2‐[(4‐Hydroxyphenyl)iminomethyl]­thiophene

The molecular structure of the title compound, C₁₁H₉NOS, has three planar moieties, two of which are rings, namely the hydroxy­phenyl and the thio­phene, with an angle of 20.76 (10)° between them. The crystal structure is stabilized by an O—H?N hydrogen bond and by C—H?O intermolecular interactions. The C?O intermolecular contact distance is 3.443 (2) Å.     

6‐Chloro‐2‐oxindole: X‐ray and DFT‐calculated study

The molecule of the title compound (systematic name: 6‐chloroindolin‐2‐one), C₈H₆ClNO, is almost planar, with a dihedral angle of 1.13 (9)° between the planes of the constituent pyrrolidine and benzene rings. Centrosymmetric dimers are formed in the crystal structure by N—H...O hydrogen bonds, and these dimers are additionally linked by Cl...Cl and C—H...O interactions. Density functional theory (DFT) calculations at the B3LYP/6‐31 G(d,p) level of theory were used to optimize the molecular structure and the geometry was best reproduced by optimization of two interacting molecules. The bond orders in the molecule, estimated using the natural bond orbitals (NBO) formalism, are consistent with the observed bond lengths. In particular, the contribution of the lone pair of electrons on the N atom to the N—C bond in the N—C=O group is revealed. The measured IR spectrum of the compound shows a red shift of the N—H stretching frequency compared with the free molecule, due to the formation of the hydrogen bonds.     

(E)‐Methyl 2‐[(2‐fluorophenyl)aminomethylene]‐3‐oxobutanoate: X‐ray and density functional theory (DFT) study

The title compound, C₁₂H₁₂FNO₃, a potential precursor for fluoroquinoline synthesis, is essentially planar, with the most outlying atoms displaced from the best‐plane fit through all non‐H atoms by 0.163 (2) and 0.118 (2) Å. Molecules are arranged in layers oriented parallel to the (011) plane. The arrangement of the molecules in the structure is controlled mainly by electrostatic interactions, as the dipole moment of the molecule is 5.2 D. In addition, the molecules are linked by a weak C—H...O hydrogen bond which gives rise to chains with the base vector [1,1,1]. Electron transfer within the molecule is analysed using natural bond orbital (NBO) analysis. Deviations from the ideal molecular geometry are explained by the concept of non‐equivalent hybrid orbitals.     

X‐ray structure and density functional theory studies of an unexpected product: trans‐bis{2‐[(2‐cyanoethyl)iminomethyl]phenolato}copper(II)

The title compound, [Cu(C₁₀H₉N₂O)₂] or [Cu^II(CYMB)₂], (I), was obtained in an attempt to reduce trans‐bis(2‐{[3,5‐bis(trifluoromethyl)phenyl]iminomethyl}phenolato)copper(II), [Cu(TIMB)₂], (II), with bis(pentamethylcyclopentadienyl)cobalt(II) [decamethylcobaltocene, Cp*₂Co, (III)]. The molecular structure of (I) has the Cu^II centre located on an inversion centre of the C2/c space group. A density functional theory (DFT) analysis at the B3LYP/Lanl2dz(CuF);6‐31G**(CHNO) level performed in order to optimize the structures of the free ligands CYMB⁻ and TIMB⁻, and the metal complexes [Cu^I/II(CYMB)₂]^−/0 and [Cu^I/II(TIMB)₂]^−/0, reproduced well the X‐ray diffraction structure and allowed us to infer the insertion of the cyanomethide anion on the 3,5‐bis(trifluoromethyl)phenyl system from an evaluation of the Mulliken atomic charges and the electronic energies.     

9‐Methyl‐3‐phenyl­diazenyl‐9H‐carbazole: X‐ray and DFT‐calculated structures

The title compound, C₁₉H₁₅N₃, was prepared by condensation of 3‐nitroso­carbazole and aniline with subsequent methyl­ation. The structure is built up of stacks of almost planar mol­ecules. Density functional theory (DFT) calculations predict a completely planar conformation, different from that observed in the crystal lattice. HOMA (harmonic oscillator model of aromaticity) indices, calculated for three aromatic rings, demonstrate the small influence of the azo substituent on π electrons in the carbazole system.     

