In the title compound, C20H14N2O, the phenyl ring is almost normal to the naphthalene ring system with a dihedral angle of 86.72 (9)°. The 4H-pyran ring fused with the naphthalene ring system has a boat conformation. In the crystal, mol­ecules are linked into a helical supra­molecular chain along the b axis via N—H⋯N hydrogen bonds. The chains are consolidated into a three-dimensional architecture by C—H⋯π inter­actions.

In the title mol­ecule, C13H7N3O8, the phenyl and benzene rings are rotated from the mean plane of the central ester group by 18.41 (9) and 81.80 (5)°, respectively. The dihedral angle between the rings is 80.12 (14)°. In the crystal, mol­ecules are linked by weak C—H⋯O inter­actions, forming helical chains along [010].

In the title compound, C15H12N2O, the phenyl ring makes a dihedral angle of 32.45 (9)° with the benzene ring of the 1,5-benzodiazepin-2-one unit. The seven-membered ring adopts a boat conformation with the methyl­ene group as the prow and the fused benzene-ring C atoms as the stern. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R 2 2(8) loops. The dimers are further linked by C—H⋯O hydrogen bonds, so forming a column along the a-axis direction.

The title compound, [Na2(C6H18NSi2)2(C6H16N2)]n, was found to consist of dimeric [Na(NSiMe3)2] units with crystallographically imposed centrosymmetry based upon four-membered NaNNaN rings. The dimers are bridged by N,N,N′,N′-tetra­methyl­ethylenediamine ligands, which act in an unusual extended non-chelating coordination mode. This gives a one-dimensional coordination polymer that extends parallel to the a-axis direction.

In the title compound, C14H16O4S2, the thieno[2,3-b]thio­phene ring systems are planar [maximum deviation = 0.008 (2) Å]. The mol­ecular conformation is stabilized by intra­molecular C—H⋯O hydrogen bonds, while the crystal packing is stabilized by C—H⋯O, C—H⋯π and π–π stacking [centroid–centroid distance = 3.6605 (14) Å] inter­actions, which lead to supra­molecular layers in the ab plane.

Except two F atoms of the –CF3 group, the title compound, C14H8BrF3N2O3, has an almost planar conformation, the dihedral angle between the aromatic rings being 3.60 (16)°. The mol­ecule adopts the enol–imine tautomeric form, with an intra­molecular O—H⋯N hydrogen bond, which generates an S(6) ring motif. In the crystal, face-to-face π–π stacking [centroid–centroid distances = 3.669 (2) and 3.732 (2) Å] between the aromatic rings of the mol­ecules, which lie in sheets parallel to (202), help to establish the packing.

In the title mol­ecule, C19H21BrN2O, the piperidone ring adopts a chair conformation with a total puckering amplitude Q T of 0.554 (2) Å. The dihedral angle between the benzene rings is 64.10 (7)°. There are no significant inter­molecular inter­actions.

The title salt, [NH3CH2CH2NH2]+·I−, has an array structure based on strong inter­molecular N—H⋯N hydrogen bonding formed between the ammonium and amine groups of adjacent cations. This inter­action gives a helical chain of cations that runs parallel to the b axis. The four remaining NH group H atoms all form hydrogen bonds to the iodide anion, and these iodide anions lie in channels parallel to the cation–cation chains.

The asymmetric unit of the title compound, C16H13N3O2, contains two independent mol­ecules in which the pyridine and benzene rings form dihedral angles of 81.7 (2) and 79.8 (2)°, indicating the twist in the mol­ecules. In the crystal, weak C—H⋯N inter­actions link mol­ecules into chains along [100].

The reaction of 1,4-dimethyl­piperazine and 3-hy­droxy-2-naphthoic acid gives the title 1:1 salt, C6H15N2 +·C11H7O3 −, with a singly protonated piperazinium cation. In the crystal, a single N—H⋯O hydrogen bond links the cations and anions into discrete pairs and the aromatic anions stack along the crystallographic a-axis direction. This results in layers of cations and anions alternating along the crystallographic c-axis direction. An intra­molecular O—H⋯O hydrogen bond is also present.

In the title mol­ecule, C10H11BrClNO, there is a twist between the mean plane of the amide group and the benzene ring [C(=O)—N—C—C torsion angle = −27.1 (3)°]. In the crystal, inter­molecular N—H⋯O and weak C—H⋯O hydrogen bonds link the mol­ecules into chains along [010].

In the title mol­ecule, C11H14BrNO2, there is twist between the mean plane of the amide group and the benzene ring [the C—N—C—C torsion angle is −172.1 (2)°]. The amide H atom forms an intra­molecular hydrogen bond with the Br atom. In the crystal, inter­molecular O—H⋯O and weak C—H⋯O hydrogen bonds link mol­ecules into a chain along [100].

The asymmetric unit of the title compound, [Ag(NO2)(C14H14N4)]n, contains half of the repeating formula unit (Z′ = 1/2). The AgI ion lies on a twofold rotation axis. The primary structure consists of a one-dimensional coordination polymer formed by the AgI ions and the bipyridyl azine ligand in which there is an inversion center at the mid-point of the N—N bond. The nitrite anion inter­acts with the AgI ion through a chelating μ2 inter­action involving both O atoms. In the crystal, the coordination chains are parallel and inter­act through Ag⋯π [3.220 (2) Å] and π–π [3.489 (3) Å] inter­actions.

In the title mol­ecule, C11H14BrNO, there is twist between the mean plane of the amide group and the benzene ring [C(=O)—N—C C torsion angle = −31.2 (5)°]. In the crystal, inter­molecular N—H⋯O and weak C—H⋯O hydrogen bonds link mol­ecules into chains along [100]. The methyl group H atoms are disordered over two sets of sites with equal occupancy.

