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Journal ArticleDOI

Dendrimer encapsulated Silver nanoparticles as novel catalysts for reduction of aromatic nitro compounds

01 Nov 2017-Vol. 263, Iss: 2, pp 022010
TL;DR: In this article, polyethylene glycol (PEG) core dendrimer encapsulated silver nanoparticles (AgNPs) were synthesized through normal chemical reduction method, where Dendrimers acts as reducing and stabilizing agent.
Abstract: Polyethylene glycol (PEG) core dendrimer encapsulated silver nanoparticles (AgNPs) were synthesized through normal chemical reduction method, where dendrimer acts as reducing and stabilizing agent. The encapsulated AgNPs were well characterized using TEM, DLS and XPS techniques. The synthesized AgNPs showed excellent catalytic activity towards the reduction of aromatic nitro compounds with sodium borohydride as reducing agent and the results substantiate that dendrimer encapsulated AgNPs can be an effective catalyst for the substituted nitro aromatic reduction reactions. Also the kinetics of different nitro compounds reductions was studied and presented.
Citations
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Journal ArticleDOI
TL;DR: In this paper, a review on the different methods for preparing antimicrobial nanocomposites loaded with Ag NPs, the release of Ag nanoparticles from these nanostructures in different media, analyzing techniques for the evaluation of Ag release from nan composites, potential applications, and safety issues of nanocom composites containing Ag NP.

38 citations

Journal ArticleDOI
TL;DR: In this article, a review summarizes the latest advances in the preparation of metal-polymer nanocomposites by chemical reduction of metal ions in polymer matrices that are classified according to their functions as stabilizing agents, templates and reducing agents.
Abstract: This review summarizes the latest advances in the preparation of metal-polymer nanocomposites by chemical reduction of metal ions in polymer matrices that are classified according to their functions as stabilizing agents, templates and reducing agents. Particular attention is paid to various factors affecting the size and morphology of particles, the composition and structure of metal-polymer nanocomposites. Problems and prospects of development of metal-polymer nanocomposites obtained by chemical reduction of metal ions are considered.

31 citations

Journal ArticleDOI
Xue Lv1, Chuang Liu1, Zhubao Shao1, Shixin Song1, Shulin Sun1 
TL;DR: Two new mesoporous materials have been reported on the market for nanoparticles absorption byIonic liquids hydrogels as an appropriate candidate for the absorption of nanoparticles and their applications in materials science and nanofiltration.
Abstract: Ionic liquids (ILs) hydrogels as an appropriate candidate for the absorption of nanoparticles, had gained immense interests due to its friendly environment, low cost, high efficiency, and insensiti...

17 citations

Journal ArticleDOI
TL;DR: It has been found that increasing the time of annealing raises the ratio of the copper(II) oxide (CuO) tenorite phase in the structure, which leads to a significant increase in the catalytic activity of the composites.
Abstract: One of the promising applications of nanomaterials is to use them as catalysts and sorbents to remove toxic pollutants such as nitroaromatic compounds and heavy metal ions for environmental protection. This work reports the synthesis of Cu/CuO-deposited composite track-etched membranes through low-temperature annealing and their application in catalysis and sorption. The synthesized Cu/CuO/poly(ethylene terephthalate) (PET) composites presented efficient catalytic activity with high conversion yield in the reduction of nitro aryl compounds to their corresponding amino derivatives. It has been found that increasing the time of annealing raises the ratio of the copper(II) oxide (CuO) tenorite phase in the structure, which leads to a significant increase in the catalytic activity of the composites. The samples presented maximum catalytic activity after 5 h of annealing, where the ratio of CuO phase and the degree of crystallinity were 64.3% and 62.7%, respectively. The catalytic activity of pristine and annealed composites was tested in the reduction of 4-nitroaniline and was shown to remain practically unchanged for five consecutive test cycles. Composites annealed at 140 °C were also tested for their capacity to absorb arsenic(III) ions in cross-flow mode. It was observed that the sorption capacity of composite membranes increased by 48.7% compared to the pristine sample and reached its maximum after 10 h of annealing, then gradually decreased by 24% with further annealing.

