The reaction of bis­(3-oxo-1,3-di­phenyl­prop-1-enolato-κ2O,O')zinc(II), [Zn(dbm)2], with tris­[4-(pyridin-3-yl)phen­yl]amine (T3PyA) in tetra­hydro­furan (THF) afforded the title crystalline coordination polymer, {[Zn(C15H11O2)2(C33H24N4)]·C4H8O}n. The asymmetric unit contains two independent halves of Zn(dbm)2, one T3PyA and one THF. Each ZnII atom is located on an inversion centre and adopts an elongated octa­hedral coordination geometry, ligated by four O atoms of two dbm ligands in equatorial positions and by two N atoms of pyridine moieties from two different bridging T3PyA ligands in axial positions. The crystal packing shows a one-dimensional polymer chain in which the two pyridyl groups of the T3PyA ligand bridge two independent Zn atoms of Zn(dbm)2. In the crystal, the coordination polymer chains are linked via C—H⋯π inter­actions into a sheet structure parallel to (010). The sheets are cross-linked via further C—H⋯π inter­actions into a three-dimensional network. The solvate THF mol­ecule shows disorder over two sets of atomic sites having occupancies of 0.631 (7) and 0.369 (7).

The title compound, [Ni(C64H33F10N5S2)]·xCH2Cl2, consists of discrete NiII porphyrin complexes, in which the five-coordinate NiII cations are in a distorted square-pyramidal coordination geometry. The four porphyrin nitro­gen atoms are located in the basal plane of the pyramid, whereas the pyridine N atom is in the apical position. The porphyrin plane is strongly distorted and the NiII cation is located above this plane by 0.241 (3) Å and shifted in the direction of the coordinating pyridine nitro­gen atom. The pyridine ring is not perpendicular to the N4 plane of the porphyrin moiety, as observed for related compounds. In the crystal, the complexes are linked via weak C—H⋯F hydrogen bonds into zigzag chains propagating in the [001] direction. Within this arrangement cavities are formed, in which highly disordered di­chloro­methane solvate mol­ecules are located. No reasonable structural model could be found to describe this disorder and therefore the contribution of the solvent to the electron density was removed using the SQUEEZE option in PLATON [Spek (2015). Acta Cryst. C71, 9–18].

In the title compound, C24H31N3O2, the mean plane of the central pyrazole ring [r.m.s. deviation = 0.095 Å] makes dihedral angles of 11.93 (9) and 84.53 (8)°, respectively, with the phenyl and benzene rings. There is a short intra­molecular N—H⋯N contact, which generates an S(5) ring motif. In the crystal, pairs of N—H⋯O hydrogen bonds link inversion-related mol­ecules into dimers, generating an R22(8) ring motif. The Hirshfeld surface analysis indicates that the most significant contribution involves H⋯H contacts of 68.6%

Single crystals of the title compound barium zinc copper, BaCu2.6Zn2.4, were obtained from a sample prepared by heating metal chips of Ba, Cu, and Zn in an Ar atmosphere up to 973 K, followed by slow cooling. Single-crystal X-ray structure analysis revealed that BaCu2.6Zn2.4 crystallizes in an ortho­rhom­bic cell [a = 12.9858 (3), b = 5.2162 (1), and c = 6.6804 (2) Å] with an α-SrZn5-type structure (space group Pnma). The three-dimensional framework consists of Cu and Zn atoms, with Ba atoms in the tunnels extending in the b-axis direction. Although the Ba atom is larger than the Sr atom, the cell volume of BaCu2.6Zn2.4 [452.507 (19) Å3] is smaller than that of α-SrZn5 [466.08 Å3]. This decrease in volume can be attributed to the partial substitution of Cu atoms by Zn atoms in the framework because the Cu—Zn and Cu—Cu bonds are shorter than the Zn—Zn bond. The increase in Ba—Zn inter­atomic distances from the Sr—Zn distances is cancelled out by the partial replacement of Zn with Cu atoms, which leads to shorter average Ba—Zn/Cu distances.

In the title tri-substituted thio­urea derivative, C13H18N2O3S, the thione-S and carbonyl-O atoms lie, to a first approximation, to the same side of the mol­ecule [the S—C—N—C torsion angle is −49.3 (2)°]. The CN2S plane is almost planar (r.m.s. deviation = 0.018 Å) with the hy­droxy­ethyl groups lying to either side of this plane. One hy­droxy­ethyl group is orientated towards the thio­amide functionality enabling the formation of an intra­molecular N—H⋯O hydrogen bond leading to an S(7) loop. The dihedral angle [72.12 (9)°] between the planes through the CN2S atoms and the 4-tolyl ring indicates the mol­ecule is twisted. The experimental mol­ecular structure is close to the gas-phase, geometry-optimized structure calculated by DFT methods. In the mol­ecular packing, hydroxyl-O—H⋯O(hydrox­yl) and hydroxyl-O—H⋯S(thione) hydrogen bonds lead to the formation of a supra­molecular layer in the ab plane; no directional inter­actions are found between layers. The influence of the specified supra­molecular inter­actions is apparent in the calculated Hirshfeld surfaces and these are shown to be attractive in non-covalent inter­action plots; the inter­action energies point to the important stabilization provided by directional O—H⋯O hydrogen bonds.

The title compound, C10H13Cl2NO2·C6H4Cl2O, was formed from the incomplete Mannich condensation reaction of 3-amino­propan-1-ol, formaldehyde and 2,4-di­chloro­phenol in methanol. This resulted in the formation of a co-crystal of the zwitterionic Mannich base, 2,4-di­chloro-6-{[(3-hy­droxy­prop­yl)azaniumyl]­meth­yl}phenolate and the unreacted 2,4-di­chloro­phenol. The compound crystallizes in the monoclinic crystal system (in space group Cc) and the asymmetric unit contains a mol­ecule each of the 2,4-di­chloro­phenol and 2,4-di­chloro-6-{[(3-hy­droxy­prop­yl)azaniumyl]­meth­yl}phenolate. Examination of the crystal structure shows that the two components are clearly linked together by hydrogen bonds. The packing patterns are most inter­esting along the b and the c axes, where the co-crystal in the unit cell packs in a manner that shows alternating aromatic di­chloro­phenol fragments and polar hydrogen-bonded channels. The 2,4-di­chloro­phenol rings stack on top of one another, and these are held together by π–π inter­actions. The crystal studied was refined as an inversion twin.

