Professor Heinz D. Roth, of the Department of Chemistry at Rutgers, the State University of New Jersey, carries out chemical and spectroscopic studies of organic radical cations with the support of the Organic and Macromolecular Chemistry Program. Organic radical cations are generated by photo-induced electron transfer and by chemical oxidation in a range of media, including fluid solutions, frozen glasses, and solid supports (zeolites). Spectroscopic techniques, including optical spectroscopy, electron paramagnetic resonance, and chemically induced dynamic nuclear polarization, permit the study of the structures of these radical cations. Through a combination of experimental and theoretical techniques, Professor Roth explores the regiochemistry of radical cation reactions, focusing on ring strain, extent of conjugation, and steric hindrance as determinants of regioselectivity. Also explored are issues relating to the reactions of triplet radical pairs, including biradical formation, generation of biradicals or triplet states from `vertical` radical cations, formation of perpendicular triplet states, and generation of extended biradicals by coupling of triplet ion pairs. Many chemical reactions proceed via a sequence of chemical steps, each producing a reactive intermediate species which undergoes further reaction, ultimately leading to the final reaction product. The intermediates in chemical reactions often display unusual chemical and structural features, and often bear a positive charge (`cations`) or negative charge or a lone electron (`radicals`). With the support of the Organic and Macromolecular Chemistry Program, Professor Heinz D. Roth, of the Department of Chemistry at Rutgers, the State University of New Jersey, studies the formation, structure, and reactivity of reactive intermediates containing both a positive charge and an unpaired electron. Through the application of a variety of physical and chemical techniques, complemented by calculational studies, Professor Roth elucidates the chemical nature of these `radical cations,` contributing to our fundamental knowledge of how chemical reactions occur.
