Theoretical characterization of cyclic thiolated gold clusters

Area of Science:

• Computational chemistry
• Materials science
• Nanotechnology

Background:

• Thiolated gold clusters are of interest due to their unique structural and electronic properties.
• Understanding the relationship between structure, bonding, and properties is crucial for designing new materials.

Purpose of the Study:

• To investigate the structural, energetic, vibrational, and optical properties of methylthiolated gold clusters (MeSAu)x for x = 2-12 using density functional theory.
• To explore the effect of ligand substitution on the properties of thiolated gold clusters, specifically focusing on the tetramer.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• Structural, energetic, vibrational, and optical properties were systematically explored.
• Ligand substitution effects were studied by comparing methylthiolate with hexylthiolate, benzenethiolate, and glutathionate (GS) in the tetrameric cluster.

Main Results:

• Clusters (MeSAu)x adopt ring conformations for x ≤ 4 and crownlike structures for larger sizes, exhibiting polymeric characteristics.
• Structural and energetic properties converge at (MeSAu)4.
• The Au-S bond is polar covalent with cyclic electron delocalization. Characteristic Au-S vibrations occur around 300 cm(-1).
• Ligand choice significantly influences electronic properties, with the optical gap of (GSAu)4 being approximately 1.5 eV lower than that of (MeSAu)4.

Conclusions:

• Thiolated gold clusters display size-dependent structural transitions and polymeric behavior.
• The electronic and optical properties of these clusters are sensitive to the nature of the capping ligand.
• DFT provides a robust framework for understanding the fundamental properties of thiolated gold nanoclusters.