organic compounds
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In the title molecular salt, C6H6NO2+.C4H3O4−, the 2-carboxypyridinium cation is essentially planar with a maximum deviation of 0.003 (3) Å. In the crystal, adjacent cations and anions are linked by an extensive system of weak N—HO, O—HO and C—HO interactions, forming a layer parallel to the ab plane.