Lanthanide coordination chemistry potential applications

Lanthanide coordination chemistry has seen a considerable increase in interest in recent years due to potential applications in a variety of fields, including catalysis (9), biochemical analysis (3-8,10-14), and non-invasive diagnostics (8,15,16). 

Lanthanide-based catalysts, despite finding a lot of application in homogeneous catalysis, can be rather problematic due to the lability of some ligand types and the versatility of their coordination chemistry in the -1-3 oxidation state this makes the controlled synthesis of single-site Ln complexes a quite ambitious goal [92]. McLain and coworkers first demonstrated the high potential of a homoleptic yttrium complex Y(OCH2CH2NMe2)3 as ROP catalyst for the preparation of PLA from rac-lactide and that it promotes a rapid and controlled polymerization... 

To date very little is known about the coordination chemistry of the sapphyrin macrocycle, and no complexes have been reported for the dioxosapphyrin or the thiosapphyrin. In the free-base form, sapphyrin is a potential trianionic ligand and thus, on paper at least, seems perfectly suited for complexing the normally trivalent cations of the lanthanide series. Presumably, lanthanide(III) complexes of sapphyrin, which would be neutral (and potentially useful for magnetic resonance imaging applications see Sect. 12.2), would be expected to form easily under typical porphyrin metalation conditions. However, in spite of the apparent correspondence in the sapphyrin core size and the ionic radii of the lanthanides, to date no lanthanide cation has been inserted into the core of the sapphyrin macrocycle using a variety of standard metal insertion techniques [156]. Nor, have any other pentaligated complexes of any other metal cations been reported to... 

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