Issue 43, 2024

Theoretical insight into photodeactivation mechanisms of adenine–uracil and adenine–thymine nucleobase pairs

Abstract

In this work, several plausible intra- and intermolecular photoinduced processes of the Watson–Crick base pairs of adenine with uracil (A–U) or thymine (A–T) according to the results of spin component scaling variant of algebraic diagrammatic construction up to the second order [SCS-ADC(2)] calculations are discussed. Although widely explored, these systems lack complete characterization of possible intramolecular relaxation channels perturbed by intermolecular interactions. In particular, we address the still open debate on photodeactivation via purine-ring puckering at the C2 or C6-atom position of adenine. We also show that the presence of low-lying, long-lived 1nπ* states can be a significant factor in hindering relaxation via an electron-driven proton transfer process, as the population of these states can lead to an efficient intersystem crossing to a triplet manifold, the estimated rate of which is 1.6 × 1010 s−1 which exceeds the corresponding internal conversion to the ground state by an order of magnitude. Additionally, the SCS variant of the ADC(2) method is shown to provide a more balanced description of valence and charge-transfer excited states.

Graphical abstract: Theoretical insight into photodeactivation mechanisms of adenine–uracil and adenine–thymine nucleobase pairs

Supplementary files

Article information

Article type
Paper
Submitted
16 Jul 2024
Accepted
19 Oct 2024
First published
22 Oct 2024
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2024,26, 27807-27816

Theoretical insight into photodeactivation mechanisms of adenine–uracil and adenine–thymine nucleobase pairs

K. Szkaradek and R. W. Góra, Phys. Chem. Chem. Phys., 2024, 26, 27807 DOI: 10.1039/D4CP02817A

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