Eur. Phys. J. D (2021) 75: 119
https://doi.org/10.1140/epjd/s10053-021-00129-0

Regular Article - Molecular Physics and Chemical Physics

Gas phase structure and fragmentation of [Cytosine-Guanine]${\text{Ag}}^{+}$ complex studied by mass-resolved IRMPD spectroscopy

¹ INFIQC (CONICET-UNC), Ciudad Universitaria, Pabellón Argentina, 5000, Córdoba, Argentina
² Departamento de Fisicoquímica, Fac. de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Pabellón Argentina, X5000HUA, Córdoba, Argentina
³ Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, Pabellón Argentina, X5000HUA, Córdoba, Argentina
⁴ Université Paris-Saclay, CNRS, Institut de Chimie Physique, 91405, Orsay, France
⁵ Departamento de Química Teórica y Computacional, Fac. de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Pabellón Argentina, X5000HUA, Córdoba, Argentina

^e gpino@unc.edu.ar

Received: 16 December 2020
Accepted: 14 March 2021
Published online: 7 April 2021

Abstract

The silver-mediated cytosine-guanine [CGAg]${}^{+}$ pair was characterized by mass-resolved IRMPD spectroscopy and electronic structure calculations at the DFT level. Three fragments were observed: [GAg]${}^{+}$, [CAg]${}^{+}$ and [CH]${}^{+}$. From the mass-resolved IRMPD spectra recorded on the mass of each fragment, two isomers of the [CGAg]${}^{+}$ complex were identified. The most populated isomer is a Hoogsteen structure [HooAg]${}^{+}$ between canonical cytosine (CKA(1)) and canonical guanine (GKA(9)), while the second isomer is an altered-Hoogsteen-like pair [*HooAg]${}^{+}$ in which guanine is in a non-canonical form (GKA(7)). The determined yields of each fragment are strongly dependent of the isomer of the precursor ion because of the fragmentation energy of the different channels. Finally, the [CH]${}^{+}$ is suggested to be produced by a metal-assisted proton transfer from guanine to cytosine preceded by an isomerization of the [HooAg]${}^{+}$ isomer.