Porphyrin polymers, conductive

Another approach uses a cobalt tetrakis(o-aminophenyl)porphyrin polymer film, prepared by electrooxidative polymerization of the monomer on top of the electrode as conductive film-mediator-couple [19]. 

Studies in the areas of conductive polymers and ferroelectric materials constitute a relatively small subset of porphyrin materials research. Nonetheless, the versatility of porphyrins has allowed for some interesting and useful results in these areas. We will examine the variety of approaches toward the creation of porphyrin-based conductive polymers and the potential applicability of porphyrinic polymers as ferroelectric materials. 

T. Shimidzu, H. Segawa, F. Wu and N. Nakayama, Approaches to conducting polymer devices with nanostructures photoelectrochemical function of one-dimensional and two-dimensional porphyrin polymers with ofigoth-ienyl molecular wire, J. Photochem. Photobiol. A, 92, 121-127 (1995). 

In conclusion, the electrochemical behaviour of the polymers presented Fig. 8 and the summary of the electrochemical behaviour of all studied polymers presented in Table 2 show that the oxidation of the SBF-porphyrin polymers may not be described as easily as that of the classical p-doping process of conducting polymers. It must be characterized by an onset oxidation potential, the number of successive oxidation steps and a potential limit of stability. All these values depend of the nature of the porphyrin core (free or metallated porphyrin) and the number of SBF unit decorating the porphyrin and give a sort of fingerprint of each polymer. 

Intensive research on the electrocatalytic properties of polymer-modified electrodes has been going on for many years Until recently, most known coatings were redox polymers. Combining redox polymers with conducting polymers should, in principle, further improve the electrocatalytic activity of such systems, as the conducting polymers are, in addition, electron carriers and reservoirs. One possibility of intercalating electroactive redox centres in the conducting polymer is to incorporate redoxactive anions — which act as dopants — into the polymer. Most research has been done on PPy, doped with inter alia Co 96) RyQ- 297) (--q. and Fe-phthalocyanines 298,299) Co-porphyrines Evidently, in these... 

Tetra(o-aminophenyl)porphyrin, H-Co-Nl TPP, can for the purpose of electrochemical polymerization be simplistically viewed as four aniline molecules with a common porphyrin substituent, and one expects that their oxidation should form a "poly(aniline)" matrix with embedded porphyrin sites. The pattern of cyclic voltammetric oxidative ECP (1) of this functionalized metal complex is shown in Fig. 2A. The growing current-potential envelope represents accumulation of a polymer film that is electroactive and conducts electrons at the potentials needed to continuously oxidize fresh monomer that diffuses in from the bulk solution. If the film were not fully electroactive at this potential, since the film is a dense membrane barrier that prevents monomer from reaching the electrode, film growth would soon cease and the electrode would become passified. This was the case for the phenolically substituted porphyrin in Fig. 1. 

Pyrroles prepared by the Barton-Zard reaction are very important as precursors of porphyrins and also of conducting polymers. The ester group at the 2-position is readily removed on heating with KOH in ethylene glycol at 170 °C to give a-free pyrroles, which are useful for preparing porphyrins (Eq. 10.42)47 or polypyrroles (Eq. 10.43).38a,4S... 

The use of porphyrinic ligands in polymeric systems allows their unique physio-chemical features to be integrated into two (2D)- or three-dimensional (3D) structures. As such, porphyrin or pc macrocycles have been extensively used to prepare polymers, usually via a radical polymerization reaction (85,86) and more recently via iterative Diels-Alder reactions (87-89). The resulting polymers have interesting materials and biological applications. For example, certain pc-based polymers have higher intrinsic conductivities and better catalytic activity than their parent monomers (90-92). The first example of a /jz-based polymer was reported in 1999 by Montalban et al. (36). These polymers were prepared by a ROMP of a norbor-nadiene substituted pz (Scheme 7, 34). This pz was the first example of polymerization of a porphyrinic macrocycle by a ROMP reaction, and it represents a new general route for the synthesis of polymeric porphyrinic-type macrocycles. 

Transition metal compounds, such as organic macrocycles, are known to be good electrocatalysts for oxygen reduction. Furthermore, they are inactive for alcohol oxidation. Different phthalocyanines and porphyrins of iron and cobalt were thus dispersed in an electron-conducting polymer (polyaniline, polypyrrole) acting as a conducting matrix, either in the form of a tetrasulfonated counter anion or linked to... 

Preparation, electrochemical, and spectroscopic properties of zinc-porphyrins and anthraquinone-based polymers [481] and also conducting polymers with Zn(II)-5 -vinyl-10,15,20-triphenylporphyrin [482] coated electrodes were described. 

Title Conducting Polymers with Porphyrin Crosslinkers... 

Research Focus Development of high-efficiency porphyrin hybrid conducting polymers. Originality Although polyporphyrins have been previously prepared, poly... 

In this chapter, we describe three different systems with which to construct electro- and photo-functional molecular assemblies on electrode surfaces. The first is the bottom-up fabrication of redox-conducting metal complex oligomers on an electrode surface and their characteristic redox conduction behavior, distinct from conventional redox polymers.11-13 The second is a photoelectric conversion system using a porphyrin and redoxconducting metal complex.14 The third is the use of a cyanobacterial photosystem I with molecular wires for a biophotosensor and photoelectrode.15 16 These systems will be the precursors of new types of molecular devices working in electrolyte solution. 

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