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In the title hydrate, C13H11N3O·H2O, the benzotriazole ring system is planar (r.m.s. deviation = 0.007 Å) and is almost orthogonal to the phenyl ring to which it is linked by a methylene group, forming a dihedral angle of 81.87 (15)°. In the crystal, molecules are linked into chains along [001] by O—H...O hydrogen bonds. The chains are consolidated into a three-dimensional architecture by C—H...O, C—H...π and π–π [centroid–centroid distance between the five- and six-membered rings of the benzotriazole ring system = 3.595 (3) Å] interactions.

In the title compound, C6H5N3O·C13H11N3O, the benzotriazole ring system in the 1-benzyl-1H-benzotriazole 3-oxide (A) molecule is close to being planar (r.m.s. deviation = 0.011 Å); its mean plane forms a dihedral angle of 67.56 (7)° with that of the attached phenyl ring. The benzotriazole ring system in the 1-hydroxybenzotriazole (B) molecule is also close to being planar (r.m.s. deviation = 0.010 Å). In the crystal, weak C—H...O and C—H...π interactions are present. The A and B molecules are linked by an O—H...N hydrogen bond.

In the title compound, C13H11N3O, the dihedral angle between the benzotriazole ring system [maximum deviation = 0.027 (16) Å] and the benzene ring is 10.28 (9)°. The C—C—O—N bond adopts an anti conformation [torsion angle = −177.11 (16)°]. In the crystal, the molecules interact via weak C—H...π interactions and aromatic π–π stacking [centroid-to-centroid distance = 3.731 (12) Å].

In the title compound, [K2PtCl4(C12H24O6)2], the PtII ion is located on an inversion centre and is coordinated by four Cl atoms, forming a square-planar geometry. The KI ion is coordinated by six O atoms of the crown ether and two bridging Cl atoms. The KI ion is displaced by 0.756 (2) Å from the mean plane of the six O atoms of the crown ether. The molecules are connected by weak C—H...O hydrogen bonds, forming an infinite two-dimensional network parallel to the (10overline{2}) plane. Intra- and intermolecular C—H...Cl hydrogen bonds are also observed.

In the structure of the title compound, [KPt(C6H4N3O)Cl2(C6H5N3O)(C12H24O6)], the PtII atom is in a distorted square-planar geometry. The crystal structure is consolidated by O—H...O hydrogen bonds. The measured crystal was a non-merohedral twin with four components.

In the title compound, C16H17N3O, the benzotriazole ring forms a dihedral angle of 77.25 (6)° with the phenyl ring. The benzotriazole ring is essentially planar with a maximum deviation of 0.012 (19) Å. Weak intermolecular C—H...O hydrogen bonds form R22(10) motifs. The crystal packing is consolidated by π—π interactions with centroid–centroid distances of 3.5994 (12) Å together with very weak C—H...π interactions.

There are two monomeric units in the asymmetric unit of the polymeric title compound, [Na(C5H4NOS)(C10H8N2O2S2)(H2O)]n. The NaI ions are six coordinated by four O atoms, one S atom and one water molecule, forming a slightly distorted octahedral geometry. An intramolecular O—H...O hydrogen bond stabilizes the conformation of the molecule. The crystal packing is consolidated by intermolecular O—H...O, O—H...N and O—H...S hydrogen bonds, π–π interactions [with centroid–centroid distances of 3.587 (2) Å] together with weak C—H...π interactions. The molecules are linked into polymeric chains along the b-axis direction.

The asymmetric unit of the title compound, C11H12N2O4, contains 12 crystallographically independent molecules, labelled A to L. The nitro and carboxyl groups are twisted slightly out of the plane of the attached benzene ring in all independent molecules except molecules G and D. The nitro group is coplanar with the benzene ring in molecule G and the carboxyl group is coplanar with the benzene ring in molecule D. The orientation of the butyl group with respect to the rest of the molecule is different in some of the independent molecules, with the C—C—C—C torsion angles varying from 104.2 (5) to 126.6 (7)°. In each independent molecule, an intramolecular N—H...O hydrogen bond generates an S(6) ring motif. In the crystal structure, the 12 independent molecules exist as six pairs of O—H...O hydrogen-bonded R22(8) dimers. In addition, C—H...O hydrogen bonds are observed.

