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N-Protected derivatives of 1-aminocyclohexaneacetic acid (β3,3-Ac6c), namely Valeroyl-β3,3-Ac6c-OH [2-(1-pentanamidocyclohexyl)acetic acid, C13H23NO3], (I), Fmoc-β3,3-Ac6c-OH [2-(1-{[(9H-fluoren-9-yloxy)carbonyl]amino}cyclohexyl)acetic acid, C23H25NO4], (II), and Pyr-β3,3-Ac6c-OH {2-[1-(pyrazine-2-amido)cyclohexyl]acetic acid, C13H17N3O3}, (III), were synthesized and their conformational properties were determined by X-ray diffraction analysis. The backbone torsion angles (ϕ, θ) for β3,3-Ac6c-OH are restricted to gauche conformations in all the derivatives, with a chair conformation of the cyclohexane ring. In the crystal structure of (I), the packing of molecules shows both carboxylic acid R22(8) O—H...O and centrosymmetric R22(14) N—H...O hydrogen-bonding interactions, giving rise to chains along the c-axis direction. In (II), centrosymmetric carboxylic acid R22(8) O—H...O dimers are extended through N—H...O hydrogen bonds and together with inter-ring π–π interactions between Fmoc groups [ring centroid distance = 3.786 (2) Å], generate a layered structure lying parallel to (010). In the case of compound (III), carboxylic acid O—H...Npyrazine hydrogen bonds give rise to zigzag ribbon structures extending along the c-axis direction.

In the title molecule, C19H21FN6O4, the dihedral angles between the benzene ring and essentially planar pyrimidine rings [maximum deviations of 0.036 (2) and 0.056 (2) Å] are 73.32 (7) and 63.81 (8)°. The dihedral angle between the mean planes of the pyrimidine rings is 61.43 (6)°. In the crystal, N—H...O hydrogen bonds link molecules, forming a two-dimensional network parallel to (001) and in combination with weak C—H...O hydrogen bonds, a three-dimensional network is formed. Weak C—H...π interactions and π–π interactions, with a centroid–centroid distance of 3.599 (2) Å are also observed.

The title compound, C18H14Cl2N2O2, crystallizes with two molecules, A and B, in the asymmetric unit. In molecule A, the dihedral angles between the central pyrazole ring and pendant dichlorobenzene and p-tolyl rings are 2.18 (16) and 46.78 (16)°, respectively. In molecule B, the equivalent angles are 27.45 (16) and 40.45 (18)°, respectively. Each molecule features an intramolecular O—H...O hydrogen bond, which closes an S(6) ring and molecule A also features a C—H...O interaction. In the crystal, weak C—H...π interactions and aromatic π–π stacking [shortest centroid–centroid separation = 3.707 (2) Å] generate a three-dimensional network.

The title Schiff base compound, C28H21Cl2N3O, was synthesized by the condensation of 1-(3,4-dichlorophenyl)-3-methyl-4-(4-methylbenzoyl)-1H-pyrazol-5(4H)-one with 1-aminonaphthalene. The p-tolyl ring is normal to the pyrazole ring, with a dihedral angle of 88.02 (14)°, and inclined to the naphthalene ring system by 78.60 (12)°. The pyrazole ring is inclined to the naphthalene ring system and the dichloro-substituted benzene ring by 63.30 (12) and 11.03 (13)°, respectively. The amino group and carbonyl oxygen atom are involved in an intramolecular N—H...O hydrogen bond enclosing an S(6) ring motif. There is also a short C—H...O contact involving the carbonyl O atom and the adjacent benzene ring. In the crystal, molecules are linked by C—H...π interactions, forming a three-dimensional structure.

In the title molecule, C17H15ClN4S, the benzene rings form dihedral angles of 16.6 (1) and 77.2 (1)° with the triazole ring. The dihedral angle between the benzene rings is 86.6 (1)°. In the crystal, pairs of N—H...S hydrogen bonds form inversion dimers with graph-set notation R22(8). Weak C—H...S hydrogen bonds link these dimers into layers parallel to (100). Weak intramolecular C—H...S and C—H...N contacts are observed.

