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3-Methylation alters excited state decay in photoionised uracil
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3-Methylation alters excited state decay in photoionised uracil
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| dc.contributor.author | Segarra Martí, Javier | |
| dc.contributor.author | Tran, Thierry | |
| dc.contributor.author | Bearpark, Michael J. | |
| dc.date.accessioned | 2023-05-02T16:34:38Z | |
| dc.date.available | 2023-09-21T04:45:05Z | |
| dc.date.issued | 2022 | |
| dc.identifier.citation | Segarra Martí, Javier Tran, Thierry Bearpark, Michael J. 2022 3-Methylation alters excited state decay in photoionised uracil Physical Chemistry Chemical Physics 24 27038 27046 | |
| dc.identifier.uri | https://hdl.handle.net/10550/86281 | |
| dc.description.abstract | UV and VUV-induced processes in DNA/RNA nucleobases are central to understand photo-damaging and photo-protecting mechanisms in our genetic material. Here we model the events following photoionisation and electronic excitation in uracil, methylated in the 1′ and 3′ positions, using the correlated XMS-CASPT2 method. We compare our results against those for uracil and 5-methyl-uracil (thymine) previously published. We find 3-methylation, an epigenetic modification in non-negligible amounts, shows the largest differences in photoionised decay of all three derivatives studied compared to uracil itself. At the S0 minimum, 3-methyl-uracil (3mUra) shows almost degenerate excited cation states. Upon populating the cation manifold, a crossing is predicted featuring different topography compared to other methylated uracil species in this study. We find an effective 3-state conical intersection accessible for 3mUra+, which points towards an additional pathway for radiationless decay. 3-Methylation reduces the potential energy barrier mediating decay to the cation ground state, making it vanish and leading to a pathway that we expect will contribute to the fastest radiationless decay amongst all methylated uracil species studied to date. 1- and 5-methylation, on the other hand, give differences from uracil in detail only: ionisation potentials are slightly red-shifted and the potential energy barrier mediating decay to the cation ground state is small but almost unchanged. By comparing against CASSCF calculations, we establish XMS-CASPT2 is essential to correctly describe conical intersections for 3mUra+. Our calculations show how a chemical modification that seems relatively small electronically can nevertheless have a significant impact on the behaviour of electronic excited states: a single methylation in the 3′ position alters the behaviour of the RNA base uracil and appears to open an additional pathway for radiationless decay following ionisation and electronic excitation. | |
| dc.language.iso | eng | |
| dc.relation.ispartof | Physical Chemistry Chemical Physics, 2022, vol. 24, p. 27038-27046 | |
| dc.subject | Química | |
| dc.title | 3-Methylation alters excited state decay in photoionised uracil | |
| dc.type | journal article | |
| dc.date.updated | 2023-05-02T16:34:38Z | |
| dc.identifier.doi | 10.1039/D2CP03460C | |
| dc.identifier.idgrec | 157756 | |
| dc.embargo.terms | 1 year | en |
| dc.rights.accessRights | embargoed access |
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