4-Methyl­pyridinium 4-hy­droxy­benzoate

In the crystal structure of the title salt, C₆H₈N⁺·C₇H₅O₃⁻, the anions and cations are linked by classical N—H...O hydrogen bonds. The anions are connected by pairs of C—H...O hydrogen bonds into inversion dimers and further linked by classical O—H...O hydrogen bonds. Weak π–π inter­actions [centroid–centroid distances = 3.740 (3) and 3.855 (3) Å] also occur. The dihedral angle between the CO₂⁻ group and the benzene ring to which it is attached is 20.95 (8)°.

4-(4-Bromo­styr­yl)-1-methylpyridinium tosyl­ate

In the cation of the title compound, C₁₄H₁₃BrN⁺·C₇H₇O₃S⁻, the dihedral angle between the benzene and pyridine rings is 8.34 (11)°. The Br atom is disordered over two positions with site occupancies of 0.74 (2) and 0.26 (2). The mol­ecular structure is stabilized by a weak intra­molecular C—H...O inter­actions. The crystal structure exhibits weak C—H...O and π–π [centroid–centroid distance = 3.7466 (17) Å] inter­actions, forming a three dimensional network.

2-Phenyl­ethanaminium 4-hy­droxy­benzoate

In the title salt, C₈H₁₂N⁺·C₇H₅O₃⁻, the cation is disordered over two orientations with site occupancies of 0.565 (7) and 0.435 (7). In the anion, the carboxyl­ate group makes the dihedral angle of 4.19 (18)° with the benzene ring. In the crystal, the ions are connected by N—H...O and O—H...O hydrogen bonds, forming a three-dimensional network.