On the population of triplet states of 2-seleno-thymine

Valverde, Danillo; Mai, Sebastian; Araújo, Adalberto Vasconcelos Sanches de; Canuto, Sylvio; González, Leticia; Borin, Antonio Carlos

doi:10.1039/d1cp00041a

Cited by 11 publications

(7 citation statements)

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“…Notably, it has allowed to rationalize the quantum yield of the population of the lowest triplet state (27) or the evolution of Watson-Crick pairing (28). The evolution of the long-lived 3ππ* state has been shown to have a characteristic time which may encompass the nanosecond range, as it has also been confirmed by the study of the decay in DNA single strand (22,29), for thymine and their analogous (30,31). Furthermore, the lifetime has also shown a dependency on the possible formation of excimeric states characterized by the delocalization of the triplet spin density over several stacked nucleobases.…”

Section: Introductionmentioning

confidence: 90%

The Behavior of Triplet Thymine in a Model B‐DNA Strand. Energetics and Spin Density Localization Revealed by ab initio Molecular Dynamics Simulations^†*

Allahkaram

Monari

Dumont

2021

Photochem & Photobiology

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Among the naturally occurring nucleobases, thymine presents the lowest triplet state, hence it represents a hotspot for energy transfer and photosensitization. In turn, the population of the triplet state may lead to thymine dimerization and hence to the production of toxic DNA lesions and has been the subject of intensive theoretical and experimental investigations. Relying on QM/MM molecular dynamics simulations, we have sought to situate the energy of the lowest triplet state of thymine embedded in a B‐DNA environment. The energy gap varies between 305 and 329 kJ mol−1 when a single thymine is treated at the quantum chemistry level, depending on its position in the model double‐stranded 16‐bp oligonucleotide. The energy of triplet state decreases up to 300 kJ mol−1, due to polarization effects, when we consider coupled stacked nucleobases up to the inclusion of four nucleobases. Our value lies in good agreement with the energy inferred experimentally by Miranda and coworkers (270 kJ mol−1), and our theoretical exploration opens the door to investigations toward other more complex and biologically relevant environments, such as thymines embedded in nucleosome core particles. Our investigations also provide a reference for further studies using semi‐empirical approaches such as density functional‐based tight‐binding, allowing to further rationalize sequence effects.

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Section: Introductionmentioning

confidence: 90%

The Behavior of Triplet Thymine in a Model B‐DNA Strand. Energetics and Spin Density Localization Revealed by ab initio Molecular Dynamics Simulations^†*

Allahkaram

Monari

Dumont

2021

Photochem & Photobiology

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“…291 Although ISC is often regarded as a much slower process than IC due to the spin-forbidden character of this nonadiabatic transition, in some cases it may be ultrafast even in the absence of heavy-atom induced strong spin-orbit coupling. [292][293][294] In a nonrelativistic description ultrafast ISC involves a singlet-triplet crossing, which is topologically not a CoIn (in a fully relativistic description this can be seen as a CoIn) 295 but rather a linear-i.e. not conical-crossing part of a 3N À 7 IS as the off-diagonal elements are zero for different spin multiplicities (eqn (2), Section 1).…”

Section: Other Photochemical and Photophysical Processesmentioning

confidence: 99%

From a one-mode to a multi-mode understanding of conical intersection mediated ultrafast organic photochemical reactions

Boeije

Olivucci

2023

Chem. Soc. Rev.

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“…Still, the computed energy barriers along the LIIC pathway are commonly overestimated. Spin-orbit couplings (SOCs) were computed using the Atomic Mean Field Integrals (AMFI) [ 55 , 56 ], as in previous works [ 57 , 58 ]. Water solvation effects were mimicked by applying the Polarizable Continuum Model (PCM) [ 35 ].…”

Section: Methodsmentioning

confidence: 99%

Photophysical Deactivation Mechanisms of the Pyrimidine Analogue 1-Cyclohexyluracil

2021

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The photophysical relaxation mechanisms of 1-cyclohexyluracil, in vacuum and water, were investigated by employing the Multi-State CASPT2 (MS-CASPT2, Multi-State Complete Active-Space Second-Order Perturbation Theory) quantum chemical method and Dunning’s cc-pVDZ basis sets. In both environments, our results suggest that the primary photophysical event is the population of the S11(ππ*) bright state. Afterwards, two likely deactivation pathways can take place, which is sustained by linear interpolation in internal coordinates defined via Z-Matrix scans connecting the most important characteristic points. The first one (Route 1) is the same relaxation mechanism observed for uracil, its canonical analogue, i.e., internal conversion to the ground state through an ethylenic-like conical intersection. The other route (Route 2) is the direct population transfer from the S11(ππ*) bright state to the T23(nπ*) triplet state via an intersystem crossing process involving the (S11(ππ*)/T23(nπ*))STCP singlet-triplet crossing point. As the spin-orbit coupling is not too large in either environment, we propose that most of the electronic population initially on the S11(ππ*) state returns to the ground following the same ultrafast deactivation mechanism observed in uracil (Route 1), while a smaller percentage goes to the triplet manifold. The presence of a minimum on the S11(ππ*) potential energy hypersurface in water can help to understand why experimentally it is noticed suppression of the triplet states population in polar protic solvent.

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On the population of triplet states of 2-seleno-thymine

Abstract: The population and depopulation mechanisms leading to the lowest-lying triplet states of the 2-Se-Thymine were studied at the MS-CASPT2/cc-pVDZ level of theory. Several critical points on different potential energy hypersurfaces...

Cited by 11 publications

References 58 publications

The Behavior of Triplet Thymine in a Model B‐DNA Strand. Energetics and Spin Density Localization Revealed by ab initio Molecular Dynamics Simulations^†*

The Behavior of Triplet Thymine in a Model B‐DNA Strand. Energetics and Spin Density Localization Revealed by ab initio Molecular Dynamics Simulations^†*

From a one-mode to a multi-mode understanding of conical intersection mediated ultrafast organic photochemical reactions

Photophysical Deactivation Mechanisms of the Pyrimidine Analogue 1-Cyclohexyluracil

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On the population of triplet states of 2-seleno-thymine

Abstract: The population and depopulation mechanisms leading to the lowest-lying triplet states of the 2-Se-Thymine were studied at the MS-CASPT2/cc-pVDZ level of theory. Several critical points on different potential energy hypersurfaces...

Cited by 11 publications

References 58 publications

The Behavior of Triplet Thymine in a Model B‐DNA Strand. Energetics and Spin Density Localization Revealed by ab initio Molecular Dynamics Simulations†*

The Behavior of Triplet Thymine in a Model B‐DNA Strand. Energetics and Spin Density Localization Revealed by ab initio Molecular Dynamics Simulations†*

From a one-mode to a multi-mode understanding of conical intersection mediated ultrafast organic photochemical reactions

Photophysical Deactivation Mechanisms of the Pyrimidine Analogue 1-Cyclohexyluracil

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Product

Resources

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The Behavior of Triplet Thymine in a Model B‐DNA Strand. Energetics and Spin Density Localization Revealed by ab initio Molecular Dynamics Simulations^†*

The Behavior of Triplet Thymine in a Model B‐DNA Strand. Energetics and Spin Density Localization Revealed by ab initio Molecular Dynamics Simulations^†*