The Reaction of Gold(III) with Some Bidentate Coördinating Groups1

Block, B. P.; Bailar, John C.

doi:10.1021/ja01154a071

Cited by 190 publications

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“…To eliminate organic impurities the zeolite was calcined in air at 510 • C for 12 h. Au(III) is introduced into the zeolite by means of cation exchange of the [Au(en) 2 ] 3+ complex, where en is ethylenediamine (H 2 N-CH 2 -CH 2 -NH 2 ), whose synthesis is according to Block and Bailar. [15] The reaction to obtain metallic precursors is schematically represented as follows:…”

Section: Methodsmentioning

confidence: 99%

In situ ESR study of gold supported on NaY zeolite

Roduner

2009

Asia-Pacific J Chem Eng

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Electron spin resonance (ESR) spectroscopy was used to study the anchoring of a Au complex and gold nanoparticles in NaY type zeolites. The complex of Au(II) with two nitrogen atoms of two ethylenediamine ligands [g iso = 2.053, A (Au) = 16.4 G, A (N) = 15.0 G.] in the supercage of the zeolite and conduction electron spin resonance (CESR) of gold particles with 1.56-nm diameter (g = 2.064) were observed. Their formation and stability were related with the gold concentration and the pre-treatment conditions. The small gold particles stabilized in the supercage of zeolite were formed in the samples with low gold concentration after oxygen pre-treatment. The confinement in the zeolite pores obviously prevents the Au(II) complex bound to two nitrogen ligands from undergoing disproportionation.

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Section: Methodsmentioning

confidence: 99%

In situ ESR study of gold supported on NaY zeolite

Roduner

2009

Asia-Pacific J Chem Eng

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“…quality and purchased from Fluka (Buchs, Switzerland). [Au(en) 2 ]Cl 3 was synthesized from HAuCl 4 · aq and ethylenediamine as described elsewhere [28].…”

Section: Methodsmentioning

confidence: 99%

Highly dispersed gold on activated carbon fibers for low-temperature CO oxidation

Bulushev

Yuranov

Suvorova

et al. 2004

Journal of Catalysis

204

132

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Gold nanoparticles of 2-5 nm supported on woven fabrics of activated carbon fibers (ACF) were effective during CO oxidation at room temperature. To obtain a high metal dispersion, Au was deposited on ACF from aqueous solution of ethylenediamine complex [Au(en) 2 ]Cl 3 via ion exchange with protons of surface functional groups. The temperature-programmed decomposition method showed the presence of two main types of functional groups on the ACF surface: the first type was associated with carboxylic groups easily decomposing to CO 2 and the second one corresponded to more stable phenolic groups decomposing to CO. The concentration and the nature of surface functional groups was controlled using HNO 3 pretreatment followed by either calcination in He (300-1273 K) or by iron oxide deposition. The phenolic groups are able to attach Au 3+ ions, leading to the formation of small Au nanoparticles (< 5 nm) after reduction by H 2 . This was confirmed by high-resolution electron microscopy combined with X-ray energy-dispersive analysis. The catalyst with high Au dispersion demonstrated high activity in CO oxidation. The surface carboxylic groups decomposed during interaction with [Au(en) 2 ]Cl 3 solution and reduced Au 3+ to Au 0 , resulting in the formation of bigger (> 9 nm) Au agglomerates after reduction by H 2 . These catalysts demonstrated lower activity as compared to the ones containing mostly small Au nanoparticles. Complete removal of surface functional groups rendered an inert support that would not interact with the Au precursor. The oxidation state of gold in the Au/ACF catalysts was controlled by X-ray photoelectron spectroscopy before and after the reduction in H 2 . The high-temperature reduction in H 2 (673-773 K) was necessary to activate the catalyst, indicating that metallic gold nanoparticles are active during catalytic CO oxidation.  2004 Elsevier Inc. All rights reserved.

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“…formed in aqueous solutions [17,18]. This complex formation reduces the formal potential from the Nernst equation, and thus the reduction of gold(III) by dl--tocopherol tends not to occur.…”

Section: +mentioning

confidence: 99%

In Situ Microscope Measurements of the Formation of Nanometer-Sized Gold Particles at the Dodecane/Water Interface through the Direct Reduction of Aqueous Tetrachloroaurate(III) by Hydrophobic dl-α-Tocopherol in the Presence of 1,10-Phenanthroline

Tsukahara

Kobayashi

Fujiwara

2014

SERDJ

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The contact of a dodecane solution of hydrophobic dl--tocopherol with an aqueous solution of tetrachloroaurate(III) resulted in the direct reduction of tetrachloroaurate(III) and the formation of gold particles at the dodecane/water interface. Without other additives, the gold particles were unfavorably aggregated with each other and chains of gold particles were formed. In the present study, a chemical preventing the aggregation was sought. Fourteen types of chemicals were individually added to the two-phase system, and then the size, shape, and movements of the gold particles formed at the dodecane/water interface were observed through an optical microscope using bright-field illumination, using dark-field illumination, or with scattered laser light under total internal reflection conditions. Of the 14 chemicals, 1,10-phenanthroline (phen) effectively prevented the aggregation of gold particles at the interface. The gold particles formed in the presence of phen under the optimized conditions were recovered on a coverslip, and their size and shape were recorded using an atomic force microscope. Almost all of the recovered gold particles were not higher than 50 nm and this meant that nanometer-sized gold particles were formed.

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The Reaction of Gold(III) with Some Bidentate Coördinating Groups¹

Cited by 190 publications

References 0 publications

In situ ESR study of gold supported on NaY zeolite

In situ ESR study of gold supported on NaY zeolite

Highly dispersed gold on activated carbon fibers for low-temperature CO oxidation

<i>In Situ</i> Microscope Measurements of the Formation of Nanometer-Sized Gold Particles at the Dodecane/Water Interface through the Direct Reduction of Aqueous Tetrachloroaurate(III) by Hydrophobic <i>dl</i>-α-Tocopherol in the Presence of 1,10-Phenanthroline

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