Two-dimensional assembly and local redox-activity of molecular hybrid structures in an electrochemical environment

Li, Zhihai; Han, Bo; Mészáros, Gábor; Pobelov, Ilya; Wandlowski, Thomas; Błaszczyk, Alfred; Mayor, Marcel (2006). Two-dimensional assembly and local redox-activity of molecular hybrid structures in an electrochemical environment. Faraday Discussions, 131, pp. 121-143. Royal Society of Chemistry 10.1039/B506623A

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The self-assembly and redox-properties of two viologen derivatives, N-hexyl-N-(6-thiohexyl)-4,4-bipyridinium bromide (HS-6V6-H) and N,N-bis(6-thiohexyl)-4,4-bipyridinium bromide (HS-6V6-SH), immobilized on Au(111)-(1x1) macro-electrodes were investigated by cyclic voltammetry, surface enhanced infrared spectroscopy (SEIRAS) and in situ scanning tunneling microscopy (STM). Depending on the assembly conditions one could distinguish three different types of adlayers for both viologens: a low coverage disordered and an ordered striped phase of flat oriented molecules as well as a high coverage monolayer composed of tilted viologen moieties. Both molecules, HS-6V6-H and HS-6V6-SH, were successfully immobilized on Au(poly) nano-electrodes, which gave a well-defined redox-response in the lower pA–current range. An in situ STM configuration was employed to explore electron transport properties of single molecule junctions Au(T)|HS-6V6-SH(HS-6V6-H)|Au(S). The observed sigmoidal potential dependence, measured at variable substrate potential ES and at constant bias voltage (ET–ES), was attributed to electronic structure changes of the viologen moiety during the one-electron reduction/re-oxidation process V2+ V+. Tunneling experiments in asymmetric, STM-based junctions Au(T)-S-6V6-H|Au(S) revealed current (iT)–voltage (ET) curves with a maximum located at the equilibrium potential of the redox-process V2+ V+. The experimental iT–ET characteristics of the HS-6V6-H–modified tunneling junction were tentatively attributed to a sequential two-step electron transfer mechanism.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Li, Zhihai; Han, Bo; Mészáros, Gábor; Pobelov, Ilya; Wandlowski, Thomas and Mayor, Marcel

Subjects:

500 Science > 540 Chemistry

ISSN:

1364-5498

Publisher:

Royal Society of Chemistry

Funders:

[UNSPECIFIED] IFMIT
[UNSPECIFIED] Volkswagen Stiftung
[UNSPECIFIED] Research Center Juelich
[UNSPECIFIED] German Academic Exchange Service (DAAD)
[UNSPECIFIED] Hungarian Scientific Research Fund
[UNSPECIFIED] German Ministry of Education and Research

Language:

English

Submitter:

Ilya Pobelov

Date Deposited:

16 Jan 2014 11:10

Last Modified:

06 Dec 2014 07:56

Publisher DOI:

10.1039/B506623A

Web of Science ID:

000235543600009

BORIS DOI:

10.7892/boris.39805

URI:

https://boris.unibe.ch/id/eprint/39805

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