Photochemistry of 2-Aminooxazole, a Hypothetical Prebiotic Precursor of RNA Nucleotides

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Authors	SZABLA Rafal Kazimierz TUNA Deniz GORA Robert W ŠPONER Jiří SOBOLEWSKI Andrzej L DOMCKE Wolfgang
Year of publication	2013
Type	Article in Periodical
Magazine / Source	Journal of Physical Chemistry Letters
MU Faculty or unit	Central European Institute of Technology
Citation
Web	http://pubs.acs.org/doi/abs/10.1021/jz401315e
Doi	http://dx.doi.org/10.1021/jz401315e
Field	Physical chemistry and theoretical chemistry
Keywords	EXCITED-STATE DYNAMICS; REPULSIVE (1)PI-SIGMA-ASTERISK STATES; CONICAL INTERSECTIONS; BUILDING-BLOCKS; AB-INITIO; PYRROLE; MOLECULES; SYSTEMS; PHOTOPHYSICS; DRIVEN
Description	2-Aminooxazole has recently been proposed as a hypothetical precursor of RNA nucleotides on early earth. UV irradiation was considered as a crucial environmental factor in the proposed reaction sequence. We report on state-of-the-art multireference quantum-chemical calculations elucidating the possible nonradiative deactivation channels of this compound. According to our findings, the gas-phase photochemistry of 2-aminooxazole should be dominated by the photodetachment of the hydrogen atom of the NH2 group via a (1)pi sigma(NH)* state leading either to ultrafast nonradiative deactivation, phototautomerization, or photodissociation of a hydrogen atom. We also identified a possible ring-opening reaction and a ring-puckering process that could occur after electronic excitation. These reactions seem to be less probable because they are driven by a higher-lying excited singlet state and are inherently slower than the hydrogen-atom dynamics.
Related projects:	CEITEC - Central European Institute of Technology