The asymmetric unit of the title compound, C16H34N4 2+·2I−·2H2O, contains one half-cation, one iodide anion and one water mol­ecule. The cation has crystallographically imposed centrosymmetric symmetry. Despite some differences in the unit-cell dimensions, packing analysis on a cluster of 15 cations and a comparison of the hydrogen bonding suggests that this compound is isostructural with its bromide analogue. Inter­molecular hydrogen bonding forms eight-membered [H—O—H⋯I]2 and [H—N—H⋯I]2 rings and creates a sheet structure.

The title compound, C10H11BrN2O3, exhibits a small twist between the amide residue and benzene ring [the C—N—C—C torsion angle = 12.7 (4)°]. The crystal structure is stabilized by weak N—H⋯O, C—H⋯Br and C—H⋯O inter­actions. These lead to supra­molecular layers in the bc plane.

The asymmetric unit of the title compound, C8H8O2, contains two crystallographically independent mol­ecules, which form dimers linked by O⋯H—O hydrogen bonds. The benzene rings in the dimers are inclined at a dihedral angle of 7.30 (8)° and both methyl groups display rotational disorder. This redetermination results in a crystal structure with significantly higher precision than the original determination [Ellas & García-Blanco (1963 ▶). Acta Cryst. 16, 434], in which the authors reported only the unit-cell parameters and space group, without any detailed information on the atomic arrangement. In the crystal, dimers are connected by weak C—H⋯O inter­actions, forming R 2 2(10) and R 4 4(18) rings along [110] and an infinite zigzag chain of dimers along the [001] direction also occurs.

The title compound, C15H13NO3, crystallizes with three independent mol­ecules per asymmetric unit (Z′ = 3). One of these mol­ecules is found to have a configuration with a greater twist between its two aromatic rings than the other two [compare 70.26 (13) and 72.31 (12)° with 84.22 (12)°]. There are also differences in the number and nature of the weak inter­molecular C—H⋯O contacts formed by each of the three mol­ecules.

Crystallizing the cobalt(II) salt of the azo dye Orange G from water was found to give the solvent-separated ion-pair species hexa­aqua­cobalt(II) 7-oxo-8-(2-phenyl­hydrazin-1-ylidene)-7,8-dihydro­naphthalene-1,3-disulfonate tetra­hydrate, [Co(H2O)6](C16H10N2O7S2)·4H2O. The asymmetric unit of the cobalt(II) salt contains three independent octa­hedral [Co(OH2)6]2+ cations, three azo anions, all with similar configurations, and 12 uncoordinated water mol­ecules. The structure is closely related to that of one of the known magnesium analogues. Both structures have Z′ = 3, feature nearly planar azo anions [maximum displacement of azo-N atoms from the plane of the phenyl ring = 0.058 (7) Å] in their hydrazone tautomeric form, form layer structures with hydro­philic and hydro­phobic layers alternating along the b-axis direction, and are stabilized by an extensive network of hydrogen bonds..

The title compound, C14H12O2, has an essentially planar conformation with the two aromatic rings forming a dihedral angle of 5.23 (9)° and the aldehyde group lying in the plane of its aromatic group [maximum deviation = 0.204 (3) Å]. Weak inter­molecular C—H⋯O contacts are found to be shortest between the aldehyde O-atom acceptor and the H atoms of the methyl­ene group.

The mol­ecular structure of the title compound at 123 K, C12H9F3N2O, presents a rotationally disordered CF3 group. Hydrogen bonds between the amide NH group and the N atom of the isoquinoline form a chain in the b-axis direction. The packed structure forms alternate layers of isoquinoline and amide groups parallel to the ab plane.

In the title salt, C3H5N2 +·C7H6NO2 −, the carboxyl­ate group of the 4-amino­benzoate anion forms a dihedral angle of 13.23 (17)° with respect to the benzene ring. There are N—H⋯O hydrogen-bonding inter­actions between the anion and cation, and weak inter­molecular C—H⋯O contacts with carboxyl­ate O-atom acceptors of the 4-amino­benzoate anion result in extended three-dimensional R 4 4(22) and R 5 6(30) edge-fused rings along the [100], [010] and [001] directions.

In the crystal of the title compound, C6H7N2O+·C2HF2O2 −, the cation adopts a catemeric N—H⋯O hydrogen-bonded chain motif involving the carboxamide group, with two further N—H⋯O hydrogen bonds connecting the cations to adjacent difluoro­acetate anions via the carboxamide and pyridinium N atoms. The carboxamide group of the nicotinamidium ion is twisted by 32.3 (6)° from the pyridine ring plane. A number of C—H⋯O and C—H⋯F interactions consolidate the packing.

The title compound, C15H14O2, was obtained by Friedel–Crafts acyl­ation between 2,5-dimethyl­phenol and benzoyl chloride in the presence of aluminium chloride as a catalyst. The dihedral angle between the benzene rings is 61.95 (4)°. In the crystal, O—H⋯O hydrogen bonding and C—H⋯O weak inter­actions lead to polymeric C(6), C(8) and C(11) chains along the a, b and c-axis directions, respectively.

The asymmetric unit of the anhydrous title compound, 2Na+·C4H4O6 2−, contains two sodium cations and one tartrate anion. Each sodium ion is six coordinate, with bonding to six O atoms from both the carboxyl­ate and hydroxyl groups of the anion. A three-dimensional coordination network is formed with sodium ions stacking in layers along the c-axis direction. This network is supported by additional O—H⋯O hydrogen bonds.