CoTPP tetraphenylporphyrin

Diphenylphosphorylazide (DPPA) has also been shown to be an excellent nitrene source in aziridination reactions <06JOC6655>. The reaction of styrene and substituted styrenes with DPPA and tetraphenylporphyrin cobalt (CoTPP) provided the A-diphenylphosphinyl aziridines in moderate yields. 

The rate of Sc -promoted photoinduced electron transfer from Ceo to CI4Q determined from the decay rate of the absorbance due to Ceo at 740 nm (inset of Fig. 11) obeys pseudo-first-order kinetics and the pseudo-first-order rate constant increases linearly with increasing the p-chloranil concentration [CI4Q] [135]. From the slope of the linear correlation, the second-order rate constant of electron transfer ( et) in Scheme 15 was obtained. The A et value increases linearly with increasing the Sc + concentration. This indicates that CUQ produced in the photoinduced electron transfer forms a 1 1 complex with Sc + (Scheme 15) [78]. When CI4Q is replaced by p-benzoquinone (Q), the value for electron transfer from Ceo to Q increases with an increase in [Sc " ] to exhibit a first-order dependence on [Sc ] at low concentrations, changing to a second-order dependence at high concentrations, as shown in Fig. 13 (open circles) [135]. Such a mixture of first-order and second-order dependence on [Sc ] was also observed in electron transfer from CoTPP (TPP = tetraphenylporphyrin dianion) to Q... 

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. 

The use of cobalt(II) tetraphenylporphyrin (CoTPP) as catalyst in the decomposition of unsaturated bicyclic endoperoxides represents the... 

Recently, three TPO models have been reported bis (salicylidene)ethylenediaminato cobalt(II) [Co(salen)] in MeOH (14), cobalt(II)tetraphenylporphyrin (CoTPP) (25) in DMF, and manganese phthalocyanine (Mn-Pc) in DMF (16). These models have been reported as having the TPO-mimic function of oxygenating skatole, a tryptophan analogue, to form 2-formamidoacetophenone (FA). However, one of the most critical problems for these models is the lack of structural similarity between the TPO active site (heme) and these models. The structure of these models is not similar to the heme in TPO with respect to the central metal and/or the ligand. Furthermore, Fe(salen) does not possess the TPO-mimic function (14). 

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... 

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)]. 

Figure 5.12. Cyclic voltammograms at 50 mV on CoTPP bonded GC in N2 and C02 atmospheres. Bridging compound is 4-aminopyridine. The solution was pH 6.8 phosphate buffer solution. Reprinted from Figure 5 H. Tanaka, A. Aramata, Aminopyridyl cation radical method for bridging between metal complex and glassy carbon Cobalt(II) tetraphenylporphyrin bonded on glassy carbon for enhancement of CO2 electroreduction. Journal of Electroanalytical Chemistry, 437 (1997) 29-35. Copyright 1997, with permission of Elsevier.

Zheng, G., M. Stradiotto, and L. Li (1998). An electrochemical and spectroelec-trochemical (IR) investigation of the reduction of Rco(II)TPP (R = benzyl or butyl TPP = tetraphenylporphyrin) Mechanistic implications in the CoTPP catalysed elec-trocarboxylation of alkyl halides. J. Electroanal. Chem. 453(1-2), 79-88. 

Table 12.2. Main Geometrical Parameters (A and degrees) of the Co(II) Tetraphenylporphyrin (CoTPP), Co(II) Tetrabenzoporphyrin (CoTBP) and of... 

The heat-treated M/N/C composite materials, such as CoPPy/C, can also be considered as multifunctional catalysts, featuring Co nanoparticles coated with Co oxides and Co " species associated with N-C moieties that originate from the polypyrrole structures [82]. An illustration of the CoPPy/C catalyst surface and the ORR processes is shown in Fig. 15.30. The Co-N type site (shown as a C0-N4 complex) supports the initial adsorption of the O2 molecule and conversion of O2 to the intermediate reaction prcxluct, H02, by a 2e reduction reacticm. The H02 species can further react at a decorating Cof)y/Co nanopaiticle phase. Chu et al. [126] found that the mixture of the heat-treated Co- and Fe-tetraphenylporphyrins (CoTPP/FeTPP) had better catalytic performance for ORRs in acid media than that of the respective heat-treated single components. All of the above cited research results point to the fact that carefully designed bifuncticmal or multifunctional catalysts can be much more active for ORR than their single components. 

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.)...

Cobalt(ii) tetraphenylporphyrin (CoTPP) can also act as an electron donor in PCET to 02. In the absence of HCIO4, CoTPP is stable toward O2 in... 

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. 

Ozoemena [125] performed the anodic oxidation and amperometric sensing of hydrazine using a glassy carbon electrode modified with a cobalt(ll) phthalocya-nine-cobalt(n) tetraphenylporphyrin (CoPc-(CoTPP)4) supramolecular complex. This amperometric sensor displayed excellent characteristics for the determination of hydrazine in 0.2 M NaOH at low overpotential (+100 mV vs. Ag/AgCl), with very fast amperometric response time (1 s), linear range of 10-230 pmol LT, limit of detection of 1 pmol L and sensitivity of 0.0157 pA L pmol . ... 

Ozoemena KI (2006) Anodic oxidation and amperometric sensing of hydrazine at a glassy carbon electrode modified with cobalt (II) phthalocyanine-cobalt (II) tetraphenylporphyrin (CoPc-(CoTPP)4) supramolecular complex. Sensors 6 874—891... 

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