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A 1:1 epimeric mixture of 3-[(4-nitrobenzylidene)amino]-2(R,S)-(4-nitrophenyl)-5(S)-(propan-2-yl)imidazolidin-4-one, C19H19N5O5, was isolated from a reaction mixture of 2(S)-amino-3-methyl-1-oxobutanehydrazine and 4-nitrobenzaldehyde in ethanol. The product was derived from an initial reaction of 2(S)-amino-3-methyl-1-oxobutanehydrazine at its hydrazine group to provide a 4-nitrobenzylidene derivative, followed by a cyclization reaction with another molecule of 4-nitrobenzaldehyde to form the chiral five-membered imidazolidin-4-one ring. The formation of the five-membered imidazolidin-4-one ring occurred with retention of the configuration at the 5-position, but with racemization at the 2-position. In the crystal, N—H...O(nitro) hydrogen bonds, weak C—H...O(carbonyl) and C—H...O(nitro) hydrogen bonds, as well as C—H...π, N—H...π and π–π interactions, are present. These combine to generate a three-dimensional array. Hirshfeld surface analysis and PIXEL calculations are also reported.

The syntheses and crystal structures of five 2-benzylidene-1-benzosuberone [1-benzosuberone is 6,7,8,9-tetrahydro-5H-benzo[7]annulen-5-one] derivatives, viz. 2-(4-methoxybenzylidene)-1-benzosuberone, C19H18O2, (I), 2-(4-ethoxybenzylidene)-1-benzosuberone, C20H20O2, (II), 2-(4-benzylbenzylidene)-1-benzosuberone, C25H22O2, (III), 2-(4-chlorobenzylidene)-1-benzosuberone, C18H15ClO, (IV) and 2-(4-cyanobenzylidene)-1-benzosuberone, C19H15NO, (V), are described. The conformations of the benzosuberone fused six- plus seven-membered ring fragments are very similar in each case, but the dihedral angles between the fused benzene ring and the pendant benzene ring differ somewhat, with values of 23.79 (3) for (I), 24.60 (4) for (II), 33.72 (4) for (III), 29.93 (8) for (IV) and 21.81 (7)° for (V). Key features of the packing include pairwise C—H...O hydrogen bonds for (II) and (IV), and pairwise C—H...N hydrogen bonds for (V), which generate inversion dimers in each case. The packing for (I) and (III) feature C—H...O hydrogen bonds, which lead to [010] and [100] chains, respectively. Weak C—H...π interactions consolidate the structures and weak aromatic π–π stacking is seen in (II) [centroid–centroid separation = 3.8414 (7) Å] and (III) [3.9475 (7) Å]. A polymorph of (I) crystallized from a different solvent has been reported previously [Dimmock et al. (1999) J. Med. Chem. 42, 1358–1366] in the same space group but with a packing motif based on inversion dimers resembling that seen in (IV) in the present study. The Hirshfeld surfaces and fingerprint plots for (I) and its polymorph are compared and structural features of the 2-benzylidene-1-benzosuberone family of phases are surveyed.

The asymmetric unit of the title compound, C13H11N3O2S2, comprises two independent molecules (A and B); the crystal structure was determined by employing synchrotron radiation. The molecules exhibit essentially the same features with an almost planar benzothiazole ring (r.m.s. deviation = 0.026 and 0.009 Å for A and B, respectively), which forms an inclined dihedral angle with the phenyl ring [28.3 (3) and 29.1 (3)°, respectively]. A difference between the molecules is noted in a twist about the N—S bonds [the C—S—N—N torsion angles = −56.2 (5) and −68.8 (5)°, respectively], which leads to a minor difference in orientation of the phenyl rings. In the molecular packing, A and B are linked into a supramolecular dimer via pairwise hydrazinyl-N—H...N(thiazolyl) hydrogen bonds. Hydrazinyl-N—H...O(sulfonyl) hydrogen bonds between A molecules assemble the dimers into chains along the a-axis direction, while links between centrosymmetrically related B molecules, leading to eight-membered {...HNSO}2 synthons, link the molecules along [001]. The result is an undulating supramolecular layer. Layers stack along the b-axis direction with benzothiazole-C—H...O(sulfonyl) points of contact being evident. The analyses of the calculated Hirshfeld surfaces confirm the relevance of the above intermolecular interactions, but also serve to further differentiate the weaker intermolecular interactions formed by the independent molecules, such as π–π interactions. This is also highlighted in distinctive energy frameworks calculated for the individual molecules.

