(R)‐4‐(4‐Aminophenyl)‐2,2,4‐trimethylchroman and (S)‐4‐(4‐aminophenyl)‐2,2,4‐trimethylthiachroman

The title compounds, C₁₈H₂₁NO and C₁₈H₂₁NS, in their enantiomerically pure forms are isostructural with the enantiomerically pure 4‐(4‐hydroxyphenyl)‐2,2,4‐trimethylchroman and 4‐(2,4‐dihydroxyphenyl)‐2,2,4‐trimethylchroman analogues and form extended linear chains via N—H...O or N—H...S hydrogen bonding along the [100] direction. The absolute configuration for both compounds was determined by anomalous dispersion methods with reference to both the Flack parameter and, for the light‐atom compound, Bayesian statistics on Bijvoet differences.     

(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.     

(E)‐N′‐(4‐Chlorobenzylidene)‐, (E)‐N′‐(4‐bromobenzylidene)‐ and (E)‐N′‐[4‐(diethylamino)benzylidene]‐ derivatives of 4‐hydroxybenzohydrazide

The 4‐chloro‐ [C₁₄H₁₁ClN₂O₂, (I)], 4‐bromo‐ [C₁₄H₁₀BrN₂O₂, (II)] and 4‐diethylamino‐ [C₁₈H₂₁N₃O₂, (III)] derivatives of benzylidene‐4‐hydroxybenzohydrazide, all crystallize in the same space group (P2₁/c), (I) and (II) also being isomorphous. In all three compounds, the conformation about the C=N bond is E. The molecules of (I) and (II) are relatively planar, with dihedral angles between the two benzene rings of 5.75 (12) and 9.81 (17)°, respectively. In (III), however, the same angle is 77.27 (9)°. In the crystal structures of (I) and (II), two‐dimensional slab‐like networks extending in the a and c directions are formed via N—H...O and O—H...O hydrogen bonds. The molecules stack head‐to‐tail viaπ–π interactions involving the aromatic rings [centroid–centroid distance = 3.7622 (14) Å in (I) and 3.8021 (19) Å in (II)]. In (III), undulating two‐dimensional networks extending in the b and c directions are formed via N—H...O and O—H...O hydrogen bonds. The molecules stack head‐to‐head viaπ–π interactions involving inversion‐related benzene rings [centroid–centroid distances = 3.6977 (12) and 3.8368 (11) Å].     

4‐Amino‐3‐methyl‐6‐phenyl‐1,2,4‐triazin‐5(4H)‐one (metamitron) and 4‐amino‐6‐methyl‐3‐phenyl‐1,2,4‐triazin‐5(4H)‐one (isometamitron)

The title structures, both C₁₀H₁₀N₄O, are substitutional isomers. The N—N bond lengths are longer and the C=N bond lengths are shorter by ca 0.025 Å than the respective average values in the C=N—N=C group of asymmetric triazines; the assessed respective bond orders are 1.3 and 1.7. There are N—H⋯O and N—H⋯N hydrogen bonds in both structures, with 4‐­amino‐3‐methyl‐6‐phenyl‐1,2,4‐triazin‐5(4H)‐one containing a rare bifurcated N—H⋯N,N hydrogen bond. The structures differ in their mol­ecular stacking and the hydrogen‐bonding patterns.     

4‐(4‐Chloro­phen­yl)‐3‐(4‐phenyl­pent‐4‐en­yloxy)‐1,3‐thia­zole‐2(3H)‐thione

The title compound, C₂₀H₁₈ClNOS₂, is a thia­zole‐derived thio­hydroxamic acid O‐ester. The value of Z′ is 3 and the asymmetric unit comprises three mol­ecules of identical helicity along the N—O bond. Two of these show an anti and the third a syn arrangement of substituents attached in positions 3 and 4 to the 1,3‐thia­zole nucleus.     

(E)‐4‐(4‐Bromo­phenyl­diazen­yl)‐2,6‐dimethyl­phenyl acrylate and (E)‐2,6‐dimethyl‐4‐(4‐methyl­phenyl­diazen­yl)­phenyl acrylate

The crystal structures of the title compounds, C₁₇H₁₅BrN₂O₂, (I), and C₁₈H₁₈N₂O₂, (II), determined at room temperature, have a trans configuration with respect to the diazene linkage, as found for other azo (diazene) derivatives. The aromatic mean planes are nearly coplanar, with a dihedral angle between these planes of 8.31 (2)° for (I) and 3.74 (2)° for (II). In both complexes, the mean plane of the ester group is nearly perpendicular to the aromatic ring planes. In both compounds, the crystal packing involves only π–π and π–ring inter­actions, which combine to stabilize the extended structure.     

