Ligand control of the metal coordination sphere by design in coordination and organometallic chemistry

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The research outlined in this proposal is aimed at controlling the physical and chemical properties of metal ions in compounds. Compounds of the lanthanide metals are the main focus of this work because they offer important advantages over other metals including higher reactivity, different selectivity, moderate cost and desirable electronic and nuclear properties. In spite of these factors, lanthanide chemistry has been slow to develop, partly because these metals require special coordination environments to form reactive compounds. In catalysis, for example, a fine balance must be achieved between formation of stable, isolable compounds and metal centres with sufficient reactivity to carry out useful chemical transformations. The development of new coordination environments for the lanthanides that forms the basis of this proposal is therefore critical to the practical implementation of these metals. The new coordination systems described here are designed to achieve two different purposes: (i) improved catalytic activity and selectivity in C-C bond forming reactions in water and organic solvents, and (ii) water and air stable complexes with pharmaceutical applications in medical imaging (magnetic resonance, gamma imaging, fluorescence imaging) or therapy (radio-lanthanide complexes as targeted anti-cancer drugs). A second major project, involves using metal coordination to improve the photochemical switching of organic molecules between different states with potential application in optical data storage. In all cases, success in achieving the desired reactivity or properties rests with careful design of the metal coordination environment.