Abstract
Formamide has been recognized in the literature as a key species in the formation of the complex molecules of life, such as nucleobases. Furthermore, several studies reported the impact of mineral phases as catalysts for its decomposition/polymerization processes, increasing the conversion and also favoring the formation of specific products. Despite the progresses in the field, in situ studies on these mineral-catalyzed processes are missing. In this work, we present an in situ UV-Raman characterization of the chemical evolution of formamide over amorphous SiO2 samples, selected as a prototype of silicate minerals. The experiments were carried out after reaction of formamide at 160 °C on amorphous SiO2 (Aerosil OX50) either pristine or pre-calcined at 450 °C, to remove a large fraction of surface silanol groups. Our measurements, interpreted on the basis of density functional B3LYP-D3 calculations, allow to assign the spectra bands in terms of specific complex organic molecules, namely, diaminomaleonitrile (DAMN), 5-aminoimidazole (AI), and purine, showing the role of the mineral surface on the formation of relevant prebiotic molecules.
Highlights
The understanding of atomistic processes underlying the origin of life is nowadays a hot multidisciplinary research topic [1]
UV-Raman collectedin insitu situduring during1212h h reaction of formamide at UV-Raman(λ=
DFT simulation describingofthe the formation of reaction, testifying ofthe progressive formation and allows accumulation related nucleobases via dehydrative decomposition of formamide
Summary
The understanding of atomistic processes underlying the origin of life is nowadays a hot multidisciplinary research topic [1]. The last point is of particular interest with respect to the formation of the building blocks of biopolymers: HCN polymerization can lead to nucleobases as originally discovered by Orò for adenine [8], i.e., the main constituents of nucleic acids, involving stable intermediate compounds [6,9,10,11,12]. This reactions cascade can take place in bulk formamide in Molecules 2020, 25, 2274; doi:10.3390/molecules25102274 www.mdpi.com/journal/molecules
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