Spectroelectrochemical Investigations of Ferrocene-substituted Self Assembled Monolayers on Gold Electrodes
State of Research
Over the past decade, self-assembled monolayers (SAMs) on metal surfaces including electrodes emerged as particularly interesting and therefore have been intensively studied because of their unique interfacial behavior and structural properties. The Langmuir-Blodgett (LB) method is one of the most popular techniques used to form mono- and multilayers of self-assembled molecules on solid substrates. Unfortunately, the monolayer formed by LB method on substrates is only physically adsorbed, and usually it is not stable. In order to overcome this problem, a new approach has been developed: the self-assembly method, where the molecules are chemically adsorbed by making covalent bonds with the atoms on the substrate and form well defined structures[1]. SAMs offers a number of applications in sensors [2], catalysis [3], molecular electronic devices [4], and other areas [5]. SAMs have been formed from a variety of compounds and substrates including fatty acids, trichlorosilanes, trialkoxysilanes on glass, silicon, carboxylic acids, and alkyl phosphates on metal oxides [6, 7]. So far most of the fundamental studies have been performed with aliphatic thiols and only very recently aromatic thiols moved into the focus of interest due to their highly anisotropic nature and high electrical conductivity.
Ferrocene substituted alkanethiols
Ferrocene has interesting properties attracting researchers in many fields including electrochemistry. It is used in many electrochemical measurements where ferrocene is one of the most popular electrochemically active groups [8] and is also a good organometallic one-electron reservoir [9].
Planned research
In this present work, the research will be extended by using the ferrocenyl substituted alkanethiol monolayers with different functional groups on gold electrode as a model system to study the electron exchange between ferrocenyl groups and gold substrate, because of the simple and good electrochemical behavior of the ferrocene groups. In this present work, the research will be extended by using the ferrocenyl substituted alkanethiol monolayers with different functional groups on gold electrode as a model system to study the electron exchange between ferrocenyl groups and gold substrate, because of the simple and good electrochemical behavior of the ferrocene groups. In this present work, the research will be extended by using the ferrocenyl substituted alkanethiol monolayers with different functional groups on gold electrode as a model system to study the electron exchange between ferrocenyl groups and gold substrate, because of the simple and good electrochemical behavior of the ferrocene groups.
The ferrocenyl-substituted SAMs will be characterized and compared with the results obtained for biphenyl ethynyl thioacetyl molecule which has been characterized already in our group.
Structure of ferrocenyl-substituted biphenyl ethynyl thioacetyl molecule (bottom) and of biphenyl ethynyl thioacetyl (top)
Calculation of vibrational spectra of the ferrocenyl substituted SAMs adsorbed on the gold electrode will be performed using density function theory (DFT) calculations. Turbomole and Gaussian software will be used to animate and describe the calculated vibrational modes.Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) will be used to evaluate the redox properties of a ferrocene unit over a wide potential range and behavior of double layer capacitance. Surface enhanced Raman spectroscopy (SERS) will be used to study the interaction of the molecule with the gold electrode and the structure and orientation of the molecules adsorbed on the gold surface. The surfaces and surface-bound assemblies will be analyzed by atomic force microscopy (AFM). Other than ferrocene, ruthenocene substituted SAMs will be characterized by electrochemical and spectroscopic techniques.
References
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