Dendrimer-encapsulated Metal Nanoparticles Research Articles

Magnetic dendrimer-encapsulated metal nanoparticles (Au, Ag): effect of dendrimerization on catalytic reduction of 4-nitrophenol

Magnetic dendrimer-encapsulated metal nanoparticles (Au, Ag): effect of dendrimerization on catalytic reduction of 4-nitrophenol

A review on poly(amidoamine) dendrimer encapsulated nanoparticles synthesis and usage in energy conversion and storage applications

A review on poly(amidoamine) dendrimer encapsulated nanoparticles synthesis and usage in energy conversion and storage applications. • The Dend-NPs for electrochemical energy conversion and storage is reviewed. • Synthesis methods to prepare active and durable Dend-NPs are summarized. • The best practice and beforehand knowledge of Dend-NPs are recommended. • The electrocatalytic activity of Dend-NPs towards multiple reactions are discussed. • The reasons for high performance in multiple energy systems are highlighted. The direction of this review is concentrating on the development of poly(amidoamine) (PAMAM) dendrimer encapsulated metal nanoparticles (NPs), so-called Dend-NPs as catalysts in the field of electrochemical energy conversion and storage. To date, Dend-NPs have been pointed out as well-organized and effective catalysts in the most popular electrochemical technologies, such as fuel cells, batteries, supercapacitors and water electrolyzers. Different strategies and technological progresses targeting efficient power and energy productions with excellent durability and performance retentions in such systems are emphasized. Dend-NPs action in electrochemical energy systems thrived by cathodic catalytic reactions, particularly, hydrogen evolution reaction (HER) in electrolyzers and oxygen reduction reaction (ORR) in fuel cells, and electrochemical (Faradaic and non-Faradaic) processes in batteries and supercapacitors are summarized. The metal NPs produced within the dendrimer by various approaches, conditions for obtaining zero-valent metals and synthesis methods for different types of metal NPs are discussed. Advancing knowledge of Dend-NPs synthesis, difficulties and their solutions and the best practice recommended for readers are explained in brief. Besides, stability, role of dendrimer, generation effects, terminal group effects and mechanisms to encapsulate each transition and precious metal NPs such as copper (Cu), nickel (Ni), platinum (Pt), palladium (Pd), silver (Ag), gold (Au) and bimetallic within the cavity of PAMAM dendrimers are highlighted. Moreover, PAMAM dendrimer and its generation are classified bearing in mind their viable use in energy technologies and applications where possible.

Synthesis and catalytic activity of DAB-dendrimer encapsulated Pd nanoparticles for the Suzuki coupling reaction

Palladium based dendrimer-encapsulated metal nanoparticles (DEMNs) are prepared by reduction of an aqueous solution of palladium (II) and five generations of amino terminated dendrimers (DAB (diaminobutane) dendrimers). The average size of the palladium nanoparticles formed is 1.7–2.8 nm. Catalytic performances of these DEMNs have been studied in the Suzuki cross-coupling reaction.

Thiophene Dendron Jacketed Poly(amidoamine) Dendrimers: Nanoparticle Synthesis and Adsorption on Graphite

The peripheral functionalization of amine-terminated fourth-generation poly(amidoamine) (PAMAM) with thiophene dendrons and the preparation of dendrimer-encapsulated metal nanoparticles are described. Interesting nanoparticle stabilization and energy-transfer properties were observed with these hybrid materials. The synthesis involved imine coupling of the dendron derivatives to the peripheral amine groups of PAMAM followed by reduction. The formation of these metal-organic nanoparticle hybrid materials was monitored by UV-vis spectroscopy. The complexation of metal ions and the stabilization effect of PAMAM on metal nanoparticles were investigated by FT-IR. Energy transfer was observed between the metal surface plasmon absorption and fluorescence of the terthiophene dendrons. Noncontact magnetic-AC mode AFM imaging revealed the formation of monodispersed and very stable nanoparticles adsorbed on an HOPG flat substrate.

Dendrimer‐Encapsulated Metal Nanoparticles and Their Applications to Catalysis

AbstractFor Abstract see ChemInform Abstract in Full Text.

Preparation of Dendrimer-Encapsulated Metal Nanoparticles Using Organic Solvents

Preparation of dendrimer-encapsulated metal nanoparticles (DEMNs) within amphiphilic dendrimers in an organic solvent is reported. The important new result is that metal ion encapsulation is driven by solubility differences between the metal salt in solution and the dendrimer interior. This contrasts with previous studies, which have relied on specific interactions between metal ions and ligands within the dendrimer interior to drive encapsulation. This new approach makes it possible to prepare relatively large DEMNs. Both Cu and Pd DEMNs have been prepared and the latter are shown to be catalytically active for hydrogenation reactions.

Dendrimer-encapsulated metal nanoparticles and their applications to catalysis

This account describes the synthesis, characterization, and applications to catalysis of dendrimer-encapsulated metal nanoparticles (DEMNs). These materials are synthesized by a template approach in which metal ions are sorbed into the interior of dendrimers and then subsequently chemically reduced to yield nearly size-monodisperse, zero-valent metal particles having dimensions of less than 4 nm. The dendrimer component of these composites serve not only as a template for preparing the nanoparticle replica, but they also stabilize the nanoparticle, make it possible to tune solubility, and enhance catalytic selectivity. These materials have been used for a broad range of catalytic reactions, including hydrogenations, Heck coupling, and Suzuki reactions, in water, organic solvents, biphasic fluorous/organic solvents, and supercritical CO 2. In many cases it is very simple to recycle the dendrimer-encapsulated catalysts. In addition to monometallic DEMNs, bimetallic materials have also recently been prepared and their catalytic properties are reported. To cite this article: Y. Niu et al., C. R. Chimie 6 (2003).

Dendrimer-Mediated Immobilization of Catalytic Nanoparticles on Flat, Solid Supports

Sixth-generation poly(amidoamine) (PAMAM) dendrimers have been used to explore methods for immobilizing Pd nanoparticles on atomically flat surfaces. Two methods are investigated. In the first method, dendrimer-encapsulated metal nanoparticles (DEMNs) are prepared using a PAMAM dendrimer with hydroxyl terminal groups. These particles are then deposited on a mica surface. Tapping-mode AFM images reveal a monodispersed size distribution of DEMNs that has an average composition of 40 Pd atoms per dendrimer. When thermal combustion in an O2 stream is used to remove the dendrimer host at 630 °C, Pd particles aggregate via surface diffusion, resulting in an increase in particle diameter. In the second method, the step edges of a HOPG surface are first oxidized in an oxygen atmosphere. A PAMAM dendrimer with amine terminal groups is then allowed to adsorb selectively on the step edges, followed by immobilization of Pd particles via surface chemical reactions. The Pd particles prepared by this method are shown to be catalytically active for electroless copper deposition.

Dendrimer-encapsulated metal nanoparticles: synthesis, characterization, and applications to catalysis.

This Account reports the synthesis and characterization of dendrimer-encapsulated metal nanoparticles and their applications to catalysis. These materials are prepared by sequestering metal ions within dendrimers followed by chemical reduction to yield the corresponding zerovalent metal nanoparticle. The size of such particles depends on the number of metal ions initially loaded into the dendrimer. Intradendrimer hydrogenation and carbon-carbon coupling reactions in water, organic solvents, biphasic fluorous/organic solvents, and supercritical CO2 are also described.