The development of novel pharmaceutical tools to efficiently tackle tuberculosis is the order of the day due to the rapid development of resistant strains of Mycobacterium tuberculosis. Herein, we report novel potential formulations of a repurposed drug, the antimalarial mefloquine (MFL), which was combined with organic anions as chemical adjuvants. Eight mefloquine organic salts were obtained by ion metathesis reaction between mefloquine hydrochloride ([MFLH][Cl]) and several organic acid sodium salts in high yields. One of the salts, mefloquine mesylate ([MFLH][MsO]), presented increased water solubility in comparison with [MFLH][Cl]. Moreover, all salts with the exception of mefloquine docusate ([MFLH][AOT]) showed improved permeability and diffusion through synthetic membranes. Finally, in vitro activity studies against Mycobacterium tuberculosis revealed that these ionic formulations exhibited up to 1.5-times lower MIC values when compared with [MFLH][Cl], particularly mefloquine camphorsulfonates ([MFLH][(1R)-CSA], [MFLH][(1S)-CSA]) and mefloquine HEPES ([MFLH][HEPES]).

The crystal structures of four (E)-methoxybenzaldehyde oxime derivatives, namely (2-methoxybenzaldehyde oxime, 1, 2,3-dimethoxybenzaldehyde oxime, 2, 4-dimethoxybenzaldehyde oxime, 3, and 2,5-dimethoxybenzaldehyde oxime, 4, are discussed. The arrangements of the 2-methoxy group and the H atom of the oxime unit are s-cis in compounds 1–3, but in both independent molecules of compound 4, the arrangements are s-trans. There is also a difference in the conformation of the two molecules in 4, involving the orientations of the 2- and 5-methoxy groups. The primary intermolecular O—H(oxime)...O(hydroxy) hydrogen bonds generate C(3) chains in 1 and 2. In contrast, in compound 3, the O—H(oxime)...O(hydroxy) hydrogen bonds generate symmetric R22(6) dimers. A more complex dimer is generated in 4 from the O—H(oxime)...O(hydroxy) and C—H(2-methoxy)...O(hydroxy) hydrogen bonds. In all cases, further interactions, C—H...O and C—H...π or π–π, generate three-dimensional arrays. Hirshfeld surface and fingerprint analyses are discussed.

The crystal structures of three salicyaldoxime compounds, namely 2-hydroxy-4-methylbenzaldehyde oxime, C8H9NO2, 1, 2,4-dihydroxybenzaldehyde oxime, C7H7NO3, 2, and 2-hydroxy-4-methoxybenzaldehyde oxime, C8H9NO3, 3, are discussed. In each compound, the hydroxyl groups are essentially coplanar with their attached phenyl group. The interplanar angles between the C=N—O moieties of the oxime unit and their attached phenyl rings are 0.08 (9), 1.08 (15) and 6.65 (15)° in 1, 2 and 3, respectively. In all three molecules, the 2-hydroxy group forms an intramolecular O—H...N(oxime) hydrogen bond. In compound (1), intermolecular O—H(oxime)...O(hydroxyl) hydrogen bonds generate R22(14) dimers, related by inversion centres. In compound 2, intermolecular O—H(oxime)...O(4-hydroxy) hydrogen bonds generate C9 chains along the b-axis direction, while O—H(4-hydroxyl)...O(2-hydroxyl) interactions form zigzag C6 spiral chains along the c-axis direction, generated by a screw axis at 1, y, 1/4: the combination of the two chains provides a bimolecular sheet running parallel to the b axis, which lies between 0–1/2 c and 1/2–1 c. In compound 3, similar C9 chains, along the b-axis direction are generated by O—H(oxime)...O(4-methoxy) hydrogen bonds. Further weaker, C—H...π (in 1), π–π (in 2) and both C—H...π and π–π interactions (in 3) further cement the three-dimensional structures. Hirshfeld surface and fingerprint analyses are discussed.

