From formamide to nucleobases by meteorite impacts

Laser sparking of melted formamide ice in the presence of FeNi meteorite material produces two nitrogen-containing products from which it is possible to form diaminomaleonitrile, a compound thought to play a key role in the synthesis of nucleobases. Formamide is relatively abundant in space, as a hydrolysis product of hydrogen cyanide, and it has been proposed that icy formamide on meteorites or comets can be converted to nucleobases when these extraterrestrial bodies crash into the atmosphere of a planet. This reaction was set up to mimic the impact.

Svatopluk Civis, Judit Sponer and colleagues from the Academy of Sciences of the Czech Republic and the Central European Institute of Technology in the Czech Republic described their work in Journal of the American Chemical Society. They mixed frozen formamide with small particles of the FeNi meteorite Campo del Cielo and subjected the mixture to periodic laser pulses, at a rate of 10 every 20 minutes. The reaction products were analysed by IR spectroscopy and supported by quantum chemical calculations.

The evaporated formamide existed as dimers, then laser sparking led to the formation of 2-amino-2-hydroxy-acetonitrile (AHC) and 2-amino-2-hydroxy-malononitrile (AHM) by reaction of formamide and cyano radicals. These products were only found when the meteoritic material was present.

Further calculations indicated the existence of a spontaneous reaction from formamide to 2,3-diaminomaleonitrile via AHC and AHM. 2,3-Diaminomaleonitrile is a potential precursor of purine bases during the photochemical prebiotic synthesis of nucleobases. This novel reaction mechanism might have been in play in space during high-energy impacts of meteorites with planetary atmospheres, creating one of the building blocks of Life.