Hydrogen cyanide frozen in ice may have sparked life on Earth

Computer simulations published in ACS Central Science found that frozen hydrogen cyanide crystals can have reactive surfaces that convert HCN into hydrogen isocyanide, a change that the researchers report could help form more complex prebiotic molecules.

Hydrogen cyanide can freeze into crystals at low temperatures, and new computer modeling suggests those icy surfaces can be chemically active in ways not expected for extreme cold. The simulations, reported in ACS Central Science, examined how frozen HCN might behave and why it is of interest for the origin of life. Hydrogen cyanide is common in space and can produce polymers, amino acids and nucleobases when it reacts with water. The research team included Marco Capelletti, Hilda Sandström and Martin Rahm, who is the corresponding author of the study. Key findings: - The study modeled a stable hydrogen cyanide crystal shaped like a long cylinder about 450 nanometers long with a rounded base and a multifaceted top. - Simulations indicate that certain crystal surfaces are unusually reactive even at very low temperatures. - The researchers identified two reaction pathways on those surfaces that can convert hydrogen cyanide into hydrogen isocyanide, a more reactive form. - The conversion timescale depends on temperature and could range from minutes to several days according to the models. - The presence of hydrogen isocyanide on crystal surfaces is reported to increase the likelihood of forming more complex prebiotic molecules. - The team proposes laboratory experiments, such as crushing HCN crystals with water present to expose fresh surfaces, to test the simulation predictions. Summary: The results suggest frozen hydrogen cyanide crystals may provide surface chemistry that helps make more reactive compounds relevant to early prebiotic chemistry. The next steps reported by the authors are laboratory experiments to test whether fresh crystal surfaces indeed promote formation of more complex molecules; further details and outcomes are undetermined at this time.