Electrochemical Properties of Mixed Self-Assembled Monolayers on Gold Electrodes Containing Mercaptooctylhydroquinone and Alkylthiols

Abstract

Mixed self-assembled monolayers of 2-(mercaptooctyl)hydroquinone (QH2) and alkylthiols were formed on gold electrodes in EtOH and the redox process of the hydroquinone moiety of QH2 was characterized by cyclic voltammetry (CV) in 0.1 M H(2)SO(4). The monolayers were formed at a series of QH2:alkylthiol ratios and the QH2:alkylthiol ratio in solution was compared to the electrochemical response from QH2 in the obtained monolayer. Mixed monolayers of QH2 with hexylthiol, dodecylthiol, and octadecylthiol were studied. The length of the alkylthiol is crucial for the electrochemical response from QH2 in the monolayer. The total concentration of thiols during monolayer formation and incubation times were also studied and low concentrations of < 2.5 mM and long incubation times gave rise to lower peak separation, lower peak half widths in the CVs of the mixed monolayers, and lower background current. The stability of a pure QH2 monolayer and a 1:4 QH2:hexylthiol monolayer toward high potentials of up to 1.5 V versus Ag/AgCl was also studied and it was observed that the mixed monolayer is significantly more stable than the pure QH2 monolayer.

Electrochemical and structural properties of self-assembled monolayers of 2-methyl-3-(ω-mercaptoalkyl)-1,4-naphthoquinones on gold

“…Mixed SAMs of thiol-functionalized antraquinones and 1-alkanethiols showed the improved reversibility of redox process [23]. Studies of the mixed hydroquinone-terminated SAMs revealed the crucial influence of the chain length of diluent alkanethiol on the hydroquinone head-group electrochemical response [24]. We have composed mixed monolayers consisting of compound 2b and n-heptanethiol (HT) (Fig.…”

Long-chain alkyl thiols in Langmuir monolayers

“…SAMs from thiols have been extensively investigated since the 1980s of the preceding century [2][3][4][5] due to many diverse applications of such surfaces. For example, when a thiol monolayer is chemisorbed on a metallic electrode, the electrochemical characteristic of the metal is drastically changed and, depending on the properties of the organic moiety, the monolayer insulates the metal surface from different components of the solution [6,7]. The chemisorption of thiols on steel was investigated in the aspect of anti-corrosion protection [8].…”

Rapid and Complete Surface Modification with Strain‐Promoted Oxidation‐Controlled Cyclooctyne‐1,2‐Quinone Cycloaddition (SPOCQ)

“…As shown in previous studies, steric factors from the microenvironment surrounding the reacting site play an important role in interfacial reactions 7, 13. Therefore, SPOCQ was studied for a series of mixed monolayers with variable alkyl:quinone ratios (from 0:1 to 3:1).…”