The title compound, C14H18N2O3, crystallizes with two independent molecules in the asymmetric unit, having closely comparable geometries. Both molecules are essentially planar [maximum deviations from the mean plane of 0.069 (1) and 0.068 (1) Å for the two molecules] and contain an intramolecular N—H...O hydrogen bond which generates a ring with graph-set motif S(6). In the crystal, the molecules are linked into chains along the c axis by intermolecular C—H...O hydrogen bonds, and intermolecular C—H...π interactions are also present.

In the title compound, C22H21ClO4, the cyclohex-3-ene unit adopts an envelope conformation in both independent molecules comprising the asymmetric unit. The two benzene rings are inclined to each other at a dihedral angle of 82.03 (5)° [86.37 (5)°]. In the crystal, the molecules interact via C—H...O, C—H...Cl and C—H...π interactions.

In the title compound, C11H15N3O3, one of the methyl groups attached to the benzamide unit is slightly twisted with a C—N—C—C torsion angle of 4.04 (13)°. The crystal packing is stabilized by weak intermolecular C—H...O hydrogen bonds together with a weak C—H...π interaction.

In the title compound, C21H23BrN4S, the 4-bromobenzylidene group is disordered over two orientations with occupancies of 0.504 (5) and 0.496 (5). One of the methyl groups of the isobutyl unit is disordered over two sites with occupancies of 0.751 (19) and 0.249 (19). The benzene rings of the isobutylphenyl and bromophenyl (major disorder component) groups form dihedral angles of 71.63 (11) and 21.8 (3)°, respectively, with the triazole ring. In the crystal, centrosymmetrically related molecules exist as centrosymmetric N—H...S hydrogen-bonded dimers.

In the title molecule, C24H22O8, the mean planes of the two coumarin units are inclined to each other at a dihedral angle of 79.93 (3)°. The attached methoxy groups form torsion angles of 7.65 (19) and 78.36 (14)° with respect to one coumarin unit, and angles of 9.01 (16) and 99.08 (11)° with respect to the other coumarin unit. In the crystal structure, weak intermolecular C—H...O hydrogen bonds connect pairs of molecules to form dimers, generating R22(16) and R22(18) rings; the dimers are linked by further weak intermolecular C—H...O hydrogen bonds, forming extended chains. Additional stabilization is provided by weak C—H...π interactions.

In the title molecule, C20H16N2O2, the benzimidazole mean plane forms dihedral angles of 56.55 (3) and 81.65 (4)° with the two benzene rings. In the crystal structure, intermolecular O—H...O and O—H...N hydrogen bonds link the molecules into layers parallel to the (101) plane. The crystal packing also exhibits weak intermolecular C—H...O and C—H...π interactions.

In the title compound, C11H14N2O4, all non-H atoms lie in a mirror plane except for one of the methyl groups which deviates from the mirror plane by 0.919 (3) Å and is twisted by a torsion angle of 62.9 (2)°. An intramolecular N—H...O hydrogen bond generates an S(6) ring motif. In the crystal packing, the molecules are linked together by O—H...O hydrogen bonds, forming dimers with graph-set motif R22(8) which propagate along the a-axis direction. C—H...O contacts link adjacent dimers with a graph-set motif C22(7), forming chains along b, and further consolidate the structure into a three-dimensional network. The crystal packing is further strengthened by short intermolecular O...O=C [2.655 (4) Å] contacts.

The asymmetric unit of the title compound, C21H23ClN4S, contains nine crystallographically independent molecules, labelled A to I. The orientation of the 2-[4-(2-methylpropyl)phenyl]ethyl unit with respect to the rest of the molecule is significantly different in molecules E, F, H and I compared to the other independent molecules. The isobutyl group of molecule B is disordered over two orientations, with occupancies of 0.764 (7) and 0.236 (7). The benzene rings of the chlorophenyl and methylpropylphenyl units form dihedral angles of 21.90 (11) and 71.47 (11)°, respectively, with the triazole ring in molecule A [9.15 (11) and 80.37 (11)° in B, 7.14 (11) and 84.06 (11)° in C, 25.76 (11) and 76.59 (11)° in D, 13.68 (11) and 76.82 (10)° in E, 8.38 (11) and 69.77 (10)° in F, 30.34 (11) and 78.12 (11)° in G, 21.20 (11) and 71.58 (10)° in H, and 27.65 (11) and 65.23 (11)° in I]. In each independent molecule, a C—H...S hydrogen bond is observed. The crystal packing is stabilized by N—H...S and C—H...S hydrogen bonds, and by C—H...π interactions involving the methylpropylphenyl ring.

