N‐(4‐Cyano­phenyl)‐α‐(4‐methoxy­phenyl)­nitro­ne

In the crystal structure of the title compound, 4‐cyano‐N‐(4‐methoxy­benzyl­idene)­phenyl­amine N‐oxide, C₁₅H₁₂N₂O₂, the 4‐methoxy­phenyl is approximately coplanar with the nitrone moiety but significantly rotated with respect to the 4‐cyano­phenyl moiety. The extent of this rotation is significantly different for the two crystallographically independent mol­ecules of the asymmetric unit [dihedral angles of 19.4 (1) and 26.5 (1)°]. The geometry about the C=N bond is Z. The two mol­ecules are related to one another by a pseudo inversion centre.     

Bis(3‐nitro­phenyl) di­sulfide forms no C—H⃛O hydrogen bonds

In the title compound, C₁₂H₈N₂O₄S₂, the mol­ecules lie across twofold rotation axes in the space group C2/c. There are no intermolecular C—H?O hydrogen bonds, but the mol­ecules are linked into chains along [001] by aromatic π?π stacking interactions.     

1‐Methyl­piperazine‐1,4‐diium 4‐nitro­phthalate(2–) 4‐nitro­phthalic acid monohydrate

The title adduct, C₅H₁₄N₂²⁺·C₈H₃NO₆²⁻·C₈H₅NO₆·H₂O, crystallizes in the monoclinic space group P2₁. All O atoms of the 4‐nitro­phthalate anions and neutral 4‐nitro­phthalic acid mol­ecules are involved in hydrogen bonding with the piperazine dication and the water mol­ecule of crystallization.     

1,3‐Bis(4‐nitro­phenyl)­triazene

The structure of the title compound, C₁₂H₉N₅O₄, reveals an almost planar mol­ecule (r.m.s. deviation = 0.061 Å), in which the interplanar angle between the phenyl rings is 5.7 (1)° and the largest interplanar angle is that between the phenyl ring and the nitro group of one of the 4‐nitro­phenyl substituents [8.8 (3)°]. The observed mol­ecular conformation suggests a delocalization of π‐electrons extended over the diazo­amine group and the terminal aryl substituents. Intermolecular N—H⃛O interactions between the twofold screw‐related mol­ecules give rise to helical chains along the [010] direction. Intermolecular C—H⃛O interactions then generate sheets of mol­ecules in the (10) plane, and these sheets are held together by N⃛C and O⃛O π–π interactions.     

4‐Dimethyl­amino‐β‐nitro­styrene and 4‐dimethyl­amino‐β‐ethyl‐β‐nitro­styrene at 100 K

The structures of 4‐dimethyl­amino‐β‐nitro­styrene (DANS), C₁₀H₁₂N₂O₂, and 4‐dimethyl­amino‐β‐ethyl‐β‐nitro­styrene (DAENS), C₁₂H₁₆N₂O₂, have been solved at T = 100 K. The structure solution for DANS was complicated by the presence of a static disorder, characterized by a misorientation of 17% of the mol­ecules. The mol­ecule of DANS is almost planar, indicating significant conjugation, with a push–pull effect through the styrene skeleton extending up to the terminal substituents and enhancing the dipole moment. As a consequence of this conjugation, the hexa­gonal ring displays a quinoidal character; the lengths of the C—N [1.3595 (15) Å] and C—C [1.448 (2) Å] bonds adjacent to the benzene ring are shorter than single bonds. The mol­ecules are stacked in dimers with anti­parallel dipoles. In contrast, the mol­ecule of DAENS is not planar. The ethyl substituent pushes the nitro­propene group out of the benzene plane, with a torsion angle of −21.9 (3). Nevertheless, the mol­ecule remains conjugated, with a shortening of the same bonds as in DANS.     

Ethyl N‐[2‐(hydroxy­acetyl)­phenyl]­carbamate,ethyl N‐[2‐(hydroxy­acetyl)‐4‐iodo­phenyl]­carbamate and ethyl N‐[2‐(hydroxy­acetyl)‐4‐methyl­phenyl]­carbamate

In ethyl N‐[2‐(hydroxy­acetyl)phenyl]carbamate, C₁₁H₁₃NO₄, all of the non‐H atoms lie on a mirror plane in the space group Pnma; the mol­ecules are linked into simple chains by a single C—H⋯O hydrogen bond. The mol­ecules of ethyl N‐[2‐(hydroxy­acetyl)‐4‐iodo­phenyl]carbamate, C₁₁H₁₂INO₄, are linked into sheets by a combination of O—H⋯I and C—H⋯O hydrogen bonds and a dipolar I⋯O contact. Ethyl N‐­[2‐(hydroxy­acetyl)‐4‐methyl­phenyl]carbamate, C₁₂H₁₅NO₄, crystallizes with Z′ = 2 in the space group P; pairs of mol­ecules are weakly linked by an O—H⋯O hydrogen bond and these aggregates are linked into chains by two independent aromatic π–π stacking inter­actions.     

