Laboratory Rotational Spectroscopy And Interstellar Search For The Protein Precursor 4-oxobutanenitrile (HCOCH2CH2CN)

Understanding the presence and distribution of prebiotic precursors in the interstellar medium (ISM) is key to tracing the chemical origins of life. Among them, 4-oxobutanenitrile (HCOCH₂CH₂CN) has been identified in laboratory simulations as a plausible intermediate in the formation of glutamic acid, a proteinogenic amino acid.

Here, we report its gas-phase rotational spectrum, measured using two complementary techniques: chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy (2−18 GHz) and free-jet millimeter-wave (FJ−AMMW) absorption spectroscopy (59.6−80 GHz).

Quantum chemical calculations revealed nine low-energy conformers, of which the TC conformer was assigned based on the measured spectra. The resulting spectroscopic parameters were used to search for the molecule in the ultradeep spectral survey of the G+0.693-0.027 molecular cloud, located in the Galactic Center.

No signal attributable to 4−oxobutanenitrile was detected. A stringent upper limit to its column density was derived (N< 4 ×10¹² cm⁻²), corresponding to a molecular abundance of < 2.9 ×10⁻¹¹ relative to H₂.

This upper limit lies well below the observed abundances of simpler structurally related species containing −HCO and −CN groups, underscoring the challenge of detecting increasingly complex prebiotic molecules in the ISM and the need for future, more sensitive astronomical facilities.

V. M. Rivilla, E. R. Alonso, W. Song, A. Insausti, A. Maris, F. J. Basterretxea, S. Melandri, I. Jiménez-Serra, E. J. Cocinero

Comments: Accepted in Monthly Notices of the Royal Astronomical Society
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2512.11500 [astro-ph.GA] (or arXiv:2512.11500v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2512.11500
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Submission history
From: Victor Manuel Rivilla
[v1] Fri, 12 Dec 2025 11:52:59 UTC (3,841 KB)
https://arxiv.org/abs/2512.11500

Astrobiology, Astrochemistry,