Exploring various chemical properties of gold monolayer protected clusters

Chapter One introduces chemical properties of gold monolayer protected clusters (MPCs). Backgrounds on topics explored in this dissertation are especially discussed.; Chapter Two presents electronic core charge effects on ligand place exchange reactions. Both the rate and extent of ligand place exchange are enhanced with increasing positive core charge. Ligand place-exchange reactions performed on original MPCs are largely inhibited with exclusion of air, yet those performed on positively charged MPCs are not affected as much.; Chapter Three investigates substituent effects on ligand place exchange reactions between the phenylethanethiolate monolayer of Au 140 MPCs and parasubstituted aryl thiols. 1H NMR monitors changes in free thiol concentrations and the result shows that the exchange reaction is initially rapid, and gradually slows almost to a standstill. This study adds crucial substance to the mechanism studies of ligand place-exchange reactions on MPCs.; Chapter Four describes reactions in which both ligand and core-metal exchange take place between monolayer protected metal clusters. Both reactions are inhibited when conducted under N2 and are accelerated with positive core charges. The result implicates the participation of an oxidized form of Au (such as Au(I) thiolate, Au(I)SR) as both the ligand and metal carrier in the exchange reactions. An improved exchange mechanistic model is proposed.; Chapter Five continues the investigation of core charge effects on MPCs' physical properties. Positive charges (up to +3) are placed on cluster cores via an established bulk electrolysis procedure. 13 C NMR monitors changes in monolayers caused by positive charging, and spectroelectrochemistry experiments investigate charge effects on MPC optical properties. Experimental results emphasize the important catalytic role of Au(I)SR.; Chapter Six presents liquid chromatographic separations of gold monolayer protected clusters, detected electrochemically based upon double layer charging of the metal-like nanoparticles by the detector electrode. Hydrodynamic current-potential curves of nanoparticles eluted are obtained, and the electrochemical half potential (E1/2) separations give estimates of cluster capacitance and thus size. Other approaches, based upon relative values of optical absorbance and current for each eluted peak, to core size determination are also discussed.; Chapter Seven describes fast-scan cyclic-voltammetric (FSCV) detection of gold MPCs, separated by high performance liquid chromatography (HPLC). This selfconstructed detector provides significantly improved nanoparticle identification in the electrochemical domain and nanoparticle core size is estimated directly from the cyclic voltammetric responses. Experiments applying FSCV detector to determine the partitioncoefficient sensitivity of the separation on HPLC to MPC's monolayer are demonstrated.