Dr. Anne Gorden from Auburn University will present “Taking Advantage of the Chemistry of Heterocycles in Ligands for Sensors and Catalyst Supports” to the department.
In an effort to develop inexpensive ligands for colorimetric selective sensing of actinides, we have developed ligands incorporating quinoxalines or imine aza-donors. These have been characterized for selectivity in distinguishing metals. The addition of a quinoxaline to the salen imparts the fluorescence to the quinoxaline and alters the coordination site. We have used these complexes to probe the contributing factors toward selectivity, signal intensity, and the differentiation between actinides (like uranium and thorium) and first row transition metals These are the basis of new chemosensors to allow for rapid in-the-field visual identification. The complexes with early transition metals originally prepared for comparison were also found to be useful as catalyst supports in oxidation reactions, and we have explored using the 2-quinoxalinol salen ligand – abbreviated salqu – as a catalyst support for Cu(II). Simple olefin substrates can be oxidized using the salqu catalyst with tert-butyl hydroperoxide TBHP (up to 99% yield) within a very short reaction time and improved selectivity.