Amine-stabilized gold nanoparticles

A one-pot method for the synthesis of amine-stabilized gold nanoparticles using... 

Purification yields 200-300 mg of triphenylphosphine-stabilized gold nanoparticles, which should be stored cold (—20°C) in the sofid state, or immediately converted to thiol- or amine-stabilized nanoparticles through subsequent reaction with the appropriate ligand. The particles decompose in solution thus manipulation of the product in solution should be minimized. 

Gold nanoparticles stabilized by primary amine, tertiary amine, sulfide, and thiols... 

Scheme 2. Production of size-regulated gold nanoparticles stabilized by primary amines, tertiary amines, sulfides, and thiols formed by the controlled thermolysis of gold(I) thiolate complex in the presence of amine (reprinted from Ref. [11], 2005, with permission from Elsevier).

The 1.5-nm nanoparticles readily react with thiol or amine-terminated ligands under mild conditions to yield thiol- or amine-stabilized nanoparticles. Triphenylphosphine-stabilized particles thermally decompose with the production of (PPh3)AuCl and metallic gold. 

Using amine chemistry for reduction and for surface stabilization at the same time, gold nanoparticles can be prepared in water directly by addition of oleyl amine (O LA) to a solution of AuCI4. The XRD measurements show the peaks that confirm the face centered cubic (fee) lattice of gold. The analysis of the obtained nanoparticles displays narrow size distributions and, for example, when high concentrations of oleyl amine are used an average core size of 10 0.6 nm is achieved [79]. 

It was really only a matter of time until researchers in the field started doping blue phases with quasi-spherical nanoparticles. This area is very much in its infancy, but the few recent reports already show some promising results. Yoshida et al., for example, reported on an expansion of the temperature range of cholesteric blue phases from 0.5 to 5°C by doping blue phases with gold nanoparticles (average diameter of 3.7nm) as well as a decrease in the clearing point of approximately 13°C [427]. A similar effect was also observed by Kutnjak et al. for CdSe quantum dots simultaneously capped with oleyl amine and TOP (diameter of the core 3.5 nm) in CE8 (Merck) and CE6 (BDH). The authors found that particularly blue phase III was stabilized in these mixtures, blue phase II destabilized, and... 

Cruickshank, K. and A. Downard. Electrochemical stability of citrate-capped gold nanoparticles electrostatically assembled on amine-modified glassy carbon. Electrochim. Acta 54, 2009 5566—5570. 

Wang, Z., Zhang, Q., Kuehner, D., Ivaska, A. Niu, L. (2008). Green synthesis of 1-2 nm gold nanoparticles stabilized by amine-terminated ionic liquid and their electrocatalytic activity in oxygen reduction. Green Chem. 10 907-909. 

The solvent-free controlled thermolysis of metal complexes in the absence or presence of amines is the simple one-pot synthesis of the metal nanoparticles such as gold, silver, platinum, and palladium nanoparticles and Au-Ag, Au-Pt, and Ag-Pd alloy nanoparticles. In spite of no use of solvent, stabilizer, and reducing agent, the nanoparticles produced by this method can be well size regulated. The controlled thermolysis in the presence of amines achieved to produce narrow size dispersed small metal nanoparticles under milder condition. This synthetic method may be highly promising as a facile new route to prepare size-regulated metal nanoparticles. Finally, solvent-free controlled thermolysis is widely applicable to other metal nanoparticles such as copper and nickel... 

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