2-Amino-4-methylpyridinium (E)-3-carboxyprop-2-enoate

In the title salt, C6H9N2 +center dot C4H3O4 -, the dihedral angle between the pyridine ring and the plane formed by the hydrogen fumarate anion is 85.67 (6)degrees. Excluding the amino and methyl groups, the atoms of the cation are coplanar, with a maximum deviation of 0.005 (1) A. In the crystal structure, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxylate O atoms of the anion via a pair of N-H...O hydrogen bonds, forming an R (2) 2(8) ring motif. These motifs are further connected through N-H...O and C-H...O hydrogen bonds, leading to a supramolecular chain along the c axis. These chains are further cross-linked via a pair of O-H...O hydrogen bonds involving centrosymmetrically related hydrogen fumarate anions, forming a two-dimensional network parallel to (101). These planes are further interconnected by O-H...O interactions into a three-dimensional network.