Radiation induced free radical formation in sulfur-substituted purines. 6-Mercaptopurine at 77 K
- 1 October 1978
- journal article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 69 (7) , 3206-3213
- https://doi.org/10.1063/1.436970
Abstract
Single crystals of the sulfur-containing purine base derivative 6-mercaptopurine have been irradiated by 4.0 MeV electrons and studied by electron spin resonance techniques at 77 K. The two main resonances observed, R1 and R3, were analyzed and identified. The R1 resonance exhibited a large g-value variation. The g-tensor principal values are 2.173, 2.002, and 1.989, and the resonance is ascribed to a thiyl radical formed by the abstraction of a hydrogen atom from N7. The R3 resonance showed an almost isotropic 1:2:1 triplet hyperfine structure with a splitting value of 38.5 G. The g-tensor principal values are 2.0138, 2.0065, and 2.0020. This resonance is assigned to a radical formed by hydrogen addition at the C8 position. The radical identifications were arrived at by a combination of the ESR data and results from molecular orbital calculations.Keywords
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