2-[3-(1H-Benzimidazol-2-yl)propyl]-1H-benzimidazol-3-ium 3,4,5-trihydroxybenzoate–1,3-bis(1H-benzimidazol-2-yl)propane–ethyl acetate (2/1/2.94): co-crystallization between a salt, a neutral molecule and a solvent

Abstract

The chemical formula of the title compound, 2C17H17N4 +·2C7H5O5 −·C17H16N4·2.94C4H8O2, was established by X-ray diffraction of a single-crystal obtained by reacting 1,3-bis(benzimidazol-2-yl)propane (L) and gallic acid (HGal) in ethyl acetate. The molecular structure can be described as a salt (HL)+(Gal)− co-crystallized with a molecule L, with a stoichiometric relation of 2:1. Moreover, large voids in the crystal are filled with ethyl acetate, the amount of which was estimated by using a solvent mask during structure refinement, affording the chemical formula (HL +·Gal−)2·L·(C4H8O2)2.94. The arrangement of components in the crystal is driven by O—H...O, N—H...O and O—H...N hydrogen bonds rather than by π–π or C—H...π interactions. In the crystal, molecules and ions shape the boundary of cylindrical tunnels parallel to [100] via R (rings) and D (discrete) supramolecular motifs. These voids, which account for about 28% of the unit-cell volume, contain disordered solvent molecules.