Poly[hexaaquabis(μ4‐4‐carboxybenzenesulfonato)bis(μ3‐4‐carboxybenzenesulfonato)calcium(II)dipotassium(I)]

This study presents the coordination modes and crystal organization of a calcium–potassium coordination polymer, poly[hexaaquabis(μ₄‐4‐carboxybenzenesulfonato‐κ⁴O¹:O^1′:O^1′′:O⁴)bis(μ₃‐4‐carboxybenzenesulfonato‐κ²O¹:O^1′)calcium(II)dipotassium(I)], [CaK₂(C₇H₅O₅S)₄(H₂O)₆]_n, displaying a novel two‐dimensional framework. The potassium ion is seven‐coordinated by four sulfonate and one carboxyl O atom located on five different acid ligands, two of which are unique, and by two symmetry‐independent water O atoms. A pair of close potassium ions share two inversion‐related sulfonate O‐atom sites to form a dimeric K₂O₁₂ unit, which is extended into a one‐dimensional array along the a‐axis direction. The six‐coordinate Ca²⁺ ion occupies a special position () at (0, , ) and is surrounded by four sulfonate O atoms from two inversion‐related pairs of unique acid monoanions and by two O atoms from aqua ligands. The compound displays a layered structure, with K₂O₁₂ and CaO₆ polyhedra in the layers and aromatic linkers between the layers. The three‐dimensional scaffold is open, with nano‐sized channels along the c axis.     

(Z)‐5‐[4‐(Dimethylamino)benzylidene]‐2‐(piperidin‐1‐yl)‐1,3‐thiazolidin‐4(5H)‐one

The molecules of the title compound, C₁₇H₂₁N₃OS, are characterized by a wide C—C—C angle at the methine C atom linking the aryl and thiazolidine rings, associated with a short repulsive intramolecular S...H contact between atoms in these two rings. A single piperidine–arene C—H...π hydrogen bond links pairs of molecules into centrosymmetric dimers.     

1‐[(1‐Ethoxypropylidene)amino]‐2‐ethyl‐4‐(4‐hydroxybenzyl)imidazol‐5(4H)‐one

The racemic title compound, C₁₇H₂₃N₃O₃, isolated from the reaction of l ‐(−)‐tyrosine hydrazide with triethyl orthopropionate in the presence of a catalytic quantity of p‐toluenesulfonic acid (p‐TsOH), crystallizes with Z′ = 1 in a centrosymmetric monoclinic unit cell. The molecule contains two planar fragments, viz. the benzene and imidazole rings, linked by two C—C single bonds. The dihedral angle between the two planes is 59.54 (5)° and the molecule adopts a synclinal conformation. The HOMA (harmonic oscillator model of aromaticity) index, calculated for the benzene ring, demonstrates no substantial interaction between the two π‐electron delocalization regions in the molecule. In the crystal structure, there is an O—H...N hydrogen bond that links the molecules along the c axis.     

The absolute configuration of (2S,4S)‐ and (2R,4R)‐2‐tert‐butyl‐4‐methyl‐3‐(4‐tolyl­sulfon­yl)‐1,3‐oxazolidine‐4‐carbaldehyde

The title enanti­omorphic compounds, C₁₆H₂₃NO₄S, have been obtained in an enanti­omerically pure form by crystallization from a diastereomeric mixture either of (2S,4S)‐ and (2R,4S)‐ or of (2R,4R)‐ and (2S,4R)‐2‐tert‐butyl‐4‐methyl‐3‐(4‐tolyl­sulfon­yl)‐1,3‐oxazolidine‐4‐carbaldehyde. These mixtures were prepared by an aziridination rearrangement process starting with (S)‐ or (R)‐2‐tert‐butyl‐5‐methyl‐4H‐1,3‐dioxine. The crystal structures indicate an envelope conformation of the oxazolidine moiety for both compounds.     