In the title compound, C17H18N4O4, the dihedral angle between the benzene ring and 2,4-dihydropyrano[2,3-c]pyrazole ring system is 89.41 (7)°. The pyran moiety adopts a strongly flattened boat conformation. In the crystal, molecules are linked by N—H...N, N—H...O, C—H...N and C—H...O hydrogen bonds into an infinite two-dimensional network parallel to (110). There are π–π interactions between the pyrazole rings in neighbouring layers [centroid–centroid distance = 3.621 (1) Å].

In the asymmetric unit of the title compound, C16H14N4O3·C2H6OS, there are two independent main molecules (A and B) and two dimethyl sulfoxide solvent molecules. In molecule A, the pyran ring is in a flattened sofa conformation, with the sp3-hydridized C atom forming the flap. In molecule B, the pyran ring is in a flattened boat conformation, with the sp3-hydridized C atom and the O atom deviating by 0.073 (3) and 0.055 (3) Å, respectively, from the plane of the other four atoms. The mean planes the pyrazole and phenyl rings form dihedral angles of 84.4 (2) and 84.9 (2)°, respectively, for molecules A and B. In the crystal, N—H...O and N—H...N hydrogen bonds link the components of the structure into chains along [010]. In both solvent molecules, the S atoms are disordered over two sites, with occupancy ratios of 0.679 (4):0.321 (4) and 0.546 (6):0.454 (6).

In the title compound, C22H21N3O2, the pyrimidine ring is essentially planar [maximum deviation = 0.018 (2) Å] and forms dihedral angles of 22.70 (8) and 0.97 (7)°, respectively, with the fused benzene ring and the hydroxy-substituted benzene ring. The piperidine ring has a chair conformation and the pyran ring has a flattened twist-boat conformation. The hydroxy group was refined as disordered over two sets of sites in a 0.702 (4):0.298 (4) ratio. The disorder corresponds to a rotation of approxomiately 180° about the C—C bond connecting the phenol group to the pyrimidine ring and hence, both the major and minor components of disorder form intramolecular O—H...N hydrogen bonds. In the crystal, pairs of weak C—H...π interactions form inversion dimers. In addition, π–π interactions are observed between the pyrimidine ring and the hydroxy-substituted benzene ring [centroid–centroid separation = 3.739 (2) Å].

In the title compound, C30H40FNO3, the dihedral angle between the benzene rings is 57.76 (7)°. The alkyl chain adopts an all-trans conformation. In the crystal, molecules are linked by pairs of C—H...O hydrogen bonds, forming inversion dimers.

In the title molecule, C24H22N4O3, the plane of the oxadiazole ring forms a dihedral angle of 32.41 (12)° with that of the phenyl ring and dihedral angles of 74.51 (10) and 56.38 (10)° with the planes of the benzene rings. In the crystal, pairs of N—H...N hydrogen bonds link molecules into inversion dimers featuring R22(8) graph-set motifs.

In the title compound, C12H11Cl3N2O4, the dihedral angle between the aromatic ring and the hydrazine (NH—N=C) grouping is 52.2 (3)°. The butanedioate groups exhibit planar conformations. An intramolecular N—H...O hydrogen bond links the N—H group of the hydrazine to one of the methoxy groups of the butanedioate moiety. In the crystal, molecules are linked by C—H...O hydrogen bonds and π–π interactions are also observed [centroid–centroid separation = 3.535 (1) Å].

In the title compound, C15H12FN3O2, the dihedral angles between the central benzene ring and the pendant benzene and oxadiazole rings are 45.05 (13) and 15.60 (14)°, respectively. The C atom of the methoxy group is roughly coplanar with its attached ring [displacement = 0.178 (4) Å]. In the crystal, N—H...N hydrogen bonds link the molecules into [010] chains. Weak C—H...π interactions are also observed.

