Preparation of methanediamine (CH₂(NH₂)₂)—A precursor to nucleobases in the interstellar medium

Although methanediamine (CH₂(NH₂)₂) has historically been the subject of theoretical scrutiny, it has never been isolated to date. Here, we report the preparation of methanediamine (CH₂(NH₂)₂)—the simplest diamine. Low-temperature interstellar analog ices composed of ammonia and methylamine were exp...

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Published inProceedings of the National Academy of Sciences - PNAS Vol. 119; no. 51; pp. 1 - 7
Main Authors Marks, Joshua H., Wang, Jia, Fortenberry, Ryan C., Kaiser, Ralf I.
Format Journal Article
LanguageEnglish
Published United States National Academy of Sciences 20.12.2022
Subjects
Ammonia
Bases (nucleic acids)
Cold Temperature
Cosmic Radiation
Cosmic rays
Diamines
Electrons
Galactic cosmic rays
Interstellar matter
Ions
Isomers
Low temperature
Mass Spectrometry
Mass spectroscopy
Methylamine
Methylhydrazine
Molecular clouds
Photoionization
Physical Sciences
Radicals
Sublimation
Vapor phases
radical reactions
ionization potentials
reaction mechanism
interstellar ice
astrochemistry
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Summary:Although methanediamine (CH₂(NH₂)₂) has historically been the subject of theoretical scrutiny, it has never been isolated to date. Here, we report the preparation of methanediamine (CH₂(NH₂)₂)—the simplest diamine. Low-temperature interstellar analog ices composed of ammonia and methylamine were exposed to energetic electrons which act as proxies for secondary electrons produced in the track of galactic cosmic rays. These experimental conditions, which simulate the conditions within cold molecular clouds, result in radical formation and initiate aminomethyl (ĊH₂NH₂) and amino (NH₂) radical chemistry. Exploiting tunable photoionization reflectron time-of-flight mass spectrometry (PI-ReToF-MS) to make isomer-specific assignments, methanediamine was identified in the gas phase upon sublimation, while its isomer methylhydrazine (CH₃NHNH₂) was not observed. The molecular formula was confirmed to be CH₆N₂ through the use of isotopically labeled reactants. Methanediamine is the simplest molecule to contain the NCN moiety and could be a vital intermediate in the abiotic formation of heterocyclic and aromatic systems such as nucleobases, which all contain the NCN moiety.
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Edited by Robert Field, Massachusetts Institute of Technology, Cambridge, MA; received October 10, 2022; accepted November 5, 2022
ISSN:0027-8424
1091-6490
1091-6490
DOI:10.1073/pnas.2217329119