Collections > Electronic Theses and Dissertations > Advances in the Synthesis, Ligand Exchange, and Electron Transfer Dynamics of Small Gold Nanoparticles

Chapter One is a general introduction into small gold nanoparticles, specifically Au25(SR)18. It highlights the achievements made by this and other research groups in the areas of synthesis, structure determination, mass spectrometry, electrochemical and optical properties, and bimetallic nanoparticles. Chapter Two is a detailed description of the synthesis of Au25(SR)18. It includes a historical account of the synthesis, along with an updated synthesis which increases the yield and purity and reduces cost, waste, an reaction work-up time. Specific reaction modifications are explained, and the results are discussed with regards to the mechanism of Au25(SR)18 formation. Chapter Three describes the characterization of electron self-exchange dynamics of the nanoparticle couple Au25(S(CH2)2Ph)181-/0 using 1H NMR line-broadening analysis. The changes in peak broadening at varied nanoparticle concentration and at varied temperatures allows for the calculation of self-exchange rate constants, activation energy barriers, and estimates of the outer-sphere and inner-sphere reorganization energies. The magnitudes of these values implicate structural differences between the two oxidation states. Chapter Four investigates the effects of strongly electron-withdrawing ligands on the redox properties of Au25(SR)18. The effect of each incoming ligand on the formal potentials was assessed using NMR and voltammetry. Density functional theory (DFT) was used to study the effects on the electronic structure induced by exchanging electron-withdrawing ligands. The calculations show how electronegative functional groups change the polarization of the nanoparticle and the charge distribution among the ligands, the semirings, and the Au13 core. Chapter Five studies the electronic communication among the ligands on Au25(SR)18 nanoparticles. Ferrocene-labeled ligands were electronically coupled to the nanoparticle core and the formal potential was assessed both in the presence and absence of electron-withdrawing ligands. The results show that there exists an electronic interaction among the ligands, yet only observable when there is a large amount of extremely electron-withdrawing ligands present. The magnitude of this effect was interpreted in relation to simple-molecule analogs and DFT calculations. Chapter Six is a survey of important ligand exchange reactions over the last five years. It details how the resulting mixed-monolayers contributed in obtaining crucial information on molecular formula, oxidation state, kinetics, electron transfer dynamics, and more.