Porphyrins conducting polymeric

The use of metalloporphyrins which show metal-metal interactions can be an effective strategy for the synthesis of metal chain complexes. Some of these complexes exhibit high or unusual electric conductivities . Although much synthetic work has been devoted to metalloporphyrin chemistry ", only a few examples of porphyrin compounds containing metal-metal interactions have been published. Apart from the conducting polymeric porphyrins described by Ibers and Hoffman , two classes of metal-metal... 

The construction of intramolecular molecular system whose photo active molecule linked with conducting molecular wire is an important subject in realization of. molecular electronic or photonic devices. For such objectives, systematization of donor-photosensitizer-acceptor triad molecules into large molecular systems is one of the feasible approaches because the exquisite incorporation of the photosensitizer and a suitable electron donor and/or acceptor into a conducting polymeric chain is useful for various molecular systems based on the photoinduced electron transfer. With this in mind, we synthesized symmetrical donor-acceptor-donor triad molecules which can be polymerized by the normal electrochemical oxidation. By the polymerization, one-dimensional donor-acceptor polymers with porphyrin moieties separated by ordered oligothienyl molecular wire which is considered as a proto-type molecular device was obtained. 

Figure 8. Schematic diagram of electrochemical nitric oxide sensor based on conductive polymeric porphyrin.

A tissue culture can be grown directly on a porphyrinic sensor and measurements of NO can be made by using voltammetric or amperometric methods. - This macrosize sensor is advantageous for screening large numbers of cells for NO relea.se without using more tedious microelectrode techniques. Sensor production consi.sts of deposition of conductive polymeric film on the surface of the conductive solid support recticulated vitrous carbon (RVC). 

Ciszewski, A., E. Kubaszewski, and M. Lozynski (1996). The role of nickel as central metal in conductive polymeric porphyrin film for electrocatalytic oxidation of nitric oxide. Electroanalysis 8(3), 293-295. 

Mafinski, T., A. Ciszewski, J. Bennett, and J.R. Fish (1991). Characterization of conductive polymeric nickel(II) tetrakis(3-methoxy-4-hydroxy-phenyl)porphyrin as an anodic material for electrocatalysis. J. Electrochem. Soc. 138(7), 2008-2015. 

Several types of porphyrin and phthalocyanine ligand modification have been performed to create a new family of electrochemically polymerizable complexes. The most commonly used porphyrins are the amino " hydroxy methoxy ° ° , vinyl- and other " substituted macrocyclic complexes (see examples in Figure 8.13). In the case of phthalocyanine, tetra-amino-substituted macrocycle was exclusively and intensively developed. Studies of these complexes have focused on the electrochemical synthesis and characterization of conductive polymeric or copolymeric materials. 

Malinski, T., A. Ciszewski, J. Fish, E. Kubaszewski, and L. Czuchajowski (1992). Conductive polymeric Cu(II) tetrakis(3-methoxy-4-hydroxyphenyl)porphyrin as a photosensitizer in a photoelectrochemical cell. Adv. Mater. 4, 354-357. 

Bennett, J.E. and T. Malinski (1991). Conductive polymeric porphyrin films Application in the electrocatalytic oxidation of hydrazine. Chem. Mater. 3, 490-495. 

Ciszewski, A. and G. Milczarek (1996). Electrocatalytic oxidation of alcohols on glassy carbon electrodes electrochemically modified by conductive polymeric nickel(II)tetrakis(3-methoxy-4-hydroxyphenyl)porphyrin film. J. Electroanal. Chem. 413, 137-142. 

Electrochemical methods for NO determination offer several features that are not available with spectroscopic approaches. Perhaps the most important is the capability of microelectrodes to directly measure NO in single cells in situ, in close proximity to the source of NO generation. Figure 2 shows sensors that have been developed for the electrochemical measurement of NO. One is based on the electrochemical oxidation of NO on a platinum electrode (the classical Clark probe for detection of oxygen) and operates in the amperometric mode [17]. The other is based on the electrochemical oxidation of NO on conductive polymeric porphyrin (porphyrinic sensor) [24]. The Clark probe uses a platinum wire as a working electrode (anode) and a silver wire serves as the counterelectrode (cathode). The electrodes are mounted in a capillary tube filled with a sodium chlo-ride/hydrochloric acid solution separated from the analyte by a gas-permeable membrane. A constant potential of 0.9 V is applied, and direct current (analytical signal) is measured from the electrochemical oxidation of NO on the platinum anode. In the porphyrinic sensor, NO is catalytically oxidized on a polymeric metalloporphyrin... 

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. 

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. 

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