Toward Smaller Aqueous-Phase Plasmonic Gold Nanoparticles: High-Stability Thiolate-Protected 4.5 nm Cores

M. Mozammel Hoque, Kathryn M. Mayer, Arturo Ponce, M. M. Alvarez, Robert L. Whetten

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Most applications of aqueous plasmonic gold nanoparticles benefit from control of the core size and shape, control of the nature of the ligand shell, and a simple and widely applicable preparation method. Surface functionalization of such nanoparticles is readily achievable but is restricted to water-soluble ligands. Here we have obtained highly monodisperse and stable smaller aqueous gold nanoparticles (core diameter 4.5 nm), prepared from citrate-tannate precursors via ligand exchange with each of three distinct thiolates: 11-mercaptoundecanoic acid, α-R-lipoic acid, and para-mercaptobenzoic acid. These are characterized by UV-vis spectroscopy for plasmonic properties; Fourier transform infrared (FTIR) spectroscopy for ligand-exchange confirmation; X-ray diffractometry for structural analysis; and high-resolution transmission electron microscopy for structure and size determination. Chemical reduction induces a blueshift, maximally +0.02 eV, in the localized surface plasmon resonance band; this is interpreted as an electronic (-) charging of the monolayer-protected cluster (MPC) gold core, corresponding to a -0.5 V change in electrochemical potential.

Original languageEnglish (US)
Pages (from-to)10610-10617
Number of pages8
Issue number32
StatePublished - Aug 13 2019
Externally publishedYes

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry


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