Metal phthalo-cyanines

In the presence of metal compounds the products are 2,9,16,23-tetrasubstituted metal phthalo-cyanines, e.g. 3. 

Kulprathipanja, S., Vora, B.V., and Li, Y. (1999) Method for treating a liquid stream contaminated with an iodide-containing compound using a solid absorbent comprising a metal phthalo-cyanine. U.S. Patent 6,007,724. 

The effect of a high radiation flux upon the structure of metal phthalo-cyanines has been investigated. Intensities of 1020 thermal neutrons/cm2 tend to convert crystalline copper phthalocyanine to an amorphous state 806). Bowden and Chadderton 86, 36), using the electron microscope, have discussed the disorder in the molecular array caused by fission damage. Tracks and dislocations due to the passage of individual fission fragments could be seen. 

The [Ru(bpy)3] complexes are not the only sensitizers that can be used for cyclic water photodecomposition, indeed metal porphyrins, metal phthalo-cyanines, proflavin, and other compounds have been investigated as possible sensitizers. 

A special situation is encountered with metal-porphyrin or metal-phthalo-cyanine molecules that can be either deposited by sublimation under UHV conditions or in solution environments. For these macrocyclic compounds, free-base species exist, i.e., the metal centers are not required per se as a construction unit. The building of supramolecular structures that incorporate porphyrin subunits is of great interest to many research groups. The rich photochemistry and redox properties (e.g., photoinduced electron transfer, luminescence, and light harvesting) of porphyrins have driven this interest. Porphyrins or phtalocyanines have a rich coordination chemistry that allows the inclusion of many different metal centers at their macrocycle. They serve in many respects as a model system since this constitutes a low-coordination complex. Recent STM studies report on the organization of metal-coordinated or free-base porphyrins as well as phthalocyanines on... 

Figure 5.17. Relevant part of Pc s and the antibonding MO and CO2. Reprinted from Figure 5.2 N. Furuya and S. Koide, Electroreduction of carbon dioxide by metal phthalo-cyanines, Electrochimica Acta, 36(8), 1309-1313 (1991). Copyright 1991, with permission of Elsevier.

Kapusta, S. and N. Hackerman (1984). Carbon dioxide reduction at a metal phthalo-cyanine catalyzed carbon electrode. J. Electrochem. Soc. 131(7), 1511-1514. 

Radiochromatographic techniques have been used to determine the rates of oxidation of cysteine by pertechnate ion, Tc04. The technetium(vu) is reduced by the thiol (and cysteine ethyl ester) to form a Tc complex which involves both S- and 7V-co-ordination of the amino-acid. The rate law is first order with respect to both [Tc ] and [RSH]. A hydrogen-ion dependence observed is attributed to the formation of pertechnic acid, the rate-determining step being the nucleophilic attack by the thiol at the metal centre of HTCO4. The oxidation of RSH (R=Et, Pr, or Bu) has been studied over the range 20—40 °C in aqueous alkaline solutions in the presence of metal phthalo-cyanines. The reaction is zero order with respect to [thiol], first order in phthalocyanin and decreases in the order M = Co>Mn> V>Feii. No effects are observed from the nature of the alkali cation. 

In another report using the CDC approach, functional modulation was achieved by controlling LbL film but without a specific biomolecule. In order to achieve this goal, Luz and co-workers [8] assembled two LbL platforms that take advantage of alternate immobilization of cobalt (II) tetrasulfonated phthalocyanine (Co TsPc), chitosan (Chit) and SWCNTs. Co TsPc belongs to a group of metallic phthalo-cyanines that show delocalized 7t-electrons and planar geometry with unique... 

Note that in Table24.3 phtalocyanines are useful target materials. Fe, Co, Cu, Zn, Ga, Mo, Pd, In, Dy, Os, and Pt radioisotopes can be separated from neutron-irradiated metal phthalo-cyanines. Metal chelate compounds such as metal oxinates are other examples. Ca, V, Mn, Ni, Cu, In, and W are separated by the Szilard-Chalmers process from their oxinates. Salts of oxyacids... 

SCHEME 10.3 Some examples of encapsulated species successfully prepared by in situ assembly of precursors inside the pores of zeolites, (a) Metal phthalo-cyanines (b) ruthenium tris-bipyridine (c) pyrylium cations (d) metal salen complexes and (e) heteropoly acid. The brackets generically represent the pore system of the solid host. 

