Based on electropolymerized porphyrin

Anion-Selective Electrodes Based on Electropolymerized Porphyrin Filins... 

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

Fiber optic sensors based on electropolymerized porphyrins... 

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],... 

Quintino MSM, Araki K, Toma HE, Angnes L (2008) New hydrazine sensors based on electropolymerized meso-tetra(4-sulphonatephenyl)porphyrinate manganese(III)/silver nanomaterial. Talanta 74(4) 730-735... 

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.)...

Blair, T.L., J.R. Allen, S. Daunert, and L.G. Bachas (1993). Potentiometric and fiber optic sensors for pH based on an electropolymerized cobalt porphyrin. Anal. Chenu 65,2155-2158. 

In all cases, the films were obtained by oxidative electropolymerization of the cited substituted complexes from organic or aqueous solutions. The mechanism of metalloporphyrin Him formation was suggested to be a radical-cation induced polymerization of the substituents on the periphery of the macrocycle. As it was reported for the case of polypyrrole-based materials ", cyclic voltammetry and UV-visible spectroscopy with optically transparent electrodes were extensively used to provide information on the polymeric films (electroactivity, photometric properties, chemical stability, conductivity, etc.). Based on the available data, it appears that the electrochemical polymerization of the substituted complexes leads to well-structured multilayer films. It also appears that the low conductivity of the formed films, combined with the cross-linking effects due to the steric hindrance induced by the macrocyclic Ugand, confers to these materials a certain number of limitations such as the limited continuous growth of the polymers due to the absence of electronic conductivity of the films. Indeed, the charge transport in many of these films acts only by electron-hopping process between porphyrin sites. 

Schaming D, Ahmed I, Hao J, Alain-Rizzo V, Farha R, Goldmann M, Xu H, Giraudeau A, Audebert P, Ruhlmann L (2011) Easy methods for the electropolymerization of porphyrins based on the oxidation of the macrocycles. Electrochim Acta 56(28) 10454—10463... 

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. 

Hrbac, J., Gregor, C., Machova, M., Kralova, J., Bystron, T., Ciz, M., Lojek, A., 2007. Nitric oxide sensor based on carbon fiber covered with nickel porphyrin layer deposited lasing optimized electropolymerization procedure. Bioelectrochemistry 71, 46—53. 

But the most smdied electropolymerizable porphyrins are the tetra-amino-and tetrahydroxyphenyl-substituted ones. Indeed, both of them were developed to elaborate electrodes having potentiometric responses to several kinds of anions, such as iodide for example . Co(II) tetrakis(p-hydroxyphenyl)porphyrin 53-based films were used for the elaboration of potentiometric and fibre optic pH sensors with minimal interferences from anions. Zn(II)-53-based films were also used and characterized for kinetics studies of hydrogen evolution at their surface . Zn(II)-53 as well as Pd(II)-53 and free base tetra(4-methyl pyridinium) porphyrin (H2-54) were electropolymerized on indium tin oxide substrates, leading thus to starting materials for the making of donor/acceptor... 

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