17 citations

References
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Journal ArticleDOI
TL;DR: The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties are equally important.
Abstract: The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102

6,852 citations

Journal ArticleDOI
Richard M. Crooks1, Mingqi Zhao1, Li Sun1, Victor Chechik1, Lee K. Yeung1 
TL;DR: Intradendrimer hydrogenation and carbon-carbon coupling reactions in water, organic solvents, biphasic fluorous/organic solvent, and supercritical CO2 are also described.
Abstract: 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.

1,925 citations

Journal ArticleDOI
16 Feb 2010-Langmuir
TL;DR: The as-prepared new solid-phase biopolymer-based catalysts are very efficient, stable, easy to prepare, eco-friendly, and cost-effective, and they have the potential for industrial applications.
Abstract: Silver and gold nanoparticles have been grown on calcium alginate gel beads using a green photochemical approach. The gel served as both a reductant and a stabilizer. The nanoparticles were characterized using UV−visible spectroscopy, X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), energy dispersive X-ray (EDS), and selected area electron diffraction (SAED) analyses. The particles are spherical, crystalline, and the size ranges for both Ag and Au nanoparticles are <10 nm. It is noticed from the sorption experiment that the loading of gold on calcium alginate beads is much more compared to that of Ag. The effectiveness of the as-prepared dried alginate-stabilized Ag and Au nanoparticles as a solid phase heterogeneous catalyst has been evaluated, for the first time, on the well-known 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP) in the presence of excess borohydride. The reduction was very efficient and followed zero-order kinetics for both Ag and Au nanocompos...

886 citations

Journal ArticleDOI
TL;DR: These materials are synthesized by a template approach in which metal ions are extracted into the interior of dendrimers and then subsequently chemically reduced to yield nearly size-monodisperse particles having dimensions of less than 3 nm.
Abstract: In this article we describe the synthesis, characterization, and applications of dendrimer-encapsulated nanoparticles (DENs). These materials are synthesized by a template approach in which metal ions are extracted into the interior of dendrimers and then subsequently chemically reduced to yield nearly size-monodisperse particles having dimensions of less than 3 nm. Monometallic, bimetallic (including core/shell), and semiconductor nanoparticles have been prepared by this route. The dendrimer component of these composites serves not only as a template for preparing the nanoparticle replica but also to stabilize the nanoparticle, makes it possible to tune solubility, and provides a means for immobilization of the nanoparticle on solid supports. These materials have a number of potential applications, but the focus here is on catalysis. Homogeneous catalytic reactions, including hydrogenations, Heck coupling, and Suzuki reactions, in water, organic solvents, biphasic fluorous/organic solvents, and liquid an...

825 citations

Journal ArticleDOI
06 Jan 2004-Langmuir
TL;DR: It is found that the rate constants for the reduction of 4-nitrophenol involving all the dendrimer-metal nanocomposites decrease with an increase in the d endrimer concentrations, and the catalytic activity of dend rimer-palladium nanocomPOSites is highest.
Abstract: Dendrimer-metal (silver, platinum, and palladium) nanocomposites are prepared in aqueous solutions containing poly(amidoamine) (PAMAM) dendrimers with surface amino groups (generations 3, 4, and 5) or poly(propyleneimine) (PPI) dendrimers with surface amino groups (generations 2, 3, and 4) The particle sizes of the metal nanoparticles obtained are almost independent of the generation as well as the concentration of the dendrimer for both the PAMAM and the PPI dendrimers; the average sizes of silver, platinum, and palladium nanoparticles are 56-75, 12-16, and 16-20 nm, respectively It is suggested that the dendrimer-metal nanocomposites are formed by adsorbing the dendrimers on the metal nanoparticles Studies of the reduction reaction of 4-nitrophenol by these nanocomposites show that the rate constants are very similar between PAMAM and PPI dendrimer-silver nanocomposites, whereas the rate constants for the PPI dendrimer-platinum and -palladium nanocomposites are greater than those for the corresponding PAMAM dendrimer nanocomposites In addition, it is found that the rate constants for the reduction of 4-nitrophenol involving all the dendrimer-metal nanocomposites decrease with an increase in the dendrimer concentrations, and the catalytic activity of dendrimer-palladium nanocomposites is highest

587 citations