Wang Jia, Nikolayev Anatoliy A, Marks Joshua H, Turner Andrew M, Chandra Sankhabrata, Kleimeier N Fabian, Young Leslie A, Mebel Alexander M, Kaiser Ralf I
W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States.
Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States.
J Am Chem Soc. 2024 Oct 7. doi: 10.1021/jacs.4c09449.
Nitrogen-substituted polycyclic aromatic hydrocarbons (NPAHs) are not only fundamental building blocks in the prebiotic synthesis of vital biomolecules such as amino acids and nucleobases of DNA and RNA but also a potential source of the prominent unidentified 6.2 μm interstellar absorption band. Although NPAHs have been detected in meteorites and are believed to be ubiquitous in the universe, their formation mechanisms in deep space have remained largely elusive. Here, we report the first bottom-up formation pathways to the simplest prototype of NPAHs, indole (CHN), along with its building blocks pyrrole (CHN) and aniline (CHNH) in low-temperature model interstellar ices composed of acetylene (CH) and ammonia (NH). Utilizing the isomer-selective techniques of resonance-enhanced multiphoton ionization and tunable vacuum ultraviolet photoionization reflectron time-of-flight mass spectrometry, indole, pyrrole, and aniline were identified in the gas phase, suggesting that they are promising candidates for future astronomical searches in star-forming regions. Our laboratory experiments utilizing infrared spectroscopy and mass spectrometry in tandem with electronic structure calculations reveal critical insights into the reaction pathways toward NPAHs and their precursors, thus advancing our fundamental understanding of the interstellar formation of aromatic proteinogenic amino acids and nucleobases, key classes of molecules central to the .
氮取代多环芳烃（NPAHs）不仅是重要生物分子如DNA和RNA的氨基酸及核碱基等益生元合成的基本组成部分，也是显著的未识别6.2微米星际吸收带的潜在来源。尽管NPAHs已在陨石中被检测到且被认为在宇宙中普遍存在，但其在深空中的形成机制仍 largely elusive。在此，我们报告了在由乙炔（CH）和氨（NH）组成的低温星际冰模型中，通往NPAHs最简单原型吲哚（CHN）及其组成部分吡咯（CHN）和苯胺（CHNH）的首个自下而上的形成途径。利用共振增强多光子电离和可调谐真空紫外光电离反射式飞行时间质谱的异构体选择性技术，在气相中鉴定出了吲哚、吡咯和苯胺，这表明它们是未来在恒星形成区域进行天文搜索的有前景的候选物。我们利用红外光谱和质谱并结合电子结构计算的实验室实验揭示了通往NPAHs及其前体的反应途径的关键见解，从而推进了我们对芳香族蛋白质氨基酸和核碱基星际形成的基本理解，这些分子是生命的关键类别。
