Zwitterionic 4-carboxy-2-(pyridinium-2-yl)-1H-imidazole-5-carboxylate

Abstract

The title compound, C10H7N3O4, is zwitterionic, with one carboxyl group deprotonated and the pyridyl group protonated. The pyridine ring is close to coplanar with the imidazole ring, making a dihedral angle of 2.79 (8)°, this conformation being maintained by the presence of an intramolecular O—H...O hydrogen bond. In the crystal, two sets of N—H...O hydrogen bonds link the molecules through three conjoined cyclic hydrogen-bonding interactions, with two R 1 2(7) and one R 2 2(10) motifs, forming centrosymmetric cyclic dimers. These are linked through C—H...O hydrogen bonds, giving a supramolecular chain structure extending along the b-axis direction.