The syntheses and crystal structures of 2-[2-(propan-2-ylidene)hydrazinyl]-1,3-benzothiazol-3-ium 3-nitrobenzenesulfonate (C10H12N2S+·C6H4NO5S−), (I), 2-[2-(3-nitrobenzenesulfonyl)hydrazinyl]-1,3-benzothiazole (C13H10N4O4S2), (II) and 2-[2-(3-nitrobenzenesulfonyl)hydrazinyl]-1,3-benzothiazol-3-ium 3-nitrobenzenesulfonate (C13H11N4O4S2+·C6H4NO5S−), (III) are reported. Salt (I) arose from an unexpected reaction of 2-hydrazinylbenzothiazole with the acetone solvent in the presence of 3-nitrobenzenesulfonyl chloride, whereas (II) and (III) were recovered from the equivalent reaction carried out in methanol. The crystal of (I) features ion pairs linked by pairs of N—H...Os (s = sulfonate) hydrogen bonds; adjacent cations interact by way of short π–π stacking interactions between the thiazole rings [centroid–centroid separation = 3.4274 (18) Å]. In (II), which crystallizes with two neutral molecules in the asymmetric unit, the molecules are linked by N—H...N and N—H...On (n = nitro) hydrogen bonds to generate [\overline{1}1\overline{1}] chains, which are cross-linked by C—H...O and π–π stacking interactions. The crystal of (III) features centrosymmetric tetramers (two cations and two anions) linked by cooperative N—H...O hydrogen bonds; C—H...O and π–π interactions occur between tetramers.

The crystal structures of three isomeric (E)-N′-(chlorophenylmethylidene)-N-methyl-2-(thiophen-2-yl)acetohydrazides (C14H13ClN2OS) are described, with the Cl atom in ortho (I), meta (III) and para (IV) positions in the benzene ring. The ortho-bromo derivative (II) (C14H13BrN2OS), which is isostructural with its chloro congener (I), is also reported. Molecules (I)–(III) have similar conformations, which approximate to l-shapes, as indicated by their N—C—C—Ct (t = thiophene) torsion angles of −90.1 (3), −91.44 (18) and −90.7 (9)°, respectively. The conformation of (IV) is different, with an equivalent torsion angle of −170.75 (11)° corresponding to a more extended shape for the molecule. The thiophene ring in each structure features `flip' rotational disorder. The packing for (I) and (II) features inversion dimers, linked by pairs of C—H...O interactions, which generate R22(14) loops. In the crystal of (III), [010] C(8) chains arise, with adjacent molecules linked by pairs of C—H...O hydrogen bonds. The packing for (IV) features unusually short C—H...O interactions arising from an H atom attached to the benzene ring (H...O = 2.18 Å), which lead to C(9) [301] chains. Hirshfeld fingerprint percentage contact contributions are similar for the four title compounds.

The syntheses and crystal structures of (E)-N′-(3-cyanobenzylidene)-N-methyl-2-(thiophen-2-yl)acetohydrazide, C15H13N3OS, (I), and (E)-N′-(4-methoxybenzylidene)-N-methyl-2-(thiophen-2-yl)acetohydrazide, C15H16N2O2S, (II), with different substituents in the meta and para position of the benzene ring are described. Compounds (I) and (II) both crystallize with two molecules in the asymmetric unit, with generally similar conformations [r.m.s. overlay fits for (I) and (II) of 0.334 and 0.280 Å, respectively] that approximate to L-shapes. The thiophene rings in (I) are well ordered, whereas those in (II) exhibit `flip' rotational disorder [occupancies 0.662 (2) and 0.338 (2) for molecule 1, and 0.549 (3) and 0.451 (3) for molecule 2]. The packing for (I) features short C—H...O interactions arising from the C—H grouping adjacent to the cyanide group and C—H...Nc (c = cyanide) links arising from the methine groups to generate [110] double chains. Weak C—H...π interactions interlink the chains into a three-dimensional network. The packing for (II) features numerous C—H...O and C—H...π interactions arising from different donor groups to generate a three-dimensional network. Hirshfeld fingerprint plots indicate significant differences in the percentage contact surfaces for (I) and (II).

The crystal structures of three isomeric (E)-N-methyl-N′-(nitrobenzylidene)-2-(thiophen-2-yl)acetohydrazides (formula C14H13N3O3S) are described, with the nitro group in ortho, meta and para positions in the benzene ring. In each crystal structure, molecules are linked by various weak interactions (C—H...O and C—H...π bonds, and π–π stacking), leading to three-dimensional networks in each case, but with little similarity between them.

