CoPc complexes

Figure 4 shows the pinane s concentration profiles when the reaction is carried out in the presence of free and encapsulated FePc and CoPc complexes. The encapsulated complexes lead to slower rates of oxidation compared to the corresponding free complexes. 

Selectivity towards pinane hydroperoxide exhibits the highest values until higher conversions when the reaction is carried out in the presence of iron phthalocyanine encapsulated complexes (Figure 5). It even can be as high as 90% at a pinane conversion higher than 80%, when the reaction is carried out at 10 C For CoPc complexes the selectivity towards 2-pinane hydroperoxide exhibits an identical behaviour with the free and the encapsulated complex. 

It has been shown that using CNTs as the substrate of M-N4 macrocycle catalysts could improve the activity and stability for ORR in alkali ne/neutral medium [128,131,132,135,136]. However, CNTs supported M-N4 macrocycle composites are instable in acid medium [134], It was reported that FePc modified CNTs exhibit higher activity than CoPc complexes modified CNTs [134]. Moreover, the FePc modified CNTs can promote 4e pathway [127, 131, 134—137] in alkaline medium. In contrast, the CoPc modified CNTs can only partially promote 4e pathway with a portion of H2O2 production [134, 139]. 

Both SCN -CoPc or NCS -CoPc complexes were evaluated considtaing the Co(II) and Co(III) oxidation states. All the ena-gies are in kcal moF . Data from [142]... 

CoPcs complexes and their electrochemical and in sim SEC characterization have been firequently studied in order to decide their possible technological applications. Since CoPcs complexes are one of the more preferred derivatives of MPc due to their rich redox properties [8, 45-49]. For instance, the voltammetric and in sim SEC behaviors of Co(II) phthalocyanine tetrasubstimted with 3,4-(dimethoxyphenylthio) moieties (CoPc2) at the nonperipheral positions were examined in different electrolytes. As shown in Fig. 16, CoPc2 showed two reduction and two oxidation reactions in DMSO/TBAP electrolyte on a Pt working electrode [47]. The apparent differences between CoPcl and CoPc2 are only... 

Scheme 3 Redox mechanism of CoPc complexes in nonpolar and noncoordinating solvent media...

Scheme 4 Proposed homogeneous electrocatalytic mechanism of oxygen reduction reaction with CoPc complexes...

Cardenas-Jiron and coworkers studied CoPc complexes adsorbed on pris-tine/defective graphene functionahzed with epoxy- (-0-), hydroxyl- (-OH),... 

There are a few examples of 02 oxidations catalyzed by zeolite-encapsulated complexes. Encapsulated CoPc was active in the oxidation of propene to aldehyde, whereas the free complex was inactive.76 A triple catalytic system, Pd(OAc)2, benzoquinone, and a metal macrocycle, was used to oxidize alk-enes with molecular oxygen at room temperature.77,78 Zeolite-encapsulated FePc79-81 and CoSalophen80,82 complexes were used as oxygen-activating catalysts. 

Polymer-supported catalysts often have lower activities than the soluble catalysts because of the intraparticle diffusion resistance. In this case the immobilization of the complexes on colloidal polymers can increase the catalytic activity. Catalysts bound to polymer latexes were used in oxidation reactions, such as the Cu-catalyzed oxidation of ascorbic acid,12 the Co-catalyzed oxidation of tetralin,13 and the CoPc-catalyzed oxidation of butylphenol14 and thiols.1516 Mn(III)-porphyrin bound to colloidal anion exchange resin was... 

Several metallophthalocyanines have been reported to be active toward the electroreduction of C02 in aqueous electrolyte especially when immobilized on an electrode surface.125-127 CoPc and, to a lesser extent, NiPc appear to be the most active phthalocyanine complexes in this respect. Several techniques have been used for their immobilization.128,129 In a typical experiment, controlled potential electrolysis conducted with such modified electrodes at —1.0 vs. SCE (pH 5) leads to CO as the major reduction product (rj = 60%) besides H2, although another study indicates that HCOO is mainly obtained.129 It has been more recently shown that the reduction selectivity is improved when the CoPc is incorporated in a polyvinyl pyridine membrane (ratio of CO to H2 around 6 at pH 5). This was ascribed to the nature of the membrane which is coordinative and weakly basic. The microenvironment around CoPc provided by partially protonated pyridine species was suggested to be important.130,131 The mechanism of C02 reduction on CoPc is thought to involve the initial formation of a hydride derivative followed by its reduction associated with the insertion of C02.128... 

Interesting results have been obtained using metallophthalocyanines supported on porous carbon gas diffusion electrodes.132-136 In the case of CoPc and NiPc, CO is formed with a current efficiency of almost 100%.135 With Sn, Pb, and In phthalocyanines, mainly HC02H is formed, while Cu and Ti phthalocyanines promote the formation of CH4. The reason why some metal Pc complexes give CO or CH4, while others yield HC02H, has been interpreted in terms of the electron configuration in the metal.137 A rather different type of reaction is the very recent demonstration of the simultaneous reduction of C02 and N02 to give urea (NH2)2CO, which can be achieved with an efficiency up to 40% at similar gas-diffusion electrode devices with a NiPc supported catalyst.138... 

