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-5-methyl­pyridinium 4-methyl­benzoate

The 4-methyl­benzoate anion of the title salt, C₆H₉N₂⁺·C₈H₇O₂⁻, is nearly planar, with a dihedral angle of 6.26 (10)° 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 of the anion via a pair of N—H...O hydrogen bonds with an R₂²(8) ring motif, forming an approximately planar ion pair with a dihedral angle of 9.63 (4)° between the pyridinium and benzene rings. The ion pairs are further connected via N—H...O and weak C—H...O hydrogen bonds, forming a two-dimensional network parallel to the bc plane.

2-Amino-5-methyl­pyridinium 2-hy­droxy-5-chloro­benzoate

In the 5-chloro­salicylate anion of the title salt, C₆H₉N₂⁺·C₇H₄ClO₃⁻, an intra­molecular O—H...O hydrogen bond with an S(6) graph-set motif is observed and the dihedral angle between the benzene ring and the –CO₂ group is 1.6 (6)°. 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 (10-1).

2-Amino-5-methyl­pyridinium 4-chloro­benzoate

The 4-chloro­benzoate anion of the title salt, C₆H₉N₂⁺·C₇H₄ClO₂⁻, is nearly planar with a dihedral angle of 5.14 (16)° 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 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 N—H...O and weak C—H...O hydrogen bonds, forming a two-dimensional network parallel to the bc plane. The crystal structure also features a π–π stacking inter­action between the pyridinium and benzene rings with a centroid–centroid distance of 3.7948 (9) Å.

3-{5-Eth­oxy­carbonyl-1-[3-(2-oxopyrrol­idin-1-yl)prop­yl]-1H-benzimidazol-2-yl}benzoic acid

In the title compound, C₂₄H₂₅N₃O₅, the eth­oxy group is disordered over two orientations in a 0.853 (14):0.147 (14) ratio. The benzimadazole ring system (r.m.s. deviation = 0.016 Å) makes a dihedral angle of 35.47 (7)° with the attached benzene ring. The pyrrolidine ring adopts an envelope conformation with a methyl­ene C atom as the flap. In the crystal, inversion dimers linked by pairs of O—H...N hydrogen bonds generate R₂²(16) loops. C—H...O inter­actions link the dimers into a three-dimensional network.

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.

N-But­oxy­carbonyl-5-oxo-L-proline ethyl ester

The mol­ecular structure of the title compound, C₁₂H₁₉NO₅, may be visualized as made up of two nearly perpendicular planes [dihedral angle = 87.39 (12)°] and its crystal structure is a good example of C—H...O inter­actions assuming significance in optimizing supra­molecular aggregation in crystals in a mol­ecule which is severely imbalanced in terms of donors to acceptor atoms. The pyrrolidine ring adopts a (³T₂) twist conformation with puckering parameters Q = 0.2630 (4) Å and φ = 59 (9)°. The crystal structure features R₂⁴(10) and R₃⁴(26) ring motifs formed by four weak C—H...O inter­actions, leading to supra­molecular sheets lying parallel to the bc plane.

1-[5-(2H-1,3-Benzodioxol-5-yl)-3-(4-methyl­phen­yl)-2-pyrazolin-1-yl]ethanone

In the title compound, C₁₉H₁₈N₂O₃, the pyrazoline ring is close to being planar (r.m.s. deviation = 0.035 Å) and subtends dihedral angles of 2.11 (8) and 82.63 (8)° with the p-tolyl and benzene rings, respectively. In the crystal, C—H...O and C—H...N hydrogen bonds link the mol­ecules, forming a three-dimensional network. A weak C—H...π inter­action involving the benzene ring is also observed.

