2-phenyl thiazolidine — its growth and characterisation

The importance of 2-phenyl thiazolidine lies in its being a model for penicillin, as the five-membered thiazolidine ring happens to be the moiety of penicillin. This material is synthesised and crystallised (Tsukerman). The crystals are white in colour, transparent, needle-shaped and of dimensions (0.2 × 0.3 × 0.4 mm³). Employing X-ray diffraction studies, it is found that the crystal belongs to the orthorhombic system with the unit cell parameters a = 8.388(1), b = 18.114(2) and c = 5.625(1) Å. The space group is P 2₁2₁2₁ and Z = 4. The absorption peaks pertaining to NH, NCS, methylene CH₂ and aromatic C₆H₄ have been identified from the infrared absorption spectrum of the sample. The Proton Magnetic Resonance (PMR) spectrum fully accounts for the hydrogens in the sample thereby unambigiously supporting the proposed structure.     

Dissociation of LiAlO2 and LiGaO2

The thermodynamic calculations of dissociation of LiAlO₂ and LiGaO₂ as function of temperature and oxygen pressure are presented. It has been found that LiGaO₂ evaporates congruently at the melting point under the oxygen pressure equal to 1 · 10^—5 atm. LiAlO₂ evaporates incongruently, the equilibrium oxygen partial pressure at the melting point is equal to 9.6 · 10^—5 atm and the partial pressure of Li and Al oxides decrease with increasing of oxygen pressure.     

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.     

On the crystal structure type of 2 CsCl · CoCl2 · 2 H2O

The following three-component systems have been studied: CsCl MnCl₂ H₂O at 25 °C; 2 CsCl · CuCl₂ · 2 H₂O—2 CsCl · CoCl₂ H₂O at 10 °C and 2 CsCl · MnCl₂ · 2 H₂O—2 CsCl · CoCl₂ H₂O at 25 °C and 10 °C. It was established that Co²⁺-ions do not substitute isodimorphously the Cu²⁺-ions in the tetragonal salt 2 CsCl · CuCl₂ · 2 H₂O, whereas in the case of the triclinic salt 2 CsCl · MnCl₂ · 2 H₂O they can substitute isodimorphously the Mn²⁺-ions. The theoretical considerations supported by the results obtained allow to predict the existence of the double salt 2 CsCl · CoCl₂ · 2 H₂O as well as the type of its crystal structure — triclinic, space group P1 .     

Preparation and Characterization of (1 — x) Pb(Mg1/3Nb2/3) O3 — x PbTiO3 Electrocaloric Ceramics

Lead magnesium niobate Pb(Mg_1/3Nb_2/3)O₃ — lead titanate PbTiO₃ [abbr. as (1 — x) PMN — x PT] ferroelectric ceramics with different excesses of MgO and PbO were systematically studied under different processing conditions for ferroelectric refrigeration application. It was found that the excess amount of MgO and PbO, and the sintering temperature have great effect on the crystallographic properties of the ceramics. In our experiments, (1 — x) PMN —x PT (x = 0.08, x = 0.10, and x = 0.25 respectively) with the excesses of 2 mol% MgO and 2 mol% PbO ceramics sintered at 1250 °C/1 hour possess the desired perovskite structures and large electrocaloric temperature change (ΔT = 1 K and more) in the vicinity of room temperature under a dc electric field of 1.5 kV/mm. It is expected that (1 — x) PMN — x PT electrocaloric ceramics could be applied for cascade refrigeration near room temperature.     

1,6‐Hexanediammonium Dihydrogendecavanadate Dihydrate, (H3N—(CH2)6—NH3)2H2V10O28 · 2 H2O

The crystal structure of (H₃N—(CH₂)₆—NH₃)₂H₂V₁₀O₂₈ � 2 H₂O consists of dihydrogendecavanadate anion with C_i symmetry, two 1,6‐hexanediammonium cations and two water molecules. The structure has a P space group symmetry with one of the cations in special position; this cation is disordered. The polyanion of most usual protonation type is similar as formed in other known dihydrogendecavanadates.     

A new supramolecular cocrystal of 2-amino-3-bromopyridine with 4-methylbenzoic acid: Synthesis,structural, spectroscopic characterization and comparative theoretical studies

The 1:1 cocrystal of 2-amino-3-bromopyridine (2A3BP) with 4-methylbenzoic acid (4MBA) has been prepared by slow evaporation method in methanol, which was crystallized in monoclinic P2₁/c space group having two molecules in the asymmetric unit. The cocrystal has been characterized by single crystal X-ray analysis, FTIR, ¹H NMR, ¹³C NMR, and Powder XRD. Theoretical investigations have been calculated by HF and density function (B3LYP) method with the 6-311+G(d,p) basis set. The vibrational frequencies together with the ¹H NMR and ¹³C NMR chemical shifts have been calculated on the fully optimized geometry of 1. Theoretical calculations of bond parameters, harmonic vibration frequencies, and isotropic chemical shifts are in good agreement with the experimental results. Solvent-free formation of these cocrystal was confirmed by powder X-ray diffraction analysis. The crystal structure was stabilized by N_pyridine—H···O = C, C = O—H···N_pyridine and C—H···Br hydrogen bonding interactions.     

