Preparation of Rare Earth Complexes with Polyaminopolycarboxylic Acids

1 Preparation of Rare Earth Complexes with Polyaminopolycarboxylic Acids 

The synthesis is normally carried out by refluxing an aqueous mixture of polyaminopolycarboxylic acid and a selected rare earth oxide in a molar ratio of RE L = 1 1. The resulting solution can be neutralized to pH 5-6 by adding a dilute solution of NaOH, KOH, NH3 H2O, NaHCOs, or NaHC03. After filtration, the complex can be crystallized by evaporation or with the addition of EtOH. The rare earth oxide can be replaced by a rare earth carbonate or other soluble salts, such as chlorides, nitrates, perchlorates, or acetates [104], The synthesis can also be done under hydrothermal conditions [105], which leads to complexes of polymeric structure, while most of the complexes obtained under ambient conditions are monomeric (see Section 3.3.2 for examples). 

---