Communication: UV photoionization of cytosine catalyzed by Ag+

Taccone Martin (1) , Geraldine Féraud (2) , Matías Berdakin (1) , Claude Dedonder-Lardeux (2) , Christophe Jouvet (2) , Gustavo A. Pino (1)

1 INFIQC - Instituto de Investigaciones en Físico Química [Córdoba]
2 PIIM - Physique des interactions ioniques et moléculaires

The photo-induced damages of DNA in interaction with metal cations, which are found in various environments, still remain to be characterized. In this paper, we show how the complexation of a DNA base (cytosine (Cyt)) with a metal cation (Ag+) changes its electronic properties. By means of UV photofragment spectroscopy of cold ions, it was found that the photoexcitation of the CytAg+ complex at lowenergy (315-282) nm efficiently leads to ionized cytosine (Cyt+) as the single product. This occurs through a charge transfer state in which an electron from the p orbital of Cyt is promoted to Ag+, as confirmed by ab initio calculations at the TD-DFT/B3LYP and RI-ADC(2) theory level using the SV(P) basis set. The low ionization energy of Cyt in the presence of Ag+ could have important implications as point mutation of DNA upon sunlight exposition.

Domaines: Agrégats Moléculaires et Atomiques [physics.atm-clus]

Taccone Martin, Geraldine Féraud, Matías Berdakin, Claude Dedonder-Lardeux, Christophe Jouvet, et al.. Communication: UV photoionization of cytosine catalyzed by Ag+. Journal of Chemical Physics, 2015, 143, pp.041103-1. ⟨10.1063/1.4927469⟩. ⟨hal-01188585⟩