The crystal structure of a novel product from the acid-catalyzed condensation of 1-benzylindole with acetone

The acid-catalyzed condensation of 1-benzylindole with acetone in the presence of N-phenylmaleimide gave a tetrahydrocarbazole, (4,5,10,10b-tetrahydro-5-methyl-2-phenyl-10-(phenylmethyl)pyrrolo[3,4-a]carbazole-1,3[2H, 3aH]-dione (1), as the major product and a novel spiro compound, 1,3,4,4-tetrahydro-1,1,3,3-tetramethyl-4,4-bis(phenylmethyl)-1,3(2H, 2H)-spiro[cyclopent[b]indole] (2), as the minor product. The structure of the spiro compound was determined by an X-ray crystallographic determination. The acid-catalyzed condensation of 1-benzylindole with acetone in the absence of N-phenylmaleimide gave a bisindole, (1,1-bis(phenylmethyl)-3,3-(1-methylethylidene)diindole (3), as the major product and the spiro-compound as the minor product.     

Crystal structure and electrochemical behavior of a novel polyoxometalate [Ni(bpy)3]2[W4V2O19] with Lindqvist‐type structure

A novel polyoxometalate [Ni(bpy)₃]₂[W₄V₂O₁₉] (Ni₂V₂W₄) has been synthesized by the hydrothermal method and the structure determined by X‐ray crystallography. Ni₂V₂W₄ crystallizes in a trigonal system with space group R ‐3c (a = 15.8984 (5) Å, b = 15.8984 (5) Å, c = 43.855 (3) Å). In the structure of the compound, terminal and bridging oxygen atoms are bond to the metal centers by σ or π bonds. The W⁶⁺ and V⁵⁺ ions in isopolyanion [W₄V₂O₁₉]^4‐ statistically distribute over the six metal centers. Using cathodic adsorptive voltammetric method with a carbon paste electrode, the redox property and the electron transferring process were studied. The results show that electrochemical behavior about W(VI) and V(V) atoms give one‐electron, three‐electron and two‐electron reduction waves. Three successive oxidation waves are observed too. The compound was also characterized by thermal gravimetric analysis and IR spectra. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A novel approach for the fabrication of planar waveguides from heavy metal oxide glasses

An extrusion process is used to fabricate preforms for the development of planar waveguides in glass ribbon format through a stretching process. The feasibility of the overall process is demonstrated using three tellurite glass compositions. The manufactured preforms present multilayered structures with the higher refractive glass layer thickness of the order of 40 μm. The longitudinal and transversal variations of the layer thicknesses are discussed with respect to waveguiding application tolerances. Advantages, limitations and improvement of the technique are also discussed. 3 mm wide multilayered planar waveguides in ribbon geometry are produced by stretching the preforms by a 1:5 ratio over a length of 400 mm. The waveguides were examined by optical and electron microscopy and no signs of crystallization or contamination are observed. Optical waveguiding is successfully assessed in 7.4 μm thick and 9 mm long film waveguides.     

Chemistry of diaminomaleonitrile: synthesis and structure of two unexpected products from its condensation with 2,5-hexanedione

For the synthesis of precursors to cellulose-based ion exchange materials, the condensation of diaminomaleonitrile with 2,4-pentanedione and 2,5-hexanedione was explored. Whilst the former diketone yielded the expected 1,4-diazepine (2), the latter gave either a pyrrole derivative (3) or an unusual triazabicyclononene (4), depending on the conditions used. Compound 2 crystallizes in the monoclinic space group P2₁/c with a = 8.9313(10) Å, b = 9.0370(7) Å, c = 11.4448(9) Å, = 102.48(8)°, V = 901.89(14) ų, and Z = 4. Compound 3 crystallizes in the orthorhombic space group Pna2₁ with a = 12.0342(8) Å, b = 8.3760(8) Å, c = 10.7026(11) Å, V = 1078.81(17) ų, and Z = 4. Compound 4 crystallizes in the monoclinic space group P2₁/c with a = 9.0157(5) Å, b = 13.5374(9) Å, c = 12.8751(16) Å, = 99.506(5)°, V = 1549.82(15) ų, and Z = 4. In both 3 and 4 the aminovinyl substituent shows evidence for involvement of the lone pair on nitrogen with the carbon -system. Also, 3 and 4 are highly associated in the solid state via hydrogen bonding.     

