A simple, green, one-pot synthesis of gold nanoparticles (AuNPs) was achieved by Kurt E. Geckeler, Gwangju Institute of Science and Technology (GIST), and Thathan Premkumar, World-Class University (WCU), Gwangju, South Korea, through the reaction of an aqueous mixture of potassium tetrachloroaurate(III) and the macrocycle cucurbit[7]uril in the presence of sodium hydroxide at room temperature without introducing any kind of traditional reducing agents and/or external energy.

The as-prepared gold nanoparticles showed catalytic activity for the reduction reaction of 4-nitrophenol in the presence of NaBH₄, which has been established by visual inspection and UV/Vis spectroscopy.

Surprisingly, the macrocycle can play a dual role in the synthesis of AuNPs: as a reducing agent as well as being a protecting agent.

This report is the first for the preparation of gold nanoparticles using cucurbit[7]uril in aqueous media through chemical reduction without employing conventional reducing agents and/or external energy.

• Cucurbit[7]uril as a Tool in the Green Synthesis of Gold Nanoparticles,
  Thathan Premkumar, Kurt E. Geckeler,
  Chem. Asian J. 2010, 5 (12), 2468–2476.
  DOI: 10.1002/asia.201000338