In the title molecule, C20H21N3O, the central pyrazole ring forms dihedral angles of 4.75 (9) and 49.11 (9)°, respectively, with the phenyl and methyl-substituted benzene rings. The dihedral angle between the phenyl and benzene rings is 51.76 (8)°. The amino group and carbonyl O atom are involved in an intramolecular N—H...O hydrogen bond. In the crystal, π–π interactions are observed between benzene rings [centroid–centroid seperation = 3.892 (2) Å] and pyrazole rings [centroid–centroid seperation = 3.626 (2) Å], forming chains along [111]. The H atoms of the methyl group on the p-tolyl substituent were refined as disordered over two sets of sites in a 0.60 (4):0.40 (4) ratio.

In the title molecule, C15H11Cl2NOS, the dihedral angle between the phenyl and benzene rings is 72.24 (1)°. In the crystal, pairs of N—H...S hydrogen bonds form dimers with twofold rotational symmetry. The dimers are connected by weak C—H...O hydrogen bonds, forming a two-dimensional network parallel to (001). An intramolecular O—H...S hydrogen bond is also observed.

The title compound, C12H23NO2·0.5H2O, crystallized with two 2-(1-amino-4-tert-butylcyclohexyl)acetic acid molecules, which are present as zwitterions, and one water molecule in the asymmetric unit. The molecular structure of each zwitterion is stabilized by an intramolecular six-membered (C6 ) N—H...O hydrogen bond. In the crystal, the two independent zwitterions are linked head-to-head by N—H...O hydrogen bonds. Further O—H...O and N—H...O hydrogen bonds link the zwitterions and the water molecules, forming sandwich-like layers, with a hydrophilic filling and a hydrophobic exterior, lying parallel to the ab plane.

In the title compound, C13H13NO3·H2O, the dihedral angle between the ethyl ester group [C—C—O—C(=O); maximum deviation = 0.003 (2) Å] and the quinoline ring system is 7.94 (12)°. The water solvent molecule is linked to the title molecule via O—H...O and O—H...N hydrogen bonds. In the crystal, molecules are linked by C—H...O hydrogen bonds, forming chains propagating along [100].

In the title compound, C4H3BrClN3, the pyrimidine ring is essentially planar (r.m.s. deviation from the plane = 0.087 Å). In the crystal, pairs of N—H...N hydrogen bonds connect the molecules into inversion dimers; these are connected by further N—H...N hydrogen bonds into a two-dimensional framework parallel to the bc plane.

In the title compound, C32H26Cl2F2N2O2, the tetrahydropyridine ring adopts a distorted boat conformation. The chlorophenyl rings are inclined to one another by 55.2 (1)°, while for the fluorophenyl rings the dihedral angle is 80.7 (1)°. The amino group and carbonyl O atom are involved in an intramolecular N—H...O hydrogen bond. In the crystal, weak C—H...O, C—H...F and C—H...Cl interactions link the molecules into a three-dimensional network.

In the title molecule, C19H17F3N2O2, the fused cyclohexene and pyran rings adopt sofa and flattened boat conformations, respectively. The four essentially planar atoms of the pyran ring [maximum deviation = 0.008 (2) Å] form a dihedral angle of 88.13 (9)° with the benzene ring. The F atoms of the trifluoromethyl group were refined as disordered over three sets of sites in a 0.507 (7):0.330 (7):0.163 (3) ratio. In the crystal, molecules are connected into inversion dimers via pairs of N—H...N hydrogen bonds and these dimers are further linked by N—H...O hydrogen bonds into a two-dimensional network parallel to (100).

In the title molecule, C31H24F4N2O2, the tetrahydropyridine ring adopts a distorted boat conformation. An intramolecular N—H...O hydrogen bond is formed by the amino group and ccarboxyl C=O atom. The crystal structure features weak C—H...F and C—H...O interactions.