3-(4-Methyl­phen­yl)-4-[(thio­semi­carba­zono)meth­yl]-1,2,3-oxa­diazol-3-ium-5-olate 1,4-dioxane hemisolvate

The asymmetric unit of the title compound, C₁₁H₁₁N₅O₂S·0.5C₄H₈O₂, contains one 3-(p-tol­yl)sydnone 4-thio­semi­carba­zone mol­ecule and a half mol­ecule of 1,4-dioxane, which lies abount an inversion centre. The sydnone ring is almost planar, with a maximum deviation of 0.002 (1) Å, and forms a dihedral angle of 46.31 (5)° with the benzene ring. In the crystal, the two components are linked into a tape along [01-1] by N—H...O and N—H...S hydrogen bonds. The crystal structure is further stabilized by C—H...O and C—H...π inter­actions, forming a three-dimensional network.

4′-(4-Fluoro­phen­yl)-1′-methyl­dispiro­[indane-2,2′-pyrrolidine-3′,2′′-indane]-1,3,1′′-trione methanol hemisolvate

The asymmetric unit of the title compound, C₂₉H₂₄FNO₅·0.5CH₃OH, contains two independent mol­ecules and a one methanol solvent mol­ecule. The methanol mol­ecule is O—H...O hydrogen bonded to one of the independent mol­ecules. The pyrrolidine rings in both mol­ecules adopt half-chair conformations, while the cyclo­pentane rings within the indane groups are in flattened envelope conformations, with the spiro C atoms forming the flaps. The benzene rings of the indane ring systems form a dihedral angle of 35.06 (7)° in one independent mol­ecule and 31.16 (8)° in the other. The fluoro-substituted benzene ring forms dihedral angles of 65.35 (6) and 85.87 (7)° with the indane group benzene rings in one mol­ecule, and 72.78 (8) and 77.27 (8)° in the other. In each mol­ecule, a weak intra­molecular C—H...O hydrogen bond forms an S(6) ring motif. In the crystal, weak C—H...O, C—H...N and C—H...F hydrogen bonds link the mol­ecules into a three-dimensional network.

Ethyl 2-[4-(di­methyl­amino)­phen­yl]-1-phenyl-1H-benzimidazole-5-carboxyl­ate

In the title compound, C₂₄H₂₃N₃O₂, the benzimidazole ring system makes dihedral angles of 7.28 (5) and 67.17 (5)°, respectively, with the planes of the benzene and phenyl rings, which in turn make a dihedral angle of 69.77 (6)°. In the crystal, mol­ecules are connected by C—H...N and C—H...O inter­actions, forming a layer parallel to the bc plane. A π–π inter­action, with a centroid–centroid distance of 3.656 (1) Å, is observed in the layer.

N-[(2,6-Di­ethyl­phen­yl)carbamo­thio­yl]-2,2-di­phenyl­acetamide

In the title compound, C₂₅H₂₆N₂OS, the diethyl-substituted benzene ring forms dihedral angles of 67.38 (9) and 55.32 (9)° with the terminal benzene rings. The mol­ecule adopts a trans–cis conformation with respect to the orientations of the di­phenyl­methane and 1,3-di­ethyl­benzene groups with respect to the S atom across the C—N bonds. This conformation is stabilized by an intra­molecular N—H...O hydrogen bond, which generates an S(6) ring. In the crystal, pairs of N—H...S hydrogen bonds link the mol­ecules into inversion dimers, forming R₂²(6) loops. The dimer linkage is reinforced by a pair of C—H...S hydrogen bonds, which generate R₂²(8) loops. Weak C—H...π and π–π [centroid–centroid seperation = 3.8821 (10) Å] inter­actions also occur in the crystal structure.

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.

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

The 4-methyl­benzoic acid mol­ecule of the title adduct, C₁₀H₁₁N₅·C₈H₈O₂, is approximately planar with a dihedral angle of 6.3 (2)° between the carb­oxy­lic acid group and the benzene ring. In the triazine mol­ecule, the plane of the triazine ring makes a dihedral angle of 29.2 (2)° with that of the adjacent benzene ring. In the crystal, the acid and base mol­ecules are linked via N—H...O and O—H...N hydrogen bonds with an R₂²(8) motif, and the acid–base pairs are further connected via N—H...N hydrogen bonds with R₂²(8) motifs, forming a supra­molecular ribbon along [101]. Between the tapes, a weak C—H...π inter­action is observed.

