title: 2-Carb-oxy-pyridinium maleate.
abstract: In the title mol-ecular salt, C(6)H(6)NO(2) (+) (.)C(4)H(3)O(4) (-), the 2-carb-oxy-pyridinium cation is essentially planar with a maximum deviation of 0.003 (3) Å. In the crystal, adjacent cations and anions are linked by an extensive system of weak N-H⋯O, O-H⋯O and C-H⋯O inter-actions, forming a layer parallel to the ab plane.
authors.affiliation: Department of Physics, Panimalar Engineering College, Chennai 600 123,  India.
authors.forename: P
authors.initials: P
authors.lastname: Pandi
authors.forename: G
authors.initials: G
authors.lastname: Peramaiyan
authors.forename: R
authors.initials: R
authors.lastname: Akilan
authors.forename: G
authors.initials: G
authors.lastname: Chakkaravarthi
authors.forename: R
authors.initials: R
authors.lastname: Mohankumar