Abstract
Abstract
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 mechanisms such as ion-molecule reactions that govern their evolution in the astrophysical environments. Employing an ion trap technique in conjunction with electronic structure calculations, we unravel multiple barrier-less reactions between gas-phase pyrimidine cations (C
4
H
4
N
2
+
) and acetylene (C
2
H
2
) which form a hitherto unreported endocyclic- N-PAH (C
8
H
7
N
2
+
) at room temperature. The present measurements on reactions involving a double-nitrogen substituted aromatic heterocycle have implications on the astrochemistry of both Titan’s atmosphere and the interstellar medium.