Alkaline haematin and nitrogenous ligands.
1. Pyridine reacts with alkaline haematin to form a dipyridine dihydroxy dimeric haematin in which there is no competition between pyridine and OH(-) for coordination positions on the iron of haematin. 2. Imidazole competes directly with OH(-) to form the monomeric imidazole parahaematin in alkaline media. 3. The monomeric imidazole parahaematin aggregates readily to form a species that is precipitated on standing. 4. A structure is proposed for the haematin-pyridine compound in alkaline media.
D055598:Chemical Phenomena; D011232:Chemical Precipitation; D002621:Chemistry; D002712:Chlorides; D006418:Heme; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides; D007093:Imidazoles; D008956:Models, Chemical; D011725:Pyridines; D013053:Spectrophotometry
D002712:Chlorides; D006878:Hydroxides; D007093:Imidazoles; D011725:Pyridines; D006418:Heme