Preparation of Alkanethiolate-Protected Palladium Nanoparticles and Their Size Dependence on Synthetic Conditions

Quiros, Ignacio; Yamada, Mami; Kubo, K.; Mizutani, Jun; Kurihara, Masato; Nishihara, Hiroshi

doi:10.1021/la0114023

Cited by 75 publications

(53 citation statements)

References 40 publications

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“…We attempted to extract the DSNs and DENs with alkanethiols (Scheme 2). [15,16] With undodecanethiol, only DSN-G 0 could be extracted. This distinction in the behavior of DSN-G 0 and the DENs is in accord with the different types of PdNP stabilization: As the nanoparticles are not encapsulated in the case of DSN-G 0 , extraction is favored even with a bulky thiol.…”

Section: Methodsmentioning

confidence: 99%

“Homeopathic” Catalytic Activity and Atom‐Leaching Mechanism in Miyaura–Suzuki Reactions under Ambient Conditions with Precise Dendrimer‐Stabilized Pd Nanoparticles

Diallo¹,

Ornelas²,

Salmon³

et al. 2007

Angew Chem Int Ed

320

216

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Low catalyst loading is essential for the development of "green" palladium-catalyzed CÀC bond-forming processes, [1] such as Heck and Suzuki reactions. [2] In this regard, transitionmetal nanoparticles (NPs) have attracted much attention as a major alternative to molecular homogeneous catalysts. [3][4][5] We now report that dendrimer-stabilized Pd nanoparticles synthesized by click chemistry catalyze the Suzuki reaction under ambient conditions with as little as 1 ppm of the PdNP catalyst: Our studies indicate that an atom-leaching mechanism is operating. We also show that the extraction of these PdNPs with thiols provides catalytically active PdNPs of complementary mechanistic interest.Polymer-stabilized [4] and dendrimer-stabilized NPs [5] have proved to be efficient catalysts for a variety of reactions. The advantage of dendrimers, besides their loose binding of the NP surface, is that a precise and predictable number of Pd atoms exist in the PdNP catalyst or precatalyst. Thus, it is possible to study the influence of NP size on the catalytic parameters (efficiency and stability) and mechanism. The use of dendrimers to form dendrimer-encapsulated NPs (DENs) [6] and dendrimer-stabilized NPs (DSNs), [7] in which dendrimers surround the NPs, was pioneered with PAMAM dendrimers. DENs have been studied largely in catalytic olefin-hydrogenation reactions [6a, c, 8] and in several cases in C À C coupling reactions, including the Suzuki reaction. [9] A leaching mechanism upon Pd catalysis has been proposed by de Vries and co-workers for the high-temperature (130-160 8C) Heck reaction with simple molecular Pd II catalysts, [10] and these catalysts indeed decompose to give PdNPs at high temperature. They propose that Pd atoms are removed from the PdNP surface subsequent to oxidative addition of the aryl halide, and that efficient Pd catalysis proceeds thereafter in solution before these catalytically active Pd atoms are trapped by a PdNP.[10] The mechanism of the Suzuki reaction, however, is controversial. One research group proposed a mechanism that operates only at the NP surface, [11] whereas another research group proposed that under microwave irradiation Pd-atom leaching occurs subsequent to oxidative addition of the aryl halide, as in the Heck reaction.[12] All of these studies were carried out at high temperature, under which conditions Oswald ripening, including atom loss from PdNPs, occurs. We wondered how the reaction would proceed under mild, ambient conditions with a PdNP catalyst. Herein, we show that the use of precise DSNs and DENs of various sizes for comparative styrenehydrogenation and Suzuki reactions at 25 8C provides a unique means to reach decisive conclusions concerning the leaching mechanism of the Suzuki reaction under ambient conditions.We recently described dendrimers synthesized by click chemistry [13] with 9, 27, and 81 ferrocenyl termini and 1,2,3-triazole ligands on the dendritic tethers: G 0 with nine terminal ferrocenyltriazole units, G 1 with 36 triazole units (9 interior and 27 termi...

