Hydrogen bonding in quinolinium-4-carboxylate dihydrate.

The title acid, C10H7NO2.2H2O, crystallized in the non-centrosymmetric space group Cc with one zwitterionic organic molecule and two water molecules in the asymmetric unit. One N-H...O and four O-H...O hydrogen bonds are present in this structure, with donor-acceptor distances ranging from 2.688 (2) to 2.852 (3) A. These hydrogen bonds generate a three-dimensional network. Structural comparisons are made with anhydrous quinoline-4-carboxylic acid.