Controlling the Structures of Lanthanide Complexes in Self-Assemblies with Tripodal Ligands

The complexity of self-assembled supramolecular systems is continuously evolving in the direction of large multicomponent polynuclear architectures. The self-assembly of such systems requires the preparation of sophisticated organic receptors with programmed multidentate sites for binding metal ions. In this review we focus on the concept of tripodal receptors specifically designed for complexing lanthanide cations. A large palette of polytopic podands is described, and the structures of their anchoring and binding moieties are discussed together with their impact on the self-assembly with Ln(III). The crystal or calculated structures of mononuclear and polynuclear complexes are shown to illustrate typical structural features in relation to their properties. Moreover, thermodynamic speciation with several ligands is analysed along the lanthanide series in order to ascertain the effects of the ionic size. Understanding and controlling the different factors discussed here should help in rational designing of more complex architectures with Ln(III).