The study of bis-chloromethyl-phosphinic acid crystal by ATR and Raman spectroscopy and X-ray diffraction

Crystals of bis-chloromethyl-phosphinic acid ((CH₂Cl)₂POOH) are studied by attenuated total reflection (ATR) and Raman spectroscopy supported by X-Ray diffraction. The bands recorded in the ATR and in Raman spectra have the same wavenumbers within experimental uncertainty. It is in agreement with the X-Ray diffraction results which show that the molecules in crystals form infinite chains through hydrogen bonds and there is no center of inversion. The parameters of the unit cell, the bond lengths and angles, and the distance between two oxygen atoms in hydrogen bond bridges are determined. The spectral features and the intermolecular distance between oxygen atoms are characteristic for a strong hydrogen bonded system.     

Structural studies of oxalohydroxamic acid by single crystal X-ray diffraction and spectroscopic methods

The structure of oxalohydroxamic acid has been investigated by X-ray and spectroscopic analyses. It has been shown that oxalohydroxamic acid exists in the oxamic form in the solid as well as in solution. The variable-temperature nuclear magnetic resonance (NMR) studies reveal an exchange of OH and NH protons, the exchange being faster at higher temperatures. The kinetic and the thermodynamic parameters such as the rate constant (K), the free energy of activation (G ^DG), and the energy of activation (E _a) for the exchange process have been obtained. The compound crystallizes in the monoclinic space groupP2₁/c witha=5.208,b=3.864,c=11.482 Å,=111.45°, andZ=2. The structure was solved withMultan 80. The refinement by block diagonal least squares and Fourier methods providedR=0.035. There is strong hydrogen bonding between the molecules which form dimer.     

Synthesis,characterization, single crystal X-ray diffraction and DFT studies of ethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate

The present study describes the synthesis, spectroscopic, and single crystal X-ray structural analysis of ethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate. The pyrazole ester of formula [C₁₃H₁₄N₂O₂] was prepared from the three-component one-pot condensation reaction of ethyl acetoacetate, N,N-dimethyldimethoxymethanamine, and phenyl hydrazine. The product was crystallized by using ethanol as solvent. The structure of the compound was confirmed by elemental analysis, Fourier transforms infrared (IR), thermogravimetric analysis, UV-visible (UV-Vis), ¹H NMR, and single-crystal X-ray diffraction studies. The gas-phase molecular geometry and the electronic structure-property of the molecule were calculated at the density functional theory. The frontier molecular orbitals, theoretical UV-Vis, and IR stretching vibrations were also reported. The compound crystallizes in the monoclinic system with the space group P2₁/c and Z = 4. The unit cell parameters are a = 12.141(3) Å, b = 13.934(4) Å, c = 7.2777(18) Å, and β = 97.816(14)⁰. The structure is stabilized by an intermolecular interaction of type C-H···O and the structure also involves C-H···π interactions.     

Confinement of selenium inside carbon nanotubes. Structural characterization by X-ray diffraction and X-ray absorption spectroscopy

In order to study the effect of confinement on crystallographic arrangement, selenium (Se) was introduced into carbon nanotubes with average diameters of 12, 23 and 50 Å. The evolution of the Se long-range crystallographic arrangement and the Se short-range atomic surroundings was characterized by X-ray diffraction and X-ray absorption spectroscopy, respectively. A transition from an initially disordered trigonal structure, where part of the chains are not well connected, to a structure exhibiting well-organized rings was observed when the tube diameter was of the order of 12 Å. Se-C bonds, detected when nanotube average diameters were of the order of 20 Å and less, might play a role in the structural transition.     

X-ray crystal structural analysis of dicyclohexylthiocarbamide

The title compound dicyclohexylthiocarbamide has been determined by single crystal X-ray crystal diffraction analysis. The crystals are monoclinic, space group P2(1)/c with a = 12.5908(9), b = 11.2158(9), c = 10.4255(8) Å, α = 90, β = 110.7360(10), γ = 90°, V = 1376.88(18) ų, Z = 4, F(000) = 528, D_c = 1.160 g/cm³, μ = 0.214 mm^?1, the final R = 0.0381 and wR = 0.1030. A total of 6836 reflections were collected, of which 2423 were independent (R_int = 0.0154). In the crystal packing diagram, intermolecular N?H···S hydrogen bonds stabilize the solid state of the title compound.     

