title: Communication: UV photoionization of cytosine catalyzed by Ag(+).
abstract: 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 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.
authors.affiliation: INFIQC (CONICET - Universidad Nacional de Córdoba), Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina.
authors.forename: Martín I
authors.initials: MI
authors.lastname: Taccone
authors.affiliation: Physique des Interactions Ioniques et Moléculaires (PIIM): UMR- 7345, CNRS, Aix Marseille Université, 13397 Marseille, France.
authors.forename: Geraldine
authors.initials: G
authors.lastname: Féraud
authors.affiliation: INFIQC (CONICET - Universidad Nacional de Córdoba), Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina.
authors.forename: Matías
authors.initials: M
authors.lastname: Berdakin
authors.affiliation: Physique des Interactions Ioniques et Moléculaires (PIIM): UMR- 7345, CNRS, Aix Marseille Université, 13397 Marseille, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Dedonder-Lardeux
authors.affiliation: Physique des Interactions Ioniques et Moléculaires (PIIM): UMR- 7345, CNRS, Aix Marseille Université, 13397 Marseille, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Jouvet
authors.affiliation: INFIQC (CONICET - Universidad Nacional de Córdoba), Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina.
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Pino
mesh_terms: D003596:Cytosine / Q000737:chemistry*; D004247:DNA / Q000737:chemistry* / Q000528:radiation effects; D004583:Electrons; D008670:Metals / Q000737:chemistry*; D017354:Point Mutation / Q000528:radiation effects; D011789:Quantum Theory; D012834:Silver / Q000737:chemistry*; D013472:Sunlight / Q000009:adverse effects; D013816:Thermodynamics
chemical_list: D008670:Metals; D012834:Silver; D003596:Cytosine; D004247:DNA