The salt of l‐prolinium picrate

A crystalline salt of prolinium picrate, C₁₁H₁₂N₄O₉, has been prepared and characterized by X‐ray crystallography. The salt crystallizes in orthorhombic space group P2₁2₁2₁ with a = 6.325(1)Å, b = 9.269(1)Å, c = 24.379(4)Å, V = 1429.4(5)ų, Z = 4. In the title salt, the picrate and prolinium ion are held by different bifurcated hydrogen bonds of N‐H—O type, and stablized by bifurcated hydrogen bonds of CH—O type. There exists a competion between hydrogen bonds and π–π stacking in determining the title crystal. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Lattice constants and site preference in the system Ni2SiO4—Co2SiO4

Most important supposition for a possible site preference in a olivine solid-solutions are besides the different crystal chemical properties of M cations (size, electronegativity, crystal field stabilization energy) the differences between the both octahedral coordinated sites M1 and M2 of the olivine structure. Using this regularities the site preference in the system Ni Co olivines is predicted. If site preferences are existing, it is possible to deduce deviations of the Vegard's rule in the system Ni₂SiO₄—Co₂SiO₄ using geometrically-structurally considerations. The plot of experimentally determined lattice parameters in this solid solutions system shows the existing of the proposed deviations of the Vegard's rule and evidences the site preferences of Ni²⁺ in the M1- and Co²⁺ in the M2 octahedra only by determination of lattice parameters.     

Crystal structure of 3‐(3‐nitrophenylhydrazonocarbonyl)‐(1H)‐1,2,4‐triazole

The title compound, C₁₀H₈N₆O₃, was synthesized by the reaction of 3‐(1H)‐1,2,4‐triazole hydrazine with 3‐nitrobenzaldehyde in ethanol. The single crystal structure has been determined by X‐ray analysis. The crystal belongs to monoclinic system, space group p2₁/c with cell constant, a = 8.0214(17) Å, b = 17.334(4) Å, c = 8.9070(18) Å, V= 1179.4(4) ų. An intramolecular N—H...O and N—H…N hydrogen bond are observed between the ‐NH group with O atom of the carbonyl group and the ‐NH group with N atom. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The Crystal and Molecular Structure of 2-(2′-Cyano-2′-amido-ethylenyl)-pyridine

The title compound (C₉H₇N₃O) has been determined from three dimensional X-ray diffraction data. The crystals are monoclinic, a = 4.858(3) Å, b = 15.008(7) Å, c = 11.787(2) Å, ß = 94.107(2)°, V= 857.2(4) ų, z = 4, D_calc = 1.342 g. cm⁻³, space group P2_1/c. The structure was solved by direct methods and refined by full-matrix least-squares method (γ MoK_α′, R = 0.0766).     

Crystal structure and electrochemical property of one‐dimensional complex: [K(cis‐syn‐cis‐ dicyclohexyl‐18‐crown‐6)]2[Cu(mnt)2]

One metalorganic complex [K(cis‐syn‐cis‐ dicyclohexyl‐18‐crown‐6)]₂[Cu(mnt)₂] (mnt = maleonitriledithiolate) has been obtained by the reaction of dicyclohexyl‐18‐crown‐6 with K₂mnt and CuCl₂·2H₂O. The title complex has been characterized by elementary analysis, FT‐IR, UV‐Vis spectroscopy and x‐ray single crystal diffraction. The title complex crystallizes in the triclinic space group P1 with crystallographic data: a = 10.870(6) Å, b = 11.536(6) Å, c = 12.904(7) Å, α = 101.541(10)°, β = 110.573(9)°, γ = 99.441(9)°, V = 1435.2(13) ų, Z = 1, D_calcd = 1.350 g/cm³, F(000) = 615, R₁ = 0.0641, wR₂ = 0.1475. It displays one‐dimensional chain‐like structure formed by [K(cis‐syn‐cis‐ dicyclohexyl‐18‐crown‐6)]⁺ complex cations and [Cu(mnt)₂]^2‐ complex anions through N‐K‐N interactions. Its electrochemical behavior has also been studied by the cyclic voltammetry. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of simultaneous doping of Tl and Bi on microstructure and critical current density of HgBa2Ca2Cu3O8+δ

