Issue 41, 2022

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

Abstract

Oxidation 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 scarce if not missing. We here report an original way to produce isomer-selected radical cations 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+ complexes produces 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. These benchmark spectroscopic data of the electronic excited states of C˙+ are used to assess the quantum chemistry calculations performed at the TD-DFT, CASSCF/CASPT2 and CASSCF/MRCI-F12 levels.

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

Supplementary files

Article information

Article type
Paper
Submitted
26 aug 2022
Accepted
08 okt 2022
First published
11 okt 2022
This article is Open Access
Creative Commons BY-NC license

Phys. Chem. Chem. Phys., 2022,24, 25182-25190

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

F. Molina, J. Dezalay, S. Soorkia, M. Broquier, M. Hochlaf, G. A. Pino and G. Grégoire, Phys. Chem. Chem. Phys., 2022, 24, 25182 DOI: 10.1039/D2CP03953B

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