Twelve 4-(4-meth­oxy­phen­yl)piperazin-1-ium salts containing organic anions have been prepared and structurally characterized. The monohydrated benzoate, 4-fluoro­benzoate, 4-chloro­benzoate and 4-bromo­benzoate salts, C11H17N2O+·C7H5O2−·H2O (I), C11H17N2O+·C7H4FO2−·H2O (II), C11H17N2O+·C7H4ClO2−·H2O (III), and C11H17N2O+·C7H4BrO2−·H2O (IV), respectively, are isomorphous and all exhibit disorder in the 4-meth­oxy­phenyl unit: the components are linked by N—H⋯O and O—H⋯O hydrogen bond to form chains of rings. The unsolvated 2-hy­droxy­benzoate, pyridine-3-carboxyl­ate and 2-hy­droxy-3,5-di­nitro­benzoate salts, C11H17N2O+·C7H5O3− (V), C11H17N2O+·C6H4NO2− (VI) and C11H17N2O+·C7H3N2O7− (VII), respectively, are all fully ordered: the components of (V) are linked by multiple N—H⋯O hydrogen bonds to form a chain of rings; those of (VI) are linked into a three-dimensional framework by a combination of N—H⋯O, C—H⋯O and C—H⋯N hydrogen bonds and those of (VII), where the anion has a structure reminiscent of the picrate anion, are linked into a three-dimensional array by N—H⋯O and C—H⋯O hydrogen bonds. The hydrogensuccinate and hydrogenfumarate salts, C11H17N2O+·C4H5O4− (VIII) and C11H17N2O+·C4H3O3− (IX), respectively, are isomorphous, and both exhibit disorder in the anionic component: N—H⋯O and O—H⋯O hydrogen bonds link the ions into sheets, which are further linked by C—H⋯π(arene) inter­actions. The anion of the hydrogenmaleate salt, C11H17N2O+·C4H3O3− (X), contains a very short and nearly symmetrical O⋯H⋯O hydrogen bond, and N—H⋯O hydrogen bonds link the anions into chains of rings. The ions in the tri­chloro­acetate salt, C11H17N2O+·C2Cl3O2− (XI), are linked into simple chains by N—H⋯O hydrogen bonds. In the hydrated chloranilate salt, 2C11H17N2O+·C6Cl2O42−·2H2O (XII), which crystallizes as a non-merohedral twin, the anion lies across a centre of inversion in space group P21/n, and a combination of N—H⋯O and O—H⋯O hydrogen bonds generates complex sheets. Comparisons are made with the structures of some related compounds.

The title compound, C18H18F2N2O3, crystallizes with two independent mol­ecules (A and B) in the asymmetric unit. They differ essentially in the orientation of the pyridine ring with respect to the benzene ring; these two rings are inclined to each other by 53.3 (2)° in mol­ecule A and by 72.9 (2)° in mol­ecule B. The 3-(cyclo­propyl­meth­oxy) side chain has an extended conformation in both mol­ecules. The two mol­ecules are linked by a pair of C—H⋯O hydrogen bonds and two C—H⋯π inter­actions, forming an A–B unit. In the crystal, this unit is linked by N—H⋯O hydrogen bonds, forming a zigzag –A–B–A–B– chain along [001]. The chains are linked by C—H⋯N and C—H⋯F hydrogen bonds to form layers parallel to the ac plane. Finally, the layers are linked by a third C—H⋯π inter­action, forming a three-dimensional structure. The major contributions to the Hirshfeld surface are those due to H⋯H contacts (39.7%), followed by F⋯H/H⋯F contacts (19.2%).

The title compounds, 6-(naphthalen-1-yl)-6a-nitro-6,6a,6 b,7,9,11a-hexa­hydro­spiro­[chromeno[3',4':3,4]pyrrolo­[1,2-c]thia­zole-11,11'-indeno­[1,2-b]quinoxaline], C37H26N4O3S, (I), and 6'-(naphthalen-1-yl)-6a'-nitro-6',6a',6b',7',8',9',10',12a'-octa­hydro-2H-spiro­[ace­naphthyl­ene-1,12'-chromeno[3,4-a]indolizin]-2-one, C36H28N2O4, (II), are new spiro derivatives, in which both the pyrrolidine rings adopt twisted conformations. In (I), the five-membered thia­zole ring adopts an envelope conformation, while the eight-membered pyrrolidine-thia­zole ring adopts a boat conformation. An intra­molecular C—H⋯N hydrogen bond occurs, involving a C atom of the pyran ring and an N atom of the pyrazine ring. In (II), the six-membered piperidine ring adopts a chair conformation. An intra­molecular C—H⋯O hydrogen bond occurs, involving a C atom of the pyrrolidine ring and the keto O atom. For both compounds, the crystal structure is stabilized by inter­molecular C—H⋯O hydrogen bonds. In (I), the C—H⋯O hydrogen bonds link adjacent mol­ecules, forming R22(16) loops propagating along the b-axis direction, while in (II) they form zigzag chains along the b-axis direction. In both compounds, C—H⋯π inter­actions help to consolidate the structure, but no significant π–π inter­actions with centroid–centroid distances of less than 4 Å are observed.

The title mol­ecular salt, (C7H11N2)2[Hg2Cl6], crystallizes with two 4-(di­methyl­amino)­pyridinium cations (A and B) and two half hexa­chlorido­dimercurate(II) anions in the asymmetric unit. The organic cations exhibit essentially the same features with an almost planar pyridyl ring (r.m.s. deviations of 0.0028 and 0.0109 Å), which forms an inclined dihedral angle with the dimethyamino group [3.06 (1) and 1.61 (1)°, respectively]. The di­methyl­amino groups in the two cations are planar, and the C—N bond lengths are shorter than that in 4-(di­methyl­amino)­pyridine. In the crystal, mixed cation–anion layers lying parallel to the (010) plane are formed through N—H⋯Cl hydrogen bonds and adjacent layers are linked by C—H⋯Cl hydrogen bonds, forming a three-dimensional network. 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 organic cations and inorganic anions, such as π–π and Cl⋯Cl inter­actions. The powder XRD data confirms the phase purity of the crystalline sample. Furthermore, the vibrational absorption bands were identified by IR spectroscopy and the optical properties were studied by using optical UV–visible absorption spectroscopy.

Benzo[1,2-c:3,4-c':5,6-c'']tri­thio­phene (D3h-BTT) is an easily prepared electron donor that readily forms charge–transfer complexes with organic acceptors. We report here two crystal structures of its charge–transfer complexes with 7,7,8,8-tetra­cyano­quinodi­methane (TCNQ) and buckminsterfullerene (C60). The D3h-BTT·TCNQ complex, C12H6S3·C12H4N4, crystallizes with mixed layers of donors and acceptors, with an estimated degree of charge transfer at 0.09 e. In the D3h-BTT·C60·toluene complex, C12H6S3·C60·C7H8, the central ring of BTT is `squeezed' by the C60 mol­ecules from both faces. However, the degree of charge transfer is low. The C60 unit is disordered over two sites in a 0.766 (3):0.234 (3) ratio and was refined as a two-component inversion twin.

