Modelling photoionisations in tautomeric DNA nucleobase derivatives 7H-adenine and 7H-Guanine: ultrafast decay and photostability
File(s)
Published version
OA Location
Author(s)
Segarra-Martí, Javier
Nouri, Sara M
Bearpark, Michael J
Type
Journal Article
Abstract
The study of radiation effects in DNA is a multidisciplinary endeavour, connecting the physical, chemical and biological sciences. Despite being mostly filtered by the ozone layer, sunlight radiation is still expected to (photo)ionise DNA in sizeable yields, triggering an electron removal process and the formation of potentially reactive cationic species. In this manuscript, photoionisation decay channels of important DNA tautomeric derivatives, 7H-adenine and 7H-guanine, are characterised with accurate CASSCF/XMS-CASPT2 theoretical methods. These simulation techniques place the onset of ionisation for 7H-adenine and 7H-guanine on average at 8.98 and 8.43 eV, in line with recorded experimental evidence when available. Cationic excited state decays are analysed next, uncovering effective barrierless deactivation routes for both species that are expected to decay to their (cationic) ground state on ultrafast timescales. Conical intersection topographies reveal that these photoionisation processes are facilitated by sloped single-path crossings, known to foster photostability, and which are predicted to enable the (VUV) photo-protection mechanisms present in these DNA tautomeric species.
Date Issued
2021-09-10
Date Acceptance
2021-08-29
Citation
Photochem, 2021, 1 (2), pp.287-301
ISSN
2673-7256
Publisher
MDPI AG
Start Page
287
End Page
301
Journal / Book Title
Photochem
Volume
1
Issue
2
Copyright Statement
© 2021 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
License URL
Sponsor
European Commission
Identifier
https://www.mdpi.com/2673-7256/1/2/18
Grant Number
Marie Sklodowska Curie Actions (MSCA-IF)
Publication Status
Published online
Date Publish Online
2021-09-10