Ligand control of lanthanide oxidation states with applications in photophysics and synthesis

We will study the role of the ligand in stabilizing +2, +3, and +4 oxidation states of lanthanides (Ln) to install and control the physico-chemical properties (e.g. luminescence, reactivity) associated with the different oxidation states.

In year 1 ligands with a variety of charge and coordination number, and their Ln complexes will be synthesized and characterized using electrochemistry, X-ray crystallography, NMR spectroscopy, and steady-state and time-resolved absorption and emission spectroscopies.

In year 2 we will create near infrared-emitting responsive luminescent probes for enzyme detection based on the target-mediated switching between Ln(II) and Ln(III). Years 2-4 we will develop catalytic Ln(II)-mediated reductions.

Using several catalyst candidates together with the results from year 1 we will study the redutions of a range of substrates (alkyl halides, heterocycles, carbonyls) under stoichiometric (year 2), and catalytic conditions in the presence of sacrificial reductants (years 3, 4).

In year 3 we will begin work to access Ln(IV) coordination compounds by photoinduced electron transfer from an easily oxidizable excited-state Ln(III) to an electron-poor oxidant. This strategy will yield a much broader variety of Ln(IV) species than currently available.

The project will yield improved methods for non-invasive detection of biologically important targets, render Ln(II) reagents less resource-intensive, and open the door to a variety of Ln(IV) structures.