In the title compounds, C16H9Cl2N2O2·C4H8O2 and C16H9Cl2N2O2, the bicyclic 4H-chromene cores are nearly planar with maximum deviations of 0.081 (2) and 0.087 (2) Å. In both structures, the chromene derivative mol­ecules are linked into centrosymmetric dimers by pairs of N—H⋯O hydrogen bonds, forming R22(16) motifs. These dimers are further linked in the 3,4-di­chloro­phenyl derivative by N—H⋯N hydrogen bonds into double layers parallel to (100) and in the 2,6-di­chloro­phenyl derivative by O—H⋯N hydrogen bonds into ribbons along the [1overline{1}0] direction. In the 3,4-di­chloro­phenyl derivative, the 1,4-dioxane solvent mol­ecules are connected to the chromene mol­ecules via O—H⋯O hydrogen bonds.

The title pull–push chromophores, 2-[4-(di­methyl­amino)­benzyl­idene]-1H-indene-1,3(2H)-dione, C18H15NO2 (ID[1]) and (E)-2-{3-[4-(di­methyl­amino)­phen­yl]allyl­idene}-1H-indene-1,3(2H)-dione, C20H17NO2 (ID[2]), have donor–π-bridge–acceptor structures. The mol­ecule with the short π-bridge, ID[1], is almost planar while for the mol­ecule with a longer bridge, ID[2], is less planar. The benzene ring is inclined to the mean plane of the 2,3-di­hydro-1H-indene unit by 3.19 (4)° in ID[1] and 13.06 (8)° in ID[2]. The structures of three polymorphs of compound ID[1] have been reported: the α-polymorph [space group P21/c; Magomedova & Zvonkova (1978). Kristallografiya, 23, 281–288], the β-polymorph [space group P21/c; Magomedova & Zvonkova (1980). Kristallografiya, 25 1183–1187] and the γ-polymorph [space group Pna21; Magomedova, Neigauz, Zvonkova & Novakovskaya (1980). Kristallografiya, 25, 400–402]. The mol­ecular packing in ID[1] studied here is centrosymmetric (space group P21/c) and corresponds to the β-polymorph structure. The mol­ecular packing in ID[2] is non-centrosymmetric (space group P21), which suggests potential NLO properties for this crystalline material. In both compounds, there is short intra­molecular C—H⋯O contact present, enclosing an S(7) ring motif. In the crystal of ID[1], mol­ecules are linked by C—H⋯O hydrogen bonds and C—H⋯π inter­actions, forming layers parallel to the bc plane. In the crystal of ID[2], mol­ecules are liked by C—H⋯O hydrogen bonds to form 21 helices propagating along the b-axis direction. The mol­ecules in the helix are linked by offset π–π inter­actions with, for example, a centroid–centroid distance of 3.9664 (13) Å (= b axis) separating the indene rings, and an offset of 1.869 Å. Spectroscopic and electrochemical measurements show the ability of these compounds to easily transfer electrons through the π-conjugated chain.

The title imidazo[1,2-a] pyridine derivative, C13H8Br2N2, was synthesized via a single-step reaction method. The title mol­ecule is planar, showing a dihedral angle of 0.62 (17)° between the phenyl and the imidazo[1,2-a] pyridine rings. An intra­molecular C—H⋯N hydrogen bond with an S(5) ring motif is present. In the crystal, a short H⋯H contact links adjacent mol­ecules into inversion-related dimers. The dimers are linked in turn by weak C—H⋯π and slipped π–π stacking inter­actions, forming layers parallel to (110). The layers are connected into a three-dimensional network by short Br⋯H contacts. Two-dimensional fingerprint plots and three-dimensional Hirshfeld surface analysis of the inter­molecular contacts reveal that the most important contributions for the crystal packing are from H⋯Br/Br⋯H (26.1%), H⋯H (21.7%), H⋯C/C⋯H (21.3%) and C⋯C (6.5%) inter­actions. Energy framework calculations suggest that the contacts formed between mol­ecules are largely dispersive in nature. Analysis of HOMO–LUMO energies from a DFT calculation reveals the pure π character of the aromatic rings with the highest electron density on the phenyl ring, and σ character of the electron density on the Br atoms. The HOMO–LUMO gap was found to be 4.343 eV.

In the title pyrazoline derivative, C16H16N2O3·H2O, the pyrazoline ring has an envelope conformation with the substituted sp2 C atom on the flap. The pyrazoline ring makes angles of 86.73 (12) and 13.44 (12)° with the tris­ubstituted and disubstituted benzene rings, respectively. In the crystal structure, the mol­ecules are connected into chains running in the b-axis direction by O—H⋯N hydrogen bonding. Parallel chains inter­act through N—H⋯O hydrogen bonds and π–π stacking of the tris­ubstituted phenyl rings. The major contribution to the surface contacts are H⋯H contacts (44.3%) as concluded from a Hirshfeld surface analysis.

In the title hydrazinecarbodi­thio­ate derivative, C27H26N2O2S2, the asymmetric unit is comprised of four mol­ecules (Z = 8 and Z' = 4). The 4-meth­oxy­phenyl rings are slightly twisted away from their attached olefinic double bonds [torsion angles = 5.9 (4)–19.6 (4)°]. The azomethine double bond has an s-trans configuration relative to one of the C=C bonds and an s-cis configuration relative to the other [C=C—C= N = 147.4 (6)–175.7 (2) and 15.3 (3)–37.4 (7)°, respectively]. The torsion angles between the azomethine C=N double bond and hydrazine-1-carbodi­thio­ate moiety indicate only small deviations from planarity, with torsion angles ranging from 0.9 (3) to 6.9 (3)° and from 174.9 (3) to 179.7 (2)°, respectively. The benzyl ring and the methyl­enesulfanyl moiety are almost perpendicular to each other, as indicated by their torsion angles [range 93.7 (3)–114.6 (2)°]. In the crystal, mol­ecules are linked by C—H⋯O, N—H⋯S and C—H⋯π(ring) hydrogen-bonding inter­actions into a three-dimensional network. Structural details of related benzyl hydrazine-1-carbodi­thio­ate are surveyed and compared with those of the title compound.