Ethyl 2-[5-(4-fluoro­phen­yl)pyridin-3-yl]-1-[3-(2-oxopyrrolidin-1-yl)prop­yl]-1H-benzimidazole-5-carboxyl­ate

In the title compound, C₂₈H₂₇FN₄O₃·H₂O, the benzimidazole ring system is essentially planar with a maximum deviation of 0.028 (1) Å. It makes dihedral angles of 47.59 (5) and 60.31 (5)°, respectively, with the pyridine and benzene rings, which make a dihedral angle of 22.58 (6)° with each other. The pyrrolidine ring shows an envelope conformation with one of the methyl­ene C atoms as the flap. In the crystal, the components are connected into a tape along the b-axis direction through O—H...O and O—H...N hydrogen bonds and a π–π inter­action between the pyridine and benzene rings [centroid–centroid distance of 3.685 (8) Å]. The tapes are further linked into layers parallel to the ab plane by C—H...O and C—H...F inter­actions.

N-[(3-Ethyl­phen­yl)carbamo­thio­yl]-2,2-di­phenyl­acetamide

In the title mol­ecule, C₂₃H₂₂N₂OS, the di­phenyl­acetyl and ethyl­benzene groups adopt a trans–cis conformation, respectively, with respect to the S atom across the (S=)C—N bonds. This conformation is stabilized by an intra­molecular N—H...O hydrogen bond and a weak C—H...S hydrogen bond. The ethyl-substituted benzene ring forms dihedral angles of 87.53 (15) and 73.94 (15)° with the phenyl rings. In the crystal, N—H...O hydrogen bonds link mol­ecules into chains along [100]. A weak C—H...π inter­action is also observed.

2-Amino-5-methyl­pyridinium 3-hy­droxy­pyridine-2-carboxyl­ate

In the 3-hy­droxy­picolinate anion of the title salt, C₆H₉N₂⁺·C₆H₄NO₃⁻, 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 9.55 (9)° between the pyridine ring and the carboxyl­ate group. 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 N—H...N and weak 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.

2,2-Diphenyl-N-{[2-(tri­fluoro­meth­yl)phen­yl]carbamo­thio­yl}acetamide

The title mol­ecule, C₂₂H₁₇F₃N₂OS, adopts a trans–cis conformation with respect to the positions of the carbonyl and tri­fluoro­methyl­benzene groups against the thio­carbonyl group across the C—N bonds. The mol­ecular structure is stabilized by an intra­molecular N—H...O hydrogen bond with an S(6) ring motif. The tri­fluoro­methyl-substituted benzene ring forms dihedral angles of 66.05 (9) and 47.19 (9)° with the terminal phenyl rings and is twisted from the O=C—N—(C=S)—N carbonyl­thio­urea plane [maximum deviation = 0.0535 (12) Å], making a dihedral angle of 63.59 (8)°. In the crystal, N—H...O and C—H...F hydrogen bonds link the mol­ecules into a layer parallel to the bc plane. A C—H...π inter­action is also observed.

N-tert-But­oxy­carbonyl-α-(2-fluoro­benzyl)-L-proline

In the title compound, C₁₇H₂₂FNO₄, the pyrrolidine ring adopts an envelope conformation with the disordered com­ponents of the methylene C atom, with site occupancies of 0.896 (7) and 0.104 (7), being the flap on either side of the mean plane involving the other atoms of the ring. The carb­oxy­lic acid group forms dihedral angles of 72.06 (11) and 45.44 (5)° with the N-tert-but­oxy­carbonyl group and the 2-fluoro­benzyl group, respectively. In the crystal, two-dimensional layers of mol­ecules parallel to (001) are built through an R₄⁴(23) motif generated via O—H...O, C—H...O and C—H...F inter­actions, and an R₂²(11) motif generated by C—H...O and C—H...F inter­actions.