Making covalent bonds through non-covalent and magnetic interactions: Generation of geminate radical pairs and geminate molecular pairs in supramolecular environments

ORGN 40

Nicholas. J Turro, njt3@columbia.edu, Department of Chemistry, Columbia University, 3000 Broadway, mail code 3119, New York, NY 10027
During the last half of the 20th century, great advances were made in molecular chemistry, for which the key intellectual unit is the strong, intramolecular covalent bond. During the last two decades of the 20th century, the field of supramolecular chemistry, for which the key intellectual unit is the weak, intermolecular non-covalent bond. Photochemistry provides a means of generating radical pairs which rapidly become free radicals in typical organic solvents. These free radicals can undergo radical-radical combination reactions to form carbon-carbon bonds. Radical-radical combination reactions to form covalent carbon-carbon bonds occur at the diffusion controlled rate and are generally relatively not selective. The lecture will describe how the chemioselectivity, the regioselectivity, and the stereoselectivity of carbon-carbon bond formation between two radicals can be controlled by supramolecular interactions and superdupermolecular magnetic interactions. The formation of a geminate radical pair in a supercage critical for the control of radical-radical combination reaction. The alpha cleavage of ketones adsorbed in zeolites will be shown to be an excellent exemplar for supramolecular photochemistry. As an extension of the geminate pair production concept, it will be shown how geminate molecular pairs can be produced in supramolecular environments to produce a family of supramolecular chiral stereoisomers whose supramolecular enantioselectivity can be investigated.
 

James Flack Norris Award in Physical Organic Chemistry
1:05 PM-5:00 PM, Sunday, 26 March 2006 Georgia World Congress Center -- Georgia Ballroom 2, Oral

Division of Organic Chemistry

The 231st ACS National Meeting, Atlanta, GA, March 26-30, 2006