Phthalocyanine molecules

The phthalocyanine molecule is remarkably stable to heat and chemical reagents. The metal-free and heavy metal compounds sublime practically unchanged at 550-580 C. 

Phthalocyanine Dyes. The phthalocyanine molecule is much too big to be used on hydrophobic fibers and therefore is only used in its sulfonated form as the basis for direct and reactive dyes (see Phthalocyanine compounds). Its forces of attraction are different from a small linear yeUow a2o dye with which it is used to form bright greens. CompatibiHty between the two is likely to be a problem in practice and to overcome this, green dyestuffs containing a phthalocyanine dye linked via a saturated chromophore blocker (—x—) have been made, eg,... 

Phthalocyanines provided with crown ethers and chiral alkyl side chains (64) have also been reported to self-assemble in nonpolar solvents.77 These molecules form helical columns as could be deduced from the presence of a Cotton effect upon aggregation. To investigate the expression of chirality at the mesoscopic level, sergeants-and-soldiers experiments75 were performed. Chiral phthalocyanine molecules 64 were used as the sergeants and achiral... 

Figure 6.9 Schematic representation of hierarchical self-assembly process for chiral phthalocya-nine 64. Phthalocyanine molecules self-assembly into helical columns with right-handed screw sense (left). These right-handed helices subsequently aggregate to give left-handed super-helices.

The phthalonitrile process has the particular advantage over the phthalic anhydride process of forming ring-substituted chloro-copper phthalocyanines. Using copper(I)chloride produces so-called semi-chloro Copper Phalocyanine Blue, a pigment which possesses a statistical average of 0.5 chlorine atoms per copper phthalocyanine molecule. Copper(II)chloride, on the other hand, affords a product which comprises an average of one chlorine atom per copper phthalocyanine molecule. A prerequisite for the formation of the chloro substituted compound, however, is the absence of ammonia or urea in the reaction mixture. 

Only a minor amount of chlorinated copper phthalocyanine, for instance, especially in the 4-position of the copper phthalocyanine molecule, prevents a change of modification from a to (3. Approximately 3 to 4% chlorine is commonly used, which corresponds to the formula CuPc-Cl0.5, also referred to as semi-chloro-CuPc . The phthalic anhydride/urea synthesis, for instance, affords a partially chlorinated product if 4-chlorophthalic anhydride is added to the reaction mixture. Copper chlorides in the phthalonitrile process have the same effect. 

Flocculation may likewise be prevented through partial introduction of dialkyl-aminomethylene groups into the aromatic ring system of the copper phthalocyanine molecule. The copper phthalocyanine structure tightly attaches the basic groups... 

Three dimensional X-ray diffraction analysis has been employed to elucidate the molecular and crystal structure of Copper Phthalocyanine Blue ((3-modifica-tion). In all modifications, the planar and almost square phthalocyanine molecules are arranged like rolls of coins, i.e., in one dimensional stacks. The modifications vary only in terms of how these stacks are arranged relative to each other. One important aspect is the angle between staple axis and molecular plane. The a-phase features an angle of 24.7°, while the stacks in the -modification deviate by as much as 45.8° [13]. 

Ordered multilayer deposits were grown on both the Cu(l 11) and Cu(lOO) substrates. Electron beam damage to the phthalocyanine molecules was not observed. Space-charge effects due to electron bombardment were not apparent below an incident electron energy of 25 eV. 

Ordered multilayer deposits of phthalocyanine molecules could be observed by low-energy electron diffraciton with no apparent electron beam induced chemical effects. This appears consistent with the general trend for molecules with highly conjugated electron systems to be more stable under electron bombardment than other organic molecules. 

Fig. 5.28 STM images, (a) at submonolayer coverage and (b) at one monolayer coverage, of Cu-phthalocyanine molecules adsorbed on a Cu (001) surface. A gray scale representation of the highest occupied molecular orbital, evaluated 2 A above the molecular plane, has been embedded in the image at a). (Courtesy of...

Fiq. 30. Change of photoelectric yield at X = 265.5 in/x by cooling of a platinum foil covered with copper-phthalocyanine molecules (a) cooling by liquid air (5) liquid air evaporated [according to (77a)],... 

Fig. 31. Fowler curves of platinum surface covered with copper-phthalocyanine molecules as in Fig. 30 at room temperature (I) and at low temperature (II) [according to (77a)].

Fig. 17. Saturation current versus NCT gas concentration for a device incorporating eight monolayers of the asymmetrically substituted phthalocyanine molecule shown in the inseri (Baker et al., 1983)...

Incorporation of chlorophyll and phthalocyanine molecules into the layers... 

Hydrogenation of the catalyst during the reaction and subsequent decrease in activity was observed with dehydrochlorinated polyvinylidene chloride 62 i and also with Mg-phthalocyanine 72 >. It has been pointed out before that on pyrolysis of organic polymers quinonic structures may be formed, and if we consider the Kekule structure of the phthalocyanine molecule... 

M. Kanai, T. Kawai, K. Motai, X. D. Wang, T. Hashizume and T. Sakura, Scanning tunneling microscopy observation of copper-phthalocyanine molecules on Si(100) and Si(lll) surfaces, Surf. Sci. 329, L619 (1995). 

With Z = 2, the iron(II) phthalocyanine molecule occupies a 1 site, and its molecular and crystal stmctures are shown in Fig. 9.6.6. 

Aggregations of the porphyrin or phthalocyanine molecules on the surface of the nano-crystalline electrode always induce massive non-radioactive decay of the excited states and thus reduce the efficiency of the electron injection. Therefore, preventing the aggregation of the dye molecules on the electrode surface will be a foremost issue during the design of new sensitizers, which can be achieved normally by axial coordination, bulky substituents at peripheral positions or the co-adsorption with other materials. 

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