Communication: UV photoionization of cytosine catalyzed by Ag+

MARTÍN I. TACCONE; GERALDINE FÉRAUD; MATÍAS BERDAKIN; CLAUDE DEDONDER-LARDEUX; CHRISTOPHE JOUVET; GUSTAVO A. PINO

JOURNAL OF CHEMICAL PHYSICS

AMER INST PHYSICS

Lugar: Melville; Año: 2015 vol. 143 p. 411031 - 411035

0021-9606

The photo-induced damages of DNA in interaction with metal cations, which are found in variousenvironments, still remain to be characterized. In this paper, we show how the complexation of aDNA base (cytosine (Cyt)) with a metal cation (Ag+) changes its electronic properties. By meansof UV photofragment spectroscopy of cold ions, it was found that the photoexcitation of the CytAg+ complex at low energy (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.