Resumen:
he study of metal ion-DNA interaction aiming to understand the stabilization of artificial base pairing and a number of non canonical motifs is of current interest, due to their potential exploitation in developing new technological devices and expanding the genetic code. A successful strategy has been the synthesis of metal-mediated base pairs, in which a coordinative bond to a central metal cation replaces a H-bond in a natural pair. In this work we characterized for the first time, the gas phase structure of the Cytosine?Ag+?Cytosine (C-Ag+-C) complex by means of InfraRed-MultiPhoton-Dissociation (IR-MPD) spectroscopy and theoretical calculation. The IR-spectrum was confidently assigned to one structure with the Ag+ acting as a bridge between the hetero-nitrogen atoms in each Cytosine (both in the keto-amino form). This structure is biological relevant since it mimics the structure of the hemiprotonated C-H+-C dimer responsible for the stabilization of the i-motif structure in DNA,