Photochemistry and Strained Molecules

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The Organic Dynamics Program supports studies of photochemistry and strained molecules carried out under the direction of Professor Richard Johnson of the University of New Hampshire at Durham. Through a combination of experimental and calculational studies, Professor Johnson explores the formation and reaction chemistry of high-energy organic compounds with distorted multiple bonds, including small-ring 1,2-dienes such as 1,2-cyclobutadiene and 1,2-cyclopentadiene and 1,2,3-trienes such as 1,2,3-cyclobutatriene and 1,2,3-cyclohexatriene. Other strained-ring compounds, cyclopropanated phenanthrenes, serve as photochemical precursors to vinylidene, vinylcarbene, cyclopropylidene, and other carbenes. Development of a fundamental understanding of chemical structure and reactivity often requires the study of compounds designed to test implicit and explicit assumptions about chemical bonding and stability. Professor Richard Johnson, of the University of New Hampshire at Durham, uses the energy of light to induce the formation of molecules designed to stretch the limits of such assumptions, focusing on cyclic compounds for which consideration of simple bonding principles would predict impossibility of existence. These studies, in addition to their importance on the fundamental level, will lead to new routes for the preparation of molecules with biological activity and for the preparation of unusual polymeric materials, and may also shed light on phenomena observed in combustion chemistry, fullerene (`Bucky ball`) synthesis, and extraterrestrial chemistry.