Kathleen Donahue '08 (Flushing, N.Y.) and Robin Joseph '09 (Watertown, Mass.) are spending their summer working with Karen Brewer, professor of chemistry. In their projects, they are synthesizing calix[4]arenes, which are chalice-shaped molecules with four aromatic rings. They coordinate rare earth metal ions with calix[4]arenes, then embed the resulting compound in sol-gels which can be processed into glasses. The students examine the light that is absorbed and emitted from the glass.
Rare earth metals fluoresce when under a UV lamp. Because water inhibits the fluorescence, the rare earth ions can be quenched in environments, such as the air, that have hydroxyl (OH) groups. This property of fluorescence makes them a good candidate for laser technology, but their performance is limited by quenching mechanisms. The idea would be, of course, to figure out some way to make them fluoresce both longer and brighter, which is what Donahue and Joseph are attempting to do. They are modifying the calix[4]arene molecule by attaching chains which hang off the bottom of the molecule. These chains encapsulate the rare earth molecule and effectively isolate it, a separation which prevents the rare earth metal from clustering and isolates it from hydroxyl groups, both of which will quench the fluorescence. The hardest part of the work is the waiting. "We have to synthesize our own starting materials," they explain, "and then wait for reaction to reflux for several days."
This is Joseph's first year of research and Donahue's second. She was in Professor Brewer's lab during the summer of 2004, and enjoyed it so much that she wanted to come back. Donahue, a chemistry major and education minor, is very interested in the issues of light and refraction involved in this study. She is a busy Hamiltonian in her spare time: aside from managing the woman's softball team, she is president of the campus Habitat for Humanity chapter and involved with HAVOC.
For her part, Joseph says she was attracted to the project because it was different: "I had some organic [background], but I wanted to try something inorganic." A rising sophomore, she is an undeclared chemistry/woman's studies major, and a member of BSU and the debate team.
-- by Lisbeth Redfield
