Gold nanoparticle decorated reduced graphene oxide sheets with high catalytic activity for Ullmann homocoupling

Abstract

A Au nanoparticle-reduced graphene oxide nanocomposite (Au NPs-RGO) was used as an effective and reusable heterogeneous catalyst for the Ullmann homocoupling of aryl iodides with short reaction times and good yields. For the first time, aryl bromides bearing electron-withdrawing groups were coupled in the presence of a catalyst giving moderate yields.Supported Au nanoparticles (Au NPs) and their catalytic applications in heterogeneous organic reactions have attracted considerable attention in recent years. Aldehyde-alkyne-amine coupling (A3-coupling), 1 oxidation of alcohols, 2 secondary amines 3 and carbon monoxide, 4 hydrogenation of olens, 5 Suzuki 6 and Sonogashira 7 reactions, formation of nitrogen containing compounds, 8 etc. are some of the most important applications of supported Au NP catalysts. The catalytic performance of Au NPs-support strongly depends on the size and shape of the Au NPs, the nature of the support, and the Au NPs-support interface interaction. 9 Supporting carriers may function by dispersing and xing the Au NPs. Supports such as oxides (CeO 2 , 10 SiO 2 , 11 Al 2 O 3 , 12 MgO 13 and TiO 2 (ref. 14)), mixed oxides (Mg-Al-O 15 and Ga-Al-O 16 ), polymers (PVP 17 and PS derivatives 18 ) and ordered mesoporous carbon 19 have been used as supports for Au NPs. Among these, it has been reported that the p-interaction of aromatic rings with gold nanoparticles leads to nanoparticle stabilization and improves the catalyst performance in a variety of gold-catalyzed reactions. 9,18,20 Graphene is a two-dimensional sheet of sp 2 bonded carbon atoms, which can be viewed as an extra-large polycyclic aromatic molecule. 21 Recently, graphene has been used as the support for metal and metal oxide that is mainly due to its large surface area, excellent electrical and thermal conductivity, low price, high chemical inertness, ease of modication and strong

Development of gold nanoparticles coated with silica containing the antibiofilm drug cinnamaldehyde and their effects on pathogenic bacteria

“…39 The existence of a strong Si-O peak at 103 eV indicated that GNP surfaces were coated with silica ( Figure S2E). Figure S2F shows two distinct binding energies at 83.8 and 87.4 eV, which were in good agreement with Au(III), 40 and minor deconvulsions indicating Au-NH bonding. Au 0 4f 7/2 and 4f 5/2 spectra were of reduced intensity, presumably because of the presence of surface silica and CNMA.…”

Graphene based metal and metal oxide nanocomposites: synthesis, properties and their applications

“…In group 11, conventional catalytic applications of graphene-supported silver and gold NP based hybrids as well as their respective binary and/or ternary nanocomposites were reported. 472,473 For instance, HRG/Ag and HRG/Ag/TiO 2 nanocomposites were applied for the catalytic reduction of 2-nitroaniline to 1,2-benzenediamine and p-nitrophenol to p-aminophenol. 451 HRG/Au hybrids catalyze the conversion of graphene into CNTs without applying additional hydrocarbons.…”

Fe3O4@RGO@Au@C Composite with Magnetic Core and Au Enwrapped in Double-Shelled Carbon: An Excellent Catalyst in the Reduction of Nitroarenes and Suzuki–Miyaura Cross-Coupling

“…Graphene is a two-dimensional sheet of sp 2 bonded carbon atoms, which can be viewed as an extra-large polycyclic aromatic molecule. Recently, graphene has been used as the support for metals and metal oxides, mainly because of its large surface area, excellent electrical and thermal conductivity, low price, high chemical inertness, ease of modification and strong interactions with metal clusters [22][23][24]. Au NPs grow well on the surface of inner shell by spontaneous redox reaction between graphene oxide (GO) and HAuCl 4 [25].…”