UV photoionization of cytosine catalyzed by Ag+

M. I. TACCONE; G. FERAUD; M. BERDAKIN; C. DEDONDER-LARDEUX; C. JOUVET; G. A. PINO

JOURNAL OF CHEMICAL PHYSICS

AMER INST PHYSICS

Lugar: New York; Año: 2015 vol. 143

0021-9606

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 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 haveimportant implications as point mutation of DNA upon sunlight exposition.