Photochemistry of 2-aminooxazole: a matrix-isolation and computational study of a putative key prebiotic molecule
Physical Chemistry Chemical Physics, cilt.27, sa.37, ss.20326-20333, 2025 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 27 Sayı: 37
- Basım Tarihi: 2025
- Doi Numarası: 10.1039/d5cp02936h
- Dergi Adı: Physical Chemistry Chemical Physics
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Chimica, Communication Abstracts, Compendex, INSPEC, MEDLINE
- Sayfa Sayıları: ss.20326-20333
- İstanbul Kültür Üniversitesi Adresli: Evet
Özet
2-Aminooxazole 1 is a key intermediate in plausible prebiotic pathways to activated pyrimidine ribonucleotides. However, its photochemistry and underlying reaction mechanism remain unclear. Here, we present a combined matrix-isolation infrared spectroscopic and computational investigation of the UV-induced photochemistry of 1. Narrowband irradiation at 220 nm of 1 isolated in cryogenic Ar or N2 matrices leads mainly to 3-amino-1-formyl nitrile ylide. Minor products included 3-amino-2-formyl-2H-azirine and, most likely, two tautomeric 2-iminooxazoles. The nitrile ylide photoreverts to 1 (380 nm), whereas 2-formyl-2H-azirine photoisomerizes to imidoylketene (320 nm). Spin–flip time-dependent density functional (SF-TDDFT) computations reveal a cascade of conical intersections following excitation to the S2 state of 1, providing a mechanistic explanation for the observed C–O ring-opening and predominant formation of the nitrile ylide. Overall, these findings elucidate the photoreactivity mechanism of 2-aminooxazole and can contribute to understanding the behavior of this pivotal molecule under early Earth UV conditions.