Studies On The Preparation, Characterization And Analytical Application Of Short-chain Mercaptan Self-assembled Monolayers Gold Electrode

Self-assembled monolayers (SAMs) have attracted considerable interests both from the fundamental point of view and from their analytical prospects in the range of electrochemistry and electroanalytical chemistry, especially the SAMs of mercapto-compounds on gold due to its features of ease of fabrication, good stablity and the possibility of introducing different chemical functional group to the SAMs. In the past two decades, the long-chain mercaptan SAMs have been lucbrated , there are few reports relatively about the short-chain mercaptan SAMs. However, the electron transfer at the short-chain mercaptan SAMs is higher man that of the long-chain mercaptan SAMs, it is easy to investigate the features of electrocatalyzation and the dissociation in the interface. In this thesis, we choose several kinds of short-chain mercaptan to fabricate SAMs on gold, the electrochemical behaviors of some bio-molecule such as dopamine, ascorbate and uric acid were investigated. The mixed SAMs have also been prepared, the features of dissociation activity of acidic group in the interface and selective desorption have also been studied. The main contents are listed as follows:(1). Mercaptoacetic acid SAMs (MA/Au SAMs) were prepared and charactered by electrochemical methods, ATR-FTIR and scanning electronic microscopy (SEM). The electrochemical behaviors of dopamine and metol have been investigated at the MA/Au SAMs. The MA/Au SAMs electrode have been used to detect the content of DA in the dopamine drug injections and metol in photographic imaging agents respectively with satisfacory results.(2). The mixed SAMs were prepared using mercaptoacetic acid and 2-mercaptobenzothiozol with different ratios. The dissociation features of carboxyl group at the surface of mixed SAMs were investigated by A. C. impedance titration method, the surface pKa of pure MA SAMs and mixed MA/Au SAMs were obtained, the shifts of surface pKa caused by the composition of mixed SAMs and ionic strength of electrolyte were explained. The selective desorption of mercaptoacetic acid and dodecanethiol mixed SAMs were investigated by cyclic voltammetry and a. c. impedance. The electro-deposition of polypyrrole on the patterned SAMs has also been investigated after reduction desorption.(3). Using a newly synthesized reagent (2-amino-5-mercapto-[ 1,3,4] triazole ) to fabricate SAMs on gold for the first time, the SAMs was charactered by cyclic voltammetry, a. c. impedance and scanning electronic microscopy. The SAMs shows electrocatalyzation to dopamine and uric acid, the analytical application were accoplished by Osteryoung Square Wave Voltammetry for dopamine and uric acid, the simultaneous determination of dopamine and uric acid has also been studied.