INFIQC   05475
INSTITUTO DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Self-assembling of aromatic compounds on metals
Autor/es:
F. A. GUTIERREZ; M. E. ALASSIA; V. BRUNETTI; M. LÓPEZ TEIJELO
Lugar:
Cancún, Mexico
Reunión:
Congreso; Joint International Meeting, 210th Meeting of The Electrochemical Society and XXI Congreso de la Sociedad Mexicana de Electroquímica; 2006
Institución organizadora:
The Electrochemical Society y la Sociedad Mexicana de Electroquímica
Resumen:
Self-assembled monolayers (SAMs) of
organothiols on metal surfaces have attracted enormous
attention in recent years owing to their ease-ofpreparation,
long-term stability, and controllable surface
chemical functionality. The understanding of the
molecular packing of SAMs is important for the
interpretation of fundamental studies and for the
development of practical applications. SAMs of aromatic
compounds with two ligands (like mercaptopyridine,
bipyridine and pyridine-carboxylic acids) on gold are
receiving a strong interest in bioelectrochemistry due to
their functionality in order to facilitate direct electron
transfer of metalloproteins such as cytochrome c [1] as
well as the possibility of interacting via the π-system [2].
In this paper, potentiodynamic and potentiostatic
methods combined with electrochemical impedance
spectroscopy (EIS) measurements as well as the
ellipsometric characterisation are used in order to
compare the adsorption of aromatic molecules in a wide
range of conditions. Cyclic voltammetry allows obtaining
the potential regions of stability and desorption of the
layers.
Preparation of monolayers of mercaptopyridine
(N or S-bonded) and isonicotinic acid (N or COObonded)
on monocrystalline and polycrystalline gold
surfaces as well as pyridine and mercaptopyridine on
nickel, is reported. The influence of temperature, pH of
dipping solution and time of dipping in the electrical and
optical properties of the adsorbed layers, is analysed. For
nickel, different cathodic pre-treatments in acidic and
alkaline solutions were applied before the adsorption in
order to electroreduce the spontaneous oxide layer
The impedance characteristics of these systems
are discussed in terms of ideal and non-ideal circuit
networks. The elements are associated with electrical
analogs of the corresponding physical and chemical
processes taking place at the interfaces. The kinetics of
electron transfer for redox couples as well as the
impedance response was employed in order to obtain
information on the compactness of the layers.
Ellipsometric results indicate that the cathodic
pre-treatments are effective for reducing the nickel oxide
as well as indicate the adsorption of pyridine.
STM images are employed for obtaining the
structural characteristics of the self-assembled layers as
well as the changes with potential.
References
[1] T. Sawaguchi, F. Mizutani, S. Yoshimoto, I.
Taniguchi, Electrochim. Acta 45 (2000) 2861.
[2] W. Azzam, C. Fuxen, A. Birkner, H.T. Rong, M.
Buck, C. Wöll, Langmuir 19 (2003) 4958.via the π-system [2].
In this paper, potentiodynamic and potentiostatic
methods combined with electrochemical impedance
spectroscopy (EIS) measurements as well as the
ellipsometric characterisation are used in order to
compare the adsorption of aromatic molecules in a wide
range of conditions. Cyclic voltammetry allows obtaining
the potential regions of stability and desorption of the
layers.
Preparation of monolayers of mercaptopyridine
(N or S-bonded) and isonicotinic acid (N or COObonded)
on monocrystalline and polycrystalline gold
surfaces as well as pyridine and mercaptopyridine on
nickel, is reported. The influence of temperature, pH of
dipping solution and time of dipping in the electrical and
optical properties of the adsorbed layers, is analysed. For
nickel, different cathodic pre-treatments in acidic and
alkaline solutions were applied before the adsorption in
order to electroreduce the spontaneous oxide layer
The impedance characteristics of these systems
are discussed in terms of ideal and non-ideal circuit
networks. The elements are associated with electrical
analogs of the corresponding physical and chemical
processes taking place at the interfaces. The kinetics of
electron transfer for redox couples as well as the
impedance response was employed in order to obtain
information on the compactness of the layers.
Ellipsometric results indicate that the cathodic
pre-treatments are effective for reducing the nickel oxide
as well as indicate the adsorption of pyridine.
STM images are employed for obtaining the
structural characteristics of the self-assembled layers as
well as the changes with potential.
References
[1] T. Sawaguchi, F. Mizutani, S. Yoshimoto, I.
Taniguchi, Electrochim. Acta 45 (2000) 2861.
[2] W. Azzam, C. Fuxen, A. Birkner, H.T. Rong, M.
Buck, C. Wöll, Langmuir 19 (2003) 4958.Electrochim. Acta 45 (2000) 2861.
[2] W. Azzam, C. Fuxen, A. Birkner, H.T. Rong, M.
Buck, C. Wöll, Langmuir 19 (2003) 4958.Langmuir 19 (2003) 4958.
Acknowledgements: Financial support from CONICET,
ANPCyT, and SECYT-UNC from Argentina is gratefully
acknowledged.Financial support from CONICET,
ANPCyT, and SECYT-UNC from Argentina is gratefully
acknowledged.