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Brister_MM UMP_ms_2019.pdf (900.84 kB)

Excited-State Dynamics in the RNA Nucleotide Uridine 5’-Monophosphate Investigated by Femtosecond Broadband Transient Absorption Spectroscopy

preprint
submitted on 19.03.2019, 01:17 and posted on 19.03.2019, 19:27 by Matthew M. Brister, Carlos Crespo-Hernández

Damage to RNA from ultraviolet radiation induce chemical modifications to the nucleobases. Unraveling the excited states involved in these reactions is essential, but investigations aimed at understanding the electronic-energy relaxation pathways of the RNA nucleotide uridine 5’-monophosphate (UMP) have not received enough attention. In this Letter, the excited-state dynamics of UMP is investigated in aqueous solution. Excitation at 267 nm results in a trifurcation event that leads to the simultaneous population of the vibrationally-excited ground state, a longlived 1nOπ* state, and a receiver triplet state within 200 fs. The receiver state internally convert to the long-lived 3ππ* state in an ultrafast time scale. The results elucidate the electronic relaxation pathways and clarify earlier transient absorption experiments performed for uracil derivatives in solution. This mechanistic information is important because long-lived nπ* and ππ* excited states of both singlet and triplet multiplicities are thought to lead to the formation of harmful photoproducts.

Funding

National Science Foundation (Grant No. CHE-1800052)

History

Email Address of Submitting Author

cxc302@case.edu

Institution

Case Western Reserve University

Country

United States

ORCID For Submitting Author

0000-0002-3594-0890

Declaration of Conflict of Interest

The authors declare no competing financial interest.

Version Notes

Submitted manuscript.

Exports