(5Z)‐4‐Amino‐2‐(4‐hydroxyphenyl)‐1H‐imidazol‐5(2H)‐one oxime 3‐oxide

The title molecule, C₉H₁₀N₄O₃, consists of benzene and imidazole rings which are almost perpendicular to each other. A hydroxyimino group is directly linked to the imidazole ring with a double C=N bond, which is the first example in this type of compound. The double bond may be a good location for the initiation of various reactions with a wide range of potential applications. In the crystal structure, there are π–π interactions between molecules related by a centre of symmetry, with the imidazole and benzene rings almost completely overlapped. The molecules are hydrogen bonded in each direction and form a three‐dimensional hydrogen‐bond network.     

4‐Phenyl‐3,5‐bis(2‐pyridyl)‐4H‐1,2,4‐triazole

In the title compound, C₁₈H₁₃N₅, the two pyridyl rings form dihedral angles of 32.7 (2) and 30.1 (2)° with the triazole ring. The most favoured orientation of the pyridyl rings is that with their N atoms on opposite sides of the triazole ring directed towards the phenyl ring. π–π‐Stacking interactions involving pyridyl rings are observed along the a axis at a perpendicular distance of 3.670 (3) Å. This arrangement is further stabilized by weak intermolecular C—H?N hydrogen bonds.     

catena‐Poly[copper(II)‐di‐μ‐acetylacetonato‐copper(II)‐bis(μ‐4‐hydroxy‐3‐methoxybenzaldehyde picoloylhydrazonato)] and (acetylacetonato)(4‐methoxybenzaldehyde picoloylhydrazonato)copper(II)

In the two title copper(II) complexes, [CuL(C₅H₇O₂)]_n, (I), and [CuL′(C₅H₇O₂)], (II), respectively, where HL is 4‐hydroxy‐3‐methoxybenzaldehyde picoloylhydrazone, C₁₄H₁₂N₃O₃, and HL′ is 4‐methoxybenzaldehyde picoloylhydrazone, C₁₄H₁₂N₃O₂, the Cu^II ions display a highly Jahn–Teller‐distorted octahedral and a square‐planar coordination geometry, respectively. In complex (I), two neighbouring Cu^II atoms are bridged by L⁻ and acetylacetonate, alternately, giving rise to a one‐dimensional chain of CuN₂O₄ octahedra interconnected by these two ligands along the a axis. In addition, the hydroxy H atom of the vanillin group connects to the carboxyl O atom of the adjacent chain via an O—H...O hydrogen bond, giving rise to a three‐dimensional supramolecular assembly. Complex (II) displays a discrete structure.     

1,3‐Bis(4‐methyl­phen­yl)triazene, 1‐(4‐chloro­phen­yl)‐3‐(4‐fluoro­phen­yl)triazene and 1‐(4‐fluoro­phen­yl)‐3‐(4‐methyl­phen­yl)triazene

The title 4,4′‐disubstituted diphen­yl‐1,3‐triazines, C₁₄H₁₅N₃, (I), C₁₂H₉ClFN₃, (II), and C₁₃H₁₂FN₃, (III), each contain a triazene group (–N=N—NH–) having an extended conformation. The dihedral angles between the two benzene rings in (I), (II) and (III) are 4.3, 3.4 and 6.5°, respectively. The mol­ecules are almost entirely planar, with maximum deviations from the mean planes of 0.1087 (2), −0.1072 (7) and 0.1401 (3) Å, respectively. In each compound, the molecules are linked by N—H⋯N hydrogen bonds to form chains and pack similarly in the crystal structures.     

3,5‐Bis(4‐methoxy­benzyl­idene)‐1‐methyl‐4‐piperidone and 3,5‐bis(4‐methoxy­benzyl­idene)‐1‐methyl‐4‐oxopiperidinium chloride: potential biophotonic materials

In the title compound 3,5‐bis(4‐methoxy­benzyl­idene)‐1‐methyl‐4‐piperidone, C₂₂H₂₃NO₃, (I), the central heterocyclic ring adopts a flattened boat conformation, while in the related salt 3,5‐bis(4‐methoxy­benzyl­idene)‐1‐methyl‐4‐oxopiperidin­ium chloride, C₂₂H₂₄NO₃⁺·Cl⁻, (II), the ring exhibits a `sofa' conformation in which the N atom deviates from the planar fragment. The pendant benzene rings are twisted from the heterocyclic ring planes in both mol­ecules in the same direction, the range of dihedral angles between the ring planes being 24.5 (2)–32.7 (2)°. The dominant packing motif in (I) involves centrosymmetric dimers bound by weak intermolecular C—H⋯O hydrogen bonds. In (II), cations and anions are linked by strong N—H⋯Cl hydrogen bonds, while weak C—H⋯O and C—H⋯Cl hydrogen bonds link the cations and anions into a three‐dimensional framework.     

