Tetraphenylporphyrin cobalt

The metalloporphyrin-catalyzed decomposition of ethyl azidoformate in the presence of an arene has been investigated but with little success in improving the yields of the 1 //-azepines.151 The nickel and copper complexes had no effect, whereas the cobalt-tetraphenylporphyrin complex accelerated the decomposition rate of the azido ester but produced more A-arylurethane rather than 1//-azepine. 

Dloxygen reduction electrocatalysis by metal macrocycles adsorbed on or bound to electrodes has been an Important area of Investigation (23 ) and has achieved a substantial molecular sophistication in terms of structured design of the macrocyclic catalysts (2A). Since there have been few other electrochemical studies of polymeric porphyrin films, we elected to inspect the dloxygen electrocatalytic efficacy of films of electropolymerized cobalt tetraphenylporphyrins. All the films exhibited some activity, to differing extents, with films of the cobalt tetra(o-aminophenylporphyrin) being the most active (2-4). Curiously, this compound, both as a monomer In solution and as an electropolymerized film, also exhibited two electrochemical waves... 

A mild aerobic palladium-catalyzed 1,4-diacetoxylation of conjugated dienes has been developed and is based on a multistep electron transfer46. The hydroquinone produced in each cycle of the palladium-catalyzed oxidation is reoxidized by air or molecular oxygen. The latter reoxidation requires a metal macrocycle as catalyst. In the aerobic process there are no side products formed except water, and the stoichiometry of the reaction is given in equation 19. Thus 1,3-cyclohexadiene is oxidized by molecular oxygen to diacetate 39 with the aid of the triple catalytic system Pd(II)—BQ—MLm where MLm is a metal macrocyclic complex such as cobalt tetraphenylporphyrin (Co(TPP)), cobalt salophen (Co(Salophen) or iron phthalocyanine (Fe(Pc)). The principle of this biomimetic aerobic oxidation is outlined in Scheme 8. 

The electrooxidation of hydrazine is also catalysed by metal compounds other than oxides, as shown by Hou et al. using an FI manifold. They employed a cobalt tetraphenylporphyrin-modified glassy carbon electrode to oxidize hydrazine at +0.5 V vj Ag/AgCl and pH 2.5, and achieved a detection limit of 0.1 ng [194]. 

It was reported that cobalt-tetraphenylporphyrin complex (CoTPP) coated on an electrode catalyzes electrocatalytic proton reduction,215 but the activity was not very high. We have found that metal porphyrins and metal phtahlocyanines when incorporated into a polymer membrane coated on an electrode show high activity in electrocatalytic proton reduction to produce H2.22,235 Some data are summarized in Table 19.2. It was shown that this catalyst is more active than a conventional platinum base electrode. 

A novel synthesis of benzosultam 164 involves a Co-based catalytic system for intramolecular C-H animation with azides <07OL4889>. The commercially available cobalt tetraphenylporphyrin complex, Co(TPP) 163, is an effective catalyst for catalyzing C-H animation with arylsulfonyl azides 162 leading to benzosultams 164 in excellent yields. In addition to benzylic C-H bond, non-benzylic C-H bonds can also be intramolecularly aminated. For example, reaction of arylsulfonyl azides 165 with Co catalyst 163 results in a mixture of 5- and 6-membered ring products, 166 and 167. 

Polymerization of MMA both thermally and pho-tochemically in the ordered media, cholesteryl oleyl carbonate and cholesteryl 2-ethylhexyl carbonate, were studied in the presence and absence of cobalt tetraphenylporphyrin. The percentage conversion and molecular weight were lowered in the presence of CoTPP for thermal polymerizations. In photopolymerizations, the percentage conversion was high and the molecular weights were low.129... 

Other studies [104-107] have shown varying degrees of success for the modification of electrode surfaces to achieve the desired four-electron reduction. Use of a monolayer film of cobalt tetraphenylporphyrin on a gold(lll) surface [104] results in hydrogen peroxide as the predominant... 

Cobalt tetraphenylporphyrin complex promotes a chain-transfer reaction in the radical polymerization of MMA to give an MMA oligomer with vinylidene unsaturation at the chain end.124 An alternative method of introducing the terminal unsaturation was disclosed by Meijs et al,125 Substituted allylic sulphides are used as chain transfer agents in which sulphide groups act as leaving group as follows ... 

Experiment 13-3 Electrocatalytic Proton Reduction to H2 Evolution by Cobalt Tetraphenylporphyrin 5 (CoTPP) Incorporated into a Naflon Membrane Coated on an Electrode (Section 13.2,3.2) [23(b)]. 

Gouerec, P, A. Biloul, O. Contamin, G. Scarbeck, M. Savy, J. M. Barbe, and R. Guilard (1995). Dioxygen reduction electrocatalysis in acid media Effect of peripheral ligand substitution on cobalt tetraphenylporphyrin, J. Electroanal. Chem. 398, 67-75. 