(E)‐(4‐Hydroxyphenyl)(4‐nitrophenyl)diazene, (E)‐(4‐methoxyphenyl)(4‐nitrophenyl)diazene and (E)‐[4‐(6‐bromohexyloxy)phenyl](4‐cyanophenyl)diazene

Syntheses and X‐ray structural investigations have been carried out for (E)‐(4‐hydroxy­phenyl)(4‐nitro­phenyl)­diazene, C₁₂H₉N₃O₃, (Ia), (E)‐(4‐methoxy­phenyl)(4‐nitro­phenyl)­diazene, C₁₃H₁₁N₃O₃, (IIIa), and (E)‐[4‐(6‐bromo­hexyl­oxy)­phenyl](4‐cyano­phenyl)­diazene, C₁₉H₂₀BrN₃O, (IIIc). In all of these compounds, the mol­ecules are almost planar and the azo­benzene core has a trans geometry. Compound (Ia) contains four and compound (IIIc) contains two independent mol­ecules in the asymmetric unit, both in space group P (No. 2). In compound (Ia), the independent mol­ecules are almost identical, whereas in crystal (IIIc), the two independent mol­ecules differ significantly due to different conformations of the alkyl tails. In the crystals of (Ia) and (IIIa), the mol­ecules are arranged in almost planar sheets. In the crystal of (IIIc), the mol­ecules are packed with a marked separation of the azo­benzene cores and alkyl tails, which is common for the solid crystalline precursors of mesogens.     

4‐(4‐Bromo­phenyl)‐2‐methyl‐1,3‐thia­zole

In the structure of the title compound, C₁₀H₈BrNS, the dihedral angles between the planes of the thia­zole and aryl rings, viz. 4.2 (6) and 7.5 (6)° for the two independent mol­ecules, are consistent with insignificant molecular perturbation by the weak intermolecular contacts. The mol­ecules are close to being related by a non‐crystallographic inversion centre, with C—H⃛π and π–π intermolecular interactions observed.     

3‐(4‐Acetyl­phenyl)‐1‐(4‐nitro­phenyl)­triazene

The crystal structure of the title compound, C₁₄H₁₂N₄O₃, shows that the stereochemistry about the N=N double bond of the N=N—N(H) moiety is trans. The whole mol­ecule is almost planar (r.m.s. deviation = 0.0654 Å), the interplanar angle between the phenyl rings being 0.7 (1)° and the largest interplanar angle being that between the phenyl ring and the nitro group of the 4‐nitro­phenyl substituent [11.5 (2)°]. Intermolecular N—H⋯O interactions between mol­ecules related by translation give rise to chains along the [110] and [10] directions, and these chains are held together by N⋯O π–π interactions. An unequal distribution of the double‐bond character among the N atoms suggests a delocalization of π electrons over the diazo­amine group and the adjacent aryl substituents.     

catena‐Poly[[[tetra­aqua­zinc(II)]‐μ‐4,4′‐bipyridine] bis­(4‐hydroxy­benzene­sulfonate) trihydrate]

In the title compound, {[Zn(C₁₀H₈N₂)(H₂O)₄](C₆H₅O₄S)₂·3H₂O}_n, the Zn atom, the bipyridine ligand and one of water mol­ecules are located on twofold rotation axes. The Zn atom is coordinated by four O atoms from four water mol­ecules and two N atoms from two 4,4′‐bipyridine mol­ecules in a distorted octa­hedral geometry. The Zn²⁺ ions are linked by the 4,4′‐bipyridine mol­ecules to form a one‐dimensional straight chain propagating along the c axis. The 4‐hydroxy­benzene­sulfonate counter‐ions are bridged by the solvent water mol­ecules through hydrogen bonds to generate a two‐dimensional layer featuring large pores. In the crystal packing, the intra­layer pores form one‐dimensional channels along the c axis, in which the one‐dimensional [Zn(C₁₀H₈N₂)(H₂O)₄]²⁺ chains are encapsulated. Electrostatic inter­actions between cations and anions and extensive hydrogen bonds result in a three‐dimensional supra­molecular structure.     