In the title compound, C10H18O5·H2O, the fucopyranoside ring adopts a chair conformation. The crystal packing is stabilized by intermolecular O—H...O and C—H...O hydrogen bonds together with intramolecular O...O [2.2936 (8) Å] and intermolecular O...O [2.7140 (8)–2.829 (3) Å] short contacts. The molecules are linked together to form an infinite chain along the a axis. This structure has been solved previously but with no R-values [Spiers (1931). Z. Kristallogr. Kristallgeom. Kristallphys. Kristallchem. 78, 101].

The asymmetric unit of the title compound, C11H14N2O4, comprises four crystallographically independent molecules (A, B, C and D) with similar geometries. In each molecule, the butylamino side chain is in an extended conformation, and the carboxyl and butylamino groups are almost coplanar with the attached benzene ring; the nitro group is slightly twisted away from the benzene ring. In the asymmetric unit, the benzene rings of molecules A, B and C are stacked parallel to one another, with a centroid–centroid distance of 3.6197 (11) or 3.6569 (11) Å, indicating π–π interactions. An intramolecular N—H...O hydrogen bond is observed in each independent molecule. In addition to the π–π interactions, the crystal packing is consolidated by intermolecular O—H...O and C—H...O hydrogen bonds and C—H...π interactions. The crystal studied was a non-merohedral twin. The minor twin component refined to a value of 0.290 (1).

In the title compound, (C5H7N2)2[CoCl4], the cobalt(II) ion is coordinated by four chloride ions in a slightly distorted tetrahedral geometry. The crystal packing is stabilized by intermolecular N—H...Cl hydrogen bonding, forming a three-dimensional network. The crystal was a non-merohedral twin emulating tetragonal symmetry, but being in fact orthorhombic.

In the title compound, C22H26N4OS, the benzene rings of the (2-methylpropyl)phenyl and 4-methoxyphenyl units form dihedral angles of 66.85 (3) and 25.96 (3)°, respectively, with the triazole ring. The dihedral angle between the two benzene rings is 87.42 (2)°. The –CH(CH3) linkage is disordered over two orientations with occupancies of 0.907 (3) and 0.093 (3). An intramolecular C—H...S hydrogen bond generates an S(6) ring motif. Intermolecular N—H...S hydrogen bonds and C—H...π interactions are observed.

The asymmetric unit of the title compound, C20H18F2N2O2S, contains four independent molecules, two of which are paired into a dimer by way of two N—H...S hydrogen bonds. The other two independent molecules are paired into two centrosymmetric dimers via pairs of intermolecular N—H...S hydrogen bonds. In one molecule, the carboxylate O atoms, methylene and methyl groups attached to the benzene ring are disordered between two positions in a 0.908 (3):0.092 (3) ratio. In two of the independent molecules, the F and H atoms of the diflourophenyl ring are flip-flop disordered (i.e. by 180° about the C—C bond axis linking the ring to the rest of the molecule) in a 3:2 ratio. The crystal packing is stabilized by weak intermolecular C—H...O hydrogen bonds.

The complete molecule of the title compound, C24H24N6O2, is generated by a crystallographic inversion centre. The benzotriazole rings form dihedral angles of 2.10 (7)° with the central aromatic ring. The crystal packing is consolidated by π–π interactions, with centroid–centroid distances of 3.6234 (10) Å, together with weak C—H...π interactions.

In the title compound, C17H19N3O, the benzotriazole ring is essentially planar, with a maximum deviation of 0.0069 (15) Å. The mean plane of the benzotriazole ring forms a dihedral angle of 13.16 (4)° with the mean plane of the benzene ring. The crystal packing is stabilized by π–π stacking interactions, with a centroid–centroid distance of 3.8077 (12) Å, together with weak C—H...π interactions. Molecules are stacked along the a axis.

In the title compound, 2C3H5N2S+·C4H4O42−·C4H6O4, the thiazolium ring is almost planar, with the maximum deviation from planarity being 0.0056 (8) Å for the C atom carrying the amine substituent. The N atom of the 2-aminothiazole molecule is protonated. Both the anion and the acid lie across inversion centres. The crystal packing is consolidated by intermolecular O—H...O, N—H...O and C—H...O hydrogen bonds. Molecules are stacked down the b axis.

