Entropy-Driven Reversible Agglomeration of Crown Ether Capped Gold Nanoparticles

Alexander P. Hill, Casper Kunstmann-Olsen, Marcin P. Grzelczak, Mathias Brust

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

It is shown that plasmonic gold nanoparticles functionalised with a thiolated 18-crown-6 ligand shell agglomerate spontaneously from aqueous dispersion at elevated temperatures. This process takes place over a narrow temperature range, is accompanied by a colour change from red to purple-blue and is fully reversible. Moreover, the temperature at which it occurs can be adjusted by the degree of complexation of the crown ether moiety with appropriate cations. More complexation leads to higher transition temperatures. The process has been studied by UV/Vis spectroscopy, electron microscopy, dynamic light scattering and zeta potential measurements. A thermodynamic rationale is provided to suggest an entropy-driven endothermic agglomeration process based on attractive hydrophobic interactions of the complexed crowns that are competing against electrostatic repulsion of the charged ligand shells.

Original languageEnglish
JournalChemistry - A European Journal
Volume24
Issue number13
Pages (from-to)3151-3155
ISSN1521-3765
DOIs
Publication statusPublished - 2. Mar 2018

Keywords

  • aggregation
  • crown ether
  • nanoparticles
  • thermoresponsive

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