2‐Meth­oxy‐4‐[(5‐oxo‐2‐phenyl‐4,5‐dihydro‐1,3‐oxazol‐4‐yl­idene)meth­yl]­phenyl 4‐methyl­benzene­sulfonate

Mol­ecules of the title compound, C₂₄H₁₉NO₆S, adopt the Z configuration and have a distorted tetra­hedral geometry around the S atom. The oxazolone, 2‐phenyl and methoxy­phenyl rings are approximately coplanar. The C atom between the methoxy­phenyl and oxazolone rings displays a distorted trigonal bonding geometry. Pairs of mol­ecules are linked into dimers through weak C—H⋯O hydrogen bonds.     

4‐(4‐Hydro­xy­benzyl­idene­amino)‐4H‐1,2,4‐triazole hemihydrate

In the title compound, 4‐(4H‐1,2,4‐triazol‐4‐yl­imino­methyl)­phenol hemi­hydrate, C₉H₈N₄O·0.5H₂O or (I)·0.5H₂O, mol­ecules of (I) are arranged as layers running along the b axis through intermolecular O—H?N and C—H?O hydrogen bonds. These layers are stabilized by hydrogen‐bonded water mol­ecules to form three‐dimensional networks.     

2‐Amino derivatives of 5‐nitro­phenyl­acet­amide

The structures of the potential non‐linear optical (NLO) materials N‐[2‐(iso­propyl­amino)‐5‐nitro­phenyl]­acet­amide, (I) C₁₁H₁₅N₃O₃, and N‐[2‐(butyl­amino)‐5‐nitro­phenyl]­acet­amide, (II) C₁₂H₁₇N₃O₃, have been investigated by X‐ray analysis. To compare them with the structure of N‐[2‐(di­methyl­amino)‐5‐nitro­phenyl]­acet­amide, (III) C₁₀H₁₃N₃O₃, a known NLO compound, we had to redetermine the structure of (III), since it was described only briefly in the literature. There are two mol­ecules in the asymmetric unit of compound (I), which have different orientations of the substituents with respect to the benzene ring. The packing of mol­ecules in (II) and (III) contains stacks but both (I) and (II) crystallize in a centrosymmetric space group, which renders them inappropriate for NLO applications.     

Supramolecular structures of 5‐[3‐(4‐methyl­phenyl)‐ and 5‐[3‐(4‐chloro­phenyl)‐2‐propenyl­idene]‐2,2‐di­methyl‐1,3‐dioxane‐4,6‐dione

2,2‐Di­methyl‐5‐[3‐(4‐methyl­phenyl)‐2‐propenyl­idene]‐1,3‐di­ox­ane‐4,6‐dione, C₁₆H₁₆O₄, crystallizes in the triclinic space group , with two mol­ecules in the asymmetric unit. These mol­ecules and a centrosymmetrically related pair, linked together by weak C—H?O hydrogen bonds, form a tetramer. 5‐[3‐(4‐Chloro­phenyl)‐2‐propenyl­idene]‐2,2‐di­methyl‐1,3‐dioxane‐4,6‐dione, C₁₅H₁₃ClO₄, also crystallizes in the triclinic space group , with one mol­ecule in the asymmetric unit. Centrosymmetrically related mol­ecules are linked together by weak C—H?O hydrogen bonds to form dimers which are further linked by yet another pair of centrosymmetrically related C—H?O hydrogen bonds to form a tube which runs parallel to the a axis.     

3‐(1‐Pyridinio)propane­sulfonate and 3‐(benzyl­dimethyl­ammonio)propane­sulfonate monohydrate

3‐(1‐Pyridinio)propane­sulfonate, C₈H₁₁NO₃S, and 3‐(benzyl­dimethyl­ammonio)propane­sulfonate monohydrate, C₁₂H₁₉NO₃S·H₂O, used as additives during protein refolding and crystallization, both crystallize in the monoclinic system in the P2₁/c space group, with one mol­ecule (or one set of mol­ecules) per asymmetric unit. The solvent water mol­ecule present in the second crystal structure results in the formation of a dimer through hydrogen bonds. The conformation of the propane­sulfonate moiety is similar in both structures.     

