2-Aminonicotinic acid.

2-Aminonicotinic acid, C6H6N2O2, crystallized in the centrosymmetric space group P2(1)/c in the zwitterionic form. Intermolecular N--H...O hydrogen bonds with N...O distances of 2.652 (2) and 2.807 (2) A link molecules into two sets of zigzag chains propagating along the b axis. The two sets of chains are crosslinked by C--H...O interactions. The dihedral angle between the planes of adjacent molecules in a chain is 9.77 (7) degrees. An intramolecular N--H...O hydrogen bond is also present.