A shell-isolated nanoparticle enhanced surface Raman technique for detection of copper(ii).

Silver nanoparticles, stabilized by a titanium dioxide shell, have been prepared and further functionalized using a bidentate 2,2′‐bipyridine ligand end‐capped with a phosphonic acid anchoring group. Then, complexation of the 2,2′‐bipyridine donor ligand with a copper(I) salt was performed. The resulting nanocomposite, while irradiating the Ag plasmon band with a blue laser at 488 nm, was found to be active for the homocoupling Ullmann reaction of iodobenzene and increased yield of 55% vs <1% for the dark reaction was observed.

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"Ligand-free" citrate-stabilized 10 nm gold nanoparticles (AuNPs) promote the hydrolysis of the thiophosphate ester methyl parathion (MeP) on the surface of gold as a function of pH and two temperature values. At 50 °C, the active surface gold atoms show catalytic turnover ∼4 times after 8 h and little turnover of gold surface atoms at 25 °C with only 40% of the total atoms being active. From Michaelis-Menten analysis, k(cat) increases between pH 8 and 9 and decreases above pH 9. A global analysis of the spectral changes confirmed the stoichiometric reaction at 25 °C and the catalytic reaction at 50 °C and mass spectrometry confirmed the identity of p-nitrophenolate (PNP) product. Additional decomposition pathways involving oxidation and hydrolysis independent of the formation of PNP were also seen at 50 °C for both catalyzed and un-catalyzed reactions. This work represents the first kinetic analysis of ligand-free AuNP catalyzed hydrolysis of a thiophosphate ester.

A comprehensive survey on methods for surface modification of noble metal–metal oxide core–shell nanoparticles is presented and highlights various strategies for binding of molecules and molecular ions to core–shell nanoparticles.