Model Calculations of Radiation-Induced Damage in Thymine Derivatives
When the thymine base is oxidized, the resulting cation may deprotonate reversibly at N3, or irreversibly at >C5-CH3. In all thymine derivatives studied so far in the solid state, there is always a significant concentration of a radical formed by net H-abstraction from the >C5-CH 3. DFT calculations on this allyl-like radical are in good agreement with the experimental results for both the isotropic and anisotropic hyperfine couplings. There is a tendency for the thymine cation to deprotonate at N3 in solution. Calculations on the N3 deprotonated thymine cation yield two structures, one planar radical with an unusually large N1-C2 bond length, and one nonplanar radical with the N3 more than 25° out of the molecular plane. Calculations show that the structure with the lowest energy is the allyl-like radical.
Close, David; Forde, Gareth; Gorb, Leonid; and Leszczynski, Jerzy. 2003. Model Calculations of Radiation-Induced Damage in Thymine Derivatives. Structural Chemistry. Vol.14(5). 451-454. https://doi.org/10.1023/B:STUC.0000004489.70088.ed ISSN: 1040-0400