Electrochemical characteristics of hydroquinone-terminated self-assembled monolayers on gold

Authors
Citation
Hg. Hong et W. Park, Electrochemical characteristics of hydroquinone-terminated self-assembled monolayers on gold, LANGMUIR, 17(8), 2001, pp. 2485-2492
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
LANGMUIR
ISSN journal
0743-7463 → ACNP
Volume
17
Issue
8
Year of publication
2001
Pages
2485 - 2492
Database
ISI
SICI code
0743-7463(20010417)17:8<2485:ECOHSM>2.0.ZU;2-F
Abstract
A series of thiol-functionalized hydroquinone derivatives with different al kyl chain lengths, 2-(n-mercaptoalkyl)hydroquinone (abbreviated as H(2)Q(CH 2)(n)SH, where n = 0, 1, 4, 6, 8, 10, and 12), has been synthesized and use d for preparation of self assembled monolayers (SAMs) on gold electrodes. T he compounds spontaneously adsorb onto a gold surface to form stable and re producible monolayers. The voltammetric behavior of the hydroquinone (H(2)Q ) SAMs has been investigated by cyclic voltammetry to study the effect of a lkyl chain length on the electrochemical characteristics for H(2)Q-SAMs. Th e H(2)Q-SAMs show well-developed voltammetric responses in aqueous solution and pH dependence with a slope of 58.5 mV/pH of surface formal potential i n the broad pH range from 1.3 to 12.1 corresponding to the two-electron two -proton redox reaction of a H(2)Q subunit. The redox response of SAMs at th e same time scale was transformed from reversibility to irreversibility as the alkyl chain length became larger. The monolayers obtained from a 0.1 mu M or lower thiol concentration solution show the most ideal current-potenti al features. From the dependence of logarithmic apparent electron-transfer rate constant on the alkyl chain length between the hydroquinone and the el ectrode, kinetic parameters and electron tunneling constants (beta) were ev aluated for H(2)Q(CH2)(n)SH SAMs. The obtained experimental value of beta = (1.04 +/- 0.06)/CH2 unit is in good agreement with the values reported for reversible redox centers in solutions or tethered monolayer systems.