Nitrogen-bearing polycyclic aromatic hydrocarbons (N-PAHs) are key precursors to complex organic molecules in both the interstellar medium and the nitrogen-rich planetary atmospheres.

Despite the recent detections of nitrogen-functionalized astromolecules, their formation pathways remain an open question. The discrepancies between their predicted and observed abundances point to unknown mechanism that govern their evolution in the astrophysical environments.

Employing an ion trap technique and electronic structure calculations, we unravel multiple barrier-less reactions between gas-phase pyrimidine cations (C4H4N+2) and acetylene (C2H2) which form an hitherto unreported endocyclic- N-PAHs (C8H7N+2).

The present measurements on reactions involving a double-nitrogen subsituted aromatic heterocycle have implications to the astrochemistry of both the Titan’s atmosphere and interstellar medium.

Siddhartha S. Payra, Pratikkumar Thakkar, Shiv Gupta, Ruth Ann Mathews, Yash Lenka, Saurav Dutta, Nihar Ranjan Behera, Krishna R. Nandipati, G. Aravind

Subjects: Astrophysics of Galaxies (astro-ph.GA); Chemical Physics (physics.chem-ph)
Cite as: arXiv:2605.14424 [astro-ph.GA](or arXiv:2605.14424v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2605.14424
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Submission history
From: Siddhartha S. Payra
[v1] Thu, 14 May 2026 06:14:07 UTC (13,108 KB)
https://arxiv.org/abs/2605.14424

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...