In the title molecule, C34H32Cl2N2O2, the tetrahydropyridine ring adopts a distorted boat conformation and both 4-chlorophenyl substituents are in axial positions. An intramolecular N—H...O hydrogen bond is formed by the amino group and carbonyl O atom. In the crystal, weak C—H...Cl interactions link the molecules into chains along [010].

In the title moleclue, C6H7N3, the mean plane of the dimethylamino group [maximum deviation = 0.006 (2) Å] forms a dihedral angle of 7.95 (18)° with the mean plane of the propanedinitrile fragment [maximum deviation = 0.008 (2) Å]. In the crystal, weak C—H...N hydrogen bonds link the molecules into a three-dimensional network.

The asymmetric unit of the title compound, C25H31NO4, contains two independent molecules. In one molecule, the benzene ring and an attached methoxy group were refined as disordered over two sets of sites in a 0.65 (4): 0.35 (4) ratio. In both molecules, the central ring of the acridinedione system adopts a flattened boat conformation. The four essentially planar atoms of this ring [maximum deviations = 0.006 (5) Å in both molecules] forms dihedral angles of 86.8 (2) and 87.6 (2)°, respectively, with the major and minor components in the disordered benzene ring and 87.3 (2)° with the benzene ring in the fully ordered molecule. The two outer rings of the acridinedione system adopt sofa conformations in both molecules. In the crystal, N—H...O hydrogen bonds form two independent chains along [100]. C—H...O hydrogen bonds link the chains, forming a three-dimensional network.

In the title molecule, C17H13FN2O2, the 3,4-dihydropyrimidine ring adopts a flattened sofa conformation with the flap atom (which bears the fluorophenyl substituent) deviating from the plane defined by the remaining five ring atoms by 0.281 (2) Å. This plane forms dihedral angles of 85.98 (6) and 60.63 (6)° with the 4-fluorophenyl and benzoyl-phenyl rings, respectively. The dihedral angle between the 4-fluorophenyl group and the benzene ring is 71.78 (6)°. In the crystal, N—H...O hydrogen bonds link molecules into inversion dimers that are further connected by another N—H...O interaction into a two-dimensional supramolecular structure parallel to (101).

In the title compound, C32H28F2N2O2, the tetrahydropyridine ring adopts a distorted boat conformation. The two fluorophenyl groups are attached to the tetrahydropyridine ring in a trans orientation. The dihedral angle between the planes of the fluoro-substituted rings is 57.0 (1)°. The amino group and carbonyl O atom are involved in intramolecular hydrogen bonding. In the crystal, weak C—H...O, C—H...F and C—H...π interactions link the molecules into columns along [010].

In the title molecule, C24H29NO4, the central ring of the acridinedione system adopts a flat boat conformation and the four essentially planar atoms of this ring [maximum deviation = 0.001 (2) Å] form a dihedral angle of 85.99 (12)° with the benzene ring. The two outer rings of the acridinedione system adopt sofa conformations. In the crystal, O—H...O and N—H...O hydrogen bonds link the molecules, forming a two-dimensional network parallel to (100).

In the title compound, C25H23N3O2, the central benzene ring makes dihedral angles of 77.14 (8) and 87.7 (2)° with the terminal benzene rings and an angle of 1.9 (1)° with the pyrazolone ring. The benzene ring and the N atom of the pyrazole ring bearing the phenyl substituent are disordered over two sets of sites with an occupancy ratio of 0.71 (2):0.29 (2). The N atoms of the pyrazole ring have a pyramidal environment, the sums of the valence angles around them being 354.6 (3) and 352.0 (6)/349.5 (15)°. In the crystal, molecules are packed into layers parallel to the ac plane. The other monoclinic polymorphic form was reported recently [Dutkiewicz et al. (2012). Acta Cryst. E68, o1324].