In the title carbohydrazide, C10H7N3O4S, the dihedral angle between the terminal five-membered rings is 27.4 (2)°, with these lying to the same side of the plane through the central CN2C(=O) atoms (r.m.s. deviation = 0.0403 Å), leading to a curved molecule. The conformation about the C=N imine bond [1.281 (5) Å] is E, and the carbonyl O and amide H atoms are anti. In the crystal, N—H...O hydrogen bonds lead to supramolecular chains, generated by a 41 screw-axis along the c direction. A three-dimensional architecture is consolidated by thienyl-C—H...O(nitro) and furanyl-C—H...O(nitro) interactions, as well as π–π interactions between the thienyl and furanyl rings [inter-centroid distance = 3.515 (2) Å]. These, and other, weak intermolecular interactions, e.g. nitro-N—O...π(thienyl), have been investigated by Hirshfeld surface analysis, which confirms the dominance of the conventional N—H...O hydrogen bonding to the overall molecular packing.

The crystal structures of three methylated hydrazine carbamate derivatives prepared by multi-step syntheses from l-serine are presented, namely benzyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopropan-2-yl}carbamate, C20H20N4O4, tert-butyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopropan-2-yl}carbamate, C17H22N4O4, and tert-butyl N-[(E)-1-(2-benzylidene-1-methylhydrazinyl)-3-hydroxy-1-oxopropan-2-yl]carbamate, C16H23N3O4. One of them shows that an unexpected racemization has occurred during the mild-condition methylation reaction. In each crystal structure, the molecules are linked into chains by O—H...O hydrogen bonds, but with significant differences between them.

Two series of N’(E)-heteroaromatic-isonicotinohydrazide derivatives (3a-f and 4a-b) and 1-(7-chloroquinolin-4-yl)-2-[(heteroaromatic)methylene]hydrazone derivatives (5a-f and 6a-b) have been synthesized and evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H37Rv. Several compounds were noncytotoxic and exhibited significant minimum inhibitory concentration (MIC) activity (3.12, 2.50, 1.25, or 0.60 μg/mL), which can be compared to that of the first-line drugs ethambutol (3.12 μg/mL) and rifampicin (2.0 μg/ml). These results can be considered an important starting point for the rational design of new leads for anti-TB compounds.

A series of 13 compounds analogous of isoniazid condensed with carbohydrate was synthesized and evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H37Rv using Alamar Blue susceptibility test and the activity expressed as the minimum inhibitory concentration (MIC90) in μg/mL. Several compounds exhibited antitubercular activity (0.31-3.12 μg/mL) when compared with first line drugs such as isoniazid (INH) and rifampicin (RIP) and could be a good starting point to develop new compounds against tuberculosis.

In the title salt, C11H12ClN2O+·Cl−, the ten non-H atoms comprising the quinolinium residue are coplanar (r.m.s. deviation = 0.041 Å) and the hydroxyethyl group is approximately perpendicular to this plane [Cring—N—Cmethylene—C torsion angle = −74.61 (18)°]. A supramolecular chain aligned along [101] mediated by charge-assisted O/N—H...Cl− hydrogen bonds features in the crystal packing. Chains are connected into a three-dimensional architecture by C—H...O(hydroxy) interactions.

The 21 non-H atoms of the title compound, C15H10Cl2N4, are almost planar (r.m.s. deviation = 0.032 Å); the conformation about the N=C bond [1.277 (6) Å] is E. In the crystal, zigzag supramolecular chains along the c axis (glide symmetry) are formed via N—H...N hydrogen bonds. These associate along the b axis by π–π interactions between the fused and terminal benzene rings [intercentroid distance = 3.602 (3) Å] so that layers form in the bc plane.

In the title hydrated salt, C16H13ClN3+·Cl−·2H2O, a small twist is evident in the cation so that the chlorobenzene ring is not coplanar with the central hydrazinyl group [the N—C—C—C torsion angle = −4.8 (12)°]. The conformation about the imine N=C bond [1.284 (10) Å] is E. The components of the structure are connected into a three-dimensional architecture via O—H...O, O—H...Cl and N—H...Cl hydrogen bonds. One water H atom is disposed over two sites of equal occupancy.

