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Direct Imaging of the Ligand Monolayer on an Anion-Protected Metal Nanoparticle through Cryogenic Trapping of its Solution-State Structure

2008; American Chemical Society; Volume: 130; Issue: 49 Linguagem: Inglês

10.1021/ja807160f

1943-2984

Alevtina Neyman, Louisa Meshi, Leila Zeiri, Ira A. Weinstock,

Advanced Nanomaterials in Catalysis

According to Derjaguin−Landau−Verwey−Overbeek (DLVO) theory, anions stabilize solutions of metal(0) nanoparticles by binding to the metal surface. However, the structure of the metal−anion interface in these colloidal systems has eluded direct observation. To address this, we deployed a 1.2-nm sized heteropolytungstate cluster anion, α-AlW11O399− (1), which features 11 W atoms (Z = 183) for effective imaging by electron microscopy, and a high negative charge to enhance binding to a prototypical Ag(0) nanoparticle. Cryogenic methods were then used to "trap" the 1-protected Ag(0) nanoparticles at liquid-N2 temperatures within a water−glass matrix. The "solution-state" structures thus captured provide the first reported TEM images of self-assembled monolayers (SAMs) of anions on a colloidal metal(0) nanoparticle.