Synthesis, structural characterization and transformation of an eight-electron superatomic alloy, [Au@Ag19{S2P(OPr)2}12]. Issue 15 (4th April 2018) - Lin, Yan-Ru
Abstract : A superatomic alloy nanocluster (NC) [Au@Ag19 (dtp)12 ] from [Ag20 (dtp)12 ] has been synthesized and structurally characterized and its surface reconstruction to Au@Ag20 has been demonstrated. Abstract : Controlling the metal nanoclusters with atomic precision is highly difficult and further studies on their transformation reactions are even more challenging. Herein we report the controlled formation of a silver alloy nanocluster [AuAg19 {S2 P(O n Pr)2 }12 ] (1 ) from an Ag20 template via a galvanic exchange route. X-ray structural analysis reveals that the alloy structure comprises of a gold-centered Ag12 icosahedron, Au@Ag12, capped by seven silver atoms. Interestingly upon reacting with one equiv. of silver(i ) salt, (1 ) can transform into a higher nuclearity nanocluster, [Au@Ag20 {S2 P(O n Pr)2 }12 ] + (2 ). The conversion process is studied via ESI mass spectrometry and 31 P NMR spectroscopy. This kind of size-structural transformation at the single atom level is quite remarkable. Furthermore, the compositions of all the doped nanoclusters (1, 2 ) were fully characterized with ESI-MS and EDS. The blue shift depicted in the UV-visible and emission spectra of the doped nanoclusters (1, 2 ) compared with the precursor, Ag20, demonstrates that the doping atoms have significant effects on the electronic structures.