In the title hydrated salt, C16H12Cl2N3+·Cl−·H2O, there is a small twist in the cation as seen in the torsion angle linking the benzene ring to the rest of the molecule [171.96 (17)°]. In the crystal, the quinolinium H atom forms a hydrogen bond to the lattice water molecule, which also forms hydrogen bonds to two Cl− anions. Each Cl− ion also accepts a hydrogen bond from the hydrazine H atom. The three-dimensional architecture is also stabilized by π–π interactions between centrosymmetrically related quinoline residues [centroid–centroid distance = 3.5574 (11) Å].

In the nearly planar title compound (r.m.s. deviation for the 24 non-H atoms = 0.064 Å), C18H16ClN3O2, the conformation about the N=C bond is E. Supramolecular chains propagated by glide symmetry along [001] are found in the crystal packing. These are sustained by N—H...N hydrogen bonds with the quinoline N atom being the acceptor. The chains are connected into a three-dimensional architecture by π–π interactions involving all three aromatic rings [centroid–centroid distances = 3.5650 (9)–3.6264 (9) Å].

In the title compound, C19H18ClN3O3, the r.m.s. deviation through the 23 non-H and non-methoxy atoms is 0.088 Å, indicating a planar molecule with the exception of the methoxy groups. One methoxy group, surrounded on either side by the other methoxy groups, is almost normal to the benzene ring to which it is connected [C—O—Car—Car torsion angle = 81.64 (15)°]. In the crystal, N—H...O, C—H...O and π–π interactions [between quinoline residues; centroid–centroid distance = 3.4375 (8) Å] link molecules into a three-dimensional architecture.

The title molecule, C22H24F6N2O3, adopts a folded conformation whereby the carboxylate residue lies over the quinolinyl residue, with the dihedral angle between the carbamate and quinoline planes being 41.64 (7)°. Helical supramolecular C(7) chains sustained by O—H...O hydrogen bonds propagating along the a-axis direction feature in the crystal packing. The F atoms of one of the CF3 groups are disordered over two orientations; the major component has a site occupancy of 0.824 (7).

The title molecule, C25H22F6N2O3, adopts an open conformation whereby the quinoline and carboxylate ester groups are orientated in opposite directions but to the same side of the piperidine ring so that the molecule has an approximate U-shape. The piperidine ring adopts a distorted boat conformation. In the crystal, inversion dimers linked by pairs of O—H...O hydrogen bonds generate R22(14) loops.

The asymmetric unit of the title salt solvate, C17H17F6N2O+·C7H5N2O4−·1.5H2O, comprises a piperidin-1-ium cation, a 3-amino-5-nitrobenzoate anion, and three fractionally occupied [i.e. 0.414 (3), 0.627 (6) and 0.459 (5)] disordered water molecules of solvation. The cation has an L shape with a C—C—C—C torsion angle of −102.9 (3)° for the atoms linking the quinolinyl group to the rest of the cation. In the anion, the carboxylate and nitro groups are essentially coplanar with the benzene ring [O—C—C—C torsion angle = 179.7 (2)° and O—N—C—C torsion angle = −3.9 (3)°]. In the crystal, extensive O—H...O, O—H...F and N—H...·O hydrogen bonding leads to the formation of a layer in the ab plane.

The title urea derivative crystallizes as a monohydrate, C19H27N3O2·H2O. The central C3N grouping is almost planar (r.m.s. deviation = 0.0092 Å), and the amide and pyridine groups are substantially twisted out this plane [dihedral angles = 62.80 (12) and 34.98 (10)°, respectively]. Supramolecular double chains propagating along the b-axis direction feature in the crystal packing whereby linear chains sustained by N—H...O hydrogen bonds formed between the amide groups are linked by helical chains of water molecules (linked by O—H...O hydrogen bonds). The H atom that participates in these water chains is disordered over two positions of equal occupancy. The double chains are connected into a two-dimensional array by C—H...O contacts and the layers stack along the a axis.

