Self-assembled molecular films of tetraamino metal (Co, Cu, Fe)
phthalocyanines on gold and silver. Electrochemical and spectroscopic
characterization*
M. P. Somashekarappa1, J. Keshavayya2, and S.
Sampath1,
1Department of Inorganic and Physical Chemistry, Indian
Institute of Science, Bangalore 560 012, India; 2Department of Industrial
Chemistry, Kuvempu University, Shimoga Karnakata, India
Abstract: The formation of molecular films of 2,9,16,23-tetraamino
metal phthalocyanines [TAM(II)Pc; M (II) = Co, Cu, and TAM(III)Pc; M
= Fe] by spontaneous adsorption on gold and silver surfaces is described.
The properties of these films have been investigated by cyclic voltammetry,
impedance, and FT-Raman spectroscopy. The charge associated with Co(II)
and Co(I) redox couple in voltammetric data leads to a coverage of (0.35
± 0.05) X 10-10
mol cm-2, suggesting that the tetraamino cobalt phthalocyanine
is adsorbed as a monolayer with an almost complete coverage. The blocking
behavior of the films toward oxygen and Fe(CN)63-/4-
redox couple have been followed by cyclic voltammetry and impedance
measurements. This leads to an estimate of the coverage of about 85%
in the case of copper and the iron analogs. FT-Raman studies show characteristic
bands around 236 cm-1 revealing the interaction between the
metal substrate and the nitrogen of the -NH2 group on the
phthalocyanine molecules.
* Special Topic Issue on the Theme
of Nanostructured Advanced Materials
**Corresponding author
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