Free radicals, and the characteristics exhibited by free radicals, have become a topic of much interest in chemical research recently. Deleterious effects have been linked to a number of free radicals produced in the human body by oxidative stress, environmental exposure, and ionizing radiation, among other routes. However, the study of radicals in solution is a very difficult task due to the high reactivity and extremely short lifetimes. Spin traps have been found to posses the ability to stabilize radicals thus more easily allowing their study. Thus, much research and effort has been put towards the design and production of novel spin traps. This work aimed to calculate the reaction rate constants for the reaction of 5,5-Dimethyl-1-pyrroline N-oxide (DMPO) and 2- ethoxycarbonyl-2-methyl-3,4-dihydro-2H-pyrrole-l-oxide (EMPO) with the hydroxyl radical using chemically accurate energies (errors ~1kcal/mol or less) obtained from composite quantum chemistry methods. DMPO and EMPO spin traps are commonly used to study radical reactions in biological systems and have been the focus of much computational and experimental research, but accurate rate constants have not been previously obtained using computational methods. On the route to obtaining chemically accurate energies, the complete basis set limits for the Hartree-Fock and second-order Møller-Plesset energies were calculated using the density functional theory optimized geometry and will be presented.

Complete basis set limits for the Hartree-Fock and second-order Møller-Plesset energies for DMPO, EMPO, and their hydroxyl radical adducts

251st National Meeting (2016)

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