The title mefloquine derivative has been crystallized as its 1:1 methanol solvate, C19H18F6N2O2·CH3OH. Each of the methinehydroxyl residue [the C—C—C—O torsion angle is −16.35 (17) °] and the piperidinyl group [distorted chair conformation] lies to one side of the quinolinyl ring system. The hydroxyl and carbonyl groups lie to either side of the molecule, enabling their participation in intermolecular interactions. Thus, the hydroxyl and carbonyl groups of two centrosymmetrically related molecules are bridged by two methanol molecules via O—H...O hydrogen bonds, leading to a four-molecule aggregate. These are linked into a supramolecular chain along the a axis via C—H...O interactions involving the hydroxyl-O atom. The chains assemble into layers that interdigitate along the c axis being connected by C—H...F interactions.

The organic molecule in the title dihydrate, C18H19N3O6·2H2O, adopts a twisted U-shape with the major twists evident about the chiral C atom [the C—N—C—C torsion angle is −88.2 (4) °] and about the oxygen–benzyl bond [C—O—C—C = 74.2 (4) °]. The conformation about the imine bond [1.290 (4) Å] is E and an intramolecular O—H...N hydrogen bond helps to establish the near coplanarity of the hydroxybenzene and hydrazine groups. The crystal packing features O—H...O and N—H...O hydrogen bonds, leading to two-dimensional supramolecular arrays in the ab plane with weak C—H...π connections between the arrays.

The molecule of the title compound, C16H23N3O6, is twisted about the chiral C atom with the dihedral angle formed between the amide residues being 76.9 (3)°. Overall, the molecule is curved with the terminal organic groups lying to the same side. The conformation about the imine bond [1.291 (5) Å] is E and an intramolecular O—H...N hydrogen bond generates an S(6) ring. In the crystal, O—H...O and N—H...O hydrogen bonds involving the hydroxy, amine and carbonyl groups lead to the formation of supramolecular layers, which stack along the c-axis direction.

The molecule of the title compound, C18H19N3O5, adopts a curved arrangement with the terminal benzene rings lying to the same side. The hydroxylbenzene ring is close to coplanar with the adjacent hydrazine residue [dihedral angle = 11.14 (12)°], an observation which correlates with the presence of an intramolecular O—H...N hydrogen bond. The benzyl ring forms a dihedral angle of 50.84 (13)° with the adjacent carbamate group. A twist in the molecule, at the chiral C atom, is reflected in the dihedral angle of 80.21 (12)° formed between the amide residues. In the crystal, two-dimensional arrays in the ac plane are mediated by O—H...O and N—H...O hydrogen bonds.

In the title compound, C13H12N4O2, all the non-H atoms lie on a crystallographic mirror plane and an intramolecular N—H...N hydrogen bond generates an S(5) ring; the conformation about the imine bond [1.280 (3) Å] is E. In the crystal, molecules assemble into a two-dimensional array via C—H...O(carbonyl) and C—H...N(pyrazine) contacts. Layers stack along the b-axis direction via weak π–π interactions between pyrazine rings [ring centroid distance = 3.8028 (8) Å].

In the title mefloquine–oxazolidine derivative, C24H20F6N2O2, the oxazoline ring adopts an envelope conformation (the flap atom is N) and the piperidine ring has a chair conformation. The oxazoline and benzene residues lie away from the C6 ring of the quinoline group and, to a first approximation, to one side of the plane through the ten atoms (r.m.s. deviation = 0.025 Å). An intramolecular O—H...N(piperidine) hydrogen bond is present. The crystal packing features C—H...O, C—H...F and C—H...π(hydroxybenzene) interactions.

The molecule of the title compound, C16H23N3O5, is twisted about the chiral C atom, the dihedral angle formed between the amide residues being 79.6 (3)°. The conformation about the imine bond [1.278 (5) Å] is E. In the crystal, O—H...O and N—H...O hydrogen bonding between the hydroxy, amine and carbonyl groups leads to the formation of supramolecular layers, which stack along the c-axis direction.

The molecule of the title compound, C18H18ClN3O4, is twisted about the chiral C atom with the dihedral angle between the two amide residues being 87.8 (5)°, but, overall, it can be described as curved, with the benzene rings lying on the same side of the molecule [dihedral angle = 62.8 (4)°]. The conformation about the imine bond [1.294 (7) Å] is E. In the crystal, a two-dimensional array in the ab plane is mediated by O—H...O and N—H...O hydrogen bonds as well as C—H...Cl interactions. The layers stack along the c-axis direction, being connected by C—H....π contacts.

