A 2:1 co-crystal of 2-methyl­benzoic acid and N,N′-bis­­(pyridin-4-ylmeth­yl)ethanedi­amide: crystal structure and Hirshfeld surface analysis

The asymmetric unit of the title 2:1 co-crystal, 2C8H8O2C14H14N4O2, comprises an acid molecule in a general position and half a diamide molecule, the latter being located about a centre of inversion. In the acid, the carboxylic acid group is twisted out of the plane of the benzene ring to which it is attached [dihedral angle = 28.51 (8)] and the carbonyl O atom and methyl group lie approximately to the same side of the molecule [hydroxy-O—C—C—C(H) torsion angle = 27.92 (17)]. In the diamide, the central C4N2O2 core is almost planar (r.m.s. deviation = 0.031 A˚ ), and the pyridyl rings are perpendicular, lying to either side of the central plane [central residue/pyridyl dihedral angle = 88.60 (5)]. In the molecular packing, three-molecule aggregates are formed via hydroxy-O— HN(pyridyl) hydrogen bonds. These are connected into a supramolecular layer parallel to (122) via amide-N—HO(carbonyl) hydrogen bonds, as well as methylene-C—HO(amide) interactions. Significant – interactions occur between benzene/benzene, pyridyl/benzene and pyridyl/pyridyl rings within and between layers to consolidate the three-dimensional packing.