Abstract: The intrinsic photostability of DNA is a unique feature that enables it to dissipate high-energy UV radiation through non-radiative, non-reactive pathways, thereby preserving the integrity of the genetic code and preventing mutations. In this work, we investigate how solvent polarity influences the excited-state relaxation mechanism of the guanine-cytosine Watson-Crick base pair – a fundamental unit of DNA – using non-adiabatic dynamics simulations with ML-MCTDH method. Our results confirm an ultrafast deactivation of initially excited bright states on a timescale of ca. 100 fs across all studied environments, underpinning DNA's general photostability. However, the specific relaxation pathway was found to be highly sensitive to the polarity of the media. In low-polarity media, the exciton population transfers rapidly from the G (ππ*2) state to the guanine-to-cytosine charge transfer (CT) and C (ππ*1) states, facilitating the intermolecular proton transfer due to the excess of electron density on the cytosine moiety. In contrast, in highly polar solvents, relaxation is confined to an internal conversion within the guanine moiety, i.e. from G (ππ*2) to G (ππ*1), shutting down the CT and proton transfer channels. This study elucidates the critical environmental dependence of DNA's photophysical mechanisms, providing key insights for understanding its stability across diverse biological contexts.

Cite: Shekhovtsov N.A. , Bushuev M.B.
Solvent-polarity-dependent ul-trafast excited state decay in guanine-cytosine base pair: a non-adiabatic dynamics study
Journal of Molecular Liquids. 2026. V.442. 129096 :1-10. DOI: 10.1016/j.molliq.2025.129096 Scopus

Dates:

Submitted:	Sep 5, 2025
Accepted:	Dec 4, 2025
Published online:	Dec 5, 2025
Published print:	Jan 15, 2026

Identifiers:

Scopus:

2-s2.0-105024470670

Citing: Пока нет цитирований

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