Host–guest supra­molecular inter­actions between a resorcinarene-based cavitand bearing a –COOH moiety and acetic acid

The cavitand 5,11,17,23-tetra­methyl-4,24:6,10:12,16:18,22-tetra­kis­(methyl­enedi­oxy)resorcin[4]arene functionalized at the upper rim with a carb­oxy­lic acid group, CavCOOH-in, of chemical formula C(37)H(32)O(10), was synthesized in order to study its supra­molecular inter­actions with acetic acid in the solid state. Crystals suitable for X-ray diffraction analysis were obtained by slow evaporation of a di­chloro­methane–acetone solution of CavCOOH-in, to which glacial acetic acid had been added. The resulting compound, C(37)H(32)O(10)·2C(2)H(4)O(2) (1) crystallizes in the space group P [Image: see text] and its asymmetric unit consists of one mol­ecule of cavitand and two mol­ecules of acetic acid, one of which is encapsulated inside the aromatic cavity and disordered over two positions with a refined occupancy ratio of 0.344 (4):0.656 (4). The guest inter­acts with the host primarily through its methyl group, which (in both orientations) forms C—H⋯π inter­actions with the benzene rings of the cavitand. The crystal structure of 1 is dominated by O—H⋯O and C—H⋯O hydrogen bonding due to the presence of acetic acid and of the carb­oxy­lic group functionalizing the upper rim. Further stabilization is provided by offset π–π stacking inter­actions between the aromatic walls of adjacent cavitands [inter­centroid distance = 3.573 (1) Å].