Hydrogen Adsorption of Alkali Metal Complexes of Polycyclic Aromatic Hydrocarbon and Graphite,and Their Solid State Properties

The hydrogen adsorption in alkali metal complexes of graphite and triphenylene has been investigated by means of ESR and electrical resistivity under hydrogen atmosphere. In the first stage graphite compound C₈Rb, hydrogen molecules are dissociated into atoms which are stabilized in graphite gaps. C⁸K has a two stage hydrogen adsorption process: dissociation and charge transfer. For C₈Cs, the catalytic activity for hydrogen comes from the surface. The second stage compounds C₂₄M (M=K, Rb, and Cs) show weaker activities for hydrogen than the first stage ones. Triphenylene-potassium complex has a two stage process for hydrogen adsorption.     

Knoevenagel condensation of the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopentene-1,3-dione with 9-anthracenecarboxaldehyde: Synthesis of the second-generation ligand 2-(anthracen-9-ylidene)-4,5-bis(diphenylphosphino)-4-cyclopentene-1,3-dione

The Knoevenangel condensation between 9-anthracenecarboxaldehyde and the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopentene-1,3-dione (bpcd) takes place rapidly in CH₂Cl₂/MeOH solution in the presence of molecular sieves (4 ?) to produce the functionalized ligand 2-(anthracen-9-ylidene)-4,5-bis(diphenylphosphino)-4-cyclopentene-1,3-dione. The title compound has been isolated and characterized in solution by IR, NMR, and UV-vis spectroscopies, and the solid-state structure has been established by X-ray diffraction analysis. 2-(anthracen-9-ylidene)-4,5-bis(diphenylphosphino)-4-cyclopentene-1,3-dione crystallizes in the triclinic space group P−1, a=10.227(2) ?, b=13.865(2) ?, c=15.905(2) ?, α=112.157(2)°, β=101.424(2)°, γ=100.065(3)°, V=1968.5(5) ?³, Z=2, and d _calc=1.101 Mg/m³; R=0.0873, R _w=0.2604 for 7452 reflections with I>2σ(I). The cyclic voltammetric behavior for 2-(anthracen-9-ylidene)-4,5-bis(diphenylphosphino)-4-cyclopentene-1,3-dione has been studied, and the observed redox data and results from extended Hückel MO calculations are discussed relative to the parent ligand bpcd.

X-ray diffraction and self condensation reaction of thionicotinamide S-oxide

Thiobenzamide and thionicotnamide S-oxide were prepared as intermediates in the dimerization of corresponding thioamides to 1,2,4-thiadiazoles and the X-ray crystal structure of thionicotinamide S-oxide water solvate was determined. Crystals belong to orthorhombic Pbca space group with a = 14.129(3), b = 7.299(2), c = 15.277(3)Å, and Z = 8. The geometry of the molecule accords well with that found in similar compounds; an intramolecular N–H···O hydrogen bond is present, while the packing is mainly determined by the hydrogen bond system involving the water molecule and the side-chain of the organic molecule. The contacts between pyridine moieties, stacked along the [010] axis, complete the packing.     

Effects of the Anthraquinone Dye on the Electro-Optical Properties of Dye Guest-Host Polymer Dispersed Ferroelectric Liquid Crystal

Abstract

The effects of the anthraquinone dye on the electro-optical characteristics of DGHPDFLC have been investigated. The results show that PDFLC doped with dichroic dye was found to have no influence on phase separation. When dye concentration is over M483-1.0%, it causes the response time of DGHPDFLC to become slower, the frequency becomes dependent, the rotational viscosity increases, and the tilt angle becomes lower, but, on the whole, electro-optical properties are still very practical.     

The effect of photo-irradiation in hydrolysis and condensation of silicon alkoxide

A silicon alkoxide-water-ethanol mixed solution was irradiated with ultraviolet rays, and the change of the silicon alkoxide molecular structure was evaluated by ²⁹Si nuclear magnetic resonance and Fourier transform infrared spectroscopies. Silicon alkoxide was hydrolyzed and the Si-OH bonds were produced by UV irradiation without any chemical catalyst for hydrolysis. The Si-O-Si bonds were also produced, and viscosity of the alkoxide solution became higher due to condensation of alkoxide.     

