analysis of small molecules. 42 Murray and coworkers have extensively studied the synthesis, reactivity, and electrochemistry of Au NPs. 57,58 The ability to chemically modify the surface of Au NPs by ligand placeexchange 73,165 and organic coupling reactions 166 has enhanced the potential use of these nanomaterials in technological applications.…”

Section: Introductionmentioning

confidence: 99%

“…42 36,38 and their electrocatalytic properties in methanol oxidation. 37,41 Pd NPs coated with nalkylamines have also been used for the electrochemical oxidation of methane.…”

mentioning

confidence: 99%

See 2 more Smart Citations