8-Hy­droxy-5,7-dimethyl­quinolin-1-ium hydrogen sulfate

The quinoline ring system of the title salt, C₁₁H₁₂NO⁺·HSO₄⁻, is essentially planar, with a maximum deviation of 0.054 (2) Å for all non H atoms. In the crystal, the cations and anions are linked via N—H...O, O—H...O and weak C—H...O hydrogen bonds, and are stacked respectively in columns along the a axis. π–π stacking inter­actions, with centroid–centroid distances of 3.5473 (12) and 3.6926 (12) Å, are also observed. The crystal studied was an inversion twin with refined components of 0.43 (7):0.57 (7).

8-Hy­droxy-5,7-dimethyl­quinolin-1-ium chloride dihydrate

In the title hydrated salt, C₁₁H₁₂NO⁺·Cl⁻·2H₂O, the quinoline ring system is essentially planar, with a maximum deviation of 0.005 (1) Å for all non-H atoms. In the crystal, the three components are linked by O—H...O, N—H...O, O—H...Cl and weak C—H...O hydrogen bonds, forming a layer structure parallel to the ac plane. The crystal structure is further stabilized by π–π stacking inter­actions, with centroid–centroid distances of 3.5213 (6) and 3.7176 (6) Å.

2,3-Diamino­pyridinium hydrogen malonate

In the title mol­ecular salt, C₅H₈N₃⁺·C₃H₃O₄⁻, the cation is essentially planar, with a maximum deviation of 0.005 (1) Å for all non-H atoms. In the anion, an intra­molecular O—H...O hydrogen bond generates an S(6) ring. In the crystal, the cations and anions are connected via N—H...O hydrogen bonds and a weak C—H...O inter­action, forming layers parallel to the ab plane.

2-Amino-6-methyl­pyridinium 3-chloro­benzoate

In the title salt, C₆H₉N₂⁺·C₇H₄ClO₂⁻, the 3-chloro­benzoate anion shows a whole-mol­ecule disorder over two positions with a refined occupancy ratio of 0.505 (4):0.495 (4). In the crystal, the cations and anions are linked via N—H...O hydrogen bonds, forming a centrosymmetric 2 + 2 aggregate with R₂²(8) and R₄²(8) ring motifs. The crystal structure also features a π–π stacking inter­action between the pyridinium rings with a centroid–centroid distance of 3.8339 (9) Å.

5-Amino-6-methyl­quinolin-1-ium hydrogen malonate–malonic acid (2/1)

The asymmetric unit of the title compound, 2C₁₀H₁₁N₂⁺·2C₃H₃O₄⁻·C₃H₄O₄, consists of one 5-amino-6-methyl­quinolin-1-ium cation, one hydrogen malonate (2-carb­oxy­acetate) anion and one-half mol­ecule of malonic acid which lies on a twofold rotation axis. The quinoline ring system is essentially planar, with a maximum deviation of 0.062 (2) Å for all non-H atoms. In the anion, an intra­molecular O—H...O hydrogen bond generates an S(6) ring. In the crystal, the components are linked via N—H...O and O—H...O hydrogen bonds into layers parallel to the ac plane. The crystal structure also features weak C—H...O hydrogen bonds and a π–π stacking inter­action with a centroid–centroid distance of 3.8189 (10) Å.

2-Amino-5-bromo­pyridinium 5-chloro-2-hy­droxy­benzoate

In the 5-chloro­salicylate anion of the title salt, C₅H₆BrN₂⁺·C₇H₄ClO₃⁻, an intra­molecular O—H...O hydrogen bond with an S(6) graph-set motif is formed, so that the anion is essentially planar with a dihedral angle of 1.3 (5)° between the benzene ring and the carboxyl­ate group. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl­ate O atoms via a pair of N—H...O hydrogen bonds, forming an R₂²(8) ring motif. The crystal structure also features N—H...O and weak C—H...O inter­actions, resulting in a layer parallel to the (10-1) plane.

5-Amino-6-methyl­quinolin-1-ium 3-carb­oxy­propano­ate

The asymmetric unit of the title salt, C₁₀H₁₁N₂⁺·C₄H₅O₄⁻, consists of two independent 5-amino-6-methyl­quinolin-1-ium cations and two 3-carb­oxy­propano­ate anions. Both cations are protonated at the pyridine N atoms and are essentially planar, with maximum deviations of 0.026 (3) and 0.016 (2) Å. In the crystal, the cations and anions are linked via N—H...O and O—H...O hydrogen bonds, forming a layer parallel to the ab plane. In the layer, weak C—H...O hydrogen bonds and π–π stacking inter­actions, with centroid-to-centroid distances of 3.7283 (15) and 3.8467 (15) Å, are observed. The crystal structure also features weak C—H...O hydrogen bonds between the layers.

6-(4-Methyl­phen­yl)-1,3,5-triazine-2,4-di­amine–benzoic acid (1/1)

The benzoic acid mol­ecule of the title adduct, C₁₀H₁₁N₅·C₇H₆O₂, is approximately planar, with a dihedral angle of 7.2 (3)° between the carb­oxy­lic acid group and the benzene ring. In the triazine mol­ecule, the plane of the triazine ring makes a dihedral angle of 28.85 (9)° with that of the adjacent benzene ring. In the crystal, the two components are linked by N—H...O and O—H...N hydrogen bonds with an R₂²(8) motif, thus generating a 1 + 1 unit of triazine and benzoic acid mol­ecules. The acid–base units are further connected by N—H...N hydrogen bonds with R₂²(8) motifs, forming a supra­molecular ribbon along [101]. The crystal structure also features weak π–π [centroid–centroid distances = 3.7638 (12) and 3.6008 (12) Å] and C—H...π inter­actions.

2-Amino-4-methyl­pyridinium 3-hy­droxy­benzoate

In the title salt, C₆H₉N₂⁺·C₇H₅O₃⁻, the anion is essentially planar, with a dihedral angle of 2.72 (17)° between the benzene ring and the carboxyl­ate group. In the crystal, the anions are connected by O—H...O hydrogen bonds, forming a 4₁ helical chain along the c axis. 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 with an R₂²(8) ring motif. The ion pairs are further connected via another N—H...O hydrogen bond, resulting in a three-dimensional network.