Synthesis, redox properties, and molecular structure of 4,5-diethylthio-4-cyclopenten-1,3-dione: Cyclic voltammetric evidence for a kinetically stable radical anion

The preparation of the new disulfide compound 4,5-diethylthio-4-cyclopenten-l,3-dione (1) from 4,5-dichloro- 4-cyclopenten-l,3-dione and ethanethiol is described. The title compound has been isolated and characterized in solution by IR and NMR spectroscopies, and the solid-state structure solved by X-ray crystallography. 4,5-Diethylthio-4-cyclopenten-l,3-dione crystallizes in the triclinic space group P-l, a = 7.230(4) Å, b = 8.191(5) Å, c = 10.187(6) Å, α = 108.48(1)°, β = 97.75(1)°, γ = 105.90(1)°, V = 533.8(6) ų, Z = 2, and d _calc = 1.346 Mg/m³; R = 0.0406, R _w = 0.0967 for 1394 reflections with I > 2σ(I). The redox properties of 4,5-diethylthio-4-cyclopenten-l,3-dione have been examined by cyclic voltammetry in CH₂C1₂ solution, where a reversible one-electron reduction was found. The reduction behavior of the diethylthio derivative is discussed relative to the closely related 4,5-bis(p-tolylthio)-4-cyclopenten-l,3-dione, whose radical anion exhibits quasi-reversible reduction behavior due to competitive C(dione ring)–S bond cleavage. The differences in the electrochemical behavior of the two disulfides are discussed with respect to the ancillary R group.     

Preparation of low-density xerogels from mixtures of TEOS with substituted alkoxysilanes. I. O NMR study of the hydrolysis–condensation process

Low-density xerogels were synthesised by incorporation of an additive to base catalysed tetraethylorthosilicate (TEOS) alcogels directly during the preparation of the sol. The nucleation mechanism by the additive was established by experiments during sol–gel transition. ¹⁷O NMR spectroscopy on TEOS–ethanol–water, 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS)–ethanol–water and EDAS–TEOS–ethanol–water solutions shows that the hydrolysis–condensation of EDAS is much faster than that of TEOS. Consequently it can be assumed that EDAS forms nuclei, onto which TEOS condenses later to form the silica particles.     

A novel sonochemical synthesis and nanostructured assembly of polyvinylpyrrolidone-capped CdS colloidal nanoparticles

Nanoparticles of cadmium sulfide (nano-CdS) have been successfully prepared from an aqueous solution of cadmium chloride and sodium sulfide by a novel sonochemical method. Through adding polyvinylpyrrolidone K30 (PVP) as the dispersant, a yellow translucent colloidal solution of cadmium sulfide which was considerably stable within at least one month was obtained. The characterizations of nanoparticles by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM) and FT-IR spectroscopy showed good properties of small size, high surface area and crystal structure. The size of the prepared nanoparticles was about 3–5 nm according to XRD spectra and TEM images. Poly(diallyldimethylammonium chloride) (PDDA) has been employed to fabricate multilayer films on quartz wafer and indium tin oxide (ITO) electrode in a layer-by-layer manner. Atomic force microscopy (AFM) displayed the dense coverage of the substrate surface by the nanoparticles. UV–vis absorption spectroscopy confirmed the consecutive growth of PDDA/nanoparticles layer pairs. The photoelectrochemical and the electrochemical behaviors of the prepared CdS particle were examined as well.     

A novel four-coordinate zinc(II) complex of the di-N-hydroxypropylated tetraaza macrocycle

The compound [Zn(L²)Cl]ClO₄·H₂O (1) (L² = 2,13,-bis(3-hydroxypropyl)-5,16-di-methyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane) has been synthesized and structurally characterized. 1 crystallizes in the monoclinic system, space group P2₁/c with a = 8.932(2), b = 16.189(2), c = 22.492(4) Å = 95.34(2)° V = 3238.3(11) ų; and Z = 4. The zinc atom is placed in a highly distorted tetrahedral environment bonding with three nitrogen atoms of the macrocycle and one chlorine atom.     

Low temperature deposition of zinc oxide nanoparticles via zinc-rich vapor phase transport and condensation

ZnO nanoparticles as small as 80 nm were successfully synthesized using a modified vapor phase transport (VPT) process at substrate temperatures as low as 222 °C. Particle size distribution and morphology were characterized by scanning electron microscopy and atomic force microscopy. Energy dispersive X-ray spectroscopy and X-ray diffraction indicate the synthesis of high quality crystalline ZnO structures. Low temperature (4.2 K) photoluminescence (PL) spectroscopy was used to characterize the optical quality of the nanoparticles. Ultraviolet emission and a nanostructure specific feature at 3.366 eV are strong in the PL spectra. The 3.366 eV feature is observed to predominate the spectrum with decrease in particle size. This size effect corroborates the luminescence as a nanostructure-specific surface related exciton feature as previously speculated in the literature. In addition, self-assembled ZnO mesoparticles (>100 nm) were realized by increasing the growth time. Low growth temperatures of the particles allow for their potential utilization in flexible organic hybrid optoelectronics. However, this work focuses mainly on the modified synthesis and optical characterization of nanoparticles.     