Faubert, G., G. Lalande, R. Cote, D. Guay, J.P. Dodelet, L.T. Weng, P. Bertrand, and G. D6nfes (1996). Heat-treated iron and cobalt tetraphenylporphyrins adsorbed on carbon black Physical characterization and catalytic properties of these materials for the reduction of oxygen in polymer electrolyte fuel cells. Electrochim. Acta 41, 1689-1701. 

Several authors have also reported the potential use of electropolyme-rized metalloporphyrin films as new electrode materials for anion detection and pH measurements. For example, Daunert et al reported that anion-selective membrane electrodes can be prepared by electropolymerizing aniline-substituted cobalt tetraphenylporphyrin complexes onto a glassy carbon surface. It was shown that the resulting electrodes are highly selective towards the detection of thiocyanate and nitrite anions. The mechanism by which these metalloporphyrin electrode sensors operate is probably related to the well-known axial complexation capability of the central metal cation of the porphyrin towards different kind of anions and bases. The same authors also reported a detection limit of 5 x 10 M for these ion-selective electrodes which have lifetimes of more than 2 months... 

More recently, hydroxy-substituted cobalt tetraphenylporphyrins, electro-polymerized onto an optically transparent electrode and adapted onto the tip of an optic fibre were used as sensing materials for the development of optic fibres as pH-sensors . The pH values by this chemically modified optic fibre were monitored by spectrophotometric measurement of the Soret band wavelength for the supported porphyrin. 

Mu, X.H. and K.M. Kadish (1989). Oxidative electrochemistry of cobalt tetraphenylporphyrin under a CO atmosphere. Interaction between carbon monoxide and electrogenerated [(TPP)Co]+ in nonbonding media. Inorg. Chem. 28, 3743-3747. 

Fig. 9 Influence of catalyst formal potential ( °) on log /ci for reaction of Co L with DBCH in a bicontinuous microemulsion (A) of DDAB/water/dodecane (21/39/40) and in dimethylformamide ( ) for dissolved catalysts vitamin B12, Co(salen), cobalt phthalocyaninetetrasulfonate (CoPCTS), cobalt tetraphenylporphyrin (CoTPP), and cobalt octaethylporphyrin (CoOEP). Points from reactions in the microemulsion (A) represent apparent k values for 0.4, 0.5,1.0, and 2.0 mM catalyst in order of decreasing log fci. (Adapted with permission from Ref [58], Copyright by American Chemical Society.)...

Bai Y, Sekita M, Schmid M, Bischof T, Steinriick HP, GottMed JM (2010) Interfacial coordination interactions studied on cobalt octaethylporphyrin and cobalt tetraphenylporphyrin monolayers on Au(lll). Phys Chem Chem Phys 12 4336-4344. doi 10.1039/b924974p Stepanow S, Lin N, Barth JV (2008) Modular assembly of low-dimensional coordination architectures on metal surfaces. J Phys Condens Matter 20 184002 (1-15). doi 10.1088/0953-8984/20/18/184002... 

A number of papers describe tedmiques for determination of cholinesterase activity based on amperometric measurement of products formed as a result of enzymatic hydrolysis (equation 1). In this case, artificial (butyryl or acetyl thiocholine) cholinesterase substrates are used. Thiocholine, formed as a result of cholinesterase-catalyzed hydrolysis can be measured amperometrically on a platinum electrode (14, 15) or mercury electrode (16). Analyses based on thiocholine determination employing an electrode modified by cobalt phthalocyanine (17-22) or cobalt tetraphenylporphyrin (23) have been described. Enzymatic hydrolysis of... 

Widelov A, Larsson R (1992) ESCA and electrochemical studies on pyrolyzed iron and cobalt tetraphenylporphyrins. Electrochim Acta 37 187-197... 

Van Doorslaer, S, Bachmann, R, Schweiger, A. 1999. A pulse EPR and ENDOR investigation of the electronic and geometric structure of cobaltous tetraphenylporphyrin (pyridine). J Phys Chem A103 5446-5455. 

A noncovalent composite of cobalt tetraphenylporphyrin with reduced graphene oxide (RGO-CoTPP) [183] was used to modify GC electrodes and its electrocatalytic properties for oxidation of ascorbic acid, dopamine, and uric acid studied by cyclic voltammetry. Three weU-resolved oxidation waves (A = 225 and 140 mV) and faster electron transfer were observed. Linear responses and detection limits were found for those substrates, respectively, in the 5.0-200.0 pM (DL =1.2 pM), 0.1-12.0 pM (DL = 0.03 pM), and 0.5 0.0 pM (DL = 0.15 pM) range. 

Deng K, Zhou J, Li X (2013) Noncovalent nanohybtid of cobalt tetraphenylporphyrin with graphene for simultaneous detection of ascrabic acid, dopamine, and uric acid. Electrochim Acta 114 341-346... 

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