Polymeric -phthalocyanine

Orthmann E and Wegner G 1986 Preparation of ultrathin layers of molecularly controlled architecture from polymeric phthalocyanines by the Langmuir-Blodgett-technique 1986 Angew. Chem. Int. Edn. Engl. 25 1105-7... 

Incorporation of less than a stoichiometric amount of alkyl sulfonamides of copper phthalocyanines into copper phthalocyanine improves the pigment s properties in rotogravure inks (67). Monomeric and polymeric phthalocyanine derivatives with basic substituents adsorb strongly to the pigment surface and promote the adsorption of binder molecules (68—72). 

Synthesis and properties of polymeric phthalocyanines and their metal derivatives. A. A. Berlin and A. I. Sherle, Inorg. Macromol. Rev., 1971,1, 235-270 (129). 

Polymeric phthalocyanines 3 are available from 1,2,4,5-tetracyanoben ne 2 by deposition from the vapor phase on hot substrate surfaces, or by thermal curing of its tetramer, octacyanophthalocyanine 4 in the presence of metal cations (Scheme 2... 

For electrocatalysis, compounds of the porphyrin series are of major interest monomeric and polymeric phthalocyanines, tetraphenylporphyrins, tetraazaporphy-rins, tetraazaannulenes, and other complexes. The structures of some of these complexes are shown in Fig. 28.5. 

Polymeric dyes, such as the polymeric phthalocyanines, become more conducting as the degree of polymerization increases. This is demonstrated in Fig. 5 for polymeric Fe- and Co-polyphthalocyanines 65>. 

The dark conductivity of a number of organic solids increases reversibly with increasing pressure details are given in 10>. Because these changes range over several orders of magnitude, the possibility of using them to measure pressure should be tested. For the pressure effect in Cu-phthalocyanine and polymeric phthalocyanines, see 8,141,142). 

They comprise a comparison of the activities of polymeric phthalocyanines with various central atoms. The monomers always showed lower activity than the corresponding polymers. The nature of the substrate has a decisive influence on the catalytic properties of the chelate. Electrodes with gold substrate showed only very slight activity. 

Fig. 6. Activity of polymeric phthalocyanines with various central atoms 4>...

Fig. 16. Oxygen, activity of monomeric and polymeric phthalocyanines. (Electrolyte 4.5 N H2S04)...

Metal-semiconductor-metal or metal-insulator-semiconductor (MIS) devices have been constructed using polymerized phthalocyanine derivatives with PF5 as the dopant (phosphorane structure)34. 

Many other types of polymer have been prepared which exhibit semiconductivity. All obey the equation a = a0exp — E/kT. These include xanthene polymers (109, 110), polymerized phthalocyanines (111, 112), epoxides and polydiketones (86, 113), polypentadienes (114), polydicyanoacetylenes (115), polyvinylferrocene and substituted ferrocene (116, 117, 118, 119), polymeric complexes of tetracyanoethylene and metals (120), poly(vinyl chloride) and poly(vinylidene chloride) (121), polyvinylene and polyphenylene (122) and poly(Schiff s bases) (123, 124). 

Polymeric phthalocyanine, which possess a higher stability compared to the monomers, can be obtained by combining a phthalocyanine with a polymer, The linking of the polymeric chain can occur at the central metal atom, the phenyl rings, through bridging or attachment 1o a polymeric chain. 

The well known synthesis of low molecular phthalocyanines Pc, 2) starts from phthalic add derivatives like 1,2-dicyanobenzene, 1,3-diiminoisoindolenine and jAthalic anhydride The yield of metal free or metal containing Pc is often high (80-100%). By starting with a Wfunctional material like 1,2,4,5-tetracyanobenzene (TCB) or pyromellitic dianhydride (PMDA) a polymeric phthalocyanine (polyPc) (86) must be formed under the same conditions (Eq. 40). But the determination of structure and molecular weight is very difficult. Byproducts may be formed and the resulting polymers are often less soluble. But structure investigations are very important to correlate structure and property. 

The electrocatalytic activity of Co(II) phthalocyanine is somewhat lower than that of silver for oxygen reduction in fuel cells. Activity varies with the central metal atom in the order Fe > Co > Cu for acid and neutral electrolytes (2S3). This result is in contrast to Jasinski s observation of lower activity for Fe than for Co ligands (282). The discrepancy can be explained by differences in the ligand structure and the supports used and possibly their conductivity. For instance, polymeric phthalocyanines show a fourfold increase in activity for oxygen reduction compared to monomeric ones, owing to a lO -lO increase in their conductivity (283). 

Fig. 23. Potential-current curves for some metal ligand electrocatalysts (284) solid lines, porphyrins dashed line, polymeric phthalocyanine.

In this review the physical and inorganic chemistry of the phthalocyanines will be discussed in detail. The review will be limited to nuclear unsubstituted derivatives, except where mention of a substituted derivative is pertinent to the discussion. The organic chemistry of the complexes, e.g., chlorination (12), will not be discussed. There have been many articles and books reviewing the industrial uses of the phthalocyanines (39,64,139,133, 232,304,521,365,369,382), and hence this aspect will not be touched upon here. A more general review has also appeared recently (251). Polymeric phthalocyanines (79, 241-243) will not be covered. 

Polymeric phthalocyanines (Chap. 5.2) indude a great variety of properties. The construction of electrical devices or catalysts for spedal use is most hopeful. But all these applications depend on the reproduribility of well defined structural uniform polymers. Preparative work must help to standardize synthetic procedures and to investigate structures. The well reproducible in situ synthesis of thin layers of pure polymeric phthalocyanines from the gas phase opens a way for electrocatalysis and visible light energy changing devices. Another new kind of preparation goes via prepolymers which may be converted to mechanically and thermally stable, infusible polymers. 

The majority of photovoltaic modules use silicon as the photovoltaic cell element, but other materials are, in principle, possible. The last four chapters consider the use of organic polymers (sometimes doped) as the cell element or in some related conducting property acrylonitrile, some polymeric phthalocyanines and polymers of 2-vinylnaphthalene that is doped with pyrene and 1,2,4,5-tetracyanobenzene. The study on the last group of polymers was initiated by the idea that they could be used to transfer solar energy to a reaction center and produce some type of chemical reaction. The final chapter carries this approach further in the consideration of polymeric electrodes that could be used to split water into oxygen and hydrogen. The latter could then be utilized as a source of storable, readily transportable chemical energy. 

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