Synthesis and crystal structure determination of 6,7‐dihydro‐2‐methoxy‐4‐(substituted)‐5H ‐benzo[6,7]cyclohepta[1,2‐b ]pyridine‐3‐carbonitrile

The compounds 6,7‐dihydro‐2‐methoxy‐4‐(4‐methylphenyl)‐5H ‐benzo[6.7]cyclohepta[1,2‐b ]pyridine‐3‐carbonitrile (compound IIIa) and 4‐(4‐chlorophenyl)‐6,7‐dihydro‐2‐methoxy‐5H ‐benzo[6,7]cyclohepta[1,2‐b ]pyridine‐3‐carbonitrile (compound IIIb) were synthesized and their structures have been determined from three dimensional X‐ray data using direct method and refined by full matrix least squares with anisotropic thermal parameters for non‐hydrogen atoms to conventional R(gt) of 0.036 and 0.038 for the two compounds respectively. For compound (IIIa) the crystals are monoclinic, space group C_c, with a=11.2909 (5) Å, b=17.7755(8) Å, c=9.1437(4) Å and β=95.428(3)°, while the crystals of the second compound (IIIb) are triclinic, space group P1, with a=8.7465(3)Å, b=10.3958(3)Å, c=10.9011(4)Å, α= 108.3870(10)°, β=101.3741(12)°, γ=97.9594(12)°. The molecular structure of the two compounds have nearly the same configuration, where the cyclohepta ring takes the boat shape and the methoxy and the carbonitrile groups are attached at the same position C₂ and C₈. The difference occurs only at the position C₄, where the substituent is methylphenyl for compound (IIIa) and chlorophenyl for the other. The bond lengths, valency angles and the hydrogen bonding were calculated and fully discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

3 β ‐Acetoxy‐5 α ‐cholestan‐6‐one: A Steroid

The crystal and molecular structure of 3 β ‐Acetoxy‐5 α ‐cholestan‐6‐one has been determined by X‐ray crystallographic techniques. The compound crystallizes in the space group P2₁ with cell parameters : a = 13.060(3), b=6.299(2), c=17.152(6)Å; β =96.47(3)o, V = 1402.02ų, Z = 2, R = 0.072 for 1921 observed reflections. The six‐membered rings (A, B and C) exist in the chair conformations while the five‐membered ring‐d assumes half‐chair. All rings of the steroid skeleton are trans connected.     

Crystallographic Investigations of 3β‐acetoxy‐5α‐cholestan‐6‐one‐semicarbazone ‐ A Steroid

The crystal structure of 3b‐acetoxy‐5a‐cholestan‐6‐one‐semicarbazone (C₃₀H₅₁O₃N₃) has been determined by X‐ray diffraction methods. It crystallizes in the orthorhombic space group P2₁2₁2₁ with cell parameters a = 11.641(1), b = 16.552(1) c = 31.181(4) Å and Z = 8. The structure has been refined to an R‐value of 0.050 for 4407 observed reflections. Two molecules in the asymmetric unit have been observed. In both the crystallographically independent molecules, all the three six‐membered rings (A, B and C ) of steroid nucleus exist in chair conformation, while the five‐ membered ring D exists in 13β distorted‐envelope in molecule‐I and 13β, 14α half‐chair conformation in molecule‐II. Three intermolecular N‐H … O hydrogen bonds have been observed.     

The Crystal and Molecular Structure of tert‐Butoxycarbonyl ‐ α‐aminoisobutyryl ‐ isoleucyl ‐methylester

The crystal structure of the synthetic peptide Boc — Aib — Ile ‐ OMe (C₁₆ H₃ 0 N₂ O₅ ) has been determined from three‐dimensional X — ray diffraction data. The peptide crystallizes in triclinic space group P1 with a = 9.570(9), b = 10.261(7), c = 10.610(2) Å , α = 101.9(0), β = 91.7(0), γ = 98.6(0)° V = 1006.1(12) ų, Z = 2, D_calc = 1.09 Mg m^‐3. The structure was solved by direct methods and refined by full‐matrix least‐squares method to an R value of 0.072 (λ = 1.5418Å). The conformation of Aib residue in molecule A is αL and in molecule B is αR. The Ile residue in molecule A adopts folded conformation, while in molecule B it is in the extended region. The peptide units are trans and show significant deviations from planarity.     

Synthesis and characterization of 4,4′‐dihydroxy‐α‐methylstilbene crystal

4,4′‐dihydroxy‐α‐methylstilbene (DHAMS) was synthesized by condensation reaction with chloroacetone and phenol in the presence of concentrated sulfuric acid, and has been successfully grown by solution growth technique. This is the first report in the literature on the crystallization of DHAMS and exhibited the birefringent melt (liquid crystal property) of the optical properties. FTIR and FTNMR studies are in accordance with the structure. Good quality crystals were grown by slow evaporation technique by acetone as solvent. A transmission spectrum of the crystal was obtained in the region of 285 nm. The structural and optical properties were studied. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of 2,6‐dibenzylidenecyclohexanone single crystal

Following the temperature reduction method, growth of single crystals of organic 2,6‐dibenzylidenecyclohexanone (DBCH) material from ethanol solution is reported in the present work. Solubility and metastable zone width measurements were carried out under stirring and nonstirring conditions of solution. Cell dimensions were obtained from single crystal X‐ray diffraction study. From FT‐IR spectral analysis, various functional groups of this crystal were identified. UV‐Visible spectral analysis was made. Mechanical strength of the grown crystal was estimated on the prominent (110) face using a Vickers microhardness tester. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal structure of 17α‐acetoxyprogesterone,C23H32O4

The crystal structure of the title compound (C₂₃H₃₂O₄) has been determined by X‐ray diffraction methods. It crystallizes in the orthorhombic space group P2₁2₁2₁ with cell parameters: a = 10.86(1), b = 11.95(2), c = 15.65(5) Å and Z = 4. The structure has been refined to an R‐value of 0.045 for 1610 observed reflections. Ring A exists in sofa conformation, Ring B adopts a distorted chair conformation while as Ring C assumes a chair conformation. The five membered ring D adopts a half‐chair conformation. The crystal structure is stabilized by intra‐ and intermolecular C‐H…O interactions. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystallographic Analysis of Acetyl β ‐boswellic acid

The crystal structure of the title compound (3 α ‐acetoxy‐urs‐12‐en‐24‐oic acid, C₃₂H₅₀O₄) has been determined by X‐ray crystallographic techniques. The compound crystallizes into orthorhombic space group P2₁2₁2₁ with unit cell parameters : a = 12.773(2), b=16.381(4), c=27.929(7)Å. The structure has been solved by direct methods and refined to R = 0.054 for 4930 observed reflections. The structure contains two crystallographically independent molecules in the asymmetric unit which are almost identical in geometry. Rings A, B, D and E have chair conformations while ring C assumes a sofa conformation in both the molecules. The molecules in the structure are linked together by intra‐ and intermolecular O‐H…= and C‐H…O hydrogen bonds.     

Growth and characterization of 4‐(2‐hydroxyphenylamino)‐pent‐3‐en‐2‐one single crystals

4‐(2‐hydroxyphenylamino)‐pent‐3‐en‐2‐one (HPAP) was synthesized and single crystals were grown by the solution growth technique using methanol as a solvent. The crystals having orthorhombic symmetry were characterized by single crystal XRD, FTIR spectroscopy, NMR spectroscopy, TGA, DSC and dielectric studies. Very less variation in the value of dielectric constant is found for different frequencies of applied field. The crystals were exhibiting positive photoconductivity and poor NLO responses. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,bulk growth,polarizability and nonlinear optical properties of γ‐glycine single crystals

The role of sodium acetate, sodium nitrate, sodium hydroxide and malonic acid as additives in assisting the nucleation of γ‐polymorph from solution has been investigated. For the first time large dimensional bulk single crystals of γ‐glycine have been grown at the optimized concentration of the additives by the top seeded slow cooling technique. The bulk growth of single crystals elucidates well the unidirectional growth characteristics and the existence of merohedral twinning in γ‐ glycine. Polarizability, plasmon energy and Fermi energy has been evaluated for the first time for γ‐glycine single crystals based on an analytical approach. Structural affirmation of the nucleated polymorph has been carried out by Powder x‐ray diffraction and the thermal characteristics of the nucleated polymorph are well revealed by Differential Scanning Calorimetry. The non linear optical characteristics of γ‐glycine studied by Kurtz and Perry technique revealed increased SHG efficiency with the highest of about 2.2 in the presence of malonic acid compared to the standard Potassium dihydrogen orthophosphate (KDP).     

Crystal Structure Analysis of 1′,2′,3′,4′‐tetrahydro‐1,3‐diphenyl‐4‐chlorospiro[2‐pyrazoline‐5,2‐napthalen]1′one

The crystal structure of the title compound “1′,2′,3′,4′‐tetrahydro‐1,3‐diphenyl‐4‐chlorospiro[2‐pyrazoline‐5,2‐napthalen] 1′one” has been determined. The structure consists of a pyrazoline ring, three aromatic rings and a tetralone moiety. All the aromatic rings are planar while the cyclohexonone ring of the tetralone moiety is in the distorted sofa conformation. The molecular packing is stabilized by C‐H…O and C‐H…π type inter molecular interactions.     

The crystal structure of α‐SrGaBO4

A new compound α‐SrGaBO₄ has been synthesized by solid state reaction at high temperatures, and its structure has been solved by direct methods from powder X‐ray diffraction. α‐SrGaBO₄ has an orthorhombic system, Pccn space group, with lattice parameters a = 15.3154(7) Å, b = 8.9186(4) Å, c = 5.8130(3) Å, and Z = 8. The structure consists of infinite chains run parallel to the c axis and built up of GaO₄ tetrahedral and BO₃ triangles. The basic unit of these chains is a six ‐ membered Ga₂BO₈ ring formed by two GaO₄ tetrahedra and one BO₃ triangles. The Sr atom is bonded to eight oxygen atoms. The strontium atoms serve to hold the chains together through co‐ordination with oxygen atoms. DTA curve of noncrystalline glassy SrGaBO₄ was discussed. The XRD results show no phase transition occurs between ‐173 °C and 127 °C. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Nano‐sized silver crystals and their dispersion over α‐alumina for ethylene epoxidation

Ethylene oxide catalyst is a high metal loading catalyst, in which silver crystals is impregnated on α‐Al₂O₃ support. In this type of catalyst, metal dispersion plays an important role on catalyst selectivity for desired products. In this work, silver nitrate and silver oxide together with oxalic and lactic acid as the raw materials were used with different impregnation techniques to make catalysts with high silver content and dispersion. It is also known that the use of promoters affect the metal dispersion on the catalyst support and for that cesium was used as the promoter to improve the silver crystal dispersion. Physical and chemical characteristics of the prepared catalysts, i.e., surface area, pore volume, silver content, nano‐sized silver crystals and their dispersion were measured using BET method, Atomic Absorption Spectroscopy, X‐ray diffraction and TEM. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Ionic liquid‐assisted hydrothermal synthesis of γ‐Al2O3hierarchical nanostructures

The boehmite (Al₂O₃·H₂O) hierarchical nanostructure with spindle‐like morphology has been successfully synthesized via ionic liquid‐assisted hydrothermal synthetic method under mild condition using an ionic liquid 1‐butyl‐3‐dimethylimidazolium bromide ([Bmim][Br]) as a template. The proposed formation mechanism has been investigated and the hydrogen bond‐co‐π–π stack mechanism is used to be responsible for the present formation of the precursor hierarchical nanostructure. The γ‐Al₂O₃ hierarchical nanostructure was obtained by calcining the as‐synthesized precursor at 500 °C for 2 h, preserving the same morphology. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Refractive index dispersion of relaxor ferroelectric 0.9Pb(Zn1/3Nb2/3)O3‐0.1PbTiO3 single crystal

The refractive indices of 0.9Pb(Zn_1/3Nb_2/3)O₃‐0.1PbTiO₃ single crystal at different wavelengths have been measured by the minimum deviation method at room temperature, and their dispersion equations are obtained. The parameters connected to the energy band structure are obtained by fitting single‐oscillator dispersion equation. Despersion energies are found to take on covalent crystal values. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Domain structure and birefringence studies on a 0.91Pb(Zn1/3Nb2/3)O3 ‐0.09PbTiO3 single crystal

Domain structure and phase transition sequence of 0.91PZN‐0.09PT single crystal, grown from high temperature solution, have been analysed using polarised light microscopy. The domain structure of (001)_cub cut single crystal exhibit co‐existence of rhombohedral and tetragonal phases. The sequence and phase transition temperatures have been determined from temperature dependence of birefringence. Birefringence measurements during heating and cooling reveal a first order nature of phase transition between rhombohedral (R3m) and tetragonal (P4mm). The birefringence was measured with accuracy of 10^‐3. However, dielectric measurement does not provide any evidence of R3m ‐ P4mm phase transition. It is shown that in‐situ analysis of domain structure and phase transition can be used as non‐destructive analytical tool for determination of local composition and phase transition sequence. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The Crystal Structure of Hop‐17(21)‐en‐3β‐yl acetate of Pluchea pteropoda Hemsl. from Vietnam

The title compound isolated from the roots of a Vietnamese plant and being known for its activity against fever was identified by this X‐ray analysis to be a pentacyclic triterpene of hopanoide type with a C17=C21 endocyclic double bond in the five membered ring. The presence of several axially substituted methyl groups on both the α and β side causes the so called "mid‐molecule strain" having already been reported in the literature for other hopane type ring systems.     

The Crystal Structures of O,O‐Dimethylalpinumisoflavone and 5‐O‐Methyl‐4'‐O‐(3‐methyl‐but‐2‐en‐1‐yl)alpinumisoflavone

The petrol extract of the rootbark of Milletia Thonningii obtained by column chromatography afforded sixteen different crystalline samples to be isolated. The crystal structures of two of these compounds, O,O‐Dimethylalpinumisoflavone (I) and 5‐O‐Methyl‐4'‐O‐(3‐methyl‐but‐2‐en‐1‐yl)alpinumisoflavone (II) are being reported here. (II) has two independent molecules in the asymmetric unit and differs from (I) in a longer side chain attached to C(15) of the phenyl ring. The structural features of the three molecules in the title compounds are reported and compared. The derivatives, being subject of this article are the first reported crystal structures where the isoflavone fragment is fused to a further six membered ring that results in a tricyclic ring system. The benzopyrone fragments are planar. The dihedral angles between the benzopyrone fragment and the phenyl ring being 55.38(6)° for (I) and 44.75(15)° /44.64(15)° for the respective independent molecules of (II) are within the range of values observed for similar structures.     

Analysis of the crystal structures of 1,3‐di‐tert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazasilol‐2‐ylidene and 1,3‐di‐tert‐butyl‐2,2‐dichloro‐1,3‐diaza‐2‐sila‐4‐cyclopentene

The crystal structures of the title compounds, 1,3‐di‐tert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazasilol‐2‐ylidene, C₁₀H₂₀N₂Si ( 1 ) and 1,3‐di‐tert‐butyl‐2,2‐dichloro‐1,3‐diaza‐2‐sila‐4‐cyclopentene, C₁₀H₂₀N₂SiCl2 ( 3 ) were solved and are reported. Compound ( 1 ) crystallized in space group P mmn and each molecule has a mirror plane, which bisects the C‐C backbone of the N‐C‐C‐N framework. Compound ( 1 ) was also found to have a 2‐fold twin component. In compound ( 3 ) the space group P 2₁/m results with the mirror plane passing through the N‐C‐C‐N backbone. We compare these structures with the gas phase determination previously reported for ( 1 ) and the incomplete single crystal data for ( 3 ). (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)