Issue 35, 2022

Photochemistry of 2-thiooxazole: a plausible prebiotic precursor to RNA nucleotides

Abstract

Potentially prebiotic chemical reactions leading to RNA nucleotides involve periods of UV irradiation, which are necessary to promote selectivity and destroy biologially irrelevant side products. Nevertheless, UV light has only been applied to promote specific stages of prebiotic reactions and its effect on complete prebiotic reaction sequences has not been extensively studied. Here, we report on an experimental and computational investigation of the photostability of 2-thiooxazole (2-TO), a potential precursor of pyrimidine and 8-oxopurine nucleotides on early Earth. Our UV-irradiation experiments resulted in rapid decomposition of 2-TO into unidentified small molecule photoproducts. We further clarify the underlying photochemistry by means of accurate ab initio calculations and surface hopping molecular dynamics simulations. Overall, the computational results show efficient rupture of the aromatic ring upon the photoexcitation of 2-TO via breaking of the C–O bond. Consequently, the initial stage of the divergent prebiotic synthesis of pyrimidine and 8-oxopurine nucleotides would require periodic shielding from UV light either with sun screening chromophores or through a planetary scenario that would protect 2-TO until it is transformed into a more stable intermediate compound, e.g. oxazolidinone thione.

Graphical abstract: Photochemistry of 2-thiooxazole: a plausible prebiotic precursor to RNA nucleotides

Supplementary files

Article information

Article type
Paper
Submitted
11 Jul 2022
Accepted
20 Aug 2022
First published
23 Aug 2022
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2022,24, 21406-21416

Photochemistry of 2-thiooxazole: a plausible prebiotic precursor to RNA nucleotides

L. Bertram, S. J. Roberts, M. W. Powner and R. Szabla, Phys. Chem. Chem. Phys., 2022, 24, 21406 DOI: 10.1039/D2CP03167A

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