Phthalocyanines and Porphyrins Complexes

A number of studies of phthalocyanine and porphyrin complexes of manganese have been carried out and it is clear that both MnIn and MnlV complexes can be photoreduced in the presence of water or OH- and in the absence of an electron acceptor.309 313 These complexes can be produced from Mn11 or Mnm complexes in the presence of an electron acceptor e.g. quinones,314 and the reaction can be sensitized by, for example, zinc porphyrins in suitable model membrane environments.310... 

The H chemical shifts of phthalocyanine and porphyrine complexes with hexacoordinate siliconas well as theoretical calculations of the contribution to H magnetic shieldingshow a high degree of aromatic nature of the macrocycle compounds of this type can even be used as diamagnetic shift reagents... 

Many of the other properties of the uranyl superphthalocyanine complex 160 may also be explained in terms of the severe strain within the macrocycle. The reaction of 160 with acids, for instance, under conditions which readily demetalates many phthalocyanine and porphyrin complexes [130, 131], results in an unprecedented ring contraction giving ftee-base phthalocyanine as the product (Scheme 23)... 

A number of studies of phthalocyanine and porphyrin complexes of manganese have been carried out and it is clear that both Mn " and complexes can be photoreduced in the... 

Third-order NLO properties have been described for liquid-crystalline phthalocyanine and porphyrin complexes. The values for the meso-genic cobalt(II), nickel(II), copper(II), zinc(ll) and vanadyl complexes of 5,10,15,20-tetrakis(4-w-pentadecylphenyl)porphyrin have been measured in benzene solution by the technique of degenerate four-wave mixing (DFWM) at 532 nm. The values varied between 1.5 and... 

Mack, J. and Stillman, M.J. (2003) Electronic structure of metal phthalocyanine and porphyrin complexes from analysis of the UV-visible absorption and magnetic circular dichroism spectra and... 

Magdesieva, T.V., T. Yamamoto, D.A. Tryk, and A. Fujishima (2002). Electrochemical reduction of CO2 with transition metal phthalocyanine and porphyrin complexes supported on activated carbon fibers. J. Electrochem. Soc. 149(6), D89-D95. Atoguchi, T., A. Aramata, A. Kazusaka, and M. Enyo (1991). Cobalt (II)-tetraphenylporphyrin-pyridine complex fixed on a glassy carbon electrode and its prominent catalytic activity for reduction of carbon dioxide. J. Chem. Soc. Chem. Commun. 13, 156-157. 

Magdesieva, T.V., T. Yamamoto, D.A. Tryk, and A. Fujishima (2002). Electrochemical reduction of CO2 with transition metal phthalocyanine and porphyrin complexes supported on activated carbon fibers. J. Electrochem. Soc. 149(6), D89-D95. 

Electrolytic reduction of carbon dioxide is catalyzed by some transition metal complexes. Phthalocyanine and porphyrin complexes, as well as clusters such as... 

Figure 31 Illustration of the adaption of phthalocyanine and porphyrin complexes to the electronically preferred coordination sphere trigonal prismatic in the d° cis-[Nb(pc)Cl2] and the high-spin c/i-[Fe(TPP)N03], and octahedral in the high-spin d frawi-[Fe(TPP)Cl2] , where TPP stands for the tetraphenylpor-phyrinato ligand.

The subject matter of this chapter will be subdivided into sections concerning template synthesis of the complexes structural and thermodynamic properties of the complexes with synthetic cyclic polyamines complexes with mixed-donor macrocycles reactivity of the complexes cryptates and complexes with phthalocyanines and porphyrins. 

Partial oxidation of some nickel(II) complexes with phthalocyanine and porphyrins gives rise to conducting molecular solids of the type Ni(pc)Ij (x = 0-3) and Ni(porphyrin)I (Table 110).2884,2891 2895,2909 The oxidation of Ni(pc)Ix is reversible and the iodine can be completely removed from the compound by heating it in vacuo. The aforementioned compounds may be... 

The catalytic chemistry of immobilized Mn and Fe phthalocyanines and porphyrins largely parallels that of the dissolved complexes. However, the homogeneous complexes tend to react with each other, leading to irreversible oxidative damage. Moreover, inactive //-oxo dimers are formed in the following reaction ... 

Similarly, using phthalocyanine or porphyrin complexes of a range of transition elements, cobalt and iron again appear to be the best metal ions. Although the mechanisms of the reactions are not fully understood, it is believed that two-electron oxidation is again important and some correlation between oxygen yield and redox potential (M " /M " ) for the phthalocyanine complexes is observed. TTie anomalously low efficiency of zinc compounds compared with those of cobalt, which have similar first oxidation potentials, suggests that the second oxidation potentials are also important. ... 

Other metal ligands that can bind oxygen have also been tested for oxygen reduction, such as porphyrins, thiospinels, and diamine (Pfeiffer) complexes (284, 285). Porphyrin complexes (Fig. 22) were the most active, even better than phthalocyanines, with activity decreasing in the order Co(II) > Fe(ni) > Ni(II) Cu(II). Figure 23 shows potential-current curves for some phthalocyanine and porphyrin electrocatalysts. The higher the current at a given potential, the more active is the catalyst. 

---