The benzo­pyran ring of the title com­pound, C16H11ClN2O2, is planar [maximum deviation = 0.079 (2) Å] and is almost perpendicular to the chloro­phenyl ring [dihedral angle = 86.85 (6)°]. In the crystal, N—H⋯O, O—H⋯N, C—H⋯O and C—H⋯Cl hydrogen bonds form inter- and intra­molecular inter­actions. The DFT/B3LYP/6-311G(d,p) method was used to determine the HOMO–LUMO energy levels. The mol­ecular electrostatic potential surfaces were investigated by Hirshfeld surface analysis and two-dimensional fingerprint plots were used to analyse the inter­molecular inter­actions in the mol­ecule.

Strontium tetra­gallate(II,III) tetra­arsenide, SrGa4As4, was synthesized in a Walker-type multianvil apparatus under high-pressure/high-temperature conditions of 8 GPa and 1573 K. The com­pound crystallizes in a new structure type (P3221, Z = 3) as a three-dimensional (3D) framework of corner-sharing SrAs8 quadratic anti­prisms with strontium situated on a twofold rotation axis (Wyckoff position 3b). This arrangement is surrounded by a 3D framework which can be described as alternately stacked layers of either condensed GaIIIAs4 tetra­hedra or honeycomb-like layers built up from distorted ethane-like GaII2As6 units com­prising Ga—Ga bonds.

The title compound, C22H15Cl2NOS, contains 1,4-benzo­thia­zine and 2,4-di­­chloro­benzyl­idene units, where the di­hydro­thia­zine ring adopts a screw-boat conformation. In the crystal, inter­molecular C—HBnz⋯OThz (Bnz = benzene and Thz = thia­zine) hydrogen bonds form corrugated chains extending along the b-axis direction which are connected into layers parallel to the bc plane by inter­molecular C—HMethy⋯SThz (Methy = methyl­ene) hydrogen bonds, en­closing R44(22) ring motifs. Offset π-stacking inter­actions between 2,4-di­­chloro­phenyl rings [centroid–centroid = 3.7701 (8) Å] and π-inter­actions which are associated by C—HBnz⋯π(ring) and C—HDchlphy⋯π(ring) (Dchlphy = 2,4-di­chloro­phen­yl) inter­actions may be effective in the stabilization of the crystal structure. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (29.1%), H⋯C/C⋯H (27.5%), H⋯Cl/Cl⋯H (20.6%) and O⋯H/H⋯O (7.0%) inter­actions. Hydrogen-bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, the C—HBnz⋯OThz and C—HMethy⋯SThz hydrogen-bond energies are 55.0 and 27.1 kJ mol−1, respectively. Density functional theory (DFT) optimized structures at the B3LYP/6-311G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

The asymmetric units of the title compounds both contain one nonplanar mol­ecule. In 4-benzyl-6-phenyl-4,5-di­hydro­pyridazin-3(2H)-one, C17H14N2O, (I), the phenyl and pyridazine rings are twisted with respect to each other, making a dihedral angle of 46.69 (9)°; the phenyl ring of the benzyl group is nearly perpendicular to the plane of the pyridazine ring, the dihedral angle being 78.31 (10)°. In methyl 2-[5-(2,6-di­chloro­benz­yl)-6-oxo-3-phenyl-1,4,5,6-tetra­hydropyridazin-1-yl]acetate, C20H16Cl2N2O3, (II), the phenyl and pyridazine rings are twisted with respect to each other, making a dihedral angle of 21.76 (18)°, whereas the phenyl ring of the di­chloro­benzyl group is inclined to the pyridazine ring by 79.61 (19)°. In the crystal structure of (I), pairs of N—H⋯O hydrogen bonds link the mol­ecules into inversion dimers with an R22(8) ring motif. In the crystal structure of (II), C—H⋯O hydrogen bonds generate dimers with R12(7), R22(16) and R22(18) ring motifs. The Hirshfeld surface analyses of compound (I) suggests that the most significant contributions to the crystal packing are by H⋯H (48.2%), C⋯H/H⋯C (29.9%) and O⋯H/H⋯O (8.9%) contacts. For compound (II), H⋯H (34.4%), C⋯H/H⋯C (21.3%) and O⋯H/H⋯O (16.5%) inter­actions are the most important contributions.

The title com­pound, C22H16N4O2, contains two pyridine rings and one meth­oxy­carbonyl­phenyl group attached to a pyridazine ring which deviates very slightly from planarity. In the crystal, ribbons consisting of inversion-related chains of mol­ecules extending along the a-axis direction are formed by C—HMthy⋯OCarbx (Mthy = methyl and Carbx = carboxyl­ate) hydrogen bonds. The ribbons are connected into layers parallel to the bc plane by C—HBnz⋯π(ring) (Bnz = benzene) inter­actions. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (39.7%), H⋯C/C⋯H (27.5%), H⋯N/N⋯H (15.5%) and O⋯H/H⋯O (11.1%) inter­actions. Hydrogen-bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, C—HMthy⋯OCarbx hydrogen-bond energies are 62.0 and 34.3 kJ mol−1, respectively. Density functional theory (DFT) optimized structures at the B3LYP/6-311G(d,p) level are com­pared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

The crystal and mol­ecular structures of the title CuII complex, isolated as a dihydrate, [Cu(C21H14N3O3)2]·2H2O, reveals a highly distorted coordination geometry inter­mediate between square-planar and tetra­hedral defined by an N2O2 donor set derived from two mono-anionic bidentate ligands. Furthermore, each six-membered chelate ring adopts an envelope conformation with the Cu atom being the flap. In the crystal, imidazolyl-amine-N—H⋯O(water), water-O—H⋯O(coordinated, nitro and water), phenyl-C—H⋯O(nitro) and π(imidazol­yl)–π(nitro­benzene) [inter-centroid distances = 3.7452 (14) and 3.6647 (13) Å] contacts link the components into a supra­molecular layer lying parallel to (101). The connections between layers forming a three-dimensional architecture are of the types nitro­benzene-C—H⋯O(nitro) and phenyl-C—H⋯π(phen­yl). The distorted coordination geometry for the CuII atom is highlighted in an analysis of the Hirshfeld surface calculated for the metal centre alone. The significance of the inter­molecular contacts is also revealed in a study of the calculated Hirshfeld surfaces; the dominant contacts in the crystal are H⋯H (41.0%), O⋯H/H⋯O (27.1%) and C⋯H/H⋯C (19.6%).

