3-Carboxy-5-(pyridinium-4-yl)benzoate: a redetermination

Abstract

The title compound, C13H9NO4, crystallizes in a zwitterionic form with the pyridine N atom protonated and the carboxyl OH group deprotonated. The benzene and pyridinium rings are inclined with a dihedral angle of 31.42 (14)° between them. A previous report of this stucture claims, we believe incorrectly, that neither of the carboxylate groups is deprotonated [Zhang et al. (2010). Acta Cryst. E66, o2928–o2928]. In the crystal, intermolecular O—H...O, N—H...O and weak C—H...O hydrogen-bonding interactions link adjacent molecules into a three-dimensional supramolecular network.