Structural Chemistry of Rare Earth Complexes with Amino Acids

2 Structural Chemistry of Rare Earth Complexes with Amino Acids 

At pH 1, amino acids are in their zwitterions form. The ligands can thus be considered as simple carboxylates with a positively charged side group -NH at its a-position. In fact, the 

The 1 2(RE L) complexes are inclined to form when Gly, Ala, Val, Phe, Met, He, His, Cys, and Pro are used as the ligands. Most of these complexes are dimeric, with the general formula 

A diverse range of structures have been revealed for the 1 1 complexes with the simple amino acids, Gly, Pro, and Ala, as well as the amino acids with side groups capable of metal coordination, such as Ser, Thr, Glu, and Asp. The structures can be dimeric, ID-polymeric or 2D-layered. 

The only known 2 3 complex with the only seven-coordinate RE(III)-amino acid complex reported so far is the dimeric Ser complex, [Er2(Ser)3(H20)8](C104)6 [132]. In the structure, the two Er(III) ions are bridged through three carboxylates in their p,2-q h coordination mode, and the coordination sphere of Er(III) is completed by four water molecules, CN = 7. 

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