(S,S)‐4′′‐Cyano‐7,7′′‐dimethoxy‐3′,6′‐dioxodispiro[indane‐2,2′‐piperazine‐5′,2′′‐indane]‐4‐carboxamide methanol solvate: interrupting the amide‐to‐amide hydrogen‐bonded tape

The title methanol solvate, C₂₄H₂₂N₄O₅·CH₃OH, forms an extended three‐dimensional hydrogen‐bonded structure, assisted by the presence of several good donor and acceptor sites. It shows none of the crystal packing features typically expected of piperazinediones, such as amide‐to‐amide R₂²(8) hydrogen bonding. In this structure the methanol solvent appears to play only a space‐filling role; it is not involved in any hydrogen bonding and instead is disordered over several sites. This study reports, to the best of our knowledge, the first crystal structure of an indane‐containing piperazinedione compound which exhibits a three‐dimensional hydrogen‐bonded structure formed by classical (N—H...O and N—H...N) hydrogen‐bonding interactions.     

Herring‐bone π–π interactions in trans‐2,6‐diphenyl‐2,3,5,6‐tetrahydrothiapyran‐4‐one

The structure of the title compound, C₁₇H₁₆OS, is primarily stabilized by T‐shaped and parallel‐displaced aromatic clusters. The distances between the centroids of the aromatic pairs are in the range 4.34–5.30 Å. In the crystal packing, the mol­ecules dimerize by means of π–π interactions of both face‐to‐face and edge‐to‐face types, and the aromatic rings associate in a cyclic edge‐to‐face tetrameric arrangement of the herring‐bone type. These herring‐bone interactions appear to insulate hydrogen‐bond interactions in the crystal structure.     

2‐(3‐tert‐Butyldimethylsiloxy‐4‐methoxyphenyl)‐6‐methoxy‐3‐(3,4,5‐trimethoxybenzoyl)indole

In the crystal structure of the title compound, C₃₂H₃₉NO₇Si, all geometric parameters fall within experimental error of expected values. The analysis of molecular‐packing plots reveals an infinite two‐dimensional linear array running parallel to the b axis, formed by one N—H?O intermolecular hydrogen‐bonding interaction. Several potential C—H?O interactions are also present.     

(E)‐1‐(2‐Hydro­xy‐4‐methoxy­phenyl)‐2‐(3,4,5‐tri­methoxy­phenyl)­ethene

In the crystal structure of the title compound, C₁₈H₂₀O₅, all geometric parameters fall within experimental error of the expected values. Analysis of the molecular‐packing plots reveals an infinite one‐dimensional linear array running parallel to the c axis, formed by an O—H⃛O intermolecular hydrogen‐bonding interaction. The stilbene framework and most of the substituents are approximately coplanar.     

(E)‐8‐(3‐Chloro­styr­yl)‐1,3,7‐trimethylxanthine,a caffeine derivative acting both as antagonist of adenosine A2A receptors and as inhibitor of MAO‐B

In the crystal structure of (E)‐8‐(3‐chloro­styr­yl)‐1,3,7‐trimethylxanthine (CSC) [systematic name: (E)‐8‐(3‐chloro­styr­yl)‐1,3,7‐trimethyl‐3,7‐dihydro‐1H‐purine‐2,6‐dione], C₁₆H₁₅ClN₄O₂, the xanthine ring and the lateral styryl chain are coplanar. The crystal packing involves mainly parallel stacking of these planar mol­ecules. The electrostatic potential calculated on the crystal structure conformation confirms the pharmacophore elements associated with MAO‐B inhibition.     

