Tetra phthalocyanine

They can be prepared from the respective 4-, 4,5- and 3-, 3,6-substituted phthalonitriles. Besides these most common tetra- and octasubstituted phthalocyanines, 1,3,8,10,15,17,22,24-octasub-stituted and 1,2,3,4,8,9,10.11,15,16.17,18,22,23,24,25-hexadecasubstituted phthalocyanines have been prepared.102... 

A second reaction which is very often used for the preparation of phthalonitriles, although the yields are usually not reproducible, is the Rosenmund-von Braun reaction (see Houben-Weyl, Vol. E5, p 1460).106 107 Herein, a benzene derivative with a 1,2-dibromidc or 1,2-dich-loride unit is treated with copper(I) cyanide in dimethylformamidc or pyridine. During this reaction the formation of the respective copper phthalocyanine often occurs. This can be used as an easy procedure for the exclusive synthesis of copper phthalocyanines (see Section 2.1.1.7.),1 os-109 but can also lead to problems if the phthalonitrile is required as the product. For example, if l,2-dibromo-4-trifluoromethyl-benzene is subjected to a Rosenmund-von Braun reaction no 4-trifluoromethylphthalonitrile but only copper tetra(tri-fluoromethyljphthalocyanine is isolated.110... 

Although many attempts have been made to separate or exclusively synthesize one isomer of an unsymmetrically substituted phthalocyanine,72-89-296,297 the product mixture has been separated in only two cases.96 103,104 Besides the chromatographic separation of the statistical product mixture it is also possible to prepare exclusively the D4h isomer by use of steric hindrance of bulky substituents, e.g. 7-ferr-butylnaphthalene-l,2-dicarbonitrile only forms the respective An isomer of the tetra(to -butyl)-substituted 1,2-NcFe by heating in hexan-l-ol.73 Recently, some 1,8,1 5,22-substituted pure isomers have also been synthesized by the use of bulky substituents in 3-substituted phthalonitriles298,299 at low temperature (see Section 2.1.4.).94... 

In contrast to phthalocyanines (tetra- or octasubstituted) in which the isoindoline units carry all the same substituents, reports of phthalocyanines with lower symmetry, which have been prepared by using two different phthalonitriles, have rarely appeared. This is due to the problems which are associated with their preparation and separation. For the preparation of unsymmetrical phthalocyanines with two different isoindoline units four methods are known the polymer support route,300 " 303 via enlargement of subphthalocyanines,304 " 308 via reaction ofl,3,3-trichloroisoindoline and isoindolinediimine309,310 and the statistical condensation followed by a separation of the products.111,311 319 Using the first two methods, only one product, formed by three identical and one other isoindoline unit, should be produced. The third method can be used to prepare a linear product with D2h symmetry formed by two identical isoindoline units. For the synthesis of the other type of unsymmetrical phthalocyanine the method of statistical condensation must be chosen. In such a condensation of two phthalonitriles the formation of six different phthalocyanines320 is possible. 

Dichlorogermanium(IV) 2,9,16,23-Tetra(trifluoromethyl)phthalocyanine (3) Typical Procedure 417... 

Dichlorosilicon(IV) 2,3-Tetra(15-crown-5)phthalocyanine (6) Single Procedure 158... 

Copper(II) 2 3,9 10,16 17,23 24-Tetra(7-aza-15-crown-5)phthalocyanine (4h) Typical Procedure 108... 

Zinc(II) 2,9,16,23,-Tetra(diphenylmethoxy)phthalocyanine ]3, M = Zn(ll) R=OCHPh2 Typical Proce-dure 298... 

Zinc(II)2,3,16,17-Tetra(dodecyloxy)-8,9,10,ll,22,23,24,25-octaphenyl)phthalocyanine(6, ABAB type) Typical Procedure 419... 

In the preparation of lutetium(III) 2,9,16,23-tetra-ter -butylbis(phthalocyanine) from lutetium(III) acetate, dilithium phthalocyanine and dilithium 2,9,16,23-tetra-terr-butyl-phthalocyaninc in refluxing 1 -chloronaphthalene for one hour, only one of the phthalocyanine moieties carries all of the substituents (yield 20%).185... 

Zinc(II) l,8,15,22-Tetra(neopentyloxy)phthalocyanine (11) Typical Procedure 94... 

Similarly, zinc(II) l,8,15,22-tetra(4-butylbenzyloxy)phthalocyanine can be prepared.298 In this case only the C4ll isomer is produced in 80% yield.298... 

