Dr. Dimitri Coucouvanis, Department of Chemistry, University of Michigan, is supported by the Inorganic, Bioinorganic, and Organometallic Program of the Chemistry Division to perform synthetic, structural and reactivity studies on supramolecules obtained from catechol functionalized macrocycles. The systems of interest include catechol-functionalized tetraazamacrocyclic complexes capable of undergoing intramolecular electron transfer upon changes in pH, supramolecular crown ethers which change their function depending on what is bound in the crown ether portion of the molecule, and optically active `propeller` molecules which could be useful as supports capable of asymmetric induction in the epoxidation of olefins. Molecular `reactors` which contain separate subunits for both the storage of electrons and the activation of small molecules will also be synthesized and their reactivity patterns delineated. The chemistry of coordinated sulfur and selenium ligands in niobium and tantalum complexes and their reactivity with heteroallenes, alkenes, alkynes, sulfur dioxide and molecular hydrogen will also be explored. Molecular architecture involves the synthesis of complex, multi-functional systems which are designed to transform a bound substrate molecule, much the way enzymes function in living systems. Metallomacrocycles, systems which incorporate metal ions into large ring structures, are examples of these so called `supramolecular` systems. These molecules may function as elementary molecular devices with potential applications in photochemically induced charge separation, photoswitching, catalytic redox processes, electron storage, or substrate molecule activation.