A novel technique to reduce the concentration of carbon in LEC gallium arsenide

An in-situ method has been developed to reduce the concentration of carbon in the liquid encapsulated growth of gallium arsenide. Sublimated As₂O₃ was bubbled through a GaAs melt to remove carbon via the production of CO₂. When a melt of known high starting carbon concentration ( 30 × 10¹⁴ atoms/cm³) was bubbled with As₂O₃, the subsequent crystal contained 4 × 10 ¹⁴ carbon atoms/cm³. This low carbon crystal was subsequently carbon doped and regrown, demonstrating the ability to return As₂O₃ treated GaAs to desired carbon concentrations and electrical properties.     

A novel sol-gel method for the synthesis of γ-aluminium oxide: development of the sol-gel transformation and characterization of the xerogel

A novel method for the synthesis of aluminium oxide gel has been developed, whereby the sol-gel transformation was investigated. Aluminium tri-sec-butoxide was used as precursor while acetone was chosen as solvent. The synthesis was carried out in a special reactor, which allowed the dosing of steam. ²⁷Al NMR spectroscopy showed that during the sol-gel process the signal at δ∼3 ppm increases strongly corresponding to the formation of hexacoordinated aluminium species. Beside hydrolysis and condensation reactions, the coordination of acetone to a strong Lewis acid aluminium site occurs, which was shown by FTIR and ²⁷Al NMR spectroscopy. Viscosimetric analysis showed that at the beginning of the sol-gel process short polymers are observed while before the gelation a three-dimensional polymer network is formed. After pyrolyzing the gel a high surface area γ-aluminium oxide xerogel was formed. The effect of heating on the morphology and structure was examined by nitrogen physisorption (BET and pore size distribution), XRD and ²⁷Al MAS NMR spectroscopy.     

Growth of benzophenone single crystals from solution: A novel approach with 100% solute ‐ crystal conversion efficiency

An unidirectional 60mm diameter benzophenone single crystal was successfully grown by utilizing a novel crystal growth method at room temperature. <110> oriented single crystal ingots were grown out of xylene as solvent and by fixing a seed at the bottom of the ampoule. The obtained benzophenone ingots with the sizes of 10mm, 25mm and 60mm diameter evident that ease in increasing the diameter of the ingot. The orientation of the ingot and the crystalline quality were justified by X‐ray studies. TG and DTA evaluated the thermal properties of the grown crystal. The optical transmission study and the powder SHG measurement show the suitability of the ingot for nonlinear optical applications. The achieved solute‐crystal conversion efficiency of hundred percent shows vital advantage of this technique for cost effectiveness. The microbial growth as in the case of amino acid based growth solutions can be more effectively controlled in the present method since the freshly prepared growth solution can be constantly made available to the growing crystal. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim     

A novel approach for the synthesis of monodispersed porous silica microspheres with high surface area

Monodispersed porous silica microspheres are synthesized by the hydrolysis and condensation of tetraethoxysilane (TEOS) in a water–ethanol mixed solution containing 1-alkylamine as a template and hydrolysis catalyst. The as-prepared products were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), small angle X-ray diffraction (SAXRD), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption, respectively. It was found that the alkyl chain length of 1-alkylamine and calcination temperature have an obvious influence on the particle size, morphology, specific surface area and pore structure of the as-prepared silica powder. The specific surface area, porosity and pore volume increased with increasing calcination temperature. Further observation showed that at 600 °C, with increasing the alkyl chain length of template from C₁₂ to C₁₈, the specific surface area decreased and the pore size, porosity and pore volume increased. This research may provide new insight into the control of morphology and pore structures of oxide materials.     

A novel method of temperature control for a crystal growth puller

A facile method to control the contracting rate of the thermal expansible bars for pulling crystal is first suggested. The thermal expansible bars, set in a modified Dewar flask whose vacuum degree is controlled, are heated to designed temperature and then switch off the power to let it cool down at a desired rate, which depends largely on the changeable vacuum degree. This new approach is expected to completely eliminate the effects, which possibly reduces the smooth extent of thermal expansion, caused by the minor temperature fluctuations during crystal growth process and to realize the utmost smooth and slow pulling rate. It is expected to install this apparatus in optical floating zone furnace, instead of traditional motor, to grow peritectic crystal, such as crystal Bi‐2223, since for the peritectic reaction, in principle, the extremely slow growing rate is considerably essential.