Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822.
W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822.
Proc Natl Acad Sci U S A. 2022 Dec 20;119(51):e2217329119. doi: 10.1073/pnas.2217329119. Epub 2022 Dec 12.
Although methanediamine (CH(NH)) has historically been the subject of theoretical scrutiny, it has never been isolated to date. Here, we report the preparation of methanediamine (CH(NH))-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 (ĊHNH) and amino ([Formula: see text]) 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 (CHNHNH) was not observed. The molecular formula was confirmed to be CHN 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.
尽管甲二胺（CH(NH)）在历史上一直是理论研究的对象，但迄今为止尚未将其分离出来。在这里，我们报告了甲二胺（CH(NH)）的制备，这是最简单的二胺。由氨和甲胺组成的低温星际模拟冰暴露于高能电子下，高能电子可作为银河宇宙射线轨迹中产生的次级电子的替代物。这些实验条件模拟了冷分子云内的条件，导致自由基的形成，并引发氨甲基（ĊHNH）和氨基（[Formula: see text]）自由基化学。利用可调谐光致电离反射飞行时间质谱（PI-ReToF-MS）进行异构体特异性分配，可以在升华时在气相中鉴定出甲二胺，而其异构体甲基肼（CHNHNH）则未观察到。通过使用同位素标记的反应物，确认其分子公式为 CHN。甲二胺是最简单的含有 NCN 部分的分子，可能是异质环和芳香族系统（如核碱基）无生物形成的重要中间体，这些系统都含有 NCN 部分。
