Transition metal complexes iron phthalocyanine

In an interesting study, phthalocyanine complexes containing four anthraquinone nuclei (5.34) were synthesised and evaluated as potential vat dyes and pigments [18]. Anthraquinone-1,2-dicarbonitrile or the corresponding dicarboxylic anhydride was reacted with a transition-metal salt, namely vanadium, chromium, iron, cobalt, nickel, copper, tin, platinum or lead (Scheme 5.6). Substituted analogues were also prepared from amino, chloro or nitro derivatives of anthraquinone-l,2-dicarboxylic anhydride. 

The biological reduction of nitrate is not heme-related a well-known family of Mo-oxo pterin enzymes facilitate O-atom transfers between nitrite and nitrate, sulfite and sulfate, and other substratesStill, the electrochemical reduction of nitrate on bare metal electrodes is well known, and can also be facilitated by addition of N4 chelates. For instance, Hobbs et al. have examined the electrochemical reduction of nitrate in basic solutions using iron and nickel electrodes coated with phthalocyanin yielding nitrite, hydroxylamine, and ammonia. The iron electrodes efficiency increased when coated with phthalocyanin while the nickel s activity decreased. A related study has been done by Shibata et al. to determine the synthetic applications of simultaneous reduction of nitrate and carbon dioxide using phthalocyanin complexes of most of the first-row transition metals and other metals with mixed success . 

The first-principles DFT calculations of ORR on various M-N4 macrocyclic complexes have been carried out by several research groups [93, 168-173]. Through comparative study of O2 dissociation on different metalloporphyrins (MnP, FeP, CoP, NiP), the trends of the activation barriers for the O2 dissociation with respect to LUMO-HOMO characters of these metalloporphyrins have been discussed by Tsuda et al. [172]. FeP is demonstrated to be the best one due to the large d electrons contribution to the LUMO-HOMO level of the FeP and the stable Fe-O bond [172]. Shi and Zhang performed the DFT calculation on the O2 adsorption on various iron and cobalt porphyrins and phthalocyanines [171]. The catalytic activities of the transition metal macrocyclic complexes were positively related with... 

Thermal treatment might lead to phase ehange in the transition metal macrocyclic complexes. Using XRD measurements, Baranton [58] found that received iron phthalocyanine was under a phase and that after being heat-treated at 450 °C it was under p phase. 

Research has been conducted on many metals including Fe, Co, Mn and Pb in order to find an adequate replacement for Pt. Cobalt and iron have attracted the most attention. These two metals are typically combined with tetramethoxyphenylporphyrin (TMPP) or phthalocyanine (Pc) to form metal macrocyclic complexes. Pyrolyzed FePc and CoTMPP complexes have proven the most effective transition metal-based materials. FePc supported on Ketjen black carbon generated a power density of 634 mW m compared to 593 mW produced by a Pt cathode in the same... 

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. ... 

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