Search results for "Gold"
showing 10 items of 1320 documents
Gold Redox Catalytic Cycles for the Oxidative Coupling of Alkynes
2011
[EN] Au(I)/Au(III) catalytic cycles are catalytically competent to perform the oxidative coupling of alkynes in the homogeneous phase at room temperature and without any protecting atmosphere. Selectfluor as oxidant, wet acetonitrile as solvent, and sodium carbonate as base are the reagents of choice. Both aromatic and alkyl alkynes can be coupled, and mechanistic studies reveal that at least two gold species having different oxidation states are implicated in the key step of the coupling.
Synthesis, crystal structures, and solid state quadratic nonlinear optical properties of a series of stilbazolium cations combined with gold cyanide …
2011
Three salts built up from (E)-4′-(dimethylamino)-stilbazolium (DMAS)H+, (E)-4′-(diethylamino)-stilbazolium (DEAS)H+, (E)-4′-{2-(methoxymethyl) pyrrolidinyl}-stilbazolium (MPS)H+, and gold cyanide as a counter-ion, are reported. The crystal structures have been solved for (DEAS)H+ Au(CN)2− (Cc space group), and for (MPS)H+ Au(CN)2− (P1 space group). The semi-empirical (ZINDO) calculated static hyperpolarizability (β0) of (MPS)H+ is equal to 147 × 10−30 cm5esu−1, in solid state, which is 25% higher than that of the cation of the well known (E)-4′-(dimethylamino)-methylstilbazolium tosylate (DAST). (MPS)H+ Au(CN)2− exhibits a unique crystal structure in which the cations are perfectly aligned.…
CO2 switchable nanoparticles: reversible water/organic-phase exchange of gold nanoparticles by gas bubbling
2013
Gold nanoparticles capped with oleylamine can be effectively transferred from an organic solvent to water in the presence of an acetamidine surfactant by CO2 bubbling and then effectively reverted back to the organic phase by N2 bubbling.
Gold assisted oxygen dissociation on a molybdenum-doped CaO(001) surface
2016
Using density functional theory (DFT) calculations, we address the adsorption of O2 and the coadsorption of gold species and oxygen molecules on a Mo-doped CaO(001) surface with 1.25% impurity concentration. With the help of the Born–Haber thermodynamic cycle, the enhanced binding of an oxygen molecule on Ca(Mo)O is attributed to energy gain owing to simultaneous electron transfer from the dopant to the molecule and lattice relaxations. We consider three coadsorption structures for an Au atom and O2 molecule with different Au–O2 distances. The calculations demonstrate that the coadsorption structures take one electron from the dopant and the O–Au–O chain structure is thermodynamically more …
Electrochemical monitoring of the oxidative coupling of alkynes catalyzed by triphenylphosphine gold complexes
2012
Electrochemical monitoring of the oxidative coupling of alkynes in the homogeneous phase through catalytic cycles involving triphenylphosphine gold complexes and selectfluor as oxidant reveals that at least two gold species in +3 and +1 oxidation states are implicated. Electrochemically driven homocoupling of terminal alkynes using molecular oxygen as the oxidant can be performed using such catalysts. Keywords: Gold catalysis, Oxidative coupling of alkynes, Oxygen, Voltammetry
Base-assisted synthesis of 4-pyridinate gold(I) metallaligands: a study of their use in self-assembly reactions
2021
Made available in DSpace on 2021-06-25T12:16:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-05-06 Ministerio de Economia y Competitividad (MINECO/FEDER) of Spain Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The synthesis of di- and tritopic gold(I) metallaligands of the type [(Au4-py)(2)(mu(2)-diphosphane)] (diphosphane = bis(diphenylphosphanyl)isopropane or dppip (1), 1,2-bis(diphenylphosphanyl)ethane or dppe (2), 1,3-bis(diphenylphosphanyl)propane or dppp (3) and 1,4-bis(diphenylphosphanyl)butane or dppb (4)) and [(Au4-py)(3)(mu(3)-triphosphane)] (triphosphane = 1,1,1-tris(diphenylphosph…
CCDC 1573804: Experimental Crystal Structure Determination
2017
Related Article: Paul J. Ragogna, Cameron Graham, Clement Millet, Amy N Price, Juuso Valijus, Michael J Cowley, Heikki Tuononen|2017|Chem.-Eur.J.|24|672|doi:10.1002/chem.201704337
Cittadinanza e sua commodificazione: cittadinanza come diritto, cittadinanza come bene
2019
cittadinanza e sua commodificazione
Solubility-Driven Isolation of a Metastable Nonagold Cluster with Body-Centered Cubic Structure.
2020
The conventional synthetic methodology of atomically precise gold nanoclusters using reduction in solutions offers only thermodynamically most stable nanoclusters. We report herein a solubility‐driven isolation strategy to access the synthesis of a metastable gold cluster. The cluster, with the composition of [Au 9 (PPh 3 ) 8 ] + ( 1 ), displays an unusual, nearly perfect body‐centered‐cubic (bcc) structure. As revealed by ESI‐MS and UV/Vis measurement, the cluster is metastable in solution and converts to the well‐known [Au 11 (PPh 3 ) 8 Cl 2 ] + ( 2 ) within just 90 min. DFT calculations revealed that while both 1 and 2 are eight‐electron superatoms, there is a driving force to convert 1 …
The Color of Avant-Garde: Kenneth Goldsmith’s "The Body of Michael Brown"
2018
In the following paper, I put forth a claim that literary works created according to the rules of conceptualism, seemingly devoid of expression, often reveal that values are inseparable from any textual operations. This is visible in Kenneth Goldsmith’s recent project, “The Body of Michael Brown,” which follows the format of Goldsmith’s previous book—Seven American Deaths and Disasters—a transcription of news reports of American national disasters, such as the assassination of John F. Kennedy or the attacks of 9/11. The text rewrites the autopsy report issued by the St. Louis County Coroner’s Office on the shooting of Michael Brown, an African-American teenager shot and killed by a white po…