Origin & Evolution of Life

Metal Catalysis Acting on Nitriles in Early Earth Hydrothermal Systems

By Keith Cowing
Press Release
July 31, 2023
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Metal Catalysis Acting on Nitriles in Early Earth Hydrothermal Systems
Effects observed with FeS: (a) aggregated and broken mineral particles that did not mineralize but still underwent recrystallization; (b) vial with both chemical gardening of FeS and malononitrile complex (with both acicular needles and nodules as a black mineral), and abiotic film growth (orange). These reference pictures were taken directly after 48 h at 90 °C. A 0.5 cm scale bar is included for reference. — Life

Hydrothermal systems are areas in which heated fluids and organic molecules rush through basaltic material rich in metals and minerals. By studying malononitrile and acetonitrile, we examine the effects of metal and mineral nanoparticles on nitrile compounds in anoxic, hydrothermal conditions representing a prebiotic environment of early Earth.

Polymerization, reduction, cyclization, and a phenomenon colloquially known as ‘chemical gardening’ (structure building via reprecipitation of metal compounds or complexing with organics) are all potential outcomes with the addition of metals and minerals. Reduction occurs with the addition of rhodium (Rh) or iron (II) sulfide (FeS), with positive identification of ethanol and ethylamine forming from acetonitrile reduction. We find that polymerization and insoluble product formation were associated with oxide minerals, metallic nickel (Ni), and metallic cobalt (Co) acting as catalysts.

Oxide minerals strongly promoted polymerization into insoluble, tar-like products of nitriles. FeS, iron-nickel alloy (FeNi), and rhodium are unique cases that appear to act as reagents by actively participating in chemical gardening without returning to their initial state. Further, FeS tentatively had a phase change into the mineral parabutlerite. This research aims to identify metals and metal minerals that could best serve nitrile catalysis and reactions on early Earth.

Metal Catalysis Acting on Nitriles in Early Earth Hydrothermal Systems, Life (open access)


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