Energetic and Spectroscopic Insights into the C3H6O2 Isomer Family for Astrochemical Purposes

A computational protocol based on the minimum energy principle has been applied to the C3H6O2 isomer family, providing accurate energetic hierarchies and spectroscopic parameters relevant to astrochemistry. The calculations predict propanoic acid as the most stable isomer, followed by methyl acetate, ethyl formate, 1-hydroxyacetone, 2- and 3-hydroxypropanal. The protocol delivers computed rotational spectroscopic parameters, and their accuracy has been benchmarked against literature results for seven C3H6O2 isomers and further validated through new high-frequency measurements of glycidol, c-C2H3O‑CH2OH. Its rotational spectrum has been recorded in the 65–120, 146–330, and 440–520 GHz ranges, extending the frequency coverage with respect to previous studies. The improved set of spectroscopic parameters for glycidol provides a basis for future radioastronomical searches in the interstellar medium. Furthermore, the benchmarking strategy establishes reliable uncertainties for the species not yet characterized in the laboratory.