Search results for "Palladium nanoparticle"

Ecotoxicity of halloysite nanotube–supported palladium nanoparticles in Raphanus sativus L

2015

Halloysite nanotubes (HNTs) are natural nanomaterials that are biocompatible and available in large amounts at low prices. They are emerging nanomaterials with appealing properties for applications like support for metal nanoparticles (NPs). The potential environmental impacts of NPs can be understood in terms of phytotoxicity. Current research has been focusing on HNT applications in cell or animal models, while their use in plants is limited so their ecotoxicological impact is poorly documented. To date there are no studies on the phytotoxic effects of functionalized halloysites (functionalized-HNTs). To develop a quantitative risk assessment model for predicting the potential impact of H…

Palladium–Polypyrrole Nanoparticles-Catalyzed Sonogashira Coupling

2012

Abstract Palladium nanoparticles were encapsulated into polypyrrole globules via one-step one-pot redox reaction between tetraamminepal- ladium(ii) dichloride and pyrrole in water. Such a material is an active catalyst for the Sonogashira coupling of iodo- and bromo- arenes.

Palladium nanoparticles immobilized on halloysite nanotubes covered by a multilayer network for catalytic applications

2018

The synthesis of pure fine chemicals for industrial purposes is one of the most attractive challenges of chemical research. The use of catalytic pathways mediated by palladium nanoparticles (PdNPs) for C-C bond formation is a useful way to obtain these kinds of compounds. To achieve this objective, the PdNPs can be efficiently loaded on a functionalized natural nanostructured support such as halloysite nanotubes (HNTs). Hybrid materials based on thiol functionalized halloysite nanotubes and highly cross-linked imidazolium salts were successfully developed and used for the stabilization of PdNPs. The HNT/Pd hybrids were thoroughly characterized from a physico-chemical point of view and teste…

Single-Walled Carbon Nanotube–Polyamidoamine Dendrimer Hybrids for Heterogeneous Catalysis

2016

We report the synthesis and catalytic properties of single-walled carbon nanotube-polyamidoamine dendrimers hybrids (SWCNT-PAMAM), prepared via a convergent strategy. The direct reaction of cystamine-based PAMAM dendrimers (generations 2.5 and 3.0) with pristine SWCNTs in refluxing toluene, followed by immobilization and reduction of [PdCl4](2-), led to the formation of highly dispersed small palladium nanoparticles homogeneously confined throughout the nanotube length. One of these functional materials proved to be an efficient catalyst in Suzuki and Heck reactions, able to promote the above processes down to 0.002 mol % showing a turnover number (TON) of 48 000 and a turnover frequency (T…

Suzuki-Miyaura cross-coupling of arenediazonium salts catalyzed by alginate/gellan-stabilized palladium nanoparticles under aerobic conditions in wat…

2012

The use of palladium nanoparticles stabilized by natural. beads made of an alginate/gellan mixture in the Suzuki-Miyaura cross-coupling reaction of arenediazonium. tetrafluoroborates with potassium aryltrifluoroborates. (1 : 1 molar ratio) with loading as low as 0.01–0.002. mol% under aerobic, phosphine-, and base-free conditions. in water is described. The catalyst system can be reused. several times without significant loss of activity.

ChemInform Abstract: Water-Soluble Palladium Nanoparticles: Click Synthesis and Applications as a Recyclable Catalyst in Suzuki Cross-Couplings in Aq…

2011

Polyethylene glycol-tagged macrocycle (I) is prepared by a three-fold copper-catalyzed [3 + 2] cycloaddition reaction.

Catechol-Functionalized Carbon Nanotubes as Support for Pd Nanoparticles

2022

Carbon nanotubes have been covalently functionalized with catechol moieties through the formation of the corresponding aryl radicals obtained by reacting 4-aminocatechol with isoamyl nitrite. The functionalized multiwalled carbon nanotubes have been in turn used to immobilize Pd(II) ions on its surface forming catechol-Pd complexes, which were reduced to Pd nanoparticles (NPs). The so-obtained hybrid material has been characterized by means of thermogravimetric analysis coupled with differential scanning calorimetry (TGA-DSC), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). This latter technique allowed to estimate the nanoparticle size (5.7 +/- 2.8 nm) wh…

ORGANIC-INORGANIC HYBRID CATALYSTS BASED ON IMIDAZOLIUM AND THIAZOLIUM SALTS

In the last years, great attention was focused on immobilized ionic liquids for their application in the field of catalysis. The main challenge is represented by the possibility of combining the benefits of the ionic liquids to that of the supports. In order to achieve this ambitious objective both the choice of the support and the functionalization strategy are of fundamental importance. In this context, one of the aims of this doctoral project was to develop novel catalysts based on covalently mono- or multilayer imidazolium or thiazolium networks onto a high ordered mesoporous silica or carbon nanotubes materials. The second goal of this PhD thesis was to design novel imidazolium based c…

A new efficient, highly dispersed, Pd nanoparticulate silica supported catalyst synthesized from an organometallic precursor. Study of the homogeneou…

2018

[EN] A new Pd(0) catalyst supported on silica UVM-7 has been synthesized from the organometallic [Pd-2(mu-(C6H4) Pp(2))(2)(CH3CN)(4)](BF4)(2) precursor, characterized by the high dispersion, activity, and small size of the palladium nanoclusters fixed on the silica surface. The catalyst was tested for the Suzuki-Miyaura (SM) reaction of different 4-substitutedphenyl halides with phenylboronic acid. The kinetic study concurs with most of the catalytic action was carried out by Pd species originated by the partial solubilization of Pd immobilized on mesoporous silica. The Schmidt's analysis of differential selectivity (SADS) in several competitive SM reactions, together the STEM-HAADF and HRT…

Formation and growth of palladium nanoparticles inside porous poly(4-vinyl-pyridine) monitored by operando techniques: The role of different reducing…

2017

In this work we followed the formation of palladium nanoparticles, starting from palladium (II) acetate precursor, inside a poly(4-vinylpyridine-co-divinylbenzene) polymer in presence of different reducing agents. The formation and growth of palladium nanoparticles in presence of H-2 was followed as a function of temperature by simultaneous XANES-SAXS techniques, coupled with DRIFT spectroscopy in operando conditions. It was found that the pyridyl functional groups in the polymer plays a fundamental role in the stabilization of the palladium (II) acetate precursor, as well as in the stabilization of the palladium nanoparticles. The effect of a thermal treatment in alcohol (ethanol and 2-pro…