19 Quantum chemical studies on the formamide-based origin of life

Abstract

Recently, we have applied quantum chemical calculations to supplement the experimentally available information on the prebiotic synthesis of nucleic acids with a molecular-level insight into the structure, energy, electronic structure, and spectroscopic properties of the compounds involved in these processes. In particular, in the presentation, we will focus on our studies related to the formamide-based origin of life. We will discuss the mechanism of the formamide-based synthesis of nucleobases suggested by Saladino et al. (2007). We show that the computed activation energy of the experimentally proposed pathway is noticeably higher than that of the HCN-based synthetic route, but it is still feasible under the experimental conditions of the Saladino synthesis. Our calculations thus demonstrate that the experimentally suggested reaction path without the involvement of aminoimidazole–carbonitrile intermediates is also a viable alternative for the nonaqueous synthesis of nucleobases (Šponer et al., 2012). Further, we have used quantum chemical calculations to interpret the results of high-resolution infrared spectra obtained for an icy mixture of formamide and an FeNi meteoritic material treated with high-energy laser pulses (Ferus et al., 2012). In this joint experimental-theoretical study, we have identified a new reaction channel for the formation of nucleobases from formamide ices, which might be highly relevant for the formation of nucleobases under a high-energy impact event, e.g. an atmospheric breakup of an icy extraterrestrial body. We have also shown that the theoretically proposed reaction route is highly realistic, because we could detect some of the theoretically proposed key intermediates using high-resolution IR spectroscopy. Thus, formation of nucleobases from formamide in a high-energy impact event may give new, astrobiological dimensions to the increasingly popular idea of formamide-based life originally suggested by Saladino et al., 2007.