Search results for "bimetallic"
showing 10 items of 187 documents
Bimetallic PdAg nanoparticle arrays from monolayer films of diblock copolymer micelles
2015
MICROSCOPIE+ATARI+EEH:GMA:TBG:NSP:MAO; International audience; The self-assembly technique provides a highly efficient route to generate well-ordered structures on a nanometer scale. In this paper, well-ordered arrays of PdAg alloy nanoparticles on flat substrates with narrow distributions of particle size (6-7 nm) and interparticle spacing (about 60 nm) were synthesized by the block copolymer micelle approach. A home-made PS-b-P4VP diblock copolymer was prepared to obtain a micellar structure in toluene. Pd and Ag salts were then successfully loaded in the micellar core of the PS-b-P4VP copolymer. A self-assembled monolayer of the loaded micelles was obtained by dipping the flat substrate …
Multifunctionality in hybrid molecular materials: design of ferromagnetic molecular metals and hybrid magnets
2003
We report on the synthesis and physical properties of novel hybrid organic–inorganic molecular materials combining ferromagnetic bimetallic oxalato-based networks and functional organic molecules as the donor bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) or cationic nitroxide free radicals. # 2002 Elsevier Science B.V. All rights reserved.
Enhanced H2O2 production over Au-rich bimetallic Au-Pd nanoparticles on ordered mesoporous carbons
2015
1 figures, 3 tables.-- © 2014. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Ruthenium and Osmium Complexes of Phosphine-Porphyrin Derivatives as Potential Bimetallic Theranostics: Photophysical Studies
2015
A series of (η6-p-cymene)ruthenium(II)- and osmium(II) complexes of porphyrin-phosphane derivatives have been synthesized as potential bimetallic theranostic candidates. The photophysical and electrochemical properties were investigated, and these species desirably exhibit no or almost no photoinduced intramolecular atom, energy, and electron transfer between the dye and the metallic fragment. These favorable features are mostly associated with the presence of their long chain (i.e., ∼ 1 nm) separating the two functional units. Interestingly, a decrease in emission intensity and lifetimes (up to 35-fold) has been observed, which was ascribed to a small heavy atom effect. This effect is poss…
Spin Crossover and Paramagnetic Behaviour in Two-Dimensional Iron(II) Coordination Polymers with Stilbazole Push–Pull Ligands
2009
The suitability of the stilbazole push–pull ligands, 4′-dimethylaminostilbazole (DMAS) and 4′-diethylaminostilbazole (DEAS), for the construction of bimetallic FeII–AgI/AuI cyanide-based coordination polymers that exhibit spin crossover properties is investigated. The structural and physical characterization of four novel two-dimensional FeII polymers formulated as {Fe(DMAS)2[Ag(DMAS)(CN)2]2} (1) and {Fe(L)2[M(CN)2]2} (L = DMAS, M = Au (2); DEAS, Ag (3); DEAS, Au (4)) is reported. Polymers 1 and 4 are paramagnetic over the whole range of temperatures studied (5–300 K), whereas 2 and 3 exhibit spin crossover properties.
Structural characterization of Pd-Ag and Pd-Cu bimetallic catalysts by means of EXAFS, WAXS and XPS
2000
Bimetallic Pd-Ag and Pd-Cu pumice-supported catalysts have been synthesized following different preparation procedures with the aim of improving the selectivity and reactivity of monometallic Pd/pumice systems. The structural characterization, carried out by X-ray Diffraction, X-ray Absorption and X-ray Photoelectron Spectroscopy, allowed to investigate the importance of the preparation procedures in the alloy formation.
The roles for a Lewis base and MgCl2 in third-generation Ziegler-Natta catalysts
1998
Activity of a titanium catalyst supported on a bimetallic magnesium-aluminium system, involving a Lewis base [MgCl2(THF) 2 /Al(C 2 H 5 ) 2 Cl], was studied in ethylene polymerization, and the effect of the catalyst composition on the properties of the final polymer produced was investigated. Analysis and discussion of the findings covering also some part of the kinetic study, resulted in defining the roles for MgCl 2 and a Lewis base in the third-generation Ziegler-Natta catalysts. MgCl 2 forms a bimetallic complex with an organoaluminium compound, which involves also a Lewis base. Its reaction with TiCl 4 yields a very active catalyst wherein the Mg: Ti molar ratio is close to 1. This mean…
Highly trans-stereospecific Isoprene Polymerization by Neodymium Borohydrido Catalysts
2005
Highly stereospecific polymerization of isoprene was achieved using borohydridoneodymium complexes. In combination with stoichiometric amounts of dialkylmagnesium, Nd(BH4)3(THF)3 (1) and Cp*‘Nd(BH4)2(THF)2 (2) (Cp*‘ = C5Me4nPr) afford very efficient catalysts. The activity reaches 37300 (g of polyisoprene/mol of Nd)/h. Half-lanthanidocene 2 gives rise to polyisoprene, 98.5% trans-regular, the highest content yet described for a homogeneous organometallic catalyst. NMR experiments argue for the formation of bimetallic Nd(μ-BH4)Mg active species.
A Square-Planar Dinickel(II) Complex with a Noninnocent Dinucleating Oxamate Ligand: Evidence for a Ligand Radical Species
1999
[EN] The new bimetallic nickel(II) compound (PPh4)4[Ni2(2)]·6H2O (3), where H8[2] stands for N,N',N'',N'''-1,2,4,5-benzene-tetrayltetrakis(oxamic acid), has been synthesized and its crystal structure determined by single-crystal X-ray diffraction. The structure of 3 consists of [Ni2(n4:n4-2)]4- anions, tetraphenylphosphonium cations, and water molecules. Facile one-electron oxidation of the square-planar diamagnetic dinickel(II) complex [Ni2(n4:n4-2)]4- generates the metallo-radical species [Ni2(n4:n4-2·+)]3- with characteristic intra-ligand ¿cation radical transitions in the visible region (475-550 nm) as well as a typical quasi-isotropic EPR signal at g ¿ 2.0.
Activity of SiO2 supported gold-palladium catalysts in CO oxidation
2003
Abstract Bimetallic Au-Pd catalysts supported on silica with different Au/Pd atomic ratios were prepared by simultaneous reduction of palladium and gold precursors by ethanol in the presence of the polymer, polyvinylpyrrolidone (PVP). Formation of alloyed particles was detected by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and CO chemisorption measurements. The catalysts were tested in the catalytic oxidation of CO using a plug–flow reactor. The CO conversion was determined as a function of temperature. The monometallic palladium and the palladium-rich catalysts behaved quite similarly and were the most active catalysts. …