Theoretical study of guanine-Cu and uracil-Cu (neutral, anionic, and cationic).: Is it possible to carry out a photoelectron spectroscopy experiment? -: art. no. 024311

The structure and bonding of guanine-Cu and uracil-Cu (neutral, anionic, and cationic) are discussed on the basis of the calculated structures and energies. The interaction of the metal atom with guanine and uracil has been analyzed using the B3LYP density-functional approach. The removal of one electron from the neutral complexes produces the stabilization of one of the isomers, while the addition of one electron leads to a system where the metal atom is weakly bounded to guanine or uracil, according to the metal-bases bond distance that is long (2.29-2.90). For guanine-Cu and uracil-Cu, the vertical ionization energy of the anion is close to the dissociation energy of one hydrogen atom from guanine-Cu or uracil-Cu. In these cases, it could be possible to produce the detachment of one electron from the anion and also the removal of one hydrogen atom. This is important since the photoelectron spectroscopy of atomic or mixed-atomic cluster anions has proven to be a very effective tool in the study of small systems. For the analysis of copper atoms with DNA bases such as guanine and uracil, it is expected that the photoelectron spectra of the anion-bases complexes strongly resemble the spectrum of Cu-1, just shifted to higher electron binding energies due to the product stabilization. Hopefully, this information will be useful for the experimental groups. (c) 2005 American Institute of Physics.