X‐ray and DFT‐calculated structures of bis[N‐(quinolin‐8‐yl)benzamidato‐κ2N,N′]copper(II)

The application of transition metal chelates as chemotherapeutic agents has the advantage that they can be used as a scaffold around which ligands with DNA recognition elements can be anchored. The facile substitution of these components allows for the DNA recognition and binding properties of the metal chelates to be tuned. Copper is a particularly interesting choice for the development of novel metallodrugs as it is an endogenous metal and is therefore less toxic than other transition metals. The title compound, [Cu(C₁₆H₁₁N₂O)₂], was synthesized by reacting N‐(quinolin‐8‐yl)benzamide and the metal in a 2:1 ratio. Ligand coordination required deprotonation of the amide N—H group and the isolated complex is therefore neutral. The metal ion adopts a flattened tetrahedral coordination geometry with the ligands in a pseudo‐trans configuration. The free rotation afforded by the formal single bond between the amide group and phenyl ring allows the phenyl rings to rotate out‐of‐plane, thus alleviating nonbonded repulsion between the phenyl rings and the quinolyl groups within the complex. Weak C—H…O interactions stabilize a dimer in the solid state. Density functional theory (DFT) simulations at the PBE/6‐311G(dp) level of theory show that the solid‐state structure (C1 symmetry) is 79.33 kJ mol⁻¹ higher in energy than the lowest energy gas‐phase structure (C2 symmetry). Natural bond orbital (NBO) analysis offers an explanation for the formation of the C—H…O interactions in electrostatic terms, but the stabilizing effect is insufficient to support the dimer in the gas phase.     

Sulfonamide‐derived compounds and their transition metal complexes: synthesis,biological evaluation and X‐ray structure of 4‐bromo‐2‐[(E)‐{4‐[(3,4‐dimethylisoxazol‐5 yl)sulfamoyl]phenyl} iminiomethyl] phenolate

Sulfonamide‐derived new ligands, 4‐({[(E)‐(5‐bromo‐2‐hydroxyphenyl)methylidene]‐amino}methyl)benzenesulfonamide and 4‐bromo‐2‐((E)‐{4‐[(3,4‐dimethylisoxazol‐5‐yl)sulfamoyl]phenyl}iminiomethyl)phenolate and their transition metal [cobalt(II), copper(II), nickel(II) and zinc(II)] complexes were synthesized and characterized. The nature of bonding and structure of all the synthesized compounds were deduced from physical (magnetic susceptibility and conductivity measurements), spectral (IR, ¹H and ¹³C NMR, electronic, mass spectrometry) and analytical (CHN analysis) data. The structure of the ligand, 4‐bromo‐2‐((E)‐{4‐[(3,4‐dimethylisoxazol‐5‐yl)sulfamoyl]phenyl} iminiomethyl)phenolate was also determined by X‐ray diffraction method. An octahedral geometry was suggested for all the complexes. In order to evaluate the biological activity of the ligands and the effect of metals, the ligands and their metal complexes were screened for in vitro antibacterial, antifungal and cytotoxic activity. The results of these studies revealed that all compounds showed moderate to significant antibacterial activity against one or more bacterial strains and good antifungal activity against various fungal strains. Copyright © 2011 John Wiley & Sons, Ltd.     

4‐[(2‐Hydroxyethyl)iminomethyl]‐5‐hydroxymethyl‐2‐methylpyridin‐3‐ol

The title compound, C₁₀H₁₄N₂O₃, is a Schiff base which is derived from pyridoxal and represents, therefore, a vitamin B₆‐related compound. Molecules are linked into sheets by a combination of O—H...O and O—H...N hydrogen bonds.     

The synthesis,X‐ray structure analysis,and photophysical characterization of 4‐[(E)‐2‐(4‐cyanophenyl)diazenyl]‐morpholine

A novel triazene, 4‐[(E)‐2‐(4‐cyanophenyl)diazenyl]‐morpholine ( 1 ) was prepared via a diazonium ion coupling reaction between 4‐aminobenzonitrile and morpholine. The x‐ray structure of 1 was determined and evidenced π delocalization in the triazene subunit. The room temperature absorption spectrum of 1 in acetonitrile was dominated by an intense triazene‐centered π→π* transition at 325 nm. Compound 1 was observed to be luminescent, with an emission maximum at 434 nm in room temperature acetonitrile solution. The emission spectrum of 1 in propionitrile glass at 77K exhibited a narrowed emission band with a maximum at 449 nm. Broad emission from 400–700 nm with poorly resolved vibrational structure was observed from solid 1 at room temperature. J. Heterocyclic Chem., 2011.     