In the title salt, C5H7N2+·C4H5O4−, the asymmetric unit comprises an aminopyridinium cation and a hydrogen succinate anion as protonation of the aromatic N atom of the 4-aminopyridine molecule has occurred. The crystal packing is stabilized by intermolecular O—H...O and N—H...O hydrogen bonds that lead to a two-dimensional array. Short C—H...O contacts are also present.

In the title compound, C20H16S2, the pyrene ring is planar [maximum deviation 0.0144 (15) Å] and the dithiane ring adopts a chair conformation. The crystal packing is stabilized by C—H...π interactions. An intramolecular C—H...S hydrogen bond generates an S(5) ring motif.

In the centrosymmetric title compound, [Ni(C8H8NO3S)2(H2O)4], the NiII ion, which lies on an inversion centre, is six coordinated by four water molecules and two propionate O atoms from two 2-pyridylsulfanylpropionate N-oxide ligands, forming a slightly distorted octahedral geometry. An intramolecular O—H...O hydrogen bond stabilizes the molecular conformation. The crystal packing is consolidated by intermolecular O—H...O and C—H...O hydrogen bonding.

The molecule of the title compound, C11H7ClO3, is planar, with a maximum deviation of 0.0383 (10) Å from the naphthoquinone plane. An intramolecular O—H...O hydrogen bond generates an S(6) ring motif. The crystal packing is stabilized by intermolecular C—H...O hydrogen bonds. Short intramolecular Cl...O [2.8234 (8) Å] and O...O [2.5530 (11) Å], and intermolecular Cl...Cl [3.2777 (3) Å] contacts further stabilize the crystal structure.

In the title compound, 2C5H7N2+·2C2HO4−·H2O, the asymmetric unit consists of an aminopyridinium cation, an oxalic actetate anion and a half-molecule of water, which lies on a two-fold rotation axis. The crystal packing is consolidated by intermolecular O—H...O, N—H...O and C—H...O hydrogen bonds. The molecules are linked into an infinite one dimensional chain along [010].

In the title compound, C17H14ClN5OS, the dihedral angles formed by the two benzene rings with the triazole ring are 66.88 (3) and 19.16 (3)°, and the benzene rings are inclined to each other with a dihedral angle of 78.40 (3)°. Intermolecular N—H...O hydrogen bonds link the molecules into layers parallel to the (100) planes, and centrosymmetric π–π stacking interactions [centroid–centroid distance = 3.7717 (5) Å] are formed between benzene rings in neighbouring layers.

In the crystal structure of the title compound, 4C21H22N2O2S2·0.5C3H6O·11.5H2O, there are four crystallographically independent molecules (A, B, C, D) with similar geometries, 11 water molecules and a solvent acetone molecule which is disordered with a water molecule with occupancy factors of 0.5:0.5. The dihedral angles formed by the mesitylene ring with the two pyridyl rings are 82.07 (3) and 78.39 (3)° in molecule A, 86.20 (3) and 82.29 (3)° in molecule B, 81.05 (3) and 76.0 (4)° in molecule C, 86.0 (3) and 80.9 (3)° in moleule D. The two pyridyl rings form dihedral angles of 41.17 (4), 64.01 (3), 81.9 (3) and 82.25 (3)° in molecules A, B, C and D, respectively. The crystal structure is stabilized by intermolecular O—H...O hydrogen bonds and possible weak C—H...π interactions. Some short intramolecular S...O contacts are apparent [2.684 (4)–2.702 (4) Å].

The asymmetric unit of the title compound, C21H25ClN2O, contains four crystallographically independent molecules, which differ mainly in the orientation of the isobutyl groups. The benzene rings are almost orthogonal to each other, forming dihedral angles of 87.40 (6), 88.69 (6), 84.88 (6) and 85.12 (6)° in the four molecules. The crystal structure is stabilized by intermolecular N—H...O and C—H...O hydrogen bonds, together with C—H...π interactions.

In the racemic (S,S/R,R) title compound, C19H21BrO4, the two benzene rings are almost coplanar to each other, forming a dihedral angle of 3.58 (10)°. The crystal packing is strengthened by intermolecular Br—O [2.9800 (16) Å] short contacts, which link the molecules into infinite one-dimensional chains along [001].

In the title binuclear copper(II) complex, [Cu2(C7H3ClNO4)4(H2O)2], each of the two independent CuII center is five-coordinated by four O atoms of the carboxylate groups in the basal plane and one O atom of a water molecule in the apical position, in a distorted square-pyramidal geometry. The Cu—Cu distance is 2.6458 (4) Å. In the crystal structure, the dinuclear units are linked into a three-dimensional network by O—H...O, C—H...O and C—H...Cl hydrogen bonds. One of the Cl atoms is disordered over two positions with occupancies of 0.650 (2) and 0.350 (2).

