Better View Of Solid-State Reactions

Light-driven solid-state organic reactions, while potentially useful for environmentally clean industrial processes, are difficult to probe spectroscopically in fine powders or in single crystals because of high optical densities and light scattering. An international team that includes Malcolm D. E. Forbes of the University of North Carolina, Chapel Hill; Miguel A. Garcia-Garibay of the University of California, Los Angeles; and Valery F. Tarasov of the Semenov Institute of Chemical Physics, in Moscow, has turned to nanocrystals suspended in water as a system that maintains the properties of bulk solids but enables examination by solution techniques (J. Am. Chem. Soc., DOI: 10.1021/ja909521u). The researchers studied the UV-induced conversion of dicumyl ketone to dicumene as a model system for synthesizing molecules with adjacent quaternary carbons. Laser flash photolysis of the ketone produced a nanocrystalline radical-pair triplet state, which the group observed transforming into dicumene by using time-resolved electron paramagnetic resonance spectroscopy. The work sets the stage for new depth of understanding and manipulation of organic solid-state reactions, the researchers say.