Single cocrystals of adenosine:5-iodouracil and partially deuterated adenosine:5-iodouracil were irradiated at 4.2K, 77K, and 300K with X-rays from a 3Mev Van de Graaff electron accelerator. Several types of free radicals were produced by the radiation and were studied by X-Band and Q-Band ESR from 77K to 300K. Six radicals were identified. Two electron addition products (radicals I1 and As1) and one electron abstraction product (radical I2) are stabilized at 77K. At room temperature two hydrogen addition radicals (I3 and As2) and a "singlet" radical (As3) are stabilized. Upon annealing to 165K after low temperature irradiation, radicals I1 and I2 decay to nonparamagnetic species. Radical As1 remains stable from 77K to 240K. From 240K to 300K the As1 radical decays and radicals As2 and I3 gradually grow in. Irradiation and observation at room temperature produces predominantly a "singlet" radical (As3). The electron addition radical, I1, is a (sigma)*-type radical that presents the unpaired electon spin density localized mainly on the iodine atom. This radical does not de-halogenate, to produce the reactive uracilyl radical, but instead it decays into a non paramagnetic species when annealed from 77K to 300K. The low temperature radical population obtained in this cocrystal and the subsequent radical reactions upon annealing, contradict the hypothesis that, in the presence of purine:pyrimidine stacking interactions, electrons are transfered to the pyrimidines while holes are transfered to the purines. / Source: Dissertation Abstracts International, Volume: 47-05, Section: B, page: 2043. / Thesis (Ph.D.)--The Florida State University, 1986.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75830 |
| Contributors | ZAMORANO, RAFAEL., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 224 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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