Document Type

Thesis

Date of Degree Completion

Spring 2022

Degree Name

Master of Science (MS)

Department

Chemistry

Committee Chair

Samuel Lohse

Second Committee Member

Antony Diaz

Third Committee Member

Yingbin Ge

Abstract

Functionalized gold nanoparticles (AuNPs) are of interest for their optical and electrical properties, specifically the surface plasmon resonance phenomenon and potential applications for medicine and nano-circuitry. In this study, the ligand composition of small (~5 nm diameter) thiol functionalized AuNPs with mixed ligand monolayers was investigated to better understand how the molar feed ratio of ligands used during their synthesis influences the composition of ligands on the particle’s surface. The system under study was a combination of two ω-functionalized thiols, mercapto ethoxy ethoxy ethanol (MEEE) and mercapto pentyl trimethyl ammonium chloride (MPTMA). UV/Visible spectrophotometry, dynamic light scattering, and electron microscopy were utilized to determine particle size, while 1H-NMR and FTIR spectroscopy were used to characterize monolayer composition and surface chemistry. Alkyl halide ligand precursors were analyzed via 1H-NMR to generate a signal response factor. Furthermore, the gold cores were digested with iodine to better elucidate the ligand composition without baseline broadening which accompanies metal nanoparticles. 1H-NMR data suggests that the distribution of functionalized thiols on the AuNP surface is not indicative of ligand feed ratio stoichiometry, that 10 mole % MEEE reagent is over-represented and comprises 63.66 ± 0.45% (0.71% RSD) of the mixed ligand monolayer.

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