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Section: Methodsmentioning

confidence: 99%

“Homeopathic” Catalytic Activity and Atom‐Leaching Mechanism in Miyaura–Suzuki Reactions under Ambient Conditions with Precise Dendrimer‐Stabilized Pd Nanoparticles

Diallo¹,

Ornelas²,

Salmon³

et al. 2007

Angew Chem Int Ed

320

216

View full text Add to dashboard Cite

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“…These nanoparticles have been synthesized in a nonionic inverse micelle [6], a biphasic system [12], and a single-organic-phase system [13,14]. The resulting nanoclusters are soluble and stable but confined primarily to nonpolar organic media.…”

Section: Introductionmentioning

confidence: 99%

“…One of the main differences among these routes to Pd nanoparticles is the choice of a reducing agent. The reducing agents commonly used are sodium borohydride [12], superhydride (1.0 M solution of lithium triethylborohydride in tetrahydrofuran) [13,14], lithium aluminum hydride, and lithium borohydride [6]. The stronger reducing agents favor smaller nanocluster formation.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and self-organization of soluble monodisperse palladium nanoclusters

Chen

Falkner

Guo

et al. 2005

Journal of Colloid and Interface Science

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“…extract. [37][38][39][40] This suggests that the reductive components mentioned above were coated on the surface of the nanoparticles and hence may have inhibited further aggregation in an aqueous environment.…”

Section: Ftir Spectroscopy Analysismentioning

confidence: 99%

Enhanced stability and antibacterial efficacy of a traditional Chinese medicine-mediated silver nanoparticle delivery system

Sun¹,

Qu²,

Ma³

et al. 2014

IJN

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Silver nanoparticles (AgNPs) are widely used as antibacterial products in various fields. Recent studies have suggested that AgNPs need an appropriate stabilizer to improve their stability. Some antibacterial traditional Chinese medicines (TCMs) contain various reductive components, which can not only stabilize AgNPs but also enhance their antimicrobial activity. In this study, we developed a series of novel AgNPs using a TCM extract as a stabilizer, reducing agent, and antimicrobial agent (TCM-AgNPs). A storage stability investigation of the TCM-AgNPs suggested a significant improvement when compared with bare AgNPs. Further, conjugation of TCMs onto the AgNP surface resulted in stronger antimicrobial potency on antibacterial evaluation using Pseudomonas aeruginosa , Staphylococcus epidermidis , and Staphylococcus aureus with minimum inhibitory concentration 50% (MIC 50 ) ratios (and minimum bactericidal concentration 90% [MBC 90 ] ratios) of AgNPs to respective TCM-AgNPs as assessment indices. Among these, P. cuspidatum Sieb. et-conjugated AgNPs ( P.C. -AgNPs) had the advantage of a combination of TCMs and AgNPs and was studied in detail with regard to its synthesis and characterization. The extraction time, reaction temperature, and concentrations of AgNO 3 and Polygonum cuspidatum Sieb. et extract were critical factors in the preparation of P.C. -AgNPs. Further, the results of X-ray diffraction and Fourier transform infrared spectroscopy indicated successful preparation of P.C. -AgNPs. In representative studies, P.C. -AgNPs showed a well-defined spherical shape, a homogeneous small particle size (36.78 nm), a narrow polydispersity index (0.105), and a highly negative zeta potential (−23.6 mV) on transmission electron microscopy and dynamic light scattering. These results indicate that TCM-AgNPs have a potential role as antibacterial agents in the clinic setting.

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Preparation of Alkanethiolate-Protected Palladium Nanoparticles and Their Size Dependence on Synthetic Conditions

Cited by 75 publications

References 40 publications

“Homeopathic” Catalytic Activity and Atom‐Leaching Mechanism in Miyaura–Suzuki Reactions under Ambient Conditions with Precise Dendrimer‐Stabilized Pd Nanoparticles

“Homeopathic” Catalytic Activity and Atom‐Leaching Mechanism in Miyaura–Suzuki Reactions under Ambient Conditions with Precise Dendrimer‐Stabilized Pd Nanoparticles

Synthesis and self-organization of soluble monodisperse palladium nanoclusters

Enhanced stability and antibacterial efficacy of a traditional Chinese medicine-mediated silver nanoparticle delivery system

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