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Synthesis of Near-Infrared Emitting Gold Nanoclusters for Biological Applications
Published on: March 22, 2020
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Molecular-Scale Ligand Effects in Small Gold-Thiolate Nanoclusters.
Daniel M Chevrier1, Lluís Raich2, Carme Rovira2,3
1Department of Chemistry , Dalhousie University , Halifax , Nova Scotia B3H 4R2 , Canada.
Journal of the American Chemical Society
|October 20, 2018
Summary
Protecting ligands on gold nanoclusters (Au NCs) significantly influence their structure and properties. Different ligands, like cyclohexanethiolate and glutathione, create distinct surface properties, impacting their use as catalysts or in biomedical applications.
Area of Science:
- Nanomaterials Science
- Surface Chemistry
- Computational Chemistry
Background:
- Thiolate-protected gold nanoclusters (Au NCs) possess a large surface area-to-volume ratio, making their surface ligands critical for modulating properties.
- Understanding ligand-induced structural changes at the atomic level is crucial for optimizing Au NCs in catalysis and sensing applications.
- Existing knowledge on how specific thiolate ligands influence Au NC structure and solution-phase behavior is limited.
Purpose of the Study:
- To investigate the impact of different protecting ligands on the structure and properties of small gold nanoclusters (Au18(SR)14).
- To elucidate how ligand choice affects Au NC behavior in different solvent environments (toluene and water).
- To correlate structural findings with potential applications in catalysis and biomedicine.
Main Methods:
- Combined experimental synchrotron X-ray spectroscopy with theoretical quantum mechanics/molecular mechanics (QM/MM) simulations.
- Studied two representative ligands: cyclohexanethiolate (aliphatic) and glutathione (hydrophilic).
- Analyzed Au NC structures in both solid and solution phases.
Main Results:
- Cyclohexanethiolate ligands showed significant perturbation by toluene, creating surface cavities and disorder on Au18(SR)14, indicating potential for catalysis.
- Glutathione ligands formed a protective shell around the Au NC core, minimizing solvent-induced structural changes and resulting in a rigidified surface.
- The superior protection by glutathione explains the high stability and enhanced photoluminescence of these Au NCs for biomedical applications.
Conclusions:
- Ligand choice critically dictates the structural integrity and surface accessibility of Au NCs in solution.
- Cyclohexanethiolate ligands facilitate small molecule interactions, suitable for catalytic applications.
- Glutathione ligands provide robust encapsulation, enhancing stability and photoluminescence for biomedical uses.
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