Benzene-1,3,5-tri­carb­oxy­lic acid–pyridinium-2-olate (1/3)

The asymmetric unit of the title compound, C₉H₆O₆·3C₅H₅NO, contains one benzene-1,3,5-tri­carb­oxy­lic acid mol­ecule (BTA) and three pyridin-2-ol mol­ecules each present in the zwitterion form. In the crystal, these entities are linked through O—H...O⁻ and N⁺—H...O⁻ hydrogen bonds, forming sheets parallel to (10-1). These layers contain macrocyclic rings of composition [BTA]₂[pyol]₆ and with graph-set notation R⁶₈(44), which are stacked along c through π–π inter­actions [inter-centroid distances = 3.536 (2)–3.948 (3) Å]. They are inter­connected by N⁺—H...O⁻ hydrogen-bonded chains of pyridin-2-ol mol­ecules running parallel to c, forming a three-dimensional network. There are also C—H...O hydrogen bonds present which reinforce the three-dimensional structure.