The asymmetric unit of the title compound, C22H22O4, consists of two independent molecules (A and B) which differ significantly in the orientations of ethyl carboxylate groups. The phenyl ring in molecule B is disordered over two orientations with occupancies of 0.55 (2) and 0.45 (2). The cyclohexenone ring of both molecules adopts an envelope conformation. The dihedral angle between the two aromatic rings is 81.12 (7)° in molecule A and 70.8 (3)° in molecule B [57.5 (4)° in the minor disorder component]. The crystal structure is stabilized by weak intermolecular C—H...O hydrogen bonds and C—H...π interactions.

In the title 1:1 adduct, C7H5NO4·C7H7NO2, the nitro group of the 4-nitro benzoic acid is twisted from the attached ring by 4.40 (8)°. In the crystal, the molecules are linked into ribbon-like structures along [150] and [1overline{5}0] via O—H...O, N—H...O, N—H...N and C—H...O intermolecular hydrogen bonds.

In the title compound, C21H16ClN3O2, the dihedral angles formed by the pyrazole ring with the pyridyl, phenylene and phenyl rings are 6.80 (5), 9.23 (5) and 74.96 (5)°, respectively. The phenyl and phenylene rings are inclined at 80.14 (2)°. Intramolecular O—H...O and C—H...N hydrogen bonds generate S(6) ring motifs. The crystal packing is strengthened by short intermolecular O—H...N, C—H...O hydrogen bonds and π–π stacking interactions with centroid–centroid distances of 3.6247 (5)–3.7205 (5) Å, together with intermolecular short O...N contacts [2.7682 (11) Å]. Molecules are linked into infinite chains along [100].

In the title molecule, C10H13N3O2S, the dihedral angle between benzene and –N—C(=S)—N—N=C– planes is 9.20 (6)°. The two methoxy groups are coplanar with the benzene ring [C—O—C—C torsion angles of −2.31 (18) and −6.45 (17)°]. In the crystal structure, molecules are linked by intermolecular N—H...S, N—H...O and C—H...O hydrogen bonds, forming a three-dimensional network.

In the the title compound, C27H23ClN4O2, the chlorophenyl ring forms dihedral angles of 77.70 (9) and 86.65 (9)°, respectively, with the pyrazol-3-one and pyrazole rings. The phenyl rings attached to the pyrazole rings are twisted away from them [dihedral angles 33.80 (9) and 40.34 (10)°]. An intramolecular O—H...O hydrogen bond generates an S(8) ring motif. The molecules are linked into chains running along the c axis by N—H...N hydrogen bonds, and the chains are cross-linked via C—H...O hydrogen bonds and C—H...π interactions involving the chlorophenyl ring.

The chemical name in the title and the scheme of the paper by Fun, Jebas, Patil, Karthikeyan & Dharmaprakash [Acta Cryst. (2008), E64, o1559] are corrected.

In the title compound, C15H13N3O3·H2O, the two benzene rings form a dihedral angle of 2.03 (2)°. In the crystal structure, adjacent hydrazide molecules are linked into dimers by water molecules; these dimers are then stacked along the b axis. Intermolecular O—H...O, O—H...N and C—H...O hydrogen bonds and a π–π stacking interaction between the nitrobenzene and tolyl rings with a centroid–centroid distance of 3.8208 (3) Å are observed. There is also a short O...N contact [2.6824 (7) Å].

In the title compound, C21H26N2O, the dihedral angle between the two aromatic rings is 85.90 (19)°. The propenone–hydrazide unit forms dihedral angles of 21.62 (8) and 72.83 (9)°, respectively, with the terminal and central aromatic rings. The 2-methylpropyl group is disordered over two sites, with occupancies of 0.533 (13) and 0.467 (13). In crystal structure, molecules are linked into centrosymmetric dimers by paired N—H...O and C—H...O hydrogen bonds. In addition, C—H...π interactions are observed.

In the title compound, C22H26N4S, the dihedral angles formed by the triazole ring with the two benzene rings are 87.51 (3) and 20.98 (3)°. The benzene rings are inclined at 71.88 (2)°. An intramolecular C—H...S hydrogen bond generates an S(6) ring motif. The crystal packing is strengthened by intermolecular N—H...S hydrogen bonding and π–π stacking interactions between the triazole and benzene rings, with a centroid–centroid distance of 3.6618 (5) Å, together with N...N [2.1299 (9)–2.2121 (9) Å] short contacts and C—H...π interactions. In the crystal packing, molecules are stacked along the a axis.

