Octasubstituted porphyrins

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. 

Note that other, related octasubstituted porphyrins have been prepared but little information was given concerning their mesomorphism. The zinc /3-octa(decyl)porphyrin (the eight chains were pure alkyl chains) was found to display a mesophase (probably columnar) between 117°C and 177 °C, which is in the same temperature range as the ether analogs. It also showed conductivity properties of the order of magnitude to that of (22). No mesomorphism was detected for porphyrins with eight alkoxy chains. ... 

Hemosiderin an iron storage protein of the mammalian organism, functionally related to Ferritin (see). H. is deposited in the liver and spleen (hemosiderosis), particularly in diseases associated with increased blood destruction, such as pernicious anemia, or with increased iron resorption (hemochromatosis), or even in hemorrhages Most of the deposits are located in the liver, which may contain up to 50 g H., compared with the normal content of 120 to 300 mg H. H. from horse spleen consists of 26-34 % iron(III), and up to 35 % protein (aposiderin). The rest is made up of octasubstituted porphyrin, mucopolysaccharides and fatty acid esteis. 

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