Zwitterionic 4-piperidinecarboxylic acid monohydrate.

The title compound, 4-piperidiniocarboxylate (isonipecotic acid), crystallizes as a zwitterion and incorporates one water molecule, i.e. C(6)H(11)NO(2).H(2)O. The piperidine ring adopts a chair conformation and the alpha-carboxylate group is oriented in the equatorial position. The combination of the interactions between the alpha-amino and alpha-carboxylate groups and the water molecules builds a three-dimensional assembly of hydrogen bonds.