The shape of the title compound, C19H21N3O6, is curved with the conformation about the imine bond [1.291 (3) Å] being E. While the hydroxy-substituted benzene ring is almost coplanar with the hydrazinyl residue [N—N—C—C = 177.31 (18)°], an observation correlated with an intramolecular O—H...N hydrogen bond leading to an S(6) ring, the remaining residues exhibit significant twists. The carbonyl residues are directed away from each other as are the amines. This allows for the formation of O—H...O and N—H...O hydrogen bonds in the crystal, which lead to two-dimensional supramolecular arrays in the ac plane. Additional stabilization to the layers is afforded by C—H...π interactions.

In the title molecule, C7H8ClN3O, the pyrazine and amide groups are almost co-planar [N—C—C—N torsion angle = −2.4 (2) °], a conformation stabilized by an intramolecular N—H...N hydrogen bond. The chloroethyl group lies out of the plane [N—C—C—Cl = −65.06 (17) °]. In the crystal, the presence of N—H...N hydrogen bonds leads to the formation of a C(6) supramolecular chain along the b axis. The carbonyl-O atom accepts two C—H...O interactions. These, plus Cl...Cl short contacts [3.3653 (6) Å], consolidate the packing of the chains in the crystal.

The molecule of the title compound, C11H8BrN3O, is close to planar (r.m.s. deviation of all 16 non-H atoms = 0.103 Å), a conformation stabilized by an intramolecular N—H...N hydrogen bond, which generates an S(5) ring. In the crystal structure, supramolecular chains mediated by C—H...O contacts (along a) are linked into a double layer via N...Br halogen bonds [3.207 (5) Å] and C—Br...π interactions [Br...ring centroid(pyrazine) = 3.446 (3) Å]. The layers stack along the b axis via weak π–π interactions [ring centroid(pyrazine)...ring centroid(benzene) distance = 3.803 (4) Å].

The carbamate and hydrazone groups in the title compound, C18H18N4O6, are approximately orthogonal [dihedral angle = 83.3 (4)°], and the carbonyl groups are effectively anti [O=C...C=O torsion angle = −116.2 (7)°]. The conformation about the imine bond [1.295 (11) Å] is E. The crystal packing is dominated by O—H...O and N—H...O hydrogen bonding, which leads to two-dimensional arrays in the ab plane.

A U-shaped conformation is found in the title compound, C19H21N3O5, with the benzene rings lying to the same side of the molecule; the dihedral angle between them is 10.83 (16)°. The dihedral angle formed between the hydrazinecarbonyl and carbamate residues is 68.42 (13)°. The carbonyl groups lie approximately at right angles to each other [O—C...C—O pseudo torsion angle of 107.7 (3)°], and the conformation about the C12=N3 bond [1.279 (4) Å] is E. An intramolecular Ncb—H...Ohy (cb = carbmate and hy = hydroxy) hydrogen bond occurs, generating an S(6) loop. In the crystal, intermolecular Oh—H...Oca (ca = carbonyl) and Nhz—H...Oca (hz = hydrazine) hydrogen bonds lead to the formation of a supramolecular chain, two molecules thick, which propagates along the a axis; these are connected by C—H...Oca contacts.

In the title compound, C8H17N3O4, the dihedral angle between the hydrazinecarbonyl and carbamate groups is 44.94 (12)°, and the carbonyl groups are anti to each other. In the crystal, the hydroxy group forms an O—H...Na (a = amine) hydrogen bond and each of the four N—H atoms forms an N—H...O hydrogen bond; the hydrazinecarbonyl O atom accepts two such bonds. This results in two-dimensional arrays in the ab plane, mediated by the hydrogen bonding, sandwiched by tert-butyl groups.

The organic molecule in the title hydrate, C17H14ClN3O·H2O, has a small but significant twist from planarity, as seen in the dihedral angle of 12.10 (17)° between the quinoline and benzene rings. The conformation about the C=N bond is E. Chains along the b axis are formed in the crystal structure aided by water–quinoline O—H...N (× 2) and hydrazone–water N—H...O hydrogen bonds. Layers of these chains stack along the a axis via C—H...π and π–π interactions [ring centroid–ring centroid distance = 3.674 (2) Å]. C—H...O interactions are also present.

