Catalysis cobalt phthalocyanine

We are still further from being able to explain the anodic activity of the CoTAA complex. The cobalt phthalocyanine, which is structurally identical with CoTAA in the inner coordination sphere, is completely inactive in the catalysis of anodic reactions. It therefore looks as if the central region is not exclusively responsible for the anodic activity. On the other hand, the fact that CoTAA is inactive for the oxidation of H2 points to n orbitals of the fuel participating in the formation of the chelate-fuel complex. A redox mechanism (cf. Section 5.2) can be ruled out because anodic oxidation proceeds only in the region below the redox potential of CoTAA (i.e. at about 600—650 mV). 

Nykong et al. have also smdied a variety of cobalt containing macrocycles. The electrocatalytic properties of cyanocobalamin adsorbed onto GCEs in aqueous solution was examined Along with adsorbed cobalt(II) tetrasulfonated ph-thalocyanine (Co(TSPc)) ", adsorbed cobalt phthalocyanine is examined (CoPc) in DMSO ". The proposed mechanism invokes both a ring- and metal-centered reduction during NO catalysis, Eqs. (4.35)-(4.39). 

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. 

Further evidence has been obtained to support the contention that the active catalysts are metal complexes dissolved in solution. With experiments reported in Table II, the kinetics of oxidation under standard conditions in the presence of various metal salts are compared with the rates of reaction when solid residues have been filtered from solution. The agreement between the rates in Cases 1 and 3 of Table II (where the amount of metal available is dictated by the solubility of metal complexes) shows that solid precipitates play little or no part in catalysis in all the systems studied. The amount of metal in solution has been measured in Cases 2 and 3 metal hydroxide complexes (Case 2) are not as soluble as metal-thiol complexes, and neither is as soluble as metal phthalocyanines (19). The results of experiments involving metal pyrophosphates are particularly interesting, in that it has previously been suggested that cobalt pyrophosphates act as heterogeneous catalysts. The result s in Table II show that this is not true in the present system. 

The role of Coball-dioxygen complexes in autooxidations other than phenol oxidation is less certain, and ostensibly similar reactions appear to follow radically different pathways. Thus, in the oxidation of thiols to disulfide catalyzed by Co11 species catalysis by the phthalocyanine complex [Con(TSPc)]4 apparently proceeds via a Co1 intermediate and without participation of Co—02 species,680 whereas catalysis by [CoH(TPP)] appears to involve initial formation of an >/ cobalt-dioxygen complex from which Of is displaced by thiolate.681 Several reviews giving extensive coverage to oxidations catalyzed by cobalt(II) complexes are available.649,650,682 683... 

It has been shown that this catalyst is selective in epoxidation of linear alkenes the linear epoxide yield was two to four times higher than in catalysis by ordinary porphyrin. It was also demonstrated that, in catalysis by the dendrimers, cyclic alkenes are oxidized three times more rapidly than similar linear 1-alkenes are. The catalyst activity decreases only by 10% at a turnover number (TON) of 1000, which is much higher than that for the monomolecular analogue. A cobalt complex with dendrimer phthalocyanine was much more stable, while remaining active, in... 

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. 

Reductive Dehalogenations Microemulsions are usually more useful than micelles for electrochemical synthetic applications because larger amounts of polar and nonpolar reactants can be solubilized. Electrochemical catalysis has been used in microemulsions for the electrolytic conversion of organohalide pollutants to hydrocarbons [53] using mediators such as metal phthalocyanines and cobalt complexes. Microemulsions were used for the complete electrochemical catalytic... 

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