Rare Earth Complexes with Polyaminopolycarboxylic Acids

Preparation of Rare Earth Complexes with Polyaminopolycarboxylic Acids... 

This chapter will cover the synthetic, structural, and solution chemistry of rare earth complexes with carboxylic acids, polyaminopolycarboxylic acids, and amino acids, with an emphasis on their structural chemistry. As the carboxylate groups play the key roles in the metal-ligand coordination bonding in these complexes, we will start the chapter with the coordination chemistry of rare earth-carboxylic acid complexes, followed by rare earth-polyaminopolycarboxylic acid and rare earth-amino acid coordination chemistry. Owing to length limitations, an exhaustive citation of the large amount of research activities on the subjects is not possible. Instead, only selected examples are detailed to highlight the key features of this chemistry. 

Rare Earth Complexes with Carboxylic Acids, Polyaminopolycarboxylic Acids, and Amino Acids 93... 

Figure 4 Structures of [TbL3(H20)2]2 (L = p-aminobenzonate) (a) and [SmL3(H20)2]2 (L = acetate) (b) (RE, black (large balls) O, gray N, black (small balls) C, white H, omitted). (Reproduced with permission fiom from R. Wang and Z. Zheng, Rare Earth Complexes with Carboxyhc Acids, Polyaminopolycarboxylic Acids and Amino Acids in Chun-Hni Huang, Rare Earth Coordination Chemistry Fimdamentals and Apphcations. John Wiley Sons (Asia) Pte Ltd, 2010.)...

Complexes with Carboxylic Acids, Polyaminopolycarboxylic Acids and Amino Acids in Chun-Hui Huang, Rare Earth Coordination Chemistry Fundamentals and Applications, John Wiley Sons (Asia) Pte Ltd, 2010.)... 

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). 

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