Energy frameworks and Hirshfeld surface analysis of supramolecular features in three new phosphoric triamides: tuning the intermolecular interactions via the substituent effect

Abstract

Supramolecular features observed in the crystal structures of phosphoric triamides are mostly influenced by strong hydrogen bond interaction N—H...OP. With the aid of substituent groups a scenario can be created where the crucial role of weak interactions towards the stabilization of the overall molecular packing, in the absence of any strong interaction can be evaluated more reliably. In this context, we have studied the supramolecular features of three new phosphoric triamides 1 – 3, with [NH]P(O)[N]2, [C(O)N]2P(O)[N] and [C(O)N]2P(O)[NH] segments, respectively. The compounds crystallize in the monoclinic space groups P21/c for 1 and 2 with one phosphoric triamide molecule and in P21 for 3 with two molecules in the asymmetric unit. The intermolecular interactions and their energies are evaluated using Hirshfeld surface and energy framework analyses revealing that the presence or absence of substituent groups such as 2-oxo-3-oxazolidinyl may serve as a crucial cohesive factor in the supramolecular assembly. The substituent alters the intermolecular interaction contributions, with subsequent changes in the formation of different weak interactions and molecular assemblies. The structure of 2 bearing this substituent displays the highest energy interaction without any strong interaction. The crystal packing is stabilized by a variety of interactions involving the weak hydrogen bonds with the PO and CO acceptor sites. The effects of substituent groups on the molecular frameworks formed by various intermolecular interactions are analyzed in detail via energy framework diagrams. Finally, a biological study by the molecular docking method indicates that the studied here compounds could be appropriate candidates as SARS-CoV-2 inhibitors.