3‐Butyl‐1‐(5‐nitro­benzo­[c][1,2]­thia­zol‐3‐yl)‐3‐phenyl­triazene

The mol­ecule of the title compound, C₁₇H₁₇N₅O₂S, consists of three π systems, viz. two aromatic rings and the triazene moiety, which are mutually deconjugated although coplanar. The n‐butyl chain is roughly perpendicular to the molecular plane, with the terminal methyl­ene and methyl groups disordered between two equally populated positions. The mol­ecules in the crystal associate in an antiparallel fashion, forming dimers across the centre of symmetry, the principal intradimer interaction being stacking of the π‐electron portions of the mol­ecules.     

Di‐2‐pyridyl ketone N4,N4‐(butane‐1,4‐diyl)thiosemicarbazone

The title compound, C₁₆H₁₇N₅S, is in the thione form and crystallizes with two independent mol­ecules in the asymmetric unit. In both mol­ecules, the penta­methyl­ene­imine five‐membered ring adopts an envelope conformation, and in one of the molecules this ring shows positional disorder. The thione S and hydrazine N atoms are in the Z configuration with respect to the C—N bond.     

Adducts of 1,1,1‐tris(4‐hydroxy­phenyl)­ethane with 1,2‐bis(4‐pyridyl)­ethane and 1,2‐bis(4‐pyridyl)­ethene: continuously interwoven structures in three dimensions

In the adduct 1,2‐bis(4‐pyridyl)­ethane–1,1,1‐tris(4‐hydroxy­phenyl)­ethane (1/2), C₁₂H₁₂N₂·2C₂₀H₁₈O₃, the bipyridyl component lies across an inversion centre in P. The tris‐phenol mol­ecules [systematic name: 4,4′,4′′‐(ethane‐1,1,1‐triyl)­triphenol] are linked by O—H?O hydrogen bonds to form sheets built from R(38) rings, and symmetry‐related pairs of sheets are linked by the bipyridyl mol­ecules via O—H?N hydrogen bonds to form open bilayers. Each bilayer is interwoven with two adjacent bilayers, forming a continuous three‐dimensional structure. In the adduct 1,2‐bis(4‐pyridyl)­ethene–1,1,1‐tris(4‐hydroxy­phenyl)­ethane–methanol (1/1/1), C₁₂H₁₀N₂·C₂₀H₁₈O₃·CH₄O, the mol­ecules are linked by O—H?O and O—H?N hydrogen bonds into three interwoven three‐dimensional frameworks, generated by single spiral chains along [010] and [001] and a triple‐helical spiral along [100].     

A new precursor for the synthesis of porphyrazine: 2,3‐bis(4‐methyl­phenyl)­maleo­nitrile

The structure of the title compound consists of discrete C₁₈H₁₄N₂ mol­ecules in a cis configuration. The mol­ecules are distorted from planarity.     

2,6‐Di­benzyl‐1,2,3,5,6,7‐hexa­hydro‐2,4,6,8‐tetra­aza‐s‐indacene and 2,6‐bis(4‐methoxy­benzyl)‐1,2,3,5,6,7‐hexa­hydro‐2,4,6,8‐tetra­aza‐s‐indacene

The title compounds, C₂₂H₂₂N₄ and C₂₄H₂₆N₄O₂ [alternative names: 2,6‐dibenzyl‐2,3,6,7‐tetrahydro‐1H,5H‐dipyrrolo[3,4‐b; 3′,4′‐e]pyrazine and 2,6‐bis(4‐methoxybenzyl)‐2,3,6,7‐tetrahydro‐1H,5H‐dipyrolo[3,4‐b;3′,4′‐e]pyrazine], two 1,2,3,5,6,7‐hexa­hydro‐2,4,6,8‐tetra­aza‐s‐indacene derivatives, are both centrosymmetric and have similar S‐shaped structures. In the former, there are two independent mol­ecules (A and B), both of which possess C_i symmetry. These two mol­ecules are arranged such that the benzene ring substituent of mol­ecule B is directed towards the plane of the benzene ring substituent of mol­ecule A, with a dihedral angle of 55.4 (2)° between their planes. The shortest C—H⋯C distance is, however, only 3.21 (1) Å. In both compounds, the benzene ring substituents are almost perpendicular to the plane of the central pyrazine ring, and the pyrrolidine rings have perfect envelope conformations. In the crystal structures of both compounds, the mol­ecules pack in a herring‐bone arrangement.