Cobalt-phthalocyanine-incorporated

Abe, T., T. Yoshida, S. Tokita, F. Taguchi, H. Imaya, and M. Kaneko (1996). Factors affecting selective electrocatalytic CO2 reduction with cobalt phthalocyanine incorporated in a polyvinylpyridine membrane coated on a graphite electrode. J. Elec-trvanal. Chem. 412(1-2), 125-132. 

Experiment 13-4 Electrocatalytic Carbon Dioxide Reduction by Cobalt Phthalocyanine 6 Incorporated into a Poly(4-vinyI-pyridine) (PVP) Membrane Coated on an Electrode (Section 13.2.3.3) [25]... 

Zhao, R, J. Zhang, T. Abe, D. Wohrle, and M. Kaneko (1999). Electrocatalytic proton reduction by phthalocyanine cobalt derivatives incorporated in poly(4-vinylpyridine-co-styrene) film. J. Mol. Cat. A Chem. 145, 245-256. 

Incorporation of metallo-phthalocyanines and metallo-porphyrins into PIM networks helps to allow access to the catalytic metal centers. It was shown that such network-PIMs demonstrate effective heterogeneous catalysis in reactions such as the oxidation of hydroquinone. Desulfurization of salt water has been shown to be catalyzed by a cobalt phthalocyanine network-PIM. Suzuki carbon-carbon coupling reactions can be catalyzed effectively by a hexaazatrinaphthylene-based Pd-loaded PIM network. 

The cobalt(II)15 and zinc(II)16 complexes of phthalocyanine(Pc), octcyano-Pc, and tetrasulfon-ato-Pc incorporated in poly(4-vinylpyridine-co-styrene) or Nafion films coated on graphite have also been examined as catalytic devices for dihydrogen electrogeneration in phosphate buffer. These catalytic systems were strongly suggested to be dominated by the electron transfer within the polymer matrix. The best catalytic film is that constituted of the nonsubstituted Con-Pc complex in poly(4-vinylpyridine-co-styrene), giving a turnover number of 2 x 10s h-1 at an applied potential of —0.90 V vs. Ag Ag Cl. 

Figure 10.3 Oxygen reduction at a gold/polypyiTole disc electrode modified by the incorporation of (a) tetrasulphonated iron phthalocyanine (-), (b) tctrasulplioiiated cobalt plitlialocyaiiine (---) in a 0 5 M H2SO4 oxygen saturated aqueous solution v = 2 mV s rotation rate Cl = 2500 rpm r=20°C. The dotted curve (...) cotTesponds to a bare smooth platinum electrode under the same experimental conditions. (Reprinted with permission from ref 139)...

It was reported that cobalt tetraphenylporphyrin complex (CoTPP) coated on an electrode catalyzes electrocatalytic proton reduction [21], but the activity was not very high. It has been found that metal porphyrins (such as metal tetraphenylporphyrin MTPP, 5) and metal phthalocyanines (6, MPc) when incorporated into a polymer membrane coated on an electrode exhibit high activity in electrocatalytic proton reduction to produce H2 [22,23], These polymer metal complex catalysts can be much more active than a conventional platinum-based electrode (Fig. 13-7 [23], see Experiment 13-3, Section 13-5). 

It has been found that the O2 reduction currents are directly proportional to the amount of catalyst present when the catalyst is adsorbed on the electrode surface indicating that the reaction is first order in the surface concentration of catalyst. This is not tme for cases where the catalyst is incorporated to the surface by vapor deposition or when the eatalyst is deposited from solutions and the solvent is completely evaporated . An explanation for this observation is that when the catalyst is deposited by vapor deposition or from complete evaporation of solutions, multilayers are formed, and the metal active centers are not all completely accessible to O2. This is also the case for polymerized multilayers of cobalt tetraamino phthalocyanines, where it has been shown that only the outermost layer was active for the reduction of O2 . Scherson et al. have reported that when (FeTMPP)20 is deposited on a porous support, 30% of the amount deposited is found to be electrochemically active . Anson et have found that for the case of CoPc(CN)i6 and CoPcFie that were deposited from solutions where the solvent was completely evaporated, again it was found that only 30% of the amount deposited was electrochemically active. It was concluded that only those molecules that are attached to the surface of the electrode are active... 

Bettelheim et al. investigated nitrosyl adducts of cobalt tetrasulfonated ph-thalocyanine, Co(TSPc) , dissolved in aqueous solution or incorporated into a DDAB surfactant film where Co(TSPc)" acts as the counterion for four DDA+ forming Co(TSPc)(DDA)4 (this was also done with dodecyltrimethylam-monium) " . Using FTIK and electrochemical experiments the conformational orientation of the NO adduct was determined to be bent, Eq. (4.33). When exposing the phthalocyanin to NO in solution, a sharp band at 1,646 cm appears but is quickly replaced by a broader band at about 1,700 cm implicit of the N-Co bond shortening, this also occurs for the solid form of Co(TSPc) and Co(TSPc)(DDA)4, Eq. (4.34). A plot of E v. l/[NO], using CV, yielded a slope of 65 mV, ruling out the possibility of a Co(TSPc)(NO)2, complex. 

Pioneering works on functional molecules incorporating conducting polymers firstly demonstrated them as modified electrodes, on which redox molecules such as ruthenium tetraoxide [1] for photo-oxidation of water, mesotetrakis (4-sulphonatophenyl)porphyrin cobalt [2] and iron phthalocyanine [3] for redox catalysis, were incorporated chemically or electrochemically in polypyrrole conducting polymer. They suggested that functionalized conducting polymers should show the native function of a functional molecule while maintaining the native conductivity without a big decrease. 

Cobalt(II) phthalocyanin has been incorporated into a carbon paste electrode to determine several sulphur containing compounds . ... 

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