Chemical and Spectroscopic Studies of Radical Cation Reactivity and Structures

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The structures and reactions of unusual radical cations will be investigated. A variety of organic radical cations will be generated in a range of media, including fluid solutions, frozen glasses, and solid supports, e.g., zeolites, by appropriate methods, including photo-induced electron transfer, chemical oxidation, and radiolysis. Their structures and reactions will be examined by a variety of modern spectroscopic methods, including steady-state and time-resolved optical and electron spin resonance spectroscopy. In addition, CIDNP and two-photon (radical cation photochemistry) will be used to monitor these reactions. The intermediates will be probed by a range of reagents designed to intercept the unpaired spin (free radical addition), the charge (nucleophilic capture), or both functions (cycloaddition of superoxide or semiquinone anion). The influence of surface interactions and external constraints on the three-dimensional structures of radical cations and their rearrangements will be probed by adsorbing the substrate on the microscopic surfaces of solid supports or sequestering in the three-dimensional enclaves of zeolites. %%% This grant from the Organic Dynamics Program supports the work of Professor Heinz D. Roth at Rutgers University. Radical cations are derived from neutral molecules by the loss of an electron to give a reactive intermediate with one unit of positive charge and one unpaired electron. Electrons in stable molecules are paired, while the reactive intermediates with unpaired electrons are referred to as free radicals. In this research, structures of unusual radical cations will be determined by modern instrumental methods and the reactions of these intermediates will be studied as well. Various chemical reactions will be used to intercept these reactive intermediates, and thereby determine their structures. The influence of surface interactions and external constraints on the reactions of these radical cations will also be investigated.