Crystal Structure of Synthetic High-Chromium Analogue of Yimengite

Crystallography Reports - The structure of a potassium compound with the chemical formula K0.90Ti5.16Cr2.94Fe2.54Mg0.87Al0.22Mn0.30O19 has been investigated by single-crystal X-ray diffraction...     

Crystal Structure of Niobium-Rich Lomonosovite with Symmetry P1 from the Khibiny Massif (Kola Peninsula)

Crystallography Reports - A new niobium-rich lomonosovite variety with a high degree of ordering of Ti and Nb atoms has been investigated by X-ray diffraction analysis and electron probe...     

New Data on Isomorphism in Eudialyte-Group Minerals. I. Crystal Structure of Titanium-Rich Eudialyte from the Kovdor Alkaline Massif

An abnormally titanium-rich mineral of the eudialyte group was studied by IR spectroscopy and X-ray diffraction. The trigonal unit cell parameters are a = 14.165(1) Å, c = 30.600(5) Å, V = 5317.23(4) ų, sp. gr. R3m. The crystal structure was refