Synthesis and molecular structure analysis of venlafaxine intermediate and its analog

1-(cyano-(4-methoxyphenyl) methyl cyclohexanol(2), C₂₄H₃₂N₂O₂, a Venlafaxine intermediate is found to crystallize in both monoclinic(2a) and orthorhombic(2b) crystal systems. The form2a crystallizes in the space groupC2/c with the cell parametersa = 23.506(3),b = 5.550(3),c = 23.192(3), and β = 115.116(2)^∘.2b crystallizes in space groupP2₁2₁2₁ with cell parametersa = 5.7850(6),b = 11.2680(6), andc = 20.6730(19). The intermolecular hydrogen bonding in the case of the monoclinic polymorph leads to the formation of dimer. The synthesis, characterization, and crystal structure studies of Venlafaxine analog 1-[2-1-(4-dimethylamino-phenyl)-ethylideneamino]-1-(4-methoxy-phenyl)-ethyl]-cyclohexanol(4) is reported.4 crystallizes inP―1 space group with cell parametersa = 10.801(7),b = 12.078(7),c = 9.928(5), α = 96.12(5)^∘, β = 110.49(5)^∘, and γ = 112.42(6)^∘.     

Isolation and characterization of a new polymorph of D‐sorbitol

A new polymorph of D‐sorbitol (named as F form) was discovered in this paper. A reliable isolation method for this new polymorph was developed. Three other known polymorphs of D‐sorbitol were also prepared for comparative purpose. The new F form was analyzed and characterized by using PXRD, DSC, Raman and FTIR spectroscopy. By comparing with current polymorphs' data, it was proved that F form is a new form that was not reported in any literatures. From PXRD data, it was confirmed that the crystallinity of the new form is very high. From DSC data, it was found that the new form is less stable than any known anhydrous forms. It was also found by transformation experiments that the new F form can transform into alpha form in methanol solution through a solution mediated transformation mechanism. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Preparation and characterization of amorphous,I and II forms of clopidogrel hydrogen sulfate

In this work the amorphous, I and II forms of clopidogrel hydrogen sulfate (CHS) were prepared and characterized by use of powder X‐ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The labile precipitate and oiling out during reactive crystallization were also firstly reported. Based on the solubility and thermochemical data, the amorphous form and I form is found to be monotropically related, while the I form and II form are enantiotropically related. In addition, both transformations from anhydrous form to I form and from I form to II form are greatly temperature‐dependent, which gives us a window to prepare each pure form. These results will contribute a better understanding about the polymorphic nature and crystallization mechanism of clopidogrel hydrogen sulfate. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and thermal,phase transition and FTIR spectral characterization of tetraethylammonium tetrachlorocuprate (II) crystals

Single crystals of tetraethylammonium tetrachlorocuprate (II), [N(C₂H₅)₄]₂CuCl₄, were grown by slow evaporation method at room temperature. The crystals were characterized through powder XRD, thermogravimetric (TG‐DTA), low temperature differential scanning calorimetric (DSC) studies and FTIR spectroscopy. While the powder XRD pattern of the compound shows sharp Bragg peaks confirming the crystallinity of the compound, the TG‐DTA studies confirm formation of the compound in the stoichiometric ratio. The thermal anomalies observed in DSC curve at ‐120°C in the heating cycle and around ‐30°C in the cooling cycle indicate a first order phase transition. The phase transition was predicted to be associated with the ordering of CuCl₄^2‐ and successive long range orientation of [N(C₂H₅)₄]⁺ ions which are disordered at high temperatures. The cationic [N(C₂H₅)₄]⁺ plays a role in phase transitions at low temperatures. The sharp exothermic peak observed in high temperature DSC indicates a structural phase transition when [N(C₂H₅)₄]CuCl₃ is formed on heating the compound. The FTIR spectra of the compound characterize the various chemical bonding and water molecules adsorbed in the compound. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and thermal characterization of methylammonium tetrachloro zincate (II) monohydrate crystals

Single crystals of methylammonium tetrachloro zincate (II) monohydrate were grown by slow evaporation of saturated aqueous solutions at room temperature. The grown crystals were colourless, bright and transparent. The crystals were characterized through elemental analysis, powder X‐ray diffraction, thermogravimetric (TG‐DTA) and low temperature differential scanning calorimetric (DSC) techniques. While the powder XRD pattern shows the crystallinity of the compound, the elemental analysis and the TG‐DTA confirm the stoichiometry of the compound. The low temperature DSC indicates first order structural phase transition at ‐8°C during heating cycle. The FTIR and far IR spectra of the compound show characteristic vibrational frequencies due to CH₃NH₃ and ZnCl₄^2‐ ions and other chemical bonds. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Thermal,phase transition and spectral studies in erythromycin pseudopolymorphs: dihydrate and acetone solvate

The thermal, phase transition and spectral studies of erythromycin A dihydrate and acetone solvate were performed by Differential Scanning calorimetry (DSC), Thermo Gravimetry (TG‐DTA), X‐Ray Powder Diffraction (XRPD) and Fourier Transform Infra‐Red (FTIR) spectrum. The non‐thermal kinetic analysis of erythromycin A dihydrate was carried out by DSC at different heating rates in dynamic nitrogen atmosphere. The result showed that heating rate has substantial influence on the thermal behavior of erythromycin dihydrate. The Arrhenius parameters were estimated according to the Kissinger method. Corresponding to dehydration of dihydrate, melting of dehydrated dihydrate, phase transition from dehydrated dihydrate to anhydrate, and melting of anhydrate, the calculated activation energy were 39.60, 269.85, 261.23, and 582.16 kJmol^–1, the pre‐exponential factors were 3.46 × 10³, 8.06 × 10³², 9.23 × 10³⁰, and 7.29 × 10⁶³ s^–1, respectively. Ozawa method was used to compare activation energy values calculated by Kissinger method. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and characterization of PbI2 polycrystals

Single‐phase PbI₂ polycrystalline material for single crystal growth was synthesized by two‐temperature vapor‐transporting method (TVM), directly from highly pure lead and iodine with excess lead without according to the PbI₂ stoichiometry. It is found that there is an immiscible phenomenon of two melts in the synthesis experiment, and the melts solidified until cooled down to room temperature. X‐ray diffraction (XRD) analysis and Energy dispersive X‐ray (EDX) microanalysis indicate that the solidified materials are single‐phase PbI₂ polycrystal and nearly pure lead. Considering the observed immiscible phenomenon and the data given in paper [1], it is able to confirm that there is a new immiscible region L₂+L₃ in Pb‐I phase diagram, which is very important to PbI₂ polycrystal synthesis and single crystal growth. Using single‐phase PbI₂ polycrystalline material synthesized by our method, PbI₂ single crystal with size of ?15mm×30mm was grown by vertical Bridgman method. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim     

Crystal structure and physical characterization of neotame methanol solvate

The crystal structure of the methanol solvate (empirical formula: 2C₂₀H₃₀N₂O₅·3CH₃OH) of a new dipeptide sweetener, neotame (N-(3,3-dimethylbutyl)-L--aspartyl-L-phenylalanine 1-methyl ester), has been determined. Crystal data: a = 9.8989(1), b = 18.1331(1), c = 27.5725(1) Å, orthorhombic, space group P2₁2₁2₁, with Z = 4. Each unit cell includes 8 neotame and 12 methanol molecules. Disorder exists in one neotame molecule and one methanol molecule. The crystals were characterized by the following techniques: hot-stage microscopy (HSM), Karl-Fischer titrimetry (KFT), powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC), thermogravimetry (TGA), ¹³C solid-state nuclear magnetic resonance (SSNMR) spectroscopy. Under HSM at a heating rate of 10°C/min in silicone oil, the sample melts at 64–84°C and liberates bubbles at 71–86°C. DSC in open pans shows two overlapping endotherms at 56 and 71°C, probably due to melting and desolvation, respectively. TGA in open pans shows 5.9% weight loss due to desolvation below 70°C. Under house vacuum (23 mm Hg) over phosphorus pentoxide at 23°C, the methanol solvate produces pure amorphous anhydrate, which converts to crystalline neotame monohydrate in the presence of moisture.     

Photoacoustic study of the thermal and optical properties of hippuric acid

Photoacoustic spectroscopy (PAS) is a recently developed, non‐destructive testing (NDT) tool, used for analyzing the physical properties of materials. This method is used here to determine the thermal diffusivity and conductivity of the gel‐grown single crystals of hippuric acid, a minor constituent of urinary calculi and also a non‐linear optical (NLO) material. Optical absorption of the specimen was studied using its PA spectrum and compared with UV‐visible absorption spectra. Second harmonic generation (SHG) conversion efficiency was also carried out. Characterization of the crystals was made using X‐ray powder diffraction and density determination. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of succinic acid single crystals

Single crystals of ferroelectric succinic acid were grown from aqueous solution by low temperature solution growth technique. The cell parameters and space group are found using powder X‐ray diffraction analysis. The presence of the functional groups has been estimated qualitatively by FTIR analysis. The UV‐Visible spectrum shows the cut‐off wavelength at 240 nm. The thermal stability of the crystal was studied by TG/DTA. The dielectric constant of the crystal studied as a function of frequency shows the pyroelectric property. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,spectroscopic investigations,antioxidants and DNA binding studies of a charge transfer of benzimidazole with 4-methylbenzenesulfonic acid

A new charge transfer (CT) complex benzimidazolium-4-methylbenzenesulfonate formed between benzimidazole and 4-methylbenzenesulfonic acid has been studied spectrophotometrically in methanol at room temperature. The binding of the novel CT complex with calf thymus DNA has been investigated by adsorption spectrum, the establish the ability of the CT complex for its interaction with the chosen DNA. The elemental stiochiometry and the X-ray crystallographic structure of the complex were studied, showing the significance of sulfonate anion in holding stability. Powder XRD confirms the crystalline nature of the compound. NMR signals explicitly confirmed the molecular structure crystal. Antioxidant activity of the CT complex was found to be potent. TG-DTA studies also proves the stability of the synthesized complex.     

Synthesis and structure of bis(2,6-dimethylpyrazine)(THF)copper(II) nitrate

Attempts to crystallize Cu(2,6-dmpz)(NO₃)₂ (2,6-dmpz = 2,6-dimethylpyrazine) by reaction of 2,6-dmpz with Cu(NO₃)₂·3H₂O in THF resulted in the synthesis of Cu(2,6-dmpz)₂(NO₃)₂·THF. The compound crystallized in the monoclinic space group C2/c and exists as isolated molecules with distorted square pyramidal geometry: a = 11.609(4) Å, b = 10.415(3) Å, c = 18.256(6) Å, = 108.332(4)°. The 2,6-dmpz molecules coordinate to the Cu ions through the distal (remote from the methyl) nitrogens. The molecules are arrayed in stacks parallel to the b-axis.     

Synthesis and thermal diffusion of nanostructured porous GaAs

Nanostructured porous GaAs samples were prepared by electrochemical anodic dissolution of GaAs for various current densities and etching periods. The samples are characterized by SEM and photoluminescence (PL) where a blue shift is observed in PL. Thermal properties of this nanostructured GaAs are then studied by photoacoustic (PA) spectroscopy, where one order decrease in thermal conductivity of porous GaAs compared to bulk is observed. Further it is shown that the thermal conductivity of porous GaAs decreases with decrease in size of the particles. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,structural and thermal studies of tetrathioureacopper(I) chloride crystals

Tetrathioureacopper(I) chloride, hereafter abbreviated as TCC, was synthesised and single crystals were obtained from saturated aqueous solution by slow evaporation (solution growth) method at room temperature. The crystals obtained are bright, colourless and transparent having well defined external faces. The grown crystals were characterized through elemental analysis, single crystal X‐ray diffraction study, thermal analysis, electron spin resonance spectroscopy and Fourier Transform infrared spectroscopy. The elemental analysis confirms the stoichiometry of the compound. The single crystal diffraction studies indicate that TCC crystallises in the tetragonal lattice and the unit cell parameters are a = b = 13.4082 Å, c = 13.8074 Å, V = 2482.29 ų, α = β = γ = 90°. Space group and the number of molecules per unit cell (Z) are found to be P4₁2₁2 and 8 respectively. The TG curve of the sample shows a prolonged decomposition from 210 to 628.3 °C, from which the decomposition pattern has been formulated. The endothermic peaks in the DTA curve indicate melting and decomposition of the compound at 165.2 and 633.8 °C respectively. An exothermic peak in high temperature DSC indicates a phase transition in the compound at 274.8 °C. Thermal anomalies observed in the low temperature DSC at –163.3, –152.0, –141.5, –108.3, 1.0 and 12.1 °C in the heating run and –157.1 and –153.9 °C in the cooling run reveal first order phase transitions in the crystal. The peaks observed at –146.2 °C in both the heating and cooling runs suggest occurrence of a second order phase transition in this compound. The IR spectroscopic data were used to assign the characteristic vibrational frequencies of various groups present in the compound. The ESR study confirms that the copper is in the +1 oxidation state in the complex. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Global heat loss and thermal stress analysis in Czochralski crystal growth

Based on our invention of an energy‐efficient Czochalski crystal growth furnace, a 2D‐axisymmetric numerical simulation model of LiNbO₃ crystal growth is developed. The heat transfer, melt and gas flow, radiation and the interface deflection have been examined. Heat losses in the furnace and the insulator, as well as the heating power and thermal stress distribution at three stages of crystal growth are calculated in detail. It is found that a large proportion of heat dissipates through the water‐cooling system, and at the steel shell of the furnace, gas convection heat transfer is the major cooling mechanism. Less heat dissipation by radiation and more heat flux by gas convection to the crystal sidewall results in a larger concentrated thermal stress, which may induce large crystal cracks in the growth process. The simulation results of heating power are in coincidence with the actual power of our furnace, which verifies the feasibility of our model. The detailed information with respect to the device obtained from simulation can help to optimize the energy‐saving design and growth process.     

Synthesis,thermal analysis,and crystal structure of potassium triiodomercurate monohydrate

Single crystals of potassium triiodomercurate monohydrate KHgI₃ · H₂O are synthesized and studied by X-ray diffraction: space group Pna2₁; a = 8.57961(11), b = 9.23621(13), and c = 11.38977(16) Å, Z = 4; R= 0.0574. Thermal conditions of decomposition of the compound are studied by differential scanning calorimetry.     

Synthesis and characterization of hexagonal ferrites BaFe12‐2xZnxTixO19 (0 ≤ x ≤ 2) by thermal decomposition of freeze‐dried precursors

Substituted barium hexaferrites, BaFe_12‐2xZn_xTi_xO₁₉ (0 ≤ x ≤ 2), have been synthesized by thermal decomposition of freeze‐dried acetate precursors. Decomposition and phase formation were investigated by means of thermal analysis, XRD and IR spectroscopy. The initially amorphous decomposed precursor reacts to the substituted hexaferrite via a spinel‐like maghemite (γ‐Fe₂O₃) and Zn/Ti containing spinel ferrites. The synthesis method allows a decrease of the reaction temperature and time, necessary for producing a single phase hexaferrite. At relative low reaction temperatures, the substitution rate x shows remarkable differences at different iron sublattices. For x ≤ 0,8 this selective substitution results in an increase of magnetization as x grows. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electrical conductivity of sulfamic acid single crystals

Single crystals of sulfamic acid have been grown by the method of slow evaporation at constant temperature. DC electrical conductivity was measured in the temperature range 300 ‐ 440 K along a, b and c‐axes. Conductivity measurements show slope change near 330 K and 410 K. The slope change observed around 330 K may be attributed as due to a phase transition which has been well supported by the DSC and DTA measurements. Slope change observed around 410 K is attributed as the onset of the thermal decomcoposition as evidenced by TGA curve. TGA studies show the crystal is very stable up to 440 K. Activation energies for the conduction process are calculated for all measured crystallographic directions. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal structure and thermal behaviour of (Rb,Cs)BSi2O6 solid solutions

The crystal chemistry of Rb‐Cs boroleucites has been studied by means of X‐ray powder diffraction at room and elevated temperatures. The cubic I‐43d → cubic Ia3d phase transition was investigated using a series of samples prepared by solid‐state reaction along the pseudobinary system RbBSi₂O₆ ‐ CsBSi₂O₆. The Rietveld refinement of the structures of Rb_1‐xCs_xBSi₂O₆ solid solutions (x = 0.2, 0.4, 0.6, 0.8) demonstrates that the solutions with a high Rb content crystallise in the cubic I‐43d space group, and the boroleucites with a considerable Cs content have Ia3d symmetry. Rb can substitute Cs in a wide range of compositions. Within a narrow range of x = 0.5 ‐ 0.6 immiscibility was revealed. Under Rb‐Cs substitution the cubic lattice parameter, the (Rb,Cs)‐O distances, and the angles between tetrahedra of the I‐43d phase change clearly, while those of the Ia3d phase change slightly. The HTXRD data shows that the I‐43d phase transforms into a Ia3d phase on heating analogously to a change of the composition. As the Cs content increases the transition temperature decreases. The low temperature I‐43d phase shows a higher thermal expansion than the high temperature Ia3d phase. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim     

Crystallization and characterization of nonlinear optical l‐histidinium dihydrogen orthophosphate orthophosporic acid single crystal

L‐histidinium dihydrogen orthophosphate orthophosporic acid (abbreviated as LHP) with molecular formula C₆H₁₀N₃O₂⁺·H₂PO₄^‐·H₃PO₄ was successfully grown by slow evaporation technique from aqueous solution. The crystal was characterized by X‐ray diffractometry (XRD), UV‐Vis‐NIR, TGA, DTA, microhardness and solubility studies. The dielectric constant and dielectric loss of the crystal were studied as function of frequency. Photoconductivity studies were also carried out on the sample. The SHG efficiency of the crystal is studied using the Kurtz and Perry technique. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)