Metallo Helicate chemistry
We have an active interest in the metallo-supramolecular chemistry of helical complexes (helicates). This has allowed us to probe, in solution, the processes that lead to the self-assembly of complex architectures. We reported the first metallo-helicate complex to be based upon a ligand with C3-symmetry leading to the formation of the ‘Trinity Helix', Figure 6. The field continues to be dominated by ligands with C2-symmetry. We are currently developing binuclear metallo-helicate host complexes with two addressable Fe(II) spin-crossover centres (high-spin HS; Low spin, LS) to determine the nature of intra- or inter- molecular cooperativity between spin-centres. We are also looking to develop metallo-helicate host complexes containing an intra-helical cavity of sufficient size to be capable of binding smaller guest molecules within it (see above) and to discern whether this host-guest interaction influences HS « ↔LS switching and to determine the dependence of this switching event upon the nature of the included guest. Ultimately, we wish to discern whether the host-guest interaction falls under magnetic control to develop a supramolecular device.
Figure 6: The ‘Trinity' helix (see Chem. Commun., 2003, 1274; Chem. Eng. News 2003, 81(23) , 34; J. Am. Chem. Soc. 2007, 129, 10,986 ).