The Synthesis,X‐ray Structure Analysis,and Photophysical Characterization of 4‐[(E)‐2‐(4‐Carboxyphenyl)diazenyl]‐morpholine

4‐[(E)‐2‐(4‐Carboxyphenyl)diazenyl]‐morpholine ( 1 ) was prepared in 33% yield from a coupling reaction between morpholine and the diazonium ion formed from 4‐aminobenzoic acid. X‐ray structural analysis of 1 yielded two important insights into its structure: the geometry of the N―N double bond and the partial delocalization across the linear triazene moiety. The absorption spectra of 1 in dilute acetonitrile and 2‐methyltetrahydrofuran solutions both featured an intense (ε ≈ 20,000 M^?1cm^?1) band centered at 320–324 nm that was assigned as a mixture of π → π* and n → π* transitions. Emission was observed at 383 and 379 nm from dilute acetonitrile and 2‐methyltetrahydrofuran solutions of 1 , respectively, with the latter being red‐shifted to 439 nm at 77 K. Emission lifetime data for compound 1 provided evidence that the emission was a mixture of two excited state transitions.     

Substituent effects in trans‐p,p′‐disubstituted azobenzenes: X‐ray structures at 100 K and DFT‐calculated structures

The crystal and molecular structures of two para‐substituted azobenzenes with π‐electron‐donating –NEt₂ and π‐electron‐withdrawing –COOEt groups are reported, along with the effects of the substituents on the aromaticity of the benzene ring. The deformation of the aromatic ring around the –NEt₂ group in N,N,N′,N′‐tetraethyl‐4,4′‐(diazenediyl)dianiline, C₂₀H₂₈N₄, (I), may be caused by steric hindrance and the π‐electron‐donating effects of the amine group. In this structure, one of the amine N atoms demonstrates clear sp²‐hybridization and the other is slightly shifted from the plane of the surrounding atoms. The molecule of the second azobenzene, diethyl 4,4′‐(diazenediyl)dibenzoate, C₁₈H₁₈N₂O₄, (II), lies on a crystallographic inversion centre. Its geometry is normal and comparable with homologous compounds. Density functional theory (DFT) calculations were performed to analyse the changes in the geometry of the studied compounds in the crystalline state and for the isolated molecules. The most significant changes are observed in the values of the N=N—C—C torsion angles, which for the isolated molecules are close to 0.0°. The HOMA (harmonic oscillator model of aromaticity) index, calculated for the benzene ring, demonstrates a slight decrease of the aromaticity in (I) and no substantial changes in (II).     

2‐[N‐(X‐Chlorophenyl)carbamoyl]benzenesulfonamide (with X = 2 and 4)

The structures of 2‐[N‐(2‐chlorophenyl)carbamoyl]benzenesulfonamide and 2‐[N‐(4‐chlorophenyl)carbamoyl]benzenesulfonamide, both C₁₃H₁₁ClN₂O₃S, are stabilized by extensive intra‐ and intermolecular hydrogen bonds. In both structures, sulfonamide groups are hydrogen bonded via the N and O atoms and form chains of molecules. The carbamoyl groups are also hydrogen bonded, involving the O and N atoms, further strengthening the polymeric chains running along the c and a axes in the 2‐ and 4‐chloro derivatives, respectively. Carbamoylsulfonamide derivatives are novel compounds with a great potential for medicinal applications.     

An improved synthesis of 2‐amino‐5‐[(4‐chlorophenyl)thio]‐4‐morpholinopyrimidine (BW 394U) — A potential antisenility agent

This paper describes the synthesis of 2‐amino‐5‐[(4‐chlorophenyl)thio]‐4‐morpholinopyrimidine (BW 394U, compound 4 ), a potential antisenility agent. The key intermediates 3a/3b were obtained from an in situ‐generated Vilsmeier‐Haack reagent that simultaneously protected the 2‐amino group prior to further manipulations. Displacement of the chloro group in 3a gave 4 in 40% yield and 4‐dimethylamino analogue 5. However, displacement of 3b with morpholine followed by treatment with aqueous base gave 4 in 74% yield.     