Structure and spectra character of cobalt nickel sulfate twelvehydrate (CNSH) single crystal

The title compound CoNi(SO₄)₂ · 12H₂O has been prepared and its crystal structure determined by single crystal X‐ray differaction at room temperature. The CNSH crystal structure belongs to the monoclinic space group C2/c,a = 9.966(2) Å, b = 7.2265(14) Å, c = 24.218(5) Å, β = 98.32(3)°, V = 1725.9(6) ų, z = 4, Dc = 2.024 gcm⁻³. The optical transmission character of CNSH crystal in aqueous solution is discontinuous in the range from ultraviolet to near IR wavelengths. The relationship between the structure and the optical transmission property is further discussed. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

X-ray diffraction and IR spectroscopy study of labuntsovite-group minerals

The distribution of cations over the positions in the structures of labuntsovite-group minerals was studied by X-ray diffraction analysis and IR spectroscopy. Several types of cation order over the five key positions are established depending on cation composition and their force characteristics.     

Phenomena induced by UV irradiation in PbMoO4 single crystal

Abstract

Electrical properties and optical absorption of PbMoO₄ single crystal were studied after UV irradiation. Anomalies of permittivity ε and conductivity σ were detected and attributed to the dipole centers induced by UV light. It was proposed that dipole centers were created by photoelectrons trapped by Mo within oxygen tetrahedra distorted by an oxygen vacancy V_O. At high temperatures conductivity was nearly insensitive to UV irradiation. Additional optical absorption was observed in PbMoO₄ single crystal after UV irradiation. It was argued that transfer of photoelectrons from lead to molybdenum groups was responsible for the photochromic effect found.     

Tautomeric investigations and crystal structure analysis of chlorzoxazone

The crystal structure and infrared spectra of the compound has been reported. Infrared spectra of the compound were examined in various solvents. The results of the crystal structure analysis and IR spectra assignments showed that the compound has the amino tautomeric form in the solid state and in studied solutions.     

Optical phonon modes and transmissivity in BaWO4 single crystal

Barium tungstate (BaWO₄) single crystal has been grown using Czochralski technique. It belongs to the scheelite structure, forming the space group I 4₁/a at room temperature and the primitive cell contains two molecular units. The polarized Raman spectra were recorded by a micro‐Raman spectrophotometer system in the backscattering geometry. All the observed Raman modes were assigned. The Raman mode at 924 cm^–1, which belongs to the totally symmetrical A_g optical modes, has the strongest intensity and its linewidth is 4.6 cm^–1. The infrared active lattice vibrations have been studied, eight optical modes were observed and assigned. The ultraviolet absorption edge is at 256 nm and the optical transparency range is up to 2500 nm at room temperature. The energy gap E_g of this crystal was obtained from the optical transmission spectra. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Structural analysis of CaSiO3 glass by X-ray diffraction and Raman spectroscopy

The short-range structure of CaSiO₃ glass was studied by a combination of radial distribution analysis with an intensity comparison method on the basis of X-ray diffraction data. Three main peaks appeared at 1.64, 2.43 and 3.64 Å in the radial distribution function curve. The Raman bands were observed at 367, 642, 878 and 972 cm⁻¹ and the Raman spectrum was found to be similar to that observed in pyroxenes: single chains consisting of SiO₄ tetrahedra are linked by calcium ions laterally. The calcium ion is surrounded by six oxygen atoms at an average distance of 2.34 Å and the remainder Ca---O pairs at a distance of 2.54 Å. The calculated intensity curve based on this model was in good agreement with the observed one.     

X-ray crystal structure of 2-styrylpyridine

We have crystallized the 2-styrylpyridine from the condensation reaction between the 2-methylpyridine with benzaldehyde in the formation of the model compound 2-styrylpyridine. The X-ray structure and NMR are currently reported. The main features of the structure is that is shows a localization of the double bonds rather than a delocalization of π electrons in an aromatic fashion.     

单晶应力的X射线测量方法

本文介绍了X射线测量单晶应力的原理和方法,测量了Si单晶的应力,比较了双晶摇摆和三轴晶ω～2θ扫描对结果的影响,考察了计算过程中数据组个数,无应力布拉格角θ_0对应力测量的影响.结果表明,采用三轴晶ω～2θ扫描比双晶摇摆更准确,多重线性回归方法对θ_0依赖性很小,但测量数据组个数不应低于6.     

Structural and spectroscopic study of Mg13.4(OH)6(HVO4)2(H0.2VO4)6

Single‐crystals of the polar compound magnesium hydrogen vanadate(V), Mg_13.4(OH)₆(HVO₄)₂(H_0.2VO₄)₆, were synthesized hydrothermally. It represents the first hydrogen vanadate(V) among inorganic compounds. Its structure was determined by single‐crystal X‐ray diffraction [space group P 6₃mc, a = 12.9096(2), c = 5.0755(1) Å, V = 732.55(2) ų, Z = 1]. The crystal structure of Mg_13.4(OH)₆(HVO₄)₂(H_0.2VO₄)₆ consists of well separated, vacancy‐interrupted chains of face sharing Mg2O₆ octahedra, with short Mg2—Mg2 distances of 2.537(1) Å, embedded in a porous magnesium vanadate 3D framework having the topology of the zeolite cancrinite. All three hydrogen positions in the structure were confirmed by FTIR spectroscopy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Duality in simple single atomic type crystal structures

Crystal structures can be interpreted as a systematic arrangement of atoms and interstices. Their spatial arrangement follows the duality principle. By using mathematical polyhedra it is possible to show an overall scheme in the simple crystal structures that is possibly hidden from view by the utilization of the hard‐sphere‐model or charge density distributions. In addition there is a dual connection between the shape of the atoms and the arrangement of these atoms (i.e. the crystal structure). Therefore, the shape is expected to control the arrangement, with some possible feedback from the arrangement on the shape. On the basis of the dual principle a connection can be recognized between some crystal structures. Allotrope transitions can also be explained by using this principle. Moreover, physical parameters which are connected to the crystal structure like atomic arrangement and E( k ) of delocalized electrons also follow the duality principle. Consequently, it is possible to conclude that duality represents a basic principle of the simple single atomic type crystal structures. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Structural and microhardness studies of pure and thiourea doped glycine phosphite single crystal

Ferroelectric Glycine Phosphite (GPI) crystal have been grown from aqueous solution employing the slow cooling technique. As the crystal solubility in water depends on temperature, single crystals were grown. Transparent, colourless crystals with habit morphology weighing about 8g were obtained with in a month. The same procedure was used to grow single crystals of 10 wt% of Thiourea doped GPI (TUGPI). Formation of a new crystal was confirmed by Powder X‐ray diffraction studies as well as FTIR studies. Crystalline quality were found using rocking curve for both the crystals. Due to the presence of Thiourea in TUGPI, it improves the crystalline perfection and also enhances the growth rate. The variation of hardness on (010) faces of monoclinic GPI and TUGPI crystals, with load were studied.Vickers hardness numbers, H_v were found to decrease with the increase in load. The value of Mayer's index, ‘n ’ was found to be greater than 1.6 for GPI and TUGPI showing soft‐material category. The results are discussed in detail. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

X-ray crystal structure and spectroscopy of a pseudo-square pyramidal Cu(II) complex, trans-dinitratotetrakis (trans-4-styrylpyridine)copper(II)

