Monolayer Protection Of Metal Clusters Synthesis And Quantized Capacitance Charging

1. Synthesis and characteristics of Au monolayer-protected clusters modified with thiolsA new method for synthesis of monolayer-protected clusters (MPCs) was described. In the new two-phase system of tetrahydrofuran/saturated electrolyte, the AuCl4- anion was transferred into the organic phase from aqueous phase with a transference catalyst of tetra-n-butylammonium boromide ((C4H9)4NBR) and was reduced quickly by sodium borohydride in the presence of n-hexanthiol from which the uniform smaller size of MPCs were obtained. Changing the mole ratio of S to Au could control the core dimension of MPCs. Compared with the other methods reported, it enjoyed lower cost, fast synthesis and high purity. The MPCs prepared were characterized by transmission electron microscope, ultraviolet-visible spectroscope and Fourier transform infrared spectroscope. The results show that the MPCs properties were consistent with the reports that had been published.2. Synthesis and characteristics of Cu monolayer-protected clustersCu2+ anions were combined with Cl- cations to form complex cation CuCl2+. It was transferred to organic phase by (C4H9)4Br and reduced to form alkanethiolate monolayer protected copper clusters. The pH of the water phase, the kinds of the electrolyte and protecting ligand and the deposition time have the distinguished influence on the conformation and stability of the product. TEM, UV-vis, FTIR and EDX spectroscopeswere carried out for investigation of the particle optoelectronic properties and thestructure of the protecting monolayers The UV-vis spectral of the CuMPCs show nobroad surface plasmon band. Electrochemical method was used to study their quantized charging proprieties in solutions where the nanoparticle molecular capacitance was evaluated which was about 1.14aF.3. Quantized capacitance charging of monolayer-protected Au clusters self-assembled on glassy carbon electrode in aqueous solutionA simple way to assemble monolayer-protected Au clusters (AuMPCs) onto a glassy carbon electrode and investigation of quantized capacitance charging of momolayer-protected Au clusters were reported. The electrode was immersed into dichloromethane containing AuMPCs to acquire monolayers of AuMPCs modified glassy carbon electrode with the surface coverage of 7.78 x l0-13mol/cm2. The method enjoyed rather easy, efficient and fast assembly process. The cyclic voltammetry (CV) and differential pulse voltammetry (DPV) exhibited six pairs of quantized capacitance charging peaks in 0.10 M NH4PF6 aqueous solution and one pair peak when NH4PF6concentration was less than 10-4M. In terms of the Laviron evaluation the electron transfer rate constant was measured as 4s-1 which was lower than that on the gold electrode. Investigation of double-step chronocoulometric method demonstrated each peak corresponding to 1e transfer across the interface of MPCs. The capacitance of hexanethiol AuMPCs molecule with the size of 2.0 nm was measured as 1.07aF in aqueous solution.4. Amitriptyline detected by quantized capacitance charging with a monolayer protected clusters modified glassy carbon electrodeQuantized capacitance charging of monolayer protected clusters was observed inNH₄PF6 solution with a MPCs modified glassy carbon electrode which was prepared by simply dipping the electrode into MPCs dichloromethane solution for a moment. A redox peaks of quantized capacitance charging was applied for determination of none-electroactive amitriptyline hydrochloride when NH4PF6 concentration was lower than 1.0 X 10-4M while several redox peaks of quantized capacitance charging were found when NH4PF6 concentration was larger than 1.0 X 10-4 M which didn't facilitate determination of amitriptyline. The single peak currents are proportional to amitriptyline concentration in the range of 2.32 X 10-6⁸.18 X 10-5M with the detection limit of 7.84 X 10-7M. The range of recovery is 89.6%¹00.4% by the standard addition. This is the first time to use the character of quantized charging to determine medicin...