Objective
SUMMARY
The number of reports of the synthesis, characterisation and study of polynuclear cages has increased markedly in the last few years. However much work remains before the chemistry and physics of these species are understood. The programme " Polymetallic Complexes As Molecular Nanomagnets and Novel Homogeneous Catalysts" will investigate new methods for making such compounds, and their applications as novel magnetic materials and oxidation catalysts. We will also begin the work of making nanoscale particles from polymetallic precursors.
Our synthetic studies will explore four reactions. The first involves solvathermal synthesis, where complexes are made in solvents well above their normal boiling points. This has already generated many new and exciting cage complexes. The second sub task will involve using new H-bonding templates to create new cage compounds. This work has already produced many new cages, including novel anti-ferromagnetically coupled wheels that are proving to be of enormous interest to the physics community. In the third strand we will look at more conventional "solution" routes to cage compounds, however using ideas we have developed including inducing oligomerisation by oxidation of metal cage precursors, or in situ ligand formation by oxidation of aldehydes. In the fourth strand we will look at "direct synthesis" where we will make cage complexes from either the metallic elements or metal-oxides.
Structural characterisation of the cages will involve X-ray diffraction. We will extend this work to very low temperature crystallography, intending to use electron density measurements to learn more about magnetic structure in compounds.
Magnetic properties of the cages will be studied by susceptibility measurements, however more detailed information about magnetic structure will be obtained by resonance spectroscopy. EPR spectroscopy at a range of frequencies (270 GHz to 9.4 GHz) and temperatures, and Mössbauer spectroscopy down to 1.8 K will be performed on suitable samples.
Catalytic studies will examine the propensity of the cages to catalyse peroxide decomposition as an initial screening process. Promising cages will be further studied as catalysts for oxidation of alkenes and other substrates, e.g. toluene.
The nanoscale particle preparation is the least defined strand at present. We will look at thermal decomposition of cage complexes as a method of making size-defined particles. Characterisation of these particles will be by TEM and we will study the magnetic behaviour of any well-defined particles formed.
Topic(s)
Call for proposal
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M13 9PL Manchester
United Kingdom