Electropolymerized porphyrin film

In summary, it has been demonstrated that ISEs can be designed by employing molecular recognition principles. In particular, the feasibility of using hydrophobic vitamin B12 derivatives and electropolymerized porphyrin films in the development of polymer membrane anion-selective electrodes has been demonstrated. The studies indicated that the changes in the selectivity of these ISEs can be explained by the difference in structure of the ionophores. In addition, it was shown that by electropolymerization of a cobalt porphyrin, anion-selective electrodes can be prepared that have extended lifetimes compared with PVC-based ISEs, which use a similar compound as the ionophore. 

The high background impedance of the electropolymerized porphyrin films contrasts with the relatively high intrinsic conductivity observed for the electrostatic assembled Co(TRPyP)/Zn(TPPS) bilayer films (296). In this case, a very low... 

Bettelheim, A., L. Soifer, E. Korin (2004). Electropolymerized porphyrin films as methanol barriers in direct methanol fuel cells. J. Electroanal. Chem. 571, 265-272. 

Daunert, S., S. Wallace, A. Hondo, and L.G. Bachas (1991). Anion-selective electrodes based on electropolymerized porphyrin films. Anal. Chem. 63, 1676-1679. 

Presspiich, K.A., S.G. Maybury, R.E. Thomas, R.W Linton, E.A. Irene, and R.W. Murray (1989). Molecular sieving by electropolymerized porphyrin films only a few monolayers thick. J. Phys. Chem. 93, 5568-5574. 

The authors have also reported on the comparison between the electrocatalytic activity of electropolymerized films of cobalt porphyrins and phthalocyanines (cobalt tetrakis(p-hydroxyphenyl)porphyrin cobalt tetrakis(o-aminophenyl)porphyrin and Co(II)-2), with emphasis on the effect of the film thickness on the electro-oxidation of 2-mercaptoethanol [52]. It was shown that, despite the porphyrins modified electrodes exhibit electrocatalytic activity, their activity strongly depends on the film thickness with a decrease of activity as the thickness increases, in contrast to the phthalocyanine-based electrodes. This difference in behavior was attributed to lower electronic conductivity of electropolymerized porphyrin films relative to phthalocyanine-based ones, and to the potential implication of the less reactive Co(III) form of the deposited porphyrin complexes. 

Dloxygen reduction electrocatalysis by metal macrocycles adsorbed on or bound to electrodes has been an Important area of Investigation (23 ) and has achieved a substantial molecular sophistication in terms of structured design of the macrocyclic catalysts (2A). Since there have been few other electrochemical studies of polymeric porphyrin films, we elected to inspect the dloxygen electrocatalytic efficacy of films of electropolymerized cobalt tetraphenylporphyrins. All the films exhibited some activity, to differing extents, with films of the cobalt tetra(o-aminophenylporphyrin) being the most active (2-4). Curiously, this compound, both as a monomer In solution and as an electropolymerized film, also exhibited two electrochemical waves... 

Extensive work has been carried out on microsensors built from electropolymerized nickel porphyrin films.328,329 Films of Prussian blue (Fe4[Fe(CN)6]3) 345 metal-salen complexes (M = Co, Fe, Cu, Mn)346 or the ferrocene-containing Nin-tetraaza[14] annulene (24),347 also exhibit interesting activity for NO electrooxidation and sensing. 

An imprinted poly[tetra(o-aminophenyl)porphyrin] film, deposited on a carbon fibre microelectrode by electropolymerization, was used for selective determination of dopamine [208] in the potential range of —0.15 to 1.0 V. This chemosensor has been used successfully for dopamine determination in brain tissue samples. The dopamine linear concentration range extended from 10 6 to 10-4 M with LOD of 0.3 pM. However, this LOD value is very high compared to that of the dopamine voltammetric detection using polyaminophenol MIPs prepared by electropolymerization [209]. Dopamine was determined by CV and DPV at concentrations ranging from 2 x 10 s to 0.25 x 10 6 M with LOD of 1.98 nM. This LOD value is lower than that of PM dopamine detection [133]. 

