Alpha and beta phases of 4-aminoquinoline-2-carboxylic acid monohydrate

The structures of two phases of the title compound, C10H8N2O2.H2O, are reported. While the organic molecule has very nearly the same molecular geometry in the two phases, the hydrogen-bonding patterns are quite different. In each case, however, a three-dimensional network of hydrogen bonds is formed. In the alpha phase, six N-H ... O hydrogen bonds have donor-acceptor distances ranging from 2.681 (2) to 3.206 (2) A, while three O-H...O hydrogen bonds range from 2.837 (2) to 3.173 (2) A, and in the beta phase, four N-H ... O hydrogen bonds range from 2.668 (2) to 3.038 (2) A, while two O-H...O hydrogen bonds are 2.951 (3) and 2.959 (3) A in length.