Photochemical Steps in the Prebiotic Synthesis of Purine Precursors from HCN

0394881 - ÚOCHB 2014 RIV DE eng J - Článek v odborném periodiku
Boulanger, E. - Anoop, A. - Nachtigallová, Dana - Thiel, W. - Barbatti, M.
Photochemical Steps in the Prebiotic Synthesis of Purine Precursors from HCN.
Angewandte Chemie - International Edition. Roč. 52, č. 31 (2013), s. 8000-8003. ISSN 1433-7851. E-ISSN 1521-3773
Institucionální podpora: RVO:61388963
Klíčová slova: computational chemistry * hydrogen cyanide chemistry * photochemistry * prebiotic synthesis * simulations
Kód oboru RIV: CF - Fyzikální chemie a teoretická chemie
Impakt faktor: 11.336, rok: 2013

Photoconversion of HCN tetramer into an imidazole derivative is one of the most likely routes for prebiotics. Although this reaction is known since the 1960’s, its photochemical intermediates have never been revealed. Using a combination of theoretical methods (excited and ground state reaction paths; QM/MM dynamics; RRKM chemical kinetics), it was shown that, among a number of different reaction pathways, only a specific sequence of steps is compatible with the experimental conditions. Multi-step mechanism for the DAMN→AICN reaction that is thermodynamically and kinetically compatible with the available experimental data was identified. This mechanism rationalizes the observed ketenimine absorption and its disappearance upon heating as well as the preference for the trans isomer in the photostationary state. It is consistent with a cold environment that is required to support a high HCN concentration, and it is also consistent with the lack of luminescence during the reaction. Finally, from a more general perspective, the ultrafast energy dissipation revealed by simulations provides insight into the time scales that are relevant in photochemical prebiotic reactions.
Trvalý link: http://hdl.handle.net/11104/0223116