Synthesis of urea on the surface of interstellar water ice clusters. A quantum chemical study
Perrero, Jessica (Universitat Autònoma de Barcelona. Departament de Química)
Rimola Gibert, Albert (Universitat Autònoma de Barcelona. Departament de Química)

Date:	2024
Abstract:	Urea is a prebiotic molecule that has been detected in few sources of the interstellar medium (ISM) and in Murchison meteorite. Being stable against ultraviolet radiation and high-energy electron bombardment, urea is expected to be present in interstellar ices. Theoretical and experimental studies suggest that isocyanic acid (HNCO) and formamide (NHCHO) are possible precursors of urea. However, uncertainties still exist regarding its formation routes. Previous computational works characterised urea formation in the gas phase or in presence of few water molecules by reaction of formamide with nitrogen-bearing species. In this work, we investigated the reaction of HNCO + NH on an 18 water molecules ice cluster model mimicking interstellar ice mantles by means of quantum chemical computations. We characterised different mechanisms involving both closed-shell and open-shell species at B3LYP-D3(BJ)/ma-def2-TZVP level of theory, in which the radical-radical HNCO + NH coupling has been found to be the most favourable one due to being almost barrierless. In this path, the presence of the icy surfaces is crucial for acting as reactant concentrators/suppliers, as well as third bodies able to dissipate the energy liberated during the urea formation.
Grants:	European Commission 811312 European Commission 865657 Agencia Estatal de Investigación PID2021-126427NB-I00
Note:	Altres ajuts: acords transformatius de la UAB
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Ices ; Interplanetary medium ; Organic chemistry ; Prebiotic chemistry
Published in:	Icarus, Vol. 410 (March 2024) , art. 115848, ISSN 1090-2643

DOI: 10.1016/j.icarus.2023.115848

8 p, 1.6 MB

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