Cooperative effects on the formation of supramolecular synthons of thiohydantoin derivatives

In this paper we study the manifestations of cooperative effects in the formation of supramolecular synthons observed in some thiohydantoin derivatives crystals. Energetic and structural properties were analyzed from the fully optimized clusters employing a DFT/B3LYP level of calculations, which reproduce the main features of the stereochemistry and geometries of the synthons exhibited by reported crystalline structures. The calculations performed in this work have also evidenced that the cluster stabilization is mainly due to the existence of strong cooperative effects, which display energetic as well as geometrical manifestations. The stabilization energy and stabilization energy per monomer, that comprises all the intermolecular interactions between the individual molecules that form the clusters, were computed, showing that the supramolecular clusters of 5-sec-butyl-2-tioxoimidazolidin-4-one is less stable than the compound 5-isopropyl-2-tioxoimidazolidin-4-one by 1.16 Kcal/mol. Finally, through this work it has been also evidenced the need of employing large basis sets, including polarization and diffuse effects, in order to properly model all the interactions existing in systems bonded by weak interactions.