In the crystal structure of the title com­pound, [Ni(NCS)2(CH3CN)2(C12H9NO)2] or Ni(NCS)2(4-benzoyl­pyridine)2(aceto­nitrile)2, the NiII ions are octa­hedrally coordinated by the N atoms of two thio­cyanate anions, two 4-benzoyl­pyridine ligands and two aceto­nitrile mol­ecules into discrete com­plexes that are located on centres of inversion. In the crystal, the discrete com­plexes are linked by centrosymmetric pairs of weak C—H⋯S hydrogen bonds into chains. Thermogravimetric measurements prove that, upon heating, the title com­plex loses the two aceto­nitrile ligands and transforms into a new crystalline modification of the chain com­pound [Ni(NCS)2(4-benzoyl­pyridine)2], which is different from that of the corresponding CoII, NiII and CdII coordination polymers reported in the literature. IR spectroscopic investigations indicate the presence of bridging thio­cyanate anions but the powder pattern cannot be indexed and, therefore, this structure is unknown.

The synthesis and crystal structures of 2-(4-fluoro­phen­yl)-3-phenyl-2,3-di­hydro-4H-pyrido[3,2-e][1,3]thia­zin-4-one toluene hemisolvate (1), C19H13FN2OS·0.5C7H8, and 2-(4-nitro­phen­yl)-3-phenyl-2,3-di­hydro-4H-pyrido[3,2-e][1,3]thia­zin-4-one iso­propanol 0.25-solvate 0.0625-hydrate (2), C19H13N3O3S·0.25C3H7O·0.0625H2O, are reported. Both are racemic mixtures (centrosymmetric crystal structures) of the individual com­pounds and incorporate solvent mol­ecules in their structures. Compound 2 has four thia­zine mol­ecules in the asymmetric unit. All the thia­zine rings in this study show an envelope pucker, with the C atom bearing the substituted phenyl ring displaced from the other atoms. The phenyl and aryl rings in each of the mol­ecules are roughly orthogonal to each other, with dihedral angles of about 75°. The extended structures of 1 and 2 are consolidated by C—H⋯O and C—H⋯N(π), as well as T-type (C—H⋯π) inter­actions. Parallel aromatic ring inter­actions (π–π stacking) are observed only in 2.

The structures of two isomeric com­pounds of 5-nitro­quinoline with chloro- and nitro-substituted benzoic acid, namely, 2-chloro-4-nitro­benzoic acid–5-nitro­quinoline (1/1), (I), and 5-chloro-2-nitro­benzoic acid–5-nitro­quinoline (1/1), (II), both C7H4ClNO4·C9H6N2O2, have been determined at 190 K. In each com­pound, the acid and base mol­ecules are held together by an O—H⋯N hydrogen bond. In the crystal of (I), the hydrogen-bonded acid–base units are linked by a C—H⋯O hydrogen bond, forming a tape structure along [1overline{2}0]. The tapes are stacked into a layer parallel to the ab plane via N—O⋯π inter­actions between the nitro group of the base mol­ecule and the quinoline ring system. The layers are further linked by other C—H⋯O hydrogen bonds, forming a three-dimensional network. In the crystal of (II), the hydrogen-bonded acid–base units are linked into a wide ribbon structure running along [1overline{1}0] via C—H⋯O hydrogen bonds. The ribbons are further linked via another C—H⋯O hydrogen bond, forming a layer parallel to (110). Weak π–π inter­actions [centroid–centroid distances of 3.7080 (10) and 3.7543 (9) Å] are observed between the quinoline ring systems of adjacent layers. Hirshfeld surfaces for the 5-nitro­quinoline mol­ecules of the two com­pounds mapped over shape index and dnorm were generated to visualize the weak inter­molecular inter­actions.

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 title com­pound, C15H11NO5, is relatively planar, with the planes of the two aromatic rings being inclined to each other by 3.09 (5)°. In the crystal, mol­ecules are linked by a pair of C—H⋯O hydrogen bonds, forming inversion dimers, which enclose an R22(16) ring motif. The dimers are linked by a further pair of C—H⋯O hydrogen-bonds forming ribbons enclosing R44(26) ring motifs. The ribbons are linked by offset π–π inter­actions [centroid–centroid distances = 3.6754 (6)–3.7519 (6) Å] to form layers parallel to the ac plane. Through Hirshfeld surface analyses, the dnorm surfaces, electrostatic potential and two-dimensional fingerprint (FP) plots were examined to verify the contributions of the different inter­molecular contacts within the supra­molecular structure. The shape-index surface shows that two sides of the mol­ecule are involved with the same contacts in neighbouring mol­ecules, and the curvedness plot shows flat surface patches that are characteristic of planar stacking.

In the title com­pound, C30H20Cl2O2Se, the C—Se—C angle is 99.0 (2)°, with the dihedral angle between the planes of the attached benzene rings being 79.1 (3)°. The average endocyclic angles (Se—C—C) facing the Se atom are 122.1 (5) and 122.2 (5)°. The Se atom is essentially coplanar with the attached benzene rings, deviating by 0.075 (1) and 0.091 (1) Å. In the two phenyl­ene(4-chloro­phen­yl)prop-2-en-1-one units, the benzene rings are inclined to each other by 44.6 (3) and 7.8 (3)°. In the crystal, the mol­ecules stack up the a axis, forming layers parallel to the ac plane. There are no significant classical inter­molecular inter­actions present. Hirshfeld surface analysis, two-dimensional fingerprint plots and the mol­ecular electrostatic potential surface were used to analyse the crystal packing. The Hirshfeld surface analysis suggests that the most significant contributions to the crystal packing are by C⋯H/H⋯C contacts (17.7%).

In the title com­pound, C13H14N2O3, the dihydropyridazine ring (r.m.s. deviation = 0.166 Å) has a screw-boat conformation. The dihedral angle between its mean plane and the benzene ring is 0.77 (12)°. In the crystal, inter­molecular O—H⋯O hydrogen bonds generate C(5) chains and N—H⋯O hydrogen bonds produce R22(8) motifs. These types of inter­actions lead to the formation of layers parallel to (12overline{1}). The three-dimensional network is achieved by C—H⋯O inter­actions, including R24(8) motifs. Inter­molecular inter­actions were additionally investigated using Hirshfeld surface analysis and two-dimensional fingerprint plots. The most significant contributions to the crystal packing are by H⋯H (43.3%), H⋯C/C⋯H (19.3%), H⋯O/H⋯O (22.6%), C⋯N/N⋯C (3.0%) and H⋯N/N⋯H (5.8%) contacts. C—H⋯π inter­actions and aromatic π–π stacking inter­actions are not observed.

