Vincent L. Pecoraro
Bioorganic and Metal Cluster ChemistryOur research group has programs in three areas of bioinorganic chemistry and one in the preparation and characterization of inorganic clusters. Students can receive training in synthetic inorganic chemistry and physical characterization of molecules [X-ray crystallography, NMR (multidimensional, paramagnetic and heteronuclear such as 51V or 23Na), electrochemistry, epr and uv/vis spectroscopy, etc.] or emphasize more biologically related topics. In the latter case, students gain experience in molecular biology as well as in the physical techniques described above.
Our group recently discovered a new class of metal chelating agents that have been named metallacrowns based on the structural similarity of these materials to organic crown ethers. The group is developing this new area of molecular recognition agent in numerous ways including determining stability constants for metal complexation, the ability to polymerize metallacrowns to form new materials, such as metallomesogens, and investigating the reactivity of these compounds as possible catalysts.
Manganese plays an important role in the metabolism of dioxygen and its reduced forms. Two enzymes which contain multinuclear manganese assemblies at the active site are the manganese catalases and the oxygen evolving complex. We have attempted to provide a better understanding of the structure, spectral features and reactivity patterns of small molecules that may act as models for each of these categories of enzymes. An analogous project focuses on biological vanadium chemistry, a newly emerging field in the bioinorganic sphere. Vanadium has special significance in the marine environment where it is concentrated nearly a million-fold by tunicates and forms the heart of vanadium bromoperoxidase, an enzyme that performs important halogenation reactions for marine natural products. In addition, vanadium complexes may represent an effective treatment for diabetes.
The group has expanded its synthetic interests into a bioorganic/bioinorganic hybrid program aimed at synthesizing small peptides that adopt controlled secondary structures into which metal ion binding sites can be engineered. These a-helical peptides aggregate into two, three or four helix bundles. The hydrophobic interior is modified to serve as a binding site for metals as diverse as mercury or cadmium or biologically important centers such as the Fe2S2 and Fe4S4 clusters.