A new conformer of 1,4,7‐tris(p‐tolylsulfonyl)‐1,4,7‐triazacyclononane

A second polymorphic form (form II) of the previously reported 1,4,7‐tris(p‐tolylsulfonyl)‐1,4,7‐triazacyclononane (form I), C₂₇H₃₃N₃O₆S₃, is presented. The molecular structures of the two forms display very different conformations, thus prompting the two forms to crystallize in two different space groups and exhibit quite diverse crystal structure assemblies. Form I crystallizes in the triclinic space group P, while form II crystallizes in the monoclinic space group P2₁/n. The main differences between the two molecular structures are the conformations of the p‐tosyl groups relative to each other and to the macrocyclic ring. The resulting crystal packing displays no classical hydrogen bonds, but different supramolecular synthons give rise to different packing motifs.     

3‐(Ethoxy­carbonyl­di­hydroxy­methyl)‐2‐oxo‐1,2‐di­hydro­quinox­aline

The crystal structure of the title compound, ethyl 2,2‐di­­hy­droxy‐2‐(3‐oxo‐3,4‐di­hydro­quinoxalin‐2‐yl)­acetate, C₁₂H₁₂N₂O₅, indicates a short intramolecular contact between the N1 atom and a hydroxyl group [2.772 (4) Å]. Two intermolecular hydrogen bonds participate in the molecular packing.     

Theoretical insight into the disordered structure of (Z)‐2‐[(E)‐(4‐methoxybenzylidene)hydrazinylidene]‐1,2‐diphenylethanone: the role of noncovalent interactions

A global glide disorder has been discovered during an X‐ray investigation of the crystal structure of (Z)‐2‐[(E)‐(4‐methoxybenzylidene)hydrazinylidene]‐1,2‐diphenylethanone ( MHDE , C₂₂H₁₈N₂O₂) at room temperature. In another crystal, however, such disorder disappears (still at room temperature). Even though the disorder may be partly due to the poor quality of the harvested crystal, the structure can shed light on the nature of disorder. With the help of quantum chemical calculations, it is found that the global disorder seems to be connected with the need for stabilization of the somewhat rigid but mobile and unstable molecular structure. The most relevant feature driving the packing of the disordered structure concerns the slight perturbations (such as glide) of two or more disorder components (fractional occupancies) distributed throughout the crystal.     

5‐Phenyl‐9H‐1,3‐dioxolo[4,5‐h][2,3]benzodiazepin‐8(7H)‐one

The title compound, C₁₆H₁₂N₂O₃, is a novel potent and selective non‐competitive antagonist at AMPA/kainate receptors [AMPA is 2‐amino‐3‐(3‐hydroxy‐5‐methylisoxazol‐4‐yl)­propionic acid and kainate is 3‐carboxy­methyl‐4‐isopropenyl­pyrrolidine‐2‐carboxylic acid]. The crystal structure has been determined at room temperature by X‐ray diffraction and the seven‐membered ring shows the usual boat conformation. The energy stabilization of the crystal packing of the title compound by significant hydrogen‐bond inter­actions is discussed using theoretical computations.     

Two regioisomers of condensed thioheterocyclic triazine synthesized from 6‐phenyl‐3‐thioxo‐2,3,4,5‐tetrahydro‐1,2,4‐triazin‐5‐one

In the crystal structure of 6‐phenyl‐3‐thioxo‐2,3,4,5‐tetrahydro‐1,2,4‐triazin‐5‐one, C₉H₇N₃OS, (I), the 1,2,4‐triazine moieties are connected by face‐to‐face contacts through two kinds of double hydrogen bonds (N—H...O and N—H...S), which form planar ribbons along the a axis. The ribbons are crosslinked through C—H...π interactions between the phenyl rings. The molecular structures of two regioisomeric compounds, namely 6‐phenyl‐2,3‐dihydro‐7H‐1,3‐thiazolo[3,2‐b][1,2,4]triazin‐7‐one, C₁₁H₉N₃OS, (II), and 3‐phenyl‐6,7‐dihydro‐4H‐1,3‐thiazolo[2,3‐c][1,2,4]triazin‐4‐one, C₁₁H₉N₃OS, (III), which were prepared by the condensation reaction of (I) with 1,2‐dibromoethane, have been characterized by X‐ray crystallography and spectroscopic studies. The crystal structures of (II) and (III) both show two crystallographically independent molecules. While the two compounds are isomers, the unit‐cell parameters and crystal packing are quite different and (II) has a chiral crystal structure.     