In the title hydrate, C17H14ClN3O·H2O, the dihedral angle between the quinoline fused-ring system and the benzene ring is 13.4 (2)° and the conformation about the C=N bond is E. In the crystal, Nh—H...Ow and Ow—H...Nq (h = hydrozone, w = water and q = quinoline) hydrogen bonds generate a two-dimenstional network in the ac plane. A weak C—H...O interaction helps to consolidate the packing.

The carboxylic acid residue in the title compound, C6H4BrNO2, is twisted out of the plane of the other atoms, as indicated by the (Br)C—C—C—Ocarbonyl torsion angle of −20.1 (9)°. In the crystal, supramolecular chains mediated by O—H...N hydrogen bonds are formed with base vector [201] and C—H...O interactions reinforce the packing.

The thienyl ring in the title compound, C12H10BrNOS, is disordered over two diagonally opposite positions, the major component having a site-occupancy factor of 0.660 (5). The molecule is twisted as evidenced by the dihedral angles of 70.0 (4) and 70.5 (6)° formed between the benzene ring and the two orientations of the disordered thiophene ring. Linear supramolecular chains along the a axis are found in the crystal structure through the agency of N—H...O hydrogen bonding.

The molecule of the title hydrate, C16H11ClFN3·H2O, is slightly twisted, as indicated by the dihedral angle of 9.55 (10)° formed between the quinoline ring system and the benzene ring. The conformation about the C=N double bond is E, and the amine-H atom is oriented towards the quinoline residue. In the crystal structure, the water molecule accepts an N—H...O and makes two O—H...Nquinoline hydrogen bonds, generating a two-dimensional array in the ab plane, which is further stabilized by C—H...O interactions. The most significant contacts between layers are of the type C—H...F.

In the title compound, C16H13N3O4, the dihedral angle between the terminal benzene rings is 14.02 (7)°. The carbonyl groups are anti with respect to each other, which facilitates their participation in the formation of supramolecular chains. Each side of the –C(=O)N(H)N(H)C(=O)– residue associates with a centrosymmetrically related molecule, resulting in the formation of essentially flat ten-membered {...O=CNN(H)}2 synthons. The resultant chains are further consolidated in the crystal structure via C—H...O contacts.

The title compound, C12H8Cl2N4O, is non-planar, the dihedral angle formed between the pendant pyrazine and benzene rings being 12.55 (11)°. An intramolecular N—H...N hydrogen bond occurs. The amide groups self-associate via N—H...O hydrogen bonding, forming supramolecular chains with base vector [101], which are stabilized by C—H...O contacts. C—H...N interactions are formed orthogonal to the chains.

The thienyl ring in the title compound, C14H15NOS, is disordered over two diagonally opposite positions, the major component having a site-occupancy factor of 0.569 (3). The molecule is highly twisted with respect to the central amide group, which is reflected in the dihedral angle formed between the thienyl and benzene rings of 77.01 (15)° [70.34 (18)° for the minor component]. In the crystal, molecules self-associate into chains along [100] via N—H...O hydrogen bonds. The chains are reinforced by complementary C—H...O contacts.

The title salt, C16H12Cl2N3+·C7H4ClO2−, features a non-planar cation, the dihedral angle between the quinolinium and benzene residues being 18.98 (10)°. The cation adopts an E conformation about the C—N bond, and the amine group is oriented towards the quinolinium residue. In the crystal, N—H...O hydrogen bonds link two cations with two anions, forming a 20-membered {...OCO...HNC3NH}2 synthon. The dimeric units are connected into a linear supramolecular chain along [100] via π–π interactions [centroid–centroid distance = 3.5625 (13) Å].

In the title salt hydrate, C11H12ClN2+·Cl−·H2O, the quinolinium core is essentially planar (r.m.s. deviation = 0.027 Å) with the chloroethyl side chain being almost orthogonal to the core [C—N—C—C torsion angle = −80.0 (3)°]. In the crystal packing, the water molecule bridges three species, forming donor interactions to two chloride anions and accepting a hydrogen bond from the quinolinium H atom. The chloride anion accepts a hydrogen bond from the amine N atom with the result that a two-dimensional supramolecular array is formed in the ac plane. A C—H...Cl interaction also occurs.