In the title compound, [Ni2(CO3)(C5H6N2)8(H2O)]Cl2·5H2O, one of the the NiII ions is six-coordinated in a distorted octahedral geometry, with the equatorial plane defined by four pyridine N atoms from four aminopyridine ligands, the axial positions being occupied by one water O and a carbonate O atom. The other NiII ion is also six-coordinated, by four other pyridine N atoms from four other aminopyridine ligands and two carbonate O atoms to complete a distorted octahedral geometry. In the crystal structure, molecules are linked into an infinite three-dimensional network by O—H...O, N—H...Cl, N—H...O, O—H...N, C—H...O, C—H...N and C/N—H...π interactions involving the pyridine rings.

In the title compound, C5H7N2+·C7H5O3−, the carboxylate mean plane of the 4-hydroxybenzoate anion is twisted by 8.78 (5)° from the attached ring. The cations and anions are linked via O—H...O, N—H...O and C—H...O hydrogen bonds, forming a three-dimensional network. In addition, π–π interactions involving the benzene and pyridinium rings, with centroid–centroid distances of 3.5500 (6) and 3.6594 (6) Å, are observed.

The asymmetric unit of the title compound, [Ag(C5H6N2)2]NO3, consists of one and a half each of both cations and anions, the other halves being generated by crystallographic inversion centres. One of the AgI atoms lies on an inversion center and one of the nitrate ions is disordered across an inversion center. Each AgI atom is bicoordinated in a linear geometry by two N atoms from two 2-aminopyridine ligands. In the crystal structure, the cations and anions are linked into a two-dimensional network parallel to (001) by N—H...O and C—H...O hydrogen bonds.

In the title compound, C16H19NOS, the durene ring and the oxopyridyl ring form a dihedral angle of 82.26 (7)°. The crystal structure is stabilized by intermolecular C—H...O hydrogen bonds, weak C—H...π interactions and π–π interactions [centroid–centroid distance of 3.4432 (19) Å], together with intramolecular S...O [2.657 (2) Å] short contacts.

In the asymmetric unit of the title compound, C16H16N4O3·H2O, there are two symmetry-independent hydrazide molecules with almost identical geometries, and two independent water molecules. The dihedral angles between the two benzene rings in the two hydrazide molecules are 0.11 (5) and 0.77 (5)°. In one molecule, an intramolecular C—H...O hydrogen bond generates a ring of graph-set motif S(5). Intermolecular N—H...O, O—H...O, O—H...N and C—H...O hydrogen bonds and π–π stacking interactions between the benzene rings [centroid–centroid distances in the range 3.5021 (6)–3.6403 (6) Å] are observed, together with O...O [2.7226 (11) Å], O...N [2.7072 (10) Å] and N...O [2.7072 (10)–2.8582 (12) Å] short contacts. The hydrazine molecules are stacked along the b axis and adjacent molecules are linked by water molecules.

In the title compound, C15H17NOS·H2O, the benzene and pyridine rings form a dihedral angle of 71.18 (2)°. The intramolecular S...O distance [2.737 (3) Å] is shorter than expected and, in terms of hybridization principles, the N—C—S angle [114.1 (2)°] is smaller than expected. The crystal structure is stabilized by intermolecular O—H...O and weak C—H...O hydrogen bonds. In addition, weak π–π stacking interactions with a centroid–centroid distance of 3.778 (3) Å are also observed.

The asymmetric unit of the title compound, C5H7N2+·C7H4NO4−·C7H5NO4, consists of an aminopyridinium cation, a 4-nitrobenzoate anion and a neutral 4-nitrobenzoic acid molecule. The pyridine ring forms dihedral angles of 64.70 (5)° and 70.37 (5)°, respectively, with the benzene rings of 4-nitrobenzoic acid and 4-nitrobenzoate. In the crystal structure, the cations, anions and the neutral 4-nitrobenzoic acid molecules are linked by O—H...O and N—H...O hydrogen bonds, forming a two-dimensional network parallel to (001). Adjacent networks are cross-linked via C—H...O hydrogen bonds and π–π stacking interactions [centroid–centroid distances 3.6339 (6) and 3.6566 (6) Å].