Method B A mixture of copper(II) phthalocyanine (3 1.2 g, 2 mmol) and C1S03H (5 mL) was stirred for 3 h at 138-140 C and then for 3 h with SOCI, (1.5 mL) at 80 85 C. The mixture was then cooled, poured onto ice, and filtered. The precipitate was washed on the filter with cold H,0 until neutral, pressed off well, and dried. The l,4-tetra(chlorosulfonyl)phthalocyanine 4 obtained was mixed with Et2NH (2mL) in CHCl3 (50 mL)and the mixture was stirred for 24 hat 25 30 C. By repeated chromatographic separation (alumina, CHC13/ benzene 2 1) the title compound 5 was isolated yield 0.3 g (13 %). 

Nickel(ll) 2,9,16,23-Tetra(nonadecanoylamino)phthalocyanine (5) Typical Procedure 342... 

The X-ray structure of zinc naphthalocyanate has been determined with Zn—N bond lengths of 1.983(4) A.829 Pentanuclear complexes with a zinc phthalocyanine core and four ruthenium subunits linked via a terpyridyl ligand demonstrate interaction between the photoactive and the redox active components of the molecule. The absorbance and fluorescence spectra showed considerable variation with the ruthenium subunits in place.830 Tetra-t-butylphthalocyaninato zinc coordinated by nitroxide radicals form excited-state phthalocyanine complexes and have been studied by time-resolved electron paramagnetic resonance.831... 

The photophysical properties of magnesium(II) tetra-(i-butyl)phthalocyanine (27) have been studied in solution, in micelles and in liposomes cation radical formation (CBr4 as electron acceptor) has been detected with UV excitation, or by a two-photon excitation using a pulsed laser in the therapeutic window at 670 nm.118 The Mg11 complex of octa(tri-z -propylsilylethy-nyl)tetra[6,7]quinoxalinoporphyrazine (28) has been prepared as a potential PDT sensitizer. The synthesis is shown in Figure 8. Compound (28) has Amax 770 nm (e = 512,000 M-1 cm-1), d>f = 0.46 and d>A = 0.19 (all in THF, under air).119... 

The palladium(II) phthalocyanines are satisfactory singlet oxygen generators. Thus, f>A values for tetra-t-butylphthalocyanine ((27), with stated replacement for Mg) are 2H, 0.22 Zn, 0.34 Pd, 0.54, i.e., increasing in line with the heavy atom effect.180 For palladium(II) tetra-t-butylphthalocyanine ((27), Pd instead of Mg) in benzene at 290 K, 4>f= 0.048 and X = 0.49.180 However, palladium(II) 2,3-dihydroxy-9,16,23-tri-t-butylphthalocyanine was synthesized by a mixed condensation (1 9 mix of appropriate dinitriles) as a likely amphiphilic sensitizer, but did not show bioactivity in an enzyme assay, possibly because of aggregation.180... 

As a result of their low redox potentials [173], bis(phthalocyaninato) lanthanide complexes are often inadvertently reduced or oxidized, and they are also very sensitive to acids and bases. In order to solve these problems, Veciana et al. achieved certain success on designing a series of novel compounds with characteristics that would give them improved redox stability. Electroactive ligands based on phthalo-cyaninato tetra dicarboximide [175] or perfluorinated phthalocyanine [176] were used to assemble the double-decker lanthanide complexes, with the effect of stabilizing the negative charge of the anionic state of the compounds, which resulted in a strong shift of 0.7 V of their first oxidation potentials. 

A recent review covers the redox chemistry of monomeric and oligomeric phthalocyanines in the form of monomers and stacks174. Of the group 14 elements, the electrochemical redox data described concerns mostly silicon derivatives and one germanium compound, m -oxobis(tetra-t -butyl) phthalocyanatogermanium175. 

In abroad sense, the model developed for the cobaloxime(II)-catalyzed reactions seems to be valid also for the autoxidation of the alkyl mercaptan to disulfides in the presence of cobalt(II) phthalocyanine tetra-sodium sulfonate in reverse micelles (142). It was assumed that the rate-determining electron transfer within the catalyst-substrate-dioxygen complex leads to the formation of the final products via the RS and O - radicals. The yield of the disulfide product was higher in water-oil microemulsions prepared from a cationic surfactant than in the presence of an anionic surfactant. This difference is probably due to the stabilization of the monomeric form of the catalyst in the former environment. 

The phthalic anhydride/urea process may also be employed to convert tetra-chloro phthalic anhydride to green copper hexadecachloro phthalocyanine by condensation. In this case, titanium or zirconium dioxides, particularly in the form of hydrated gels, are used instead of the molybdenum salts which are used in the phthalic anhydride process [23]. There is a certain disadvantage to the fact that the products lack brilliance and require additional purification. 

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