الفهرس 
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Abstract
The porphyrin molecule consists of a porphine nucleus I,th e base of its skeleton is composed of four pyrrole nucleus attached by unsaturated carbon bridge leading to a complete conjugation of the macrocycle All porphyrins are derived from this molecule I, known as base nucleus (or free base), by substitution of the peripheric hydrogen atoms by different groups. The heart of the porphyrin macrocycle is limited by four nitrogen atoms that permits the insertion of a great number of metals leading to rnetalloporphyrin 11. Some of these metalloporphyrin represent a biological action of great importance. Table 1 shows some of the well known naturally occurring porp hyrins. Table 1: Natural porphyrinic compounds. Compound Metal Hemoglobin Fe Myog lo bi n Fe Vitamin BI2 Co Chlorophyll M g In addition to these natural porphyrins, a great number of porphyrins and metalloporphyrins have been discovered, either by total syntheses, or by modification of natural porphyrins. I- NOMENCLATURE: The numbering of ring positions, including nitrogen, and the use of letters to indicate individual ring, is shown in structures Ia and Ib where structures Ia represents the Fischer notation (’12) and that for Ib represents the IUPAC (394) notation. I a Fischer Notation Ib IUPAC Notation The positions 5, 10, 15,20 ( in the IUPAC notation ) also denoted by ,p,& ( in the fischer notation), respectively, are called mesopositions (also called methinic bridges)