Lanthanides: Amino Acid Compounds

Abstract

Abstract The synthetic and structural chemistry of lanthanide complexes with α‐amino acids under low‐ and high‐pH conditions is summarized. The preparative methods, diverse coordination modes, fascinating solid‐state structures, and solution behavior of such complexes are discussed. Under acidic conditions, only the carboxylate group of the amino acid participates in the metal coordination. For those with a side‐chain carboxylate group, more extensive bridging interactions of the ligand and the lanthanide ions are identified. Under physiological or even higher‐pH conditions, both the amino and carboxylate groups, be they skeletal or present in the side chain, could be coordinating, leading to much more diverse coordination modes of these unique ligands in their lanthanide complexes. Distinct from their low‐pH counterparts, complexes obtained under higher‐pH conditions are products of lanthanide hydrolysis, limited by the supporting amino acid ligands. Presence of structurally well‐defined polynuclear lanthanide–oxo/hydroxo cluster motif is characteristic of these interesting compounds that provide fundamental insight into the lanthanide interactions with biological environment.