1‐[5‐(4,5‐Dimethyl‐1,3,2‐dioxaborolan‐2‐yl)thiophen‐2‐yl]ethanone and 4‐(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)benzaldehyde

In both title compounds, C₁₀H₁₃BO₃S, (I), and C₁₃H₁₇BO₃, (II), the molecules adopt nearly planar conformations. The crystal packing of (I) consists of a supramolecular two‐dimensional network with a herringbone‐like topology formed by self assembly of centrosymmetric pairs of molecules linked via dipole–dipole interactions. The crystal structure of (II) consists of a supramolecular two‐dimensional network built up from centrosymmetric pairs of molecules viaπ–π interactions. These pairs of molecules are self‐organized in an offset fashion related by a symmetry centre, generating supramolecular ribbons running along the [101] direction. Neighbouring ribbons are stacked via complementary van der Waals and hydrophobic methyl–methyl interactions.     

Incorporating two different chromophores onto a silicon atom: the crystal structure and photophysical properties of 9‐{4‐[(9,9‐dimethyl‐9H‐fluoren‐2‐yl)dimethylsilyl]phenyl}‐9H‐carbazole

The crystal structure of the title bifunctional silicon‐bridged compound, C₃₅H₃₁NSi, (I), has been determined. The compound crystallizes in the centrosymmetric space group P2₁/c. In the crystal structure, the pairs of aryl rings in the two different chromophores, i.e. 9‐phenyl‐9H‐carbazole and 9,9‐dimethyl‐9H‐fluorene, are positioned orthogonally. In the crystal packing, no classical hydrogen bonding is observed. UV–Vis absorption and fluorescence emission spectra show that the central Si atom successfully breaks the electronic conjugation between the two different chromophores, and this was further analysed by density functional theory (DFT) calculations.     

6‐Aminopyridine‐3‐thiol

The title compound, C₅H₆N₂S, is a simple but novel pyridinethiol of pharmacological interest. The mol­ecule is planar. The crystal packing is dominated by hydro­phobic contacts and a pair of hydrogen‐bond interactions between the amino group of one pyridine mol­ecule and the ring N atom of a neighbouring base, stabilizing the structure.     

Synthesis and photophysical properties of 2,5,8,11‐tetrakis(5‐hexylthiophen‐2‐yl)tetrathieno[2,3‐a:3′,2′‐c:2′′,3′′‐f:3′′′,2′′′‐h]naphthalene

The title compound, C₅₈H₆₄S₈, has been prepared by Pd‐catalysed direct C—H arylation of tetrathienonaphthalene (TTN) with 5‐hexyl‐2‐iodothiophene and recrystallized by slow evaporation from dichloromethane. The crystal structure shows a completely planar geometry of the TTN core, crystallizing in the monoclinic space group P2₁/c. The structure consists of slipped π‐stacks and the interfacial distance between the mean planes of the TTN cores is 3.456 (5) Å, which is slightly larger than that of the comparable derivative of tetrathienoanthracene (TTA) with 2‐hexylthiophene groups. The packing in the two structures is greatly influenced by both the aromatic core of the structure and the alkyl side chains.     

Redetermination of cis‐4‐cyclo­hexene‐1,2‐di­carboxyl­ic acid at 173 K

The structure of the title compound, C₈H₁₀O₄, previously determined by Küppers & Kim [Acta Cryst. (1993), C 49 , 1218–1220] has been redetermined at 173 K. The cyclo­hexene ring exhibits a half‐chair conformation. The molecular geometry and the crystal packing, which is stabilized by two hydrogen bonds, agree well with the room‐temperature structure determination.     