Luminescent copoly(aryl ether)s with new electron‐transporting bis(3‐(trifluoromethyl)phenyl)‐1,3,4‐oxadiazole or bis(3‐(trifluoromethyl)phenyl)‐4‐(4‐hexyloxyphenyl)‐4H‐1,2,4‐triazole segments

To investigate the effect of trifluoromethyl groups in enhancing electron affinity of aromatic oxadiazole and triazole chromophores, we prepared four new copoly(aryl ether)s ( P1 – P4 ) consisting of bis(3‐(trifluoromethyl) phenyl)‐1,3,4‐oxadiazole (ETO) or bis(3‐(trifluoromethyl)phenyl)‐4‐(4‐hexyloxyphenyl)‐4H‐1,2,4‐triazole (ETT) segments and hole‐transporting segments [2,5‐distyrylbenzene (HTB) or bis(styryl)fluorine (HTF)]. Molecular spectra (absorption and photoluminescence) and cyclic voltammetry were used to investigate their optical and electrochemical properties. The emissions of P1 – P4 are dominated by the hole‐transporting fluorophores with longer emissive wavelengths around 442–453 nm via efficient excitation energy transfer. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of P1 – P4 , estimated from electrochemical data, are ?5.15, ?5.18, ?5.30, ?5.27, ?3.39, ?3.49, ?3.36, and ?3.48 eV, respectively. The LUMO levels of ETO and ETT segments are significantly reduced to ?3.39～?3.36 eV and ?3.48～?3.49 eV, respectively, as compared with ?2.45 eV of P5 containing a 2,5‐diphenyl‐1,3,4‐oxadiazole segment. Moreover, electron and hole affinity can be enhanced simultaneously by introducing isolated hole‐ and electron‐transporting segments in the backbone. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5900–5910, 2004     

Two (E)‐2‐({[4‐(dialkylamino)phenyl]imino}methyl)‐4‐nitrophenols

The slow evaporation of analytical NMR samples resulted in the formation of crystals of (E)‐2‐({[4‐(dimethylamino)phenyl]imino}methyl)‐4‐nitrophenol, C₁₅H₁₅N₃O₃, (I), and (E)‐2‐({[4‐(diethylamino)phenyl]imino}methyl)‐4‐nitrophenol, C₁₇H₁₉N₃O₃, (II). Despite the small structural difference between these two N‐salicylideneaniline derivatives, they show different space groups and diverse molecular packing. The molecules of both compounds are close to being planar due to an intramolecular O—H...N hydrogen bond. The 4‐alkylamino‐substituted benzene ring is inclined at an angle of 13.44 (19)° in (I) and 2.57 (8)° in (II) with respect to the 4‐nitro‐substituted phenol ring. Only very weak intermolecular π–π stacking and C—H...O interactions were found in these structures.     

NMR studies on 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐aminophenoxy)‐4‐phenyl]‐(2H)phthalazin‐1‐one

An unsymmetrical heterocyclic diamine, 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐aminophenoxy)‐4‐phenyl]‐(2H)phthalazin‐1‐one, was synthesized. Its ¹H and ¹³C NMR spectra were completely assigned by utilizing the two‐dimensional heteronuclear ¹³C–¹H multiple‐bond coherence (HMBC) spectroscopy, and heteronuclear ¹³C–¹H one‐bond correlation spectroscopy, homonuclear shift correlation spectroscopy (H,H‐COSY) and rotating frame Overhauser enhancement spectroscopy (ROESY). The structure of the compound was shown to be the phthalazinone rather than the phthalazine ether from cross peaks and chemical shifts of the protons. Copyright © 2002 John Wiley & Sons, Ltd.     

BF3‐OEt2‐Mediated Rearrangement of (4‐Phenylpiperidin‐4‐Yl)‐Arylmethanols

Synthesis of several 4‐benzhydrylidenepiperidine analogs has been established starting from different (4‐phenylpiperidin‐4‐yl)‐arylmethanols via boron trifluoride etherate mediated rearrangement. The possible rearranged mechanism was proposed. Boron trifluoride etherate‐mediated rearrangement of the related derivatives was also examined. It presents a novel rearrangement reaction catalyzed by boron trifluoride etherate and broadens the scope of application.