EHPG complex

The more stable the chelate, the higher the pM that it can maintain, and the higher the pH required to precipitate the metal hydroxide. From equation 22 it can be seen that the smaller the solubihty product ie, the more iusoluble the metal hydroxide, the higher the pM that a chelant must maintain to prevent precipitation. The stabiUty constant of the Fe(III)—EHPG complex (/2), is so large (10 ) that iron is not precipitated even ia strongly alkaline solutions. 

In addition to different affinities for HSA in vitro, the two stereoisomers of Fe-EHPG have different distributions in vivo [133]. The meso-Fe-EHPG complex is cleared from the blood more slowly than rac-Fe-EHPG. The rate of liver uptake was also different for the two diastereomers. 

The racemic Fe(III) complex containing a hexadentate ligand, Fe(5-Br-ehpg) , can exist in racemic RR and SS) and meso (RS) forms (Structures 7a and 7b) which have different solubilities in methanol. 

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