The title com­pound, C24H24N2O6, consists of ethyl 2-(1,2,3,4-tetra­hydro-2-oxo­quinolin-1-yl)acetate and 4-[(2-eth­oxy-2-oxoeth­yl)(phen­yl)carbomoyl] units, where the oxo­quinoline unit is almost planar and the acetate substituent is nearly perpendicular to its mean plane. In the crystal, C—HOxqn⋯OEthx and C—HPh­yl⋯OCarbx (Oxqn = oxoquinolin, Ethx = eth­oxy, Phyl = phenyl and Carbx = carboxyl­ate) weak hydrogen bonds link the mol­ecules into a three-dimensional network sturucture. A π–π inter­action between the constituent rings of the oxo­quinoline unit, with a centroid–centroid distance of 3.675 (1) Å may further stabilize the structure. Both terminal ethyl groups are disordered over two sets of sites. The ratios of the refined occupanies are 0.821 (8):0.179 (8) and 0.651 (18):0.349 (18). The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (53.9%), H⋯O/O⋯H (28.5%) and H⋯C/C⋯H (11.8%) inter­actions. Weak inter­molecular hydrogen-bond inter­actions and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Density functional theory (DFT) geometric optimized structures at the B3LYP/6-311G(d,p) level are com­pared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO mol­ecular orbital behaviour was elucidated to determine the energy gap.

2-(4-Nitro­phen­yl)-2-oxoethyl picolinate, C14H10N2O5, was synthesized under mild conditions. The chemical and mol­ecular structures were confirmed by single-crystal X-ray diffraction analysis. The mol­ecules are linked by inversion into centrosymmetric dimers via weak inter­molecular C—H⋯O inter­actions, forming R22(10) ring motifs, and further strengthened by weak π–π inter­actions. Hirshfeld surface analyses, the dnorm surfaces, electrostatic potential and two-dimensional fingerprint (FP) plots were used to verify the contributions of the different inter­molecular inter­actions within the supra­molecular structure. The shape-index surface shows that two sides of the mol­ecules are involved with the same contacts in neighbouring mol­ecules and curvedness plots show flat surface patches that are characteristic of planar stacking.

The new title one-dimensional CdII coordination polymer, [Cd(C10H10N2)2(μ1,3-N3)2]n, has been synthesized and structurally characterized by single-crystal X-ray diffraction. The asymmetric unit consists of a CdII ion, one azide and one 1-benzyl­imidazole (bzi) ligand. The CdII ion is located on an inversion centre and is surrounded in a distorted octa­hedral coordination sphere by six N atoms from four symmetry-related azide ligands and two symmetry-related bzi ligands. The CdII ions are linked by double azide bridging ligands within a μ1,3-N3 end-to-end (EE) coordination mode, leading to a one-dimensional linear structure extending parallel to [100]. The supra­molecular framework is stabilized by the presence of weak C—H⋯N inter­actions, π–π stacking [centroid-to-centroid distance of 3.832 (2) Å] and C—H⋯π inter­actions between neighbouring chains.

The title mol­ecular salt, C9H12N3O2S+·HSO4−, was obtained through the protonation of the azomethine N atom in a sulfuric acid medium. The crystal com­prises two entities, a thio­semicarbazide cation and a hydrogen sulfate anion. The cation is essentially planar and is further stabilized by a strong intra­molecular O—H⋯N hydrogen bond. In the crystal, a three-dimensional network is established through O—H⋯O and N—H⋯O hydrogen bonds. A weak intermolecular C—H⋯O hydrogen bond is also observed. The hydrogen sulfate anion exhibits disorder over two sets of sites and was modelled with refined occupancies of 0.501 (6) and 0.499 (6).

In the title com­plex, [Cu(C18H12F6N2O4)]·0.5C6H6O2, the CuII ion has a square-planar coordination geometry, being ligated by two N and two O atoms of the tetra­dentate open-chain Schiff base ligand 6,6'-{(1E,1'E)-[ethane-1,2-diylbis(aza­nylyl­idene)]bis­(methanylyl­idene)}bis­[2-(tri­fluoro­meth­oxy)phenol]. The crystal packing is stabilized by intra­molecular O—H⋯O and inter­molecular C—H⋯F, C—H⋯O and C—H⋯π hydrogen bonds. In addition, weak π–π inter­actions form a three-dimensional structure. Hirshfeld surface analysis and two-dimensional fingerprint plots were performed and created to analyze the inter­molecular inter­actions present in the crystal, indicating that the most important contributions for the crystal packing are from F⋯H/H⋯F (25.7%), H⋯H (23.5%) and C⋯H/H⋯C (12.6%) inter­actions.

The title compound, C15H10ClNO5, is relatively planar with the two aromatic rings being inclined to each other by 3.56 (11)°. The central —C(=O)—C–O—C(=O)— bridge is slightly twisted, with a C—C—O—C torsion angle of 164.95 (16)°. In the crystal, mol­ecules are linked by C—H⋯O and C—H⋯Cl hydrogen bonds, forming layers parallel to the (101) plane. The layers are linked by a further C—H⋯O hydrogen bond, forming a three-dimensional supra­molecular structure. There are a number of offset π–π inter­actions present between the layers [inter­centroid distances vary from 3.8264 (15) to 3.9775 (14) Å]. Hirshfeld surface analyses, the dnorm surfaces, electrostatic potential and two-dimensional fingerprint plots were examined to verify the contributions of the different inter­molecular contacts within the supra­molecular structure. The shape-index surface shows that two sides of the mol­ecule are involved in the same contacts with neighbouring mol­ecules, and the curvedness plot shows flat surface patches that are characteristic of planar stacking.

Highly Brønsted-acidic boron trifluoride monohydrate, a widely used `super acid-catalyst', is a colourless fuming liquid that releases BF3 at room temperature. Com­pared to the liquid com­ponents, i.e. boron trifluoride monohydrate and 1,4-dioxane, their 1:1 adduct, BF3H2O·C4H8O2, is a solid with pronounced thermal stability (m.p. 401–403 K). The crystal structure of the long-time-stable easy-to-handle and weighable com­pound is reported along with new preparative aspects and the results of 1H, 11B, 13C and 19F spectroscopic investigations, particularly documenting its high Brønsted acidity in aceto­nitrile solution. The remarkable stability of solid BF3H2O·C4H8O2 is attributed to the chain structure established by O—H⋯O hydrogen bonds of exceptional strength {O2⋯H1—O1 [O⋯O = 2.534 (3) Å] and O1—H1⋯O3i [2.539 (3) Å] in the concatenating unit >O2⋯H1—O1—H2⋯O3i<}, taking into account the mol­ecular (non-ionic) character of the structural moieties. Indirectly, this structural feature documents the outstanding acidification of the H2O mol­ecule bound to BF3 and reflects the super acid nature of BF3H2O. In detail, the C22(7) zigzag chain system of hydrogen bonding in the title structure is characterized by the double hydrogen-bond donor and double (κO,κO') hydrogen-bond acceptor functionality of the aqua ligand and dioxane molecule, respectively, the almost equal strength of both hydrogen bonds, the approximatety linear arrangement of the dioxane O atoms and the two neighbouring water O atoms. Furthermore, the approximately planar arrangement of B, F and O atoms in sheets perpendicular to the c axis of the ortho­rhom­bic unit cell is a characteristic structural feature.

