Magnesium phthalocyanine preparation

Magnesium phthalocyanine (PcMg) can be prepared in a melt of the phthalonitrile and elemental magnesium. Often some ammonium molybdatc(VI) is added. Remaining phthalo-nitrilc and magnesium are removed by extraction with a suitable solvent and by washings with hydrochloric acid, respectively.55-83-97 136 137... 

Prepared from magnesium or magnesium oxide and o-cyanobenzamide (40), magnesium phthalocyanine has been the subject of much study since it is a synthetic analog of chlorophyll. Perhaps understandably, much of this work has been connected with photosynthesis, luminescence, fluorescence, etc. (see Section V,B). The molecular weight of magnesium phthalocyanine has been measured ebullioscopically in naphthalene (228). Because of the very low solubility of the substance, a very accurate platinum thermometer was employed. Nevertheless the successful measurement represents quite an achievement. 

Magnesium phthalocyanine may also be prepared from phthalonitrile, sodium cyanamide, and magnesium powder (107), phthalimide and magnesium (846), or phthalamide and magnesium imide (287). 

Phthalocyanines are tetrabenzotetraazaporphyrins. Copper(II) phthalocyanine 37 (Linstead 1934) is prepared from phthalonitrile and copper powder/copper(I) chloride. Magnesium phthalocyanine 38 is obtained from Mg and 2-cyanobenzamide by thermal reaction in nitrobenzene [29], the free ligand system is produced by demetalation with acid of the magnesium complex. 

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 photochemistry of true organomagnesium compounds remains almost completely unexplored. A literature search in preparation of this work found only a few scattered examples of photochemical studies, mostly in relation to Grignard reactions and 1,3-diketonate chelates Similar to the situation with organozinc compounds magnesium tetrapyrrole chelates, i.e. magnesium porphyrins 1, 5,10,15,20-tetraazaporphyrins (por-phyrazines) 2 and phthalocyanines 3 have found more interest. This is primarily related... 

Most reported phthalocyanine derivatives (sulfo-, nitro-, amino-, triphenylmethyl-, polymeric, etc.) are copper complexes, although at present the synthetic chemistry of other d- and /-metal Pc derivatives is being rapidly developed (Examples 30-36) [5,6,116-118]. Some of them (in particular, copper phthalocyanine sulfonic acids) are of industrial interest because of their usefulness as dyes. Phthalocyanine sulfonic acids themselves are prepared both by urea synthesis from sulfonated phthalic anhydride and by the sulfonation of the phthalocyanine [6], Some substituted metal phthalocyanines can be obtained by chemical or electrochemical reduction [118e]. Among a number of reported peculiarities of substituted phthalocyanines, the existence of three electronic isomers for magnesium derivative PcMn was recently confirmed [118f]. 

The synthetic strategy of unsymmetrical BTE-TAPs involved the co-cyclization of bis(3-thiophenyl)maleonitrile and 1,2-dicyanobenzene in different molar ratios under nitrogen atmosphere in the dark, as was described in Scheme 10. Magnesium was a template to gain the unsymmetrical macrocycles. The preparation of the symmetrical phthalocyanine hybrids began with the reaction of magnesium powder... 

Application of the same methods starting from 1,2-dicyanonaphthalene [11] yields 1,2-naphthalocyaninatometal complexes. The magnesium, lead, copper and zinc 1,2-naphthalocyanines (1,2-NcM) were first prepared by Linstead [12], Compared to the corresponding phthalocyanines the known 1,2-naphthalocyaninatometal compounds exhibit a higher thermal and chemical stability. When 1,2-NcM, is synthesized from 1,2-dicyanonaphthalene four different positional isomers are formed (compare to 2,3-NcM, Fig. 1) [11],... 

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