Astrochemistry

What Drives The Formation Of Unsaturated Molecules In The Interstellar Medium?

By Keith Cowing
Status Report
Chemical Science
January 20, 2025
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What Drives The Formation Of Unsaturated Molecules In The Interstellar Medium?
Evidence for the formation of two-center one-electron (2c–1e) bonds in the predissociation complexes of the radical cations in ethanolamine (A), propanol (B), butanenitrile (C), and glycolamide (D). The ELF basins are shown in the left column, the projections into the heavy atom planes are shown in the second column, the spin densities for the unpaired electrons are shown in the third column, and the 2c–1e AdNDP orbitals are shown in the right column. — Chemical Science

We present a computational investigation into the fragmentation pathways of ethanolamine (C2H7NO, EtA), propanol (C3H8O, PrO), butanenitrile (C4H7N, BuN), and glycolamide (C2H5NO2, GlA)—saturated organic molecules detected in the interstellar medium (ISM), particularly in the molecular cloud complex Sagittarius B2 (Sgr B2) and its molecular cloud G+0.693-0.027.

Using electron-impact ionization data and Born–Oppenheimer molecular dynamics simulations, we investigate how cosmic rays, cosmic-ray-induced UV fields, and shock-induced heating can induce the fragmentation of these molecules, resulting in the formation of unsaturated species with extended π-bond networks.

Despite the attenuation of external UV radiation in G+0.693-0.027, these energetic processes are capable of driving partial transformations of saturated into unsaturated molecules, supporting the coexistence of species like EtA and GlA alongside unsaturated nitriles such as cyanoacetylene (HC3N), cyanopropyne (CH3C3N), and cyanoallene (CH2CCHCN).

Our findings underscore the significance of high-energy mechanisms in enhancing chemical complexity within molecular clouds and offer insights into the pathways that govern the evolution of organic molecules in the ISM.

More π, please: What drives the formation of unsaturated molecules in the interstellar medium?, Chemical Science (open access)

Astrobiology, Astrochemistry,

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