A reaction of copper(II) carbonate and potassium 4-sulfo­benzoic acid in water acidified with hydro­chloric acid yielded two crystalline products. Tetra­aqua­bis­(4-carb­oxy­benzene­sulfonato)­copper(II) dihydrate, [Cu(O3SC6H4CO2H)2(H2O)4]·2H2O, (I), crystallizes in the triclinic space group Poverline{1} with the Cu2+ ions located on centers of inversion. Each copper ion is coordinated to four water mol­ecules in a square plane with two sulfonate O atoms in the apical positions of a Jahn–Teller-distorted octa­hedron. The carboxyl­ate group is protonated and not involved in coordination to the metal ions. The complexes pack so as to create a layered structure with alternating inorganic and organic domains. The packing is reinforced by several O—H⋯O hydrogen bonds involving coordinated and non-coordinated water mol­ecules, the carb­oxy­lic acid group and the sulfonate group. Hexa­aqua­copper(II) 4-carb­oxy­benzene­sulfonate, [Cu(H2O)6](O3SC6H4CO2H)2, (II), also crystallizes in the triclinic space group Poverline{1} with Jahn–Teller-distorted octa­hedral copper(II) aqua complexes on the centers of inversion. As in (I), the carboxyl­ate group on the anion is protonated and the structure consists of alternating layers of inorganic cations and organic anions linked by O—H⋯O hydrogen bonds. A reaction of silver nitrate and potassium 4-sulfo­benzoic acid in water also resulted in two distinct products that have been structurally characterized. An anhydrous silver potassium 4-carb­oxy­benzene­sulfonate salt, [Ag0.69K0.31](O3SC6H4CO2H), (III), crystallizes in the monoclinic space group C2/c. There are two independent metal sites, one fully occupied by silver ions and the other showing a 62% K+/38% Ag+ (fixed) ratio, refined in two slightly different positions. The coordination environments of the metal ions are composed primarily of sulfonate O atoms, with some participation by the non-protonated carboxyl­ate O atoms in the disordered site. As in the copper compounds, the cations and anions cleanly segregate into alternating layers. A hydrated mixed silver potassium 4-carb­oxy­benzene­sulfonate salt dihydrate, [Ag0.20K0.80](O3SC6H4CO2H)·2H2O, (IV), crystallizes in the monoclinic space group P21/c with the Ag+ and K+ ions sharing one unique metal site coordinated by two water mol­ecules and six sulfonate O atoms. The packing in (IV) follows the dominant motif of alternating inorganic and organic layers. The protonated carboxyl­ate groups do not inter­act with the cations directly, but do participate in hydrogen bonds with the coordinated water mol­ecules. (IV) is isostructural with pure potassium 4-sulfo­benzoic acid dihydrate.

The crystal structure of the title compound, [Ni3(C8H4O4)3(C3H7NO)4], is a two-dimensional coordination network formed by trinuclear linear Ni3(tp)3(DMF)4 units (tp = terephthalate = benzene-1,4-di­carboxyl­ate and DMF = di­methyl­formamide) displaying a characteristic coordination mode of acetate groups in polynuclear metal–organic compounds. Individual trinuclear units are connected through tp anions in a triangular network that forms layers. One of the DMF ligands points outwards and provides inter­actions with equivalent planes above and below, leaving the second ligand in a structural void much larger than the DMF mol­ecule, which shows positional disorder. Parallel planes are connected mainly through weak C—H⋯O, H⋯H and H⋯C inter­actions between DMF mol­ecules, as shown by Hirshfeld surface analysis.

The title compound, [Fe(C44H24N8Cl4)(CN)2][K2(C18H36N2O6)2]·2C4H8O was synthesized and characterized by single-crystal X-ray diffraction as well as FTIR and UV–vis spectroscopy. The central FeII ion is coordinated by four pyrrole N atoms of the porphyrin core and two C atoms of the cyano groups in a slightly distorted octa­hedral coordination environment. The complex mol­ecule crystallizes with two tetra­hydro­furan solvent mol­ecules, one of which was refined as disordered over two sets of sites with refined occupancies of 0.619 (5) and 0.381 (5). It has a distorted porphyrin core with mean absolute core-atom displacements Ca, Cb, Cm and Cav of 0.32 (3), 0.22 (3), 0.56 (2) and 0.37 (14) Å, respectively. The axial Fe—Ccyano bond lengths are 1.991 (2) and 1.988 (2) Å. The average Fe—Np (Np is a porphyrin N atom) bond length is 1.964 (10) Å. One of the O atoms and several C atoms of the 222 moiety [222 = 4,7,13,16,21,24-hexa­oxa-1,10-di­aza­bicyclo­[8.8.8]hexa­cosa­ne] were refined as disordered over two sets of sites with occupancy ratios of 0.739 (6):0.261 (6) and 0.832 (4):0.168 (4). Additional solvent mol­ecules were found to be highly disordered and their contribution to the scattering was removed using the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9–18], which indicated a solvent cavity of volume 372 Å3 containing approximately 83 electrons. These solvent mol­ecules are not considered in the given chemical formula and other crystal data.

In the paper by Gomes et al. [Acta Cryst. (2019), E75, 1403–1410], there was an error and omission in the author and affiliation list.

The title compound, C20H22N8O2, was synthesized by the coupling reaction of a sodium tetra­zolate salt and di­bromo­butane in a molar ratio of 2:1. The reaction can produce several possible regioisomers and the title compound was separated as the major product. The X-ray crystallographic study confirmed that the title compound crystallizes in the monoclinic P21/c space group and possesses a bridging butyl­ene group that connects two identical phenyl tetra­zole moieties. The butyl­ene group is attached not to the first but the second nitro­gen atoms of both tetra­zole rings. The dihedral angles between the phenyl groups and the adjacent tetra­zolyl rings are 5.32 (6) and 15.37 (7)°. In the crystal, the mol­ecules form centrosymmetric dimers through C—H⋯O hydrogen bonds between a C—H group of the butyl­ene linker and the O atom of a meth­oxy group.