Structurally, the molecule is formed by the union of one atom of the metal with four molecules of phthalonitrile. Copper phthalo-cyanine is typical, and has the formula... 

Metal atoms with a stable oxidation state of + IV are known to form unsubstituted bis(phthalo-cyanines) 9,10. They can be prepared by the reaction of a metal phthalocyanine, or an appropriate metal salt, and an alkali-metal phthalocyanine. 

Although direct reaction of lanthanide mono-porphyrins with free phthalo-cyanine or its lithium derivatives is generally more efficient than the template synthesis, and gives rise to mixed-ligand complexes, the template strategy can also be applied for synthesis of phthalocyanine-porphyrin complexes, as in the case of unsymmetric bisphthalocyanine complexes (Scheme 8.2, B(b)) [106, 136, 145, 146]. Thus, metallation of free porphyrins with lanthanide salts in TCB or n-octanol leads to single-decker complexes, which then react with phthalonitriles under the action of DBU in alcoholic media to give the desired compounds. 

All polycyclic pigments, with the exception of triphenylmethyl derivatives, comprise anellated aromatic and/or heteroaromatic moieties. In commercial pigments, these may range from systems such as diketopyrrolo-pyrrol derivatives, which feature two five-membered heteroaromatic fused rings (DPP pigments) to such eight-membered ring systems as flavanthrone or pyranthrone. The phthalo-cyanine skeleton with its polycylic metal complex is somewhat unique in this respect. 

One such reaction that has been studied is the electrocatalytic reduction of oxygen directly to water.25,27 The electrocatalysts for this process are often based on metal porphyrins and phthalo-cyanins. Thus a graphite electrode whose surface was modified by the irreversible adsorption of a cofacial dicobalt porphyrin dimer was able to reduce oxygen under conditions where the reduction did not occur on the bare electrode itself. Similarly, a catalytic chemically modified electrode for the oxidation of chloride to chlorine has been prepared28 where the active catalyst was reported to be a ruthenium dimer, [(bipy)2(OH)RulvORuvO(bipy)2]4+, which was reduced to the corresponding [Rum-RuIV] dimer during the reaction. 

Substitution pattern of the ring-protonated porphyrins H2 (Por) and phthalo-cyanines H2 (Pc). In the quoted tetrasubstitued porphyrins the substituents are in 5,10,15,20 meso positions, in octasubstituted porphyrins they are in 2,3,7,8,12,13,17,18 positions. In tetrasubstituted phthalocyanines the substituents are in 2,9,16,23 positions, in octasubstituted complexes they are in 2,3,9,10,16,17,23,24 positions. Metal complexes are specified by replacing the two H atoms in H2 (Por) or H2 (Pc) by the metal atom with its axial ligands, if any. 

Electrochemistry of pyropolymers obtained on pyrolysis of charge-transfer complexes of transition metals with porphyrins and phthalo-cyanins 90MI17. 

Metal-free phthalocyanine (MfPc) is another important class of polymorphic phthalo-cyanines. Many of the aspects of the polymorphic behaviour were covered in the previous section, but because of its historic importance (Robertson 1936, 1953), and current potential use as a photoconductor for laser printers (Loutfy et al. 1988), additional information is provided here. 

The viologens are alkyl derivatives of the 4,4 -dipyridylium dication. The one- or two-electron reduction leads to a radical cation or a diamagnetic product, respectively [95]. This type of redox reaction has a good reversibility. In the phthalocyanines (PCs) and other 4-chelates, the nitrogen is also a component of the ring system. Donor-type Li" " insertion compounds of metal-free phthalocyanines were formed reversibly in LiC104/PC with up to six cations [96]. At the anode, copper phthalo-cyanine (CuPC) inserted reversibly y — 0.42 CIO4 anions/mol [97]. For copper tetraphenylporphyrin, y = 0.65 was found [98] (cf. Table 4). Composites of these... 

Tryk el al. studied GDEs composed of active carbon fiber and loaded with catalysts Ni, Fe, Pd metals, porphyrins, and phthalo-cyanines. The GDEs gave partial current density of CO2 reduction up to 80 mA cm 2 with production of CO under atmospheric pressure. They presumed that the nanopores present in active carbon fiber may provide quasi high pressure atmosphere due to nanoscale effect." Thus Ni electrocatalyst, which is practically inert for CO2 reduction under atmospheric pressure, may be activated in a similar manner as observed with Ni electrode under elevated pressure. " ... 

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