In the title molecule, C23H26FNO2, the central ring of the acridinedione system adopts a slight boat conformation and the four essentially planar atoms of this ring [maximum deviation = 0.019 (1) Å] form a dihedral angle of 89.98 (6)° with the benzene ring. The two outer rings of the acridinedione system adopt sofa conformations. In the crystal, N—H...O hydrogen bonds link the molecules, forming chains along [001].

In the title molecule, C19H18F3N3O, the dihydropyridine and cyclohexene rings both adopt sofa conformations. The five essentially planar atoms of the dihydropyridine ring [maximum deviation = 0.039 (2) Å] form a dihedral angle of 88.19 (8)° with the benzene ring. The F atoms of the trifluoromethyl group were refined as disordered over two sets of sites in a 0.840 (3):0.160 (3) ratio. In the crystal, N—H...O and N—H...N hydrogen bonds link molecules into a two-dimensional network parallel to (100).

In the title compound, C23H25BrN4O3S2, the benzene rings bridged by the sulfonamide group are tilted relative to each other by 69.7 (1)° and the dihedral angle between the sulfur-bridged pyrimidine and benzene rings is 70.4 (1)°. The molecular conformation is stabilized by a weak intramolecular π–π stacking interaction between the pyrimidine and the 4-methyl benzene rings [centroid–centroid distance = 3.633 (2) Å]. The piperidine ring adopts a chair conformation. In the crystal, molecules are linked into inversion dimers by pairs of N—H...O hydrogen bonds.

There are two independent molecules in the asymmetric unit of the title compound, C21H18BrFO3, in which the dihedral angles between the fluorophenyl and bromophenyl groups are 77.0 (1) and 85.8 (1)°. In one of the molecules, two methine C—H groups of the cyclohexene ring are disordered over two sets of sites in a 0.53 (2):0.47 (2) ratio. In both molecules, the atoms of the ethyl group were refined as disordered over two sets of sites with occupancies of 0.67 (2):0.33 (2) and 0.63 (4):0.37 (4). The cyclohexene rings have slightly distorted sofa conformations in both molecules. In the crystal, C—H...O interactions link molecules into chains along the b axis.

In the title compound, C18H18ClN5O3, the hydrazinecarboxamide N—N—C(O)—N unit is nearly planar [maximum deviation = 0.074 (2) Å] and is inclined at a dihedral angle of 57.43 (7)° with respect to the plane of the attached benzene ring. The chlorophenyl group makes dihedral angles of 19.71 (7) and 34.07 (6)° with the pyrazole and benzene rings, respectively. In the crystal, pairs of N—H...O hydrogen bonds link the molecules into inversion dimers that are further linked into chains along the a-axis direction by N—H...N hydrogen bonds. In addition, π–π stacking interactions are observed between benzene rings [centroid–centroid distance = 3.680 (1) Å].

The asymmetric unit of the title compound, C19H16N2O3, contains two independent molecules in which the dihedral angles between the naphthalene ring system and the benzene ring are 10.0 (1) and 35.3 (1)°. In the crystal, molecules are linked by N—H...O and O—H...O hydrogen bonds, forming a two-dimensional framework parallel to (001). Weak C—H...O and C—H...N hydrogen bonds complete a three-dimensional network.

In the title molecule, C25H23N3O2, the pyrazole ring forms dihedral angles of 28.56 (7), 80.35 (7) and 31.99 (7)° with the phenyl ring, the p-tolyl ring and the p-tolylamino ring, respectively. The N—H group attached to the exocyclic C=C bond is in a syn arrangement with respect to the C=O bond of the pyrazolone group and an intramolecular N—H...O hydrogen bond is observed. In the crystal, weak C—H...π interactions link molecules along [100].

