Potential dependent adsorption behaviour of thiothymine derivatives on the Au(1 1 1) electrode

✍ Scribed by Moritz Hintze; Kay–Oliver Thiel; Antje Vollmer; Heiko Brunner; Constanze Donner

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 501 KB
• Volume: 55
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/j.electacta.2010.01.110

✦ Synopsis

The adsorption behaviour of 2-thiothymine and 4-thiothymine on a Au(1 1 1) single crystal electrode has been studied using cyclic voltammetry and X-ray photo electron spectroscopy. For both thio derivatives the adsorption region is restricted due to the onset of reversible oxidization to 2,2 -bis(1H-5-methylpyrimidin-4-one-2-yl)-disulphide or 4,4 -bis(1H-5-methylpyrimidin-2-one-4-yl)-disulphide at anodic potentials. Two different orientations of adsorbed 2-thiothymine have been observed. Between -350 mV and -700 mV versus Ag/Ag + the molecule is solely chemisorbed via its sulphur atom and adopts an upright orientation towards the surface. However at more negative potentials 2-thiothymine is reoriented into a slightly tilted position interacting via its S, N and O atoms with the surface. In contrast, 4-thiothymine exhibits only one adsorption geometry. Between -300 mV and -700 mV versus Ag/Ag + it is chemisorbed via sulphur and nitrogen adopting a slightly tilted position. At -950 mV versus Ag/Ag + 4-thiothymine is irreversibly reduced. The sulphur substituent is eliminated and covers the substrate.