Constructing in silico, molecular self-aggregates and micro- hydrated complexes of Oxirene and Thiirene

Oxirene, surmised to exist in the interstellar medium, was synthesized in the laboratory only recently. At the ωB97xD/6-311++G(2d,2p) level of density functional theory, it is demonstrated here that oxirene attains a local minimum on the potential energy surface; further, cooperative intermolecular hydrogen-bonding can lead to molecular self - aggregates and is conducive to ‘ micro-hydration ’ with at best three water molecules. Thiirene, its thia-analogue, at the same level of theory, displays similar however, somewhat weaker hydrogen bonding in its aggregates and water solvated complexes. Cogent molecular descriptors such as interaction energies for cluster formation, molecular electrostatic potential (MESP), effective atomic charges, infrared spectroscopic response, criticality profiles from the quantum theory of atoms in molecules (QTAIM), hydrogen-bond energies, reduced density gradient (RDG) maps identifying non-covalent interactions (NCI), all in unison characterize the aggregates. In particular, infrared spectra display frequency down-shifts for the hydrogen bonded C-H and for OH vibrations in solvated complexes. Should these aggregates exist in the interstellar medium, the present in silico endeavor provides adequate grounds for their identification.