Kynurenic Acid Monohydrate

In the structure of the title compound, 4-hydroxy-2-quinolinecarboxylic acid monohydrate, C₁₀H₇NO₃.H₂O, the carboxyl group is ionized and the ring N atom is protonated giving it a positive charge. The molecule is almost planar. The crystal structure is stabilized by both intermolecular O—H...O and N—H...O hydrogen bonds involving the solvated water molecule and ring stacking.

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