Complexation of metal ions by Pcs adsorbed on metal surfaces has also been reported. In fact, a CoPc adsorbed on Au(lll) is able to complex two Ca(II) ions by two of its four peripherally substituted crown ether macrocycles as demonstrated by high-resolution STM studies [196], Furthermore, it was demonstrated by using a Au(100)-(1 x 1) lattice surface that the relationship between the crown ether moieties of the CoPc and the underlying Au lattice is important in the trapping of the Ca(II) ions within the crown macrocycles [197],... 

The oxidation of L-cysteine on MPc (M = Fe, Mn, and Co) linked to 4-mercaptopyridine preformed SAMs (MPc-4-MPy-SAM) occurred at 0.2V, Table 3, with FePc-4-MPy-SAM showing better catalytic activity as judged by higher peak current when compared to CoPc-4-MPy-SAM and MnPc-4-MPy-SAM [86], Long term stability (over a 2-week period) of MPc-4-MPy-SAM (M = Fe, Co, Mn) towards the oxidation of L-cysteine decreased as follows FePc > MnPc > CoPc. Thus, the oxidation of cysteine is less stable on CoPc modified electrode and this complex is less catalytic compared to corresponding MnPc and FePc derivatives. 

MnPc-SAMs have been employed for the detection of thiocyanate [86] on SAMs formed by coordination of MPc complexes to preformed SAMs. On MnPc-4-MPy-SAM the oxidation of SCN- occurred at 0.50 V (Table 3). The stability of the electrode was less on MnPc compared to CoPc preformed SAM. Analysis of SCN-in the presence of possible interfering species (uric acid, oxalic acid, and ascorbic acid) in biological samples revealed insignificant effects from these compounds [86], Thus, SCN- can be analyzed in the presence of ascorbic acid. An analysis of the urine of smokers and nonsmokers showed clearly that the SAM electrode could be used to differentiate between the two groups. 

We deal here with an interesting metallo Pc and ball-type metallo Pcs as the only examples in the literature for NLO and OL. [Octakis(mercaptopropylisobutyl-POSS)phthalocyaninato]Co(II),Cu(II), and Zn(II) complexes were investigated and compared with respect to NLO and OL properties [58]. These compounds showed that the change of the central metal ion in Pc leads to the variation of the relevant NLO and OL properties. All metallo Pcs with Co(II), Cu(II), and Zn(II) reveal NL absorption. CuPc exhibits the largest NL absorption, while CoPc and ZnPc... 

As with porphyrins, solutions or suspensions of reactands are mixed to get the complexes in an easy way. For CoPc(COOH)4 (72 h) concluave evidence of axial coordination was obtained torn ESR showing 5-coordinate complex structure ... 

In the first step the metal ion is introduced into the zeolite pores by ion exchange or adsorption of a labile metal complex. In the second step the intermediate material is reacted with gaseous complexing ligands, such as 1,2-dicyanobenzene, to form a complex inside the pores that is too large to difiuse out Alternatively metal complexes can be directly encapsulated inside the zeolite cavities during hydrothermal synthesis, as has been shown for FePc, CoPc, NiPc and CuPc in zeolite X [224],... 

For chemisorption study, the adsorption isotherm (first isotherm) was obtained in each case by plotting the amount of O2 adsorbed at 300 °C against the O2 equilibrium pressure, Peq, up to 250 mm Hg. The resorption isotherm (second isotherm) was measured after outgassing for one hour at the same temperature. The total chemisorption values were taken as the difference between the first and the second isotherms. To minimize adsorption on the support and maximize adsorption on the supported complex, the total chemisorption values on pure support were subtracted from the total chemisorption producing the so called net adsorption values (a ) on the supported complex as expressed in m mol O2 g" CoPc. These values were used to calculate the degrees of dispersion (D), the chemisorption stoichiometries and specific surface areas of supported CoPc phase [18,19],... 

In conclusion, one may suggest that, in silica and silica-rich supported samples, the pore system permits preferential entrance of some CoPc molecules, affecting sensibly the pore dimensions. In alumina and alumina-rich supported samples, the pore system, with its dimensions less than those of CoPc molecules, does not permit free entrance of complex molecules. Here, CoPc molecules may be forced to occupy positions in the defective structure of alumina. All these findings should be reflected on the mode of surface dispersion of the supported CoPc molecules. 

The characteristic chemisorption data obtained for the various supported catalyst samples are summarized in Table 2. It is evident that, the 02-net adsorption (3n) has in general lower magnitude for catalyst samples supported on pure silica and silica-rich support and higher magnitudes for catalyst samples supported on alumina and alumina-rich supports. However, these adsorption values decrease markedly as the CoPc content increases on one and the same support (97.1 SA) being related most probably to the mode of surface complex dispersion. 

The specific surface area of supported CoPc shows unrealistic values in the case of supported samples on alumina and alumina-rich supports. Consequently, the calculated degrees of CoPc dispersion are relatively high. On the other hand, the specific surface area of CoPc supported on silica and silica-rich support show much lower values with much lower degrees of dispersion. These parameters decrease markedly as the complex loading increases up to 10.4% w/w. It is of interest to notice that, the stoichiometry of adsorption of oxygen on samples of supported CoPc on alumina and alumina-rich supports is almost close to 1. However, in samples of CoPc supported on silica and silica-rich supports, the stoichiometry becomes >2. These findings indicate clearly that supported CoPc molecules interact with the different support surfaces under study along widely different ways. 

Fig. 3. Evolution of ESR spectra with the cobalt content (10 mol g ). 0.37 (DSe), c 1.09 (DS7). d neat CoPc(S03Na)4 complex.

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