Potential-induced phase transition of benzoxazole-2-thiol, naphthaleneoxazole-2-thiol and anthraceneoxazole-2-thiol monolayers on gold electrodes. (1st September 2018)

• Record Type: Journal Article
• Authors: Schneider, Sebastian; Partes, Christoph; Wiesner, Adrian; Terfort, Andreas
• Is Part Of: Electrochimica acta. Volume 283(2018)
• Page Start: 167
• Page End: 173
• Publication Date: 2018-09-01
• Subjects: Self-assembled monolayer -- Cyclic voltammetry -- Electrochemical impedance spectroscopy -- Potential cycling -- Phase transition -- Scanning tunneling microscopy; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2018.06.123
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: In the present work we report the electrochemical characterization of self-assembled monolayers (SAMs) of N, O-heteroaromatic thiols, namely benzoxazole-2-thiol (1 ), naphthaleneoxazole-2-thiol (2 ) and anthraceneoxazole-2-thiol (3 ) on polycrystalline gold electrodes. SAMs were formed by immersion of pre-treated gold electrodes into ethanolic solutions of the title compounds. The modified electrodes exhibited a decrease of electroactivity, as found by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), in comparison to bare electrodes according to the length of the aromatic π-system. In addition, reductive desorption experiments confirmed that of the three compounds, 3 formed the most stable SAMs in agreement with EIS measurements which revealed better blocking properties against the redox couple in a test electrolyte indicating a charge transfer determined behaviour in the case of longer molecules. The charge transfer resistances revealed a trend towards higher resistances in the case of 3 . When performing EIS at various starting potentials and different electrolyte concentrations, it was found that at certain critical potentials ( E crit ) a potential-induced structural change of the SAM occurred, with E crit (1 ) > E crit (2 ) > E crit (3 ). In the case of SAMs of 3 the nature of this alteration was investigated via scanning tunnelling microscopy and found to presumably be caused by an order-disorder-transition. Graphical abstract: Image 1