Heterometallic Complexes Derived from Bridging and Multi-compartmental Ligands

5 Heterometallic Complexes Derived from Bridging and Multi-compartmental Ligands 

Organic transformations can be used to prepare architectures from stable starting components. We initially used this approach in the first controlled preparation of/-/ heterometallic systems, using stable 4-aminobenzylD03A as building block complexes and reacting them with DTPA anhydride (Fig. 9.10), before adding a second lanthanide ion which binds in the DTPA diamide pocket [54]. 

Tremblay and Sames [55] extended this approach to systems in which two binding sites are both coordinated to a lanthanide, before exploiting the lability of DTPA under acidic conditions to sequester one lanthanide and replace it with a second one (Fig. 9.11), while leaving the DOTA pocket untouched. 

Related approaches can be used to prepare d-f hybrid complexes and s-f hybrids by linking stable complexes to additional binding sites. In the case of the former, stable d-block complexes can be reacted with azamacrocycles to yield stable d-f hybrids (Fig. 9.12) [56]. In the case of s-f hybrid arrays, a stable lanthanide complex must be linked to a binding site for alkali metals (Fig. 9.13) [57]. 

Coordination chemistry can be used to prepare arrays from stable building blocks. Metathesis of Re(Bpy)(CO)3Cl followed by treatment with lanthanide complexes of 4-picolylD03A, TriazolylD03A or triazole bearing DOTA monoamides yields a series of d-f hybrid complexes (Fig. 9.17, a—c). The Gd-Re bimetallic systems combine long-lived 

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