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The Absorption Spectrum of Guanine Based Radicals: a Comparative Computational Analysis
Author(s) -
Martínez Fernández Lara,
Cerezo Javier,
Asha Haritha,
Santoro Fabrizio,
Coriani Sonia,
Improta Roberto
Publication year - 2019
Publication title -
chemphotochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.13
H-Index - 18
ISSN - 2367-0932
DOI - 10.1002/cptc.201900107
Subject(s) - polarizable continuum model , guanine , radical , chemistry , absorption spectroscopy , excited state , solvation , spectral line , deprotonation , computational chemistry , molecule , molecular physics , atomic physics , physics , quantum mechanics , ion , nucleotide , biochemistry , organic chemistry , gene
The excited states of three radical derivatives of guanine, i. e. guanine cation (G + ) and its two main deprotonated derivatives (G−H1 and G−H2), have been characterized in the Franck‐Condon region by TD‐DFT, using different functionals, CASPT2, and EOM‐EE‐CCSD calculations. In the gas phase, all the methods provide a similar description of the main spectral features, the pictures provided by TD‐DFT, with long range corrected functionals, and EOM‐EE‐CCSD being very close. Solvent effects are then taken into account by a mixed discrete‐continuum approach, including five water molecules of the first solvation shell and the Polarizable Continuum Model (PCM). The vibronic absorption line‐width has finally been simulated at the TD‐M052X level by a time dependent method within the harmonic approximation. The resulting absorption spectra are in good agreement with their experimental counterparts, providing useful indications on the use of PCM/TD‐DFT based approaches to interpret the spectra of guanine based radicals within DNA.