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. Author manuscript; available in PMC: 2017 Nov 1.
Published in final edited form as: Radiat Phys Chem Oxf Engl 1993. 2016 Apr 30;128:60–74. doi: 10.1016/j.radphyschem.2016.04.022

Scheme 5.

Scheme 5

This scheme represents C•+ production via one-electron oxidation of cytosine derivatives and the prototropic equilibria of C•+ in these compounds. By deprotonation and subsequent tautomerization, the C•+ π-radical forms the iminyl σ-radical. The atom numbering scheme of cytosine base is presented. The relative stabilities of C(N4-H)•syn, C(N4-H)•anti and the iminyl σ-radical in kcal/mol as well as the pKa values (Close, 2013) of C•+, C(N4-H)•syn, C(N4-H)•anti are provided. The energy values were obtained with the DFT/B3LYP/6-31G* method using geometry optimized structures. Reprinted with permission from Adhikary et al. 2015, J. Phys. Chem. B, copyright (2015), American Chemical Society.