The title compound, C9H7.5NO·C7H3.5ClNO4, was analysed as a disordered structure over two states, viz. co-crystal and salt, accompanied by a keto–enol tautomerization in the base mol­ecule. The co-crystal is 4-chloro-2-nitro­benzoic acid–quinolin-4(1H)-one (1/1), C7H4ClNO4·C9H7NO, and the salt is 4-hy­droxy­quinolinium 4-chloro-2-nitro­benzoate, C9H8NO+·C7H3ClNO4−. In the compound, the acid and base mol­ecules are held together by a short hydrogen bond [O⋯O = 2.4393 (15) Å], in which the H atom is disordered over two positions with equal occupancies. In the crystal, the hydrogen-bonded acid–base units are linked by N—H⋯O and C—H⋯O hydrogen bonds, forming a tape structure along the a-axis direction. The tapes are stacked into a layer parallel to the ab plane via π–π inter­actions [centroid–centroid distances = 3.5504 (8)–3.9010 (11) Å]. The layers are further linked by another C—H⋯O hydrogen bond, forming a three-dimensional network. Hirshfeld surfaces for the title compound mapped over shape-index and dnorm were generated to visualize the inter­molecular inter­actions.

In the title compound, C17H21NO4S, the 1,4-di­hydro­pyridine ring has an envelope conformation with the Csp3 atom at the flap. The thio­phene ring is nearly perpendicular to the best plane through the 1,4-di­hydro­pyridine ring, the dihedral angle being 82.19 (13)°. In the crystal, chains running along the b-axis direction are formed through N—H⋯O inter­actions between the 1,4-di­hydro­pyridine N atom and one of the O atoms of the ester groups. Neighbouring chains are linked by C—H⋯O and C—H⋯π inter­actions. A Hirshfeld surface analysis shows that the most prominent contributuion to the surface contacts are H⋯H contacts (55.1%).

In the title compound, C10H10N2OS, the five atoms of the thio­phene ring are essentially coplanar (r.m.s. deviation = 0.0037 Å) and the pyridazine ring is non-planar. In the crystal, pairs of N—H⋯O hydrogen bonds link the mol­ecules into dimers with an R22(8) ring motif. The dimers are linked by C—H⋯O inter­actions, forming layers parallel to the bc plane. The theoretical geometric parameters are in good agreement with XRD results. The inter­molecular inter­actions were investigated using a Hirshfeld surface analysis and two-dimensional fingerprint plots. The Hirshfeld surface analysis of the title compound suggests that the most significant contributions to the crystal packing are by H⋯H (39.7%), C⋯H/H⋯C (17.3%) and O⋯H/H⋯O (16.8%) contacts.

In the title compound, di-μ-cyanato-1:2κ2N:C;2:3κ2C:N-di­cyanato-2κ2C-bis­(1,4,7,10,13,16-hexa­oxa­cyclo­octa­deca­ne)-1κ6O;3κ6O-1,3-dipotassium(I)-2-platinum(II), [K2Pt(CN)4(C12H24O6)2] or [K(18-crown-6)]2·[Pt(CN)4], two trans-orientated cyano groups of the square-planar [Pt(CN)4]2− dianion (Pt site symmetry overline{1}) bind to one potassium ion each, which are additionally coordinated by the six O atoms of 18-crown-6. No Pt⋯Pt inter­actions occur in the crystal, but very weak Pt⋯H contacts (2.79 Å) are observed.

After crystallization during ionothermal syntheses in phospho­nium-containing ionic liquids, the structure of (NH4)3Al2(PO4)3 [tri­ammonium dialuminum tris­(phosphate)] was refined on the basis of powder X-ray diffraction data from a synchrotron source. (NH4)3Al2(PO4)3 is a member of the structural family with formula A3Al2(PO4)3, where A is a group 1 element, and of which the NH4, K, and Rb forms were previously known. The NH4 form is isostructural with the K form, and was previously solved from single-crystal X-ray data when the material (SIZ-2) crystallized from a choline-containing eutectic mixture [Cooper et al. (2004). Nature, 430, 1012–1017]. Our independent refinement incorporates NH4 groups and shows that these NH4 groups are hydrogen bonded to framework O atoms present in rings containing 12 T sites in a channel along the c-axis direction. We describe structural details of (NH4)3Al2(PO4)3 and discuss differences with respect to isostructural forms.

The title pyridazinone derivative, C20H18N2O3, is not planar. The phenyl ring and the pyridazine ring are inclined to each other by 10.55 (12)°, whereas the 4-methyl­benzyl ring is nearly orthogonal to the pyridazine ring, with a dihedral angle of 72.97 (10)°. In the crystal, mol­ecules are linked by pairs of O—H⋯O hydrogen bonds, forming inversion dimers with an R22(14) ring motif. The dimers are linked by C—H⋯O hydrogen bonds, generating ribbons propagating along the c-axis direction. The inter­molecular inter­actions were additionally investigated using Hirshfeld surface analysis and two-dimensional fingerprint plots. They revealed that the most significant contributions to the crystal packing are from H⋯H (48.4%), H⋯O/O⋯H (21.8%) and H⋯C/C⋯H (20.4%) contacts. Mol­ecular orbital calculations providing electron-density plots of HOMO and LUMO mol­ecular orbitals and mol­ecular electrostatic potentials (MEP) were also computed, both with the DFT/B3LYP/6–311 G++(d,p) basis set.

The solid-state structures of two cobalt–pyridine–sulfate compounds, namely catena-poly[[tetra­kis­(pyridine-κN)cobalt(II)]-μ-sulfato-κ2O:O'], [Co(SO4)(C5H5N)4]n, (1), and catena-poly[[tetra­kis­(pyridine-κN)cobalt(II)]-μ-sulfato-κ3O:O',O''-[bis­(pyridine-κN)cobalt(II)]-μ-sulfato-κ3O,O':O'']n, [Co2(SO4)2(C5H5N)6]n, (2), are reported. Compound (1) displays a polymeric structure, with infinite chains of CoII cations adopting octa­hedral N4O2 coordination environments that involve four pyridine ligands and two bridging sulfate ions. Compound (2) is also polymeric with infinite chains of CoII cations. The first Co center has an octa­hedral N4O2 coordination environment that involves four pyridine ligands and two bridging sulfate ligands. The second Co center has an octa­hedral N2O4 coordination environment that involves two pyridine ligands and two bridging sulfate ions that chelate the Co atom. The structure of (2) was refined as a two-component inversion twin.

The structure of the jatrophane diterpenoid (ES2), C46H56O15, has ortho­rhom­bic (P212121) symmetry. The absolute configuration in the crystal has been determined as 2R,3R,4S,5R,7S,8S,9S,13S,14S,15R [the Flack parameter is −0.06 (11)]. The mol­ecular structure features intra­molecular O—H⋯O and C—H⋯O hydrogen bonding. In the crystal, C—H⋯O hydrogen bonds link the mol­ecules into supra­molecular columns parallel to the a axis. One of the acet­oxy substituents is disordered over two orientations in a 0.826 (8):0.174 (8) ratio.