Carboranealkynyl-Protected Gold Nanoclusters: Size Conversion and UV/Vis-NIR Optical Properties

Area of Science:

• Nanomaterials Science
• Inorganic Chemistry
• Surface Chemistry

Background:

• Structure evolution is key for novel monolayer-protected metal nanomolecules.
• Alkynyl-stabilized metal clusters are an underexplored area in nanomaterial evolution.

Purpose of the Study:

• To investigate the structure evolution of alkynyl-stabilized gold nanoclusters.
• To synthesize and characterize novel carborane-alkynyl-protected gold nanoclusters.
• To explore the transformation and properties of these nanoclusters.

Main Methods:

• Facile self-reduction method using a carborane-alkynyl agent.
• Isolation and characterization of gold nanoclusters [Au28(C4B10H11)12(tht)8]3+ (Au28) and [Au23(C4B10H11)9(tht)6]2+ (Au23).
• Monitoring transformation using Electrospray Ionization Mass Spectrometry (ESI-MS) and UV/Vis absorption spectroscopy.

Main Results:

• A novel open-shell Au28 nanocluster with 13 free electrons was synthesized.
• Au28 transformed in methanol into a smaller, stable Au23 nanocluster with 12 valence electrons and 1D orbitals.
• Both Au28 and Au23 exhibit broad UV/Vis-NIR absorption and NIR emission.

Conclusions:

• The study presents a new route for synthesizing and evolving alkynyl-stabilized gold nanoclusters.
• The discovered Au28 and Au23 nanoclusters possess unique electronic and optical properties.
• These nanoclusters show promise for applications in biomedical imaging, drug delivery, and photocatalysis.