Faradaic impedance titration and control of electron transfer of 1-(12-mercaptododecyl)imidazole monolayer on a gold electrode |
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Authors: | Seongpil Hwang Bang Sook Lee Young Shik Chi Insung S Choi |
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Affiliation: | a Division of Nano Science (BK21), Ewha Womans University, 11-1 Daehyun-Dong, Seodaemun-Gu, Seoul 120-750, Republic of Korea b Department of Chemistry and School of Molecular Science (BK21), KAIST, Daejeon 305-701, Republic of Korea |
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Abstract: | In this work, we studied interfacial proton transfer of the self-assembled monolayer (SAM) of 1-(12-mercaptododecyl)imidazole on a gold electrode by faradaic impedance titration method with Fe(CN)63− as an anionic redox probe molecule. The surface pK1/2 was found to be 7.3, which was nearly the same as that of 1-alkylimidazole in solution. We also investigated the electrochemical properties of the SAM-modified electrode by cyclic voltammetry. Cyclic voltammetry was performed (1) in the solution containing Fe(CN)63− with repeated alternation of pH values to investigate the electrostatic interaction of the protonated or deprotonated imidazole with Fe(CN)63− and (2) in the acidic or basic electrolyte containing Ru(NH3)63+ as a cationic redox probe to verify the effect of the polarity of a redox probe. We observed the reversible adsorption/desorption of Fe(CN)63− and concluded that the adsorbed Fe(CN)63− catalyzed the electron transfer of both Fe(CN)63− itself and cationic Ru(NH3)63+. |
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Keywords: | 1-(12-Mercaptododecyl)imidazole Self-assembled monolayer Faradaic impedance titration Electron transfer Electrostatic interaction Surface pK1/2 |
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