It has been found that simultaneous doping of Tl and Bi at Hg site of HgBa₂Ca₂Cu₃O_8+δ HTSC phase induces interesting microstructural variants in the form of long period polytypoid (LPP) like structure embodying native defect substructures. It has been observed that the as synthesized (HgTl_0.2−xBi_x)Ba₂Ca₂Cu₃O_8+δ (with x = 0.05, 0.10, 0.15) phases have superconducting onset transition temperature (T_c) of about ∼133 K. However, the intragrain critical current density (J_c) for the various materials with different compositions varies significantly. It varies from 6.2 × 10⁶ A/cm² to 2.9 × 10⁶ A/cm² at 5 K and 1 T for (HgTl_0.10Bi₁₀)Ba₂Ca₂Cu₃O_8+δ and (HgTl_0.15Bi_0.05)Ba₂Ca₂Cu₃O_8+δ HTSC phase respectively. A correlation between the intragrain J_c and the defect substructures has been found to be present. This correlation has been described and disscussed. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

X-Ray Structure Investigation of Sr<Subscript>3</Subscript>NbGa<Subscript>3</Subscript>Si<Subscript>2</Subscript>O<Subscript>14</Subscript> Langasite Family Crystal

An accurate structure analysis of Sr₃NbGa₃Si₂O₁₄ single crystals, belonging to the langasite family, has been performed. Two datasets are obtained on an Xcalibur S diffractometer equipped with a CCD detector. The structure is been refined using an averaged dataset: sp. gr. P 321, Z = 1, 295 K, sin θ/λ ≤ 1.35 Å^–1, a = 8.2797(3) Å, c = 5.0774(5) Å; the agreement factors between the model and experiment are found to be R/wR = 0.76/0.64% and Δρ_min/Δρ_max =–0.21/0.17 e/ų for 3820 independent ref lections. The Sr₃NbGa₃Si₂O₁₄ and Sr₃NbFe₃Si₂O₁₄ structures are compared, and the role of magnetic ions in the predicted P321 → P3 phase transition is analyzed.     

Orthorhombic — tetragonal phase transition and oxygen index of YBa2Cu3O6+δ

The orthorhombic — tetragonal phase transition of YBa₂Cu₃O_6+δ has been investigated by X-ray powder diffraction methods. The transition is of the second order or very close to second order and no coexistence of tetragonal and orthorhombic phases has been observed. The transition strongly depends on the oxygen index δ which changes with temperature. Typical patterns of the triplet 006, 020, and 002 obtained by precise X-ray powder diffraction measurements have been presented and shown to be useful for identification of YBa₂Cu₃O_6+δ and estimation of oxygen index δ.     

Crystal Structure of Diethyl 2‐[2,2,2‐ trifluoro‐1‐(indole‐3‐yl)‐ethyl]‐2‐acetamidomalonate

The title compound (C₁₉H₂₁F₃N₂O₅) has been determined from three dimensional X‐ray diffraction data. The crystals are monoclinic, a = 7.626(4)Å, b = 17.515(4)Å, c = 15.066(3)Å, β = 101.02(3)°, V = 1975(1)ų, Z = 4, D_calc = 1.393g cm^‐3, space group P2₁/c. The structure was solved by direct methods and refined by full‐matrix least‐squares method (R = 0.039).     

Crystal Structure of the Fibrillar Zinc Trimolybdate ZnMo3O10 · 3.75 H2O by Powder Diffraction Methods

The crystal structure of polycrystalline fibrillar zinc trimolybdate ZnMo₃O₁₀ · 3.75 H₂O, has been solved ab initio by the Powder Diffraction — Direct Methods package POWSIM. The structure was refined by the Rietveld method with final discrepancy factors R_F = 11.0 and R_wp = 21.0%. The structure consists of polymeric chains parallel to the b axis built up of MoO₆ octahedra. The space group is Immm (71) with a = 8.8330(6), b = 3.8207(4), c = 15.737(2) Å V = 531,08(6) ų, Z= 2.     

Contribution to the Ti‐Bi phase diagram

The system Ti‐Bi has been investigated by solid/liquid diffusion couples at 400, 500, 600 and 700 °C. Indication that the growth rate of the diffusion layers at 500 °C is linear has been found, with a growth constant of around 5 × 10^–11 m.s^–1. The existence of the Ti₂Bi phase has been confirmed. Some formerly unknown binary phases (TiBi, Ti₂Bi₃, TiBi₂) have been observed. The phase TiBi is, probably, identical with Ti₈Bi₉ reported previously. All intermediate phases suffer air corrosion, but in various degrees. A tentative variant of the Ti‐Bi phase diagram, including the newly found compounds, has been constructed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The Molecular and Crystal Structure of 3β-O-(2′,3′ -O-isoropylidene-α-L-rhamnopyranosyl) — digitoxigenin

3β-O-(2′,3′ -O-isoropylidene-α-L-rhamnopyranosyl) — digitoxigenin crystallizes in the monoclinic space group P 2₁ with two molecules C₃₂H₄₈O₈ per unit cell and the lattice constants a = 7.865, b = 6.470, c = 29.803 Å, β = 93.95°. The structure was solved by direct methods of phases determination and subsequently refined by least squares technique to the final R-value 0.06. The position of the lactone ring is disordered in the crystal.