Figure 8. Selectivity pattern of an ISE based on an electropolymerized cobalt porphyrin film. The electrode was exposed to the following anions thiocyanate (1), perchlorate (2), iodide (3), nitrite (4), salicylate (5), bromide (6), chloride (7), bicarbonate (8), phosphate (9). The baseline potential was 364 mV. (Adapted from ref. 26.)...

The main impetus for the incorporation of porphyrins into conjugated polymers is to develop photosynthetic and enzyme mimics. Porphyrins were recently incorporated into rr-conjugated polymers (e.g., PPE, PPV), linear porphyrin tapes, and electropolymerized thin films. 

Figure 6-5 lists most of the pyrrole-, thiophene-, amino- and hydroxy-substituted porphyrins employed for electropolymerization and the references. Monomers 49a - k [136-147] are based on synthetic porphyrins and 50a, b on deuteroporphyrin [148-150]. Surprisingly, the electrooxidation of metal complexes of protoporphyrin-DC dimethyl ester, possibly via the vinyl groups, leads to the deposition of electroactive porphyrin films on the electrode surface [151-153],... 

Trevin, S., E. Bedioui, and J. Devynck (1996). Electrochemical and spectrophoto-metric study of the behaviour of electropolymerized nickel porphyrin films in the determination of nitric oxide. Talanta 43,303-311. 

Immobilization of Multicharged Porphyrins into Pro-Electropolymerized Polypyrrole Films Bearing Functional Groups... 

Malinski and Taha reported in 1992 on a very interesting application of an electropolymerized nickel porphyrin film electrode for in situ amperometric detection of nitric oxide in biological systems . The authors coated carbon fibres... 

Meyerhoff et al have reported the use of a non-metallated porphyrin film as an ion-selective electrode. They have shown that the electropolymerized films offer significant selectivity for the detection of iodide over a wide range of anions. The lifetime of these electrodes was estimated by analyzing some of their characteristics such as sensitivity and detection limits. The effect of pH on the detection of iodide by the film-supported electrodes was also established. For pH values from 3 to 8, there is relatively little effect of the pH on the electrochemical response of the electrodes. At pH values higher than 8, the electrode response is affected by the interference by hydroxide ions. 

Bedioui, R, J. Devynck, and C. Bied-Charreton (1996). Electropolymerized manganese porphyrin films as catalytic electrode materials for biomimetic oxidations with molecular oxygen. J. Mol. Catalysis 113, 3-11. 

Oyama, N., T. Ohsaka, M. Mizunuma, and M. Kobayashi (1988). Electropolymerized cobalt tetrakis(ort/w-aminophenyl) porphyrin film mediated enzyme electrode for amperometiic determination of glucose. Anal. Chem. 60(22), 2536-2537. 

Griveau, S. and F. Bedioui (2001). Electrocatalytic oxidation of 2-mercaptoethanol by electropolymerized cobalt porphyrin film on vitreous carbon electrodes. Electroanalysis 13(3), 253-256. 

Winnischofer H, Formiga ALB, Nakamura M, Toma HE, Araki K, Noguerra AF (2005) Conduction and photoelectrochemical properties of monomeric and electropolymerized tetraruthenated porphyrin films. Photochem Photobiol Sci 4(4) 359-366... 

White BA, Murray RW (1985) Electroactive porphyrin films from electropolymerized metallotetra(o-aminophenyl)porphyrins. J Electroanal Chem 345-352... 

De Medeiros MAC, Gorgy K, Deronzier A, Cosnier S (2008) Design of new electropolymerized polypyrrole films of polyfluorinated Zn(II) and Mn(III) porphyrins towards electrochemical sensors. Mater Sci Eng C Biomim Supramol Syst 21 731-738... 

A primary goal of this experiment was to use diffuse reflectance for evaluation of thicker porphyrin films which cannot be studied by using transparent conductive electrodes and absorption spectroscopy. The main concern was whether the integrity of the porphyrin system had been retained in the electropolymerization scheme and whether the reactions taking place in the film would be comparable to those taking place in the bulk. The cyclic voltammograms of the films in solution suggested that both of these facts were true. 

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