Single crystals of the title Cu(II) complex, [Cu(stpy)₄(ONO₂)(ONO₂)] [stpy = trans-4-styryl-pyridine] have been prepared and characterized by elemental and thermal analyses, IR, electronic and EPR spectral measurements, and X-ray crystal structure determination. The complex crystallizes in the monoclinic space group P2₁/c with unit-cell parameters, a = 12.985(2), b = 22.865(8), c = 17.024(10) Å, = 112.29(3)°, and Z = 4. The structure consists of discrete monomeric units of [Cu(stpy)₄(ONO₂)(ONO₂)]. The equatorial positions of the Cu(II) polyhedron are occupied by nitrogen atoms of the four stpy ligands and the axial positions by the oxygens of two unidentate nitrate anions. One of these oxygens is at rather longer distance [2.609(3) Å] and may be considered to be semicoordinated. If this semibond is ignored, the coordination geometry lies closer to an idealized square pyramid than to the trigonal bipyramid geometry. IR spectra reveal nitrogen coordination from stpy and asymmetry in the monodentate oxygen binding of the two nitrate ligands. The optical reflectance band at 600 nm suggests pseudo-square-based pyramidal geometry around Cu(II). Well-resolved Cu(II) hyperfine features in the EPR spectra reveal the absence of exchange interactions between adjacent copper centers. Optical and EPR spectra of a methanolic solution of the complex indicate solvent interactions. Thermogravimetric analysis shows the complex to be stable up to 175°C.     

Structural features of a new [Fe(nicotinamide)2(H2O)4]·[Fe(H2O)6]·(SO4)2·2H2O complex

A new nicotinamide complex of Fe(II) cation was prepared by reaction between ferrous sulfate and nicotinamide in aqueous solution. The complex was characterized on the basis of elemental analysis, FT IR and UV–VIS spectroscopy, electrochemistry (cyclic voltammetry) and X–ray crystallography. The complex consists of the molecular composition of [Fe(nicotinamide)₂(H₂O)₄]· [Fe(H₂O)₆]·(SO₄)₂·2H₂O. The complex crystallizes in the monoclinic space group P 2₁/c [a = 12.862(3), b = 7.110(3), c = 16.382(3) Å; β = 95.79(2)°]. It has been proven that nicotinamide is coordinated to Fe(II) through the nitrogen atom of its heterocyclic ring. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim     

X-ray crystal structure of tetraaquabis (xanthosinato)nickel(II) hexahydrate

The complex [Ni(XsH_–1)₂(H₂O)₄]·6H₂O (XsH_–1: xanthosinate) was isolated from the reaction of nickel carbonate with xanthosine in aqueous solution. The octahedral coordination is supported by the reflectance measurements. Single-crystal X-ray diffraction studies show that the crystals belong to the triclinic P1 space group, with a = 7.152(1), b = 8.830(1),c = 13.783(1) Å, = 82.024(1)°, = 86.155(1)°, = 70.900(1)°, and D = 1.643 mg/m³, forZ = 1. Nickel is six coordinate with four water molecules, and two N7 atoms from xanthosinato ligands. A complicated hydrogen-bonding network is present, all possible donors taking part in it.     

Crystal growth and spectral analysis of Dy3+ and Er3+ doped KPb2Cl5 as a mid‐infrared laser crystal

This paper reports crystal growth and optical characteristics of dysprosium (Dy³⁺) and erbium (Er³⁺) doped mid‐infrared laser crystal ternary‐potassium‐lead‐chloride (KPb₂Cl₅). Two transparent crystals with good optical quality have been grown successfully by using the Bridgman technique,the largest crystal size reaches up to ∅︁10×60mm². Measurements of X‐ray diffraction(XRD) and absorption spectra were carried out. Based on Judd‐Ofelt theory, the intensity parameters Ω_t(t=2,4,6), the experimental and theoretical oscillator strengths have been obtained.The intensity parameters Ω_t(t=2,4,6) of Er³⁺:KPb₂Cl₅ were calculated to be Ω₂=5.10×10^‐20 cm², Ω₄=1.25×10^‐20 cm², Ω₆=0.83×10^‐20 cm², and the values for Dy³⁺:KPb₂Cl₅ were calculated to be Ω₂=6.26×10^‐20 cm², Ω₄=2.45×10^‐20 cm², Ω₆=0.04×10^‐20 cm² respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)