Mesoporous Copper Nanoparticle Networks Decorated by Graphite Layers for Surface-Enhanced Raman Scattering Detection of Trace Analytes.

The assembly of 3D nanoscale structures of plasmonic nanoparticles (NPs) holds great promise for achieving enhanced optical and electronic properties. This type of materials exhibits a large number of surface hot spots, while offering the possibility for synergetic effects to be observed. Herein, a facile, yet powerful, strategy to fabricate 3D mesoporous networks of copper NPs decorated with graphite layers (denoted as Cu/G) is demonstrated by using a polymer-assisted self-assembly method.

Aryl-substituted cyclopropyl acetylenes as sensitive mechanistic probes in the gold-catalyzed hydration of alkynes. Comparison to the Ag(I)-, Hg(II)-, and Fe(III)-catalyzed processes.

The gold-catalyzed hydration of 2-phenyl- or 2,2-diphenylcyclopropyl acetylene, sensitive probes to trace the formation of vinyl carbocations, provides exclusively the corresponding cyclopropyl methyl ketones. On the other hand, in the Ag(I)- or Fe(III)-catalyzed hydration, a profound vinyl carbocationic character appears in the initially formed metal-alkyne complexes, as judged by the partial (Ag(+)) or exclusive (Fe(3+)) formation of allene-type rearrangement products. These findings provide clear evidence for subtle electronic differences in metal-alkyne complexes, including Au(I or III), Ag(I), Fe(III), and Hg(II).