Studies of porphyrins, their metallocomplexes and polymer materials have been in the
focus of interest in the scientific community because the macrocyclic compounds play an
important role in photosynthesis [1] and have unique electronic, magnetic and optical properties
[2]. Numerous studies have been devoted to applications of porphyrins in catalysis [3], as lightemitting
units, charge-storage cells [4-5]. It has been shown that electrochemical properties of
porphyrins depend on presence and nature of peripheral substitutes in the porphyrin macrocycle
[6]. At the presence of peripheral substitutes poly-porphyrin film may be formed on electrode in
the process of electrooxidation or electroreduction of the porphyrins [7]. The poly-porphyrin
coated electrodes can be applied in energy-storage accumulators, photosensors, elecroanalysis
and in the processes associated with charge transfer [8-9].
The present work is devoted to studies of the processes of electrochemical oxidation and
reduction of 5,10,15,20-tetrakis(4'-aminophenyl)porphyrin in dichlorometane by cyclic
voltammetry method and physicochemical properties of the deposited film obtained by
electropolymerization of the porphyrin. The process of electropolymerization was carried out by
cyclic voltammetry method from solutions of 5,10,15,20-tetrakis(4'-aminophenyl)porphyrin in
dichloromethane. Character of polymerization and chemical composition of the film were
determined by electron absorption spectroscopy and FTIR spectroscopy. Analysis of the spectra
indicates that π-conjugate system of the macroheterocycle persists at the electropolymarization
and the porphyrin chromophores in the poly-porphyrin film do not interact. Analyzing the FTIR
spectra it may be concluded that under polarizing anode potentials the polymerization of H2T(4'-
NH2Ph)P occurs due to formation of dihydrophenazine fragments. DSC studies show that the
film formed on platinum electrode melts in a wide temperature range and is partially crystal,
slowly melting polymer. The film has homogenous surface with uniform distribution of the
polymer globules. The surface microridges were found to be about 100 nm at an average film
thickness of 600 nm. The poly-porphyrin film participated on the electrode is insoluble in major
organic solvents (dichloromethane, ethanol, acetone, acetonitrile, dimethylformamide),
concentrated acids and bases. The studies by photo EMF method indicate that the porphyrin film
is p-type semiconductor.
References:
[1] Alstrum-Acevedo, J. H.; Brennaman, M.K.; Meyer, T.J. In: Inorg. Chem. 2005, 44, 6802.
[2] Cherian, S.; Wamser, C. C. In: J. Phys. Chem. B 2000, 104, 3624.
[3] Tesakova, M. V.et al. In: Russ. J. Phys. Chem. 2012. 86. 9.
[4] Miyairi, K.; Itoh, E.; Hashimoto, Y. In: Thin Solid Films 2003, 438, 147.
[5] Wrуbel, D. In: Comptes Rendus Chimie. 2003, 6, 417.
[6] Fujii, H. In: J. Am. Chem. Soc. 1993, 115, 4641.
[7] Bettelheim, A. et al. In: Inorg. Chem. 1987, 26. 1009.
[8] Bruti, E.M.; Gianneto, M.; Mori, G.; Seeber R. In: Electroanalysis 1999, 11, 565.
[9] Jeong, H.; Kim, H.; Jeon, S. In: Microchem. J. 2004, 78, 181.