Structural characteristic of pyridine carboxylic acid adducts with squaric acid

In this work, squaric acid (3,4-dihydroxycyclobut-3-ene-1,2-dione) was used as a coformer to pyridine carboxylic acid cocrystallization. All of the multicomponent systems mentioned were obtained by cocrystallization from solution via slow solvent evaporation. Among the three newly prepared complexes are an example of a salt–cocrystal continuum – pyridinium-2-carboxylate squaric acid adduct (1) and two ionic complexes – pyridinium-3-carboxylic acid hydrogen squarate hemihydrate (2), and pyridinium-4-carboxylic acid hydrogen squarate (3). The dataset consists of CIF files showing the packing of molecules in the crystal lattice, which may be useful for further theoretical analyses.