Cryogenic IR and UV spectroscopy of isomer-selected cytosine radical cation

F. L. MOLINA; J. DEZALAY; S. SOORKIA; M. BROQUIER; M. HOCHLAF; G. A. PINO; G. GRÉGOIRE

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

ROYAL SOC CHEMISTRY

Lugar: Cambridge; Año: 2022

1463-9076

xidation of the nucleobases is of great concern for the stability of DNA strands and is considered as a source of mutagenesis and cancer. However, precise spectroscopy data, in particular in their electronic excited states are scare if not missing. We here report an original way to produce isomer-selectedradical cation of DNA bases, exemplified in the case of cytosine, through the photodissociation of cold cytosine silver (C-Ag+) complex. IR-UV dip spectroscopy of C-Ag+ features fingerprint bands for the two keto-amino cytosine tautomers. UV photodissociation (UVPD) of the isomer-selected C-Ag+ complexesproduces the cytosine radical cation (C?+) without isomerization. IR-UV cryogenic ion spectroscopy of C?+ allows for the unambiguous structural assignment of the two keto-amino isomers of C?+. UVPD spectroscopy of the isomer-selected C?+ species is recorded at a unique spectral resolution. Thesebenchmark spectroscopic data of the electronic excited states of C?+ are used to assess the