Polymorphism of 2,5‐[(diphenylphosphanyl)methyl]‐1,1,2,4,4,5‐hexaphenyl‐1,4‐diphospha‐2,5‐diboracyclohexane

2,5‐[(Diphenylphosphanyl)methyl]‐1,1,2,4,4,5‐hexaphenyl‐1,4‐diphospha‐2,5‐diboracyclohexane shows polymorphism as two tetrahydrofuran (THF) disolvates [C₆₄H₅₈B₂P₄·2C₄H₈O, (Ia) and (Ib)] and pseudo‐polymorphism as its toluene monosolvate [C₆₄H₅₈B₂P₄·C₇H₈, (Ic)]. In each of polymorphs (Ia) and (Ib), the diphosphadiboracyclohexane molecule is located on a centre of inversion. The THF molecule of (Ib) is disordered over two sites, with a site‐occupation factor of 0.612 (8) for the major‐occupied site. Both structures crystallize in the same space group (P2₁/n), but they display a different crystal packing. For pseudo‐polymorph (Ic), although the space group is P2₁/c, which is just a different setting of the P2₁/n space group of (Ia) and (Ib), the crystal packing is completely different. Although the crystal packing in these three structures is significantly different, their molecular conformations are surprisingly the same.     

N,N‐Diethyl‐N′‐[(E)‐4‐pyridylmethylene]benzene‐1,4‐diamine: a combined X‐ray and density functional theory study

The crystal structure of the title compound, C₁₆H₁₉N₃, comprises neutral molecules of a dipolar Schiff base chromophore. A density functional theory (DFT) optimized structure at the B3LYP/6‐31G(d) level is compared with the molecular structure in the solid state. The compound crystallizes in the noncentrosymmetric space group Pna2₁ with a herring‐bone packing motif and is therefore a potential candidate for nonlinear optical effects in the bulk.     

5,5‐Dimethyl‐2‐[6‐methyl‐2‐(methylsulfanyl)pyrimidin‐4‐yloxy]‐1,3,2‐dioxaphosphorinane‐2‐thione

The title compound, C₁₁H₁₇N₂O₃PS₂, is a cyclic thio­phos­phoryl pyrimidine derivative exhibiting insecticidal properties. The crystal structure determination gives evidence for the presence of the thione isomer of the compound. The pyrimidine nucleus is planar and its substituents have small deviations from the least‐squares plane. The dioxaphos­phorinane ring adopts a chair conformation. The lack of classical hydrogen bonds and the weak intermolecular interactions lead to a `loose' packing characterized by channels in the structure.     

4‐Aminopyridinium 2‐(anthracen‐9‐yl)‐3‐oxo‐3H‐inden‐1‐olate monohydrate

The title compound, 2C₅H₇N₂⁺·2C₂₃H₁₃O₂⁻·H₂O, formed as a by‐product in the attempted synthesis of a nonlinear optical candidate molecule, contains two independent 4‐aminopyridinium cations and 2‐(anthracen‐9‐yl)‐3‐oxo‐3H‐inden‐1‐olate anions with one solvent water molecule. This is the first reported structure containing these anions. The two anions are not planar, having different interplanar angles between the anthracenyl and inden‐1‐olate moieties of 59.07 (5) and 83.92 (5)°. The crystal packing, which involves strong classical hydrogen bonds and one C—H...π interaction, appears to account for both the nonplanarity and this difference.     

1,1′‐Di­acetyl‐3‐hydroxy‐2,2′,3,3′‐tetra­hydro‐3,3′‐bi(1H‐indole)‐2,2′‐dione

In the title compound, C₂₀H₁₆N₂O₅, both of the 1‐acetyl­isatin (1‐acetyl‐1H‐indole‐2,3‐dione) moieties are planar and form a dihedral angle of 74.1 (1)°. Weak intermolecular hydrogen bonds and C—H?π interactions stabilize the packing in the crystal.