Synthesis and single crystal X‐ray determination of the Schiff base 1‐[(2‐isopropyl‐5‐methylphenoxy)hydrazono] ethyl ferrocene

The reaction of acetylferrocene [Fe(η‐C₅H₅)(η‐C₅H₄COCH₃)] (1) with (2‐isopropyl‐5‐methylphenoxy) acetic acid hydrazide [CH₃C₆H₃CH(CH₃)₂OCH₂CONHNH₂] (2) in refluxing ethanol gives the stable light‐orange–brown Schiff base 1‐[(2‐isopropyl‐5‐methylphenoxy)hydrazono] ethyl ferrocene, [CH₃C₆H₃CH(CH₃)₂OCH₂CONHN?C(CH₃)Fe(η‐C₅H₅)(η‐C₅H₄)] (3). Complex 3 has been characterized by elemental analysis, IR, ¹H NMR and single crystal X‐ray diffraction study. It crystallizes in the monoclinic space group P2₁/n, with a = 9.6965(15), b = 7.4991(12), c = 29.698(7) Å, β = 99.010(13) °, V = 2132.8(7) ų, D_calc = 1.346 Mg m^?3; absorption coefficient, 0.729 mm^?1. The crystal structure clearly shows the characteristic [N? H···O] hydrogen bonding between the two adjacent molecules of 3. This acts as a bidentale ligand, which, on treatment with [Ru(CO)₂Cl₂] _n, gives a stable bimetallic yellow–orange complex (4). Copyright © 2002 John Wiley & Sons, Ltd.     

4‐(2,5‐Dioxo‐2,5‐dihydro‐1H‐pyrrol‐1‐yl)benzoic acid: X‐ray and DFT‐calculated structure

In the title compound, C₁₁H₇NO₄, there is a dihedral angle of 45.80 (7)° between the planes of the benzene and maleimide rings. The presence of O—H...O hydrogen bonding and weak C—H...O interactions allows the formation of R₃³(19) edge‐connected rings parallel to the (010) plane. Structural, spectroscopic and theoretical studies were carried out. Density functional theory (DFT) optimized structures at the B3LYP/6–311 G(d,p) and 6–31++G(d,p) levels are compared with the experimentally determined molecular structure in the solid state. Additional IR and UV theoretical studies allowed the presence of functional groups and the transition bands of the system to be identified.     

Density functional computational studies on 2‐[(2,4‐Dimethylphenyl)iminomethyl]‐3,5‐dimethoxyphenol

Density functional calculations of the structure, molecular electrostatic potential, and thermodynamic functions have been performed at B3LYP/6‐31G(d) level of theory for the title compound of 2‐[(2,4‐dimethylphenyl)iminomethyl]‐3,5‐dimethoxyphenol ( I ). To investigate the tautomeric stability, optimization calculations at B3LYP/6‐31G(d) level were performed for the enol and keto forms of I . Calculated results reveal that the enol form of I is more stable than its keto form. The predicted nonlinear optical properties of I are much greater than ones of urea. The changes of thermodynamic properties for the formation of the title compound with the temperature ranging from 200 to 500 K have been obtained using the statistical thermodynamic method. At 298.15 K, the change of Gibbs free energy for the formation reaction of I is 32.973 kJ/mol. The title compound can not be spontaneously produced from the isolated monomers at room temperature. The tautomeric equilibrium constant is computed as 0.868 at 298.15 K for enol‐imine?keto‐amine tautomerization of I . In addition, natural bond orbital analysis of I was performed using the B3LYP/6‐31G(d) method. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

Two isomorphous azastilbene derivatives: 1‐(2‐chlorobenzyl)‐4‐[(E)‐2‐(4‐hydroxyphenyl)ethenyl]pyridinium chloride and 1‐(2‐bromobenzyl)‐4‐[(E)‐2‐(4‐hydroxyphenyl)ethenyl]pyridinium bromide

The crystal structures of the two title (E)‐stilbazolium halogenates, C₂₀H₁₇ClNO⁺·Cl⁻ and C₂₀H₁₇BrNO⁺·Br⁻, are isomorphous, with an isostructurality index of 0.985. The azastyryl fragments are almost planar, with dihedral angles between the benzene and pyridine rings of ca 4.5°. The rings of the benzyl groups are, in turn, almost perpendicular to the azastyryl planes, with dihedral angles larger than 80°. The cations and anions are connected by O—H...X⁻ (X = halogen) hydrogen bonds. The halide anions are `sandwiched' between the charged pyridinium rings of neighbouring molecules, and weak C—H...O hydrogen bonds and C—H...X and C—H...π interactions also contribute to the crystal structures.     

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.