organic compounds
4-Hydroxypyridine and terephthalic acid cocrystallize as a hydrate, 4-pyridone-terephthalic acid-water (2/1/2), 2C5H5NO·C8H6O4·2H2O, from a methanol-water solution. The molecules form a two-dimensional hydrogen-bonded network resulting in sheets of hydrogen-bonded molecules that lie parallel to the (10) plane. In contrast, 3-hydroxypyridine and terephthalic acid form the salt bis(3-hydroxypyridinium) terephthalate, 2C5H6NO+·C8H4O42-, giving rise to two-dimensional hydrogen-bonded sheets extending through the lattice parallel to the (10) plane.