In the title compound, C25H29BrN4O3S2, the benzene rings bridged by the sulfonamide group are tilted relative to each other by 63.9 (1)° and the dihedral angle between the sulfur-bridged pyrimidine and benzene rings is 64.9 (1)°. The molecular conformation is stabilized by a weak intramolecular π–π stacking interaction between the pyrimidine and the 2,4,6-trimethylbenzene rings [centroid–centroid distance = 3.766 (2) Å]. The piperidine ring adopts a chair conformation. In the crystal, molecules are linked into inversion dimers by pairs of N—H...O hydrogen bonds and these dimers are further linked by C—H...O hydrogen bonds into chains propagating along [010].

In the title compound, C21H20BrClN4O4S2, the benzene rings bridged by the sulfonamide group are tilted relative to each other by a dihedral angle of 70.2 (1)° and the dihedral angle between the sulfur-bridged pyrimidine and benzene rings is 69.5 (1)°. The molecular conformation is stabilized by a weak intramolecular π–π stacking interaction between the pyrimidine and the 4-chlorobenzene rings [centroid–centroid distance = 3.978 (2) Å]. The morpholine ring adopts a chair conformation. In the crystal, molecules are linked into inversion dimers by pairs of C—H...N hydrogen bonds and these dimers are further connected by N—H...O hydrogen bonds, forming a tape along the a axis.

In the title compound, C17H19NO3, the dihedral angle between the benzene rings is 68.0 (1)°. The C—O—C—C torsion angle of the atoms joining these rings is 179.7 (2)°. The atoms of the methanol group were refined as disordered over two sets of sites with fixed occupancies of 0.86 and 0.14. The H atoms of the hydroxy group in the major component are disordered over a further two sets of sites with equal occupancies. This is a necessary arrangement to allow for hydrogen bonding without unrealistic H...H contacts. In the crystal, O—H...N and O—H...O hydrogen bonds connect molecules into chains along [001].

The asymmetric unit of the title compound, C19H19ClO4, contains two independent molecules. The dihedral angles between the benzene rings are 63.41 (8) and 61.41 (9)°. Adjacent molecules of different types are interconnected in pairs through π–π interactions between their central benzene rings [centroid–centroid separation = 3.801 (2) Å, interplanar spacing = 3.605 (2) Å, centroid shift = 1.204 (2) Å]. Finally, C—H...O hydrogen bonds link these dimers into bilayers parallel to (100).

In the title compound, C17H17NO4, the dihedral angle between the two aromatic rings is 59.64 (5)°. The (methoxyimino)ethanoic acid fragment is nearly perpendicular to the attached benzene ring [dihedral angle = 81.07 (4)°]. In the crystal, pairs of O—H...O hydrogen bonds between carboxy groups link molecules into inversion dimers. In addition, π–π stacking interactions between inversion-related benzene rings are observed [centroid–centroid distance = 3.702 (1) Å].

In the title compound, C22H23BrN4O4S2, the benzene rings bridged by the sulfonamide group are tilted relative to each other by 68.9 (1)° and the dihedral angle between the sulfur-bridged pyrimidine and benzene rings is 69.7 (1)°. The molecular conformation is stabilized by a weak intramolecular π–π stacking interaction between the pyrimidine and the 4-methylbenzene rings [centroid–centroid distance = 3.934 (2) Å]. The morpholine ring adopts a chair conformation and is disordered over two positions with an occupancy ratio of 0.853 (6):0.147 (6). In the crystal, molecules are linked by N—H...O hydrogen bonds into chains extending along the a axis and further, through C—H...N and C—H...O interactions, into a three-dimensional supramolecular structure.

In the title compound, C35H32N4O4, the pyrazole ring forms a dihedral angle of 15.04 (8)° with the adjacent pyrimidine ring. The pyrimidine ring forms dihedral angles of 9.95 (8) and 1.86 (7)° with its adjacent methoxy-substituted benzene rings, whereas the equivalent angles are 80.24 (9) and 11.55 (9)° for the pyrazole ring and its adjacent benzene rings. The crystal packing features π–π interactions, the centroid–centroid distance between the pyrimidine and methoxyphenyl rings being 3.604 (1) Å. The pyrazole ring is nearly planar, with a maximum deviation of 0.020 (3) Å for the –CH2– carbon.

In the title molecule, C19H20N2O2, the cyclohexene ring adopts a sofa conformation, while the pyran ring adopts a flattened boat conformation. In the crystal, molecules are linked by N—H...N and N—H...O hydrogen bonds, forming a two-dimensional network parallel to (010).

The title molecule, C18H24O12, has crystallographic 2/m symmetry with two acetate group located on a mirror plane. The H—Csp3—O—Csp2 torsion angles characterizing orientation of the acetyl groups with respect to the cyclohexane ring are 0.0, 23.9 and −23.9°. The cyclohexane ring is in a chair conformation with all substituents in equatorial positions. In the crystal, molecules are connected through C—H...O hydrogen bonds into a chain extending along the c axis.

In the title compound, C29H22F2O2S, the central benzene ring makes dihedral angles of 45.83 (7), 38.90 (7) and 55.50 (7)° with the two fluoro-substituted benzene rings and the methylsulfanyl-substituted benzene ring, respectively. In the crystal, C—H...O contacts connect the molecules into layers lying perpendicular to the c axis. In addition, π–π stacking interactions between one of the fluorophenyl groups [centroid–centroid distances = 3.681 (1) and 3.818 (1) Å] are observed.

In the title compound, [Na(C11H11ClN3O3)(H2O)]n, there are two independent NaI ions, one of which lies on an inversion center and is coordinated in a slightly distorted octahedral environment. The other NaI ion lies on a twofold rotation axis and is cooordinated in a slightly distorted trigonal–bipyramidal coordination environment. In the organic ligand, the imidazolidine ring adopts a half-chair conformation. The NaI ions bridge organic ligands and water molecules, forming a two-dimensional structure parallel to (100). There are intermolecular O—H...O and weak C—H...O hydrogen bonds within the two-dimensional structure.

In the title molecule, C11H8FNO, the dihedral angle between the pyrrole and benzene rings is 49.16 (6)°. In the crystal, adjacent molecules are linked by pairs of N—H...O hydrogen bonds, forming inversion dimers.

In the title molecule, C21H14BrFN4O4, the mean planes of the two nitro groups form dihedral angles of 3.1 (2) and 7.1 (5)° with the benzene ring to which they are attached. The dinitro-substituted ring forms dihedral angles of 8.6 (2) and 71.9 (2)° with the bromo- and fluoro-substituted benzene rings, respectively. The dihedral angle between the bromo- and fluoro-substituted benzene rings is 80.6 (2)°. There is an intramolecular N—H...O hydrogen bond. In the crystal, pairs of weak C—H...O hydrogen bonds form inversion dimers. In addition, π–π stacking interactions between the bromo- and dinitro-substituted rings [centroid–centroid separation = 3.768 (2) Å] are observed.

In the title molecule, C8H7BrO2, the carboxyl group is twisted by 76.2 (3)° from the benzene ring plane. In the crystal, molecules are linked into inversion dimers through pairs of O—H...O hydrogen bonds. The dimers are further linked into layers parallel to the bc plane by weak C—H...O hydrogen bonds.

In the title compound, C8H7ClO2, the carboxyl group forms a dihedral angle of 74.83 (9)° with the benzene ring plane. In the crystal, molecules are linked into inversion dimers by pairs of O—H...O hydrogen bonds. The dimers are linked into layers parallel to the bc plane by weak C—H...O interactions.

In the title molecule, C9H10ClN3O, the dihedral angle between the pyridine ring and imidazoline ring mean plane [maximum deviation = 0.031–(3) Å] is 76.2 (1)°. In the crystal, N—H...O hydrogen bonds link pairs of molecules to form inversion dimers. In addition, weak C—H...N hydrogen bonds and π–π stacking interactions between pyridine rings [centroid–centroid distance = 3.977 (2) Å] are observed.