Time-dependent Digestive Ripening of Colloidal Gold Nanoparticles Using Thiols and Amines

open_access
Open Access
Author:
Le, Vy
Area of Honors:
Chemistry
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Benjamin James Lear, Thesis Supervisor
David D Boehr, Thesis Honors Advisor
Raymond Edward Schaak, Faculty Reader
Keywords:
Gold nanoparticle
Chemistry
Ripening
Time
Ligand Ratio
Abstract:
Gold nanoparticles have great potential for medicine, catalysis, and optics due to their surface chemistry and quantized energy gaps. However, there lacks total, atomistic control over the size and shape of these nanoparticles. To increase the versatility of these nanoparticles, researchers continue to investigate factors that can impact their growth. This study focuses on determining the effects of modifying the ratio of dodecanethiol, octanethiol, and oleylamine with the amount of gold over extended periods of time in comparison with the Brust-Schiffrin synthesis. UV-Vis spectroscopy, XPS, 1H-NMR spectroscopy, and TEM were used to analyze both the size and composition of these nanoparticles. Results indicate that an increased ligand to gold ratio continued to slightly decrease the size of the gold nanoparticle, likely due to thermodynamic stabilization. However, molar ratios less than 2:1 thiol to gold generated triangular, hexagonal, and even rectangular crystals, likely due to a lack of thiols on specific surfaces to allow more kinetically favored gold crystal growth in exposed areas. Systems with oleylamine created large, polydisperse nanoparticles no matter what, indicating the limited viability of amines as a ligand for gold. These synergistic insights on the growth of nanoparticles can help manipulate crystal growth in future studies and applications.