Cocrystallization of adamantane-1,3-dicarboxylic acid and 4,4′-bipyridine

The cocrystallization of adamantane-1,3-dicarboxylic acid (adc) and 4,4′-bipyridine (4,4′-bpy) yields a unique 1:1 cocrystal, C ₁₂H₁₆O₄·C₁₀H ₈N₂, in the C2/c space group, with half of each mol-ecule in the asymmetric unit. The mid-point of the central C - C bond of the 4,4′-bpy mol-ecule rests on a center of inversion, while the adc mol-ecule straddles a twofold rotation axis that passes through two of the adamantyl C atoms. The constituents of this cocrystal are joined by hydrogen bonds, the stronger of which are O - H⋯N hydrogen bonds [O⋯N = 2.6801 (17) Å] and the weaker of which are C - H⋯O hydrogen bonds [C⋯O = 3.367 (2) Å]. Alternate adc and 4,4′-bpy mol-ecules engage in these hydrogen bonds to form zigzag chains. In turn, these chains are linked through π-π inter-actions along the c axis to generate two-dimensional layers. These layers are neatly packed into a stable crystalline three-dimensional form via weak C - H⋯O hydrogen bonds [C⋯O = 3.2744 (19) Å] and van der Waals attractions.