Theoretical Study of Interstellar Heterocyclic Molecules

Because of their importance in biological systems, in our understanding of the solar system and in other applications, seven heterocycles; furan, imidazole, pyridine, pyrimidine, pyrrole, quinoline and isoquinoline have been astronomically searched for in different molecular clouds.

But all the efforts were in vain leaving us with only the upper limits of their column densities. Bothered by their unsuccessful detection, here we systematically examined the energy and stability of these interstellar molecules and looked for the probable candidates for astronomical searches in between the same isomeric heterocycle group. High-level quantum chemical calculations have been used to determine accurate enthalpy of formation, optimized energy and relative energy for 67 molecules from different isomeric groups of these heterocycles.

From the results, all the 7 heterocycles so far searched remain the best candidates for astronomical observations as they are found to be most stable molecules in their respective groups. Dipole moment components of all these species are calculated to make a comparative study between the same isomeric group molecules. Accurate rotational constants have been theoretically calculated for all the 67 molecular species examined in this study.

Emmanuel E. Etim, Prasanta Gorai, Ankan Das
(Submitted on 13 Jun 2019)

Comments: 21 pages, 9 Tables, 6 Figures
Subjects: Astrophysics of Galaxies (astro-ph.GA); Chemical Physics (physics.chem-ph)
Cite as: arXiv:1906.05732 [astro-ph.GA] (or arXiv:1906.05732v1 [astro-ph.GA] for this version)
Submission history
From: Emmanuel Etim
[v1] Thu, 13 Jun 2019 14:50:24 UTC (1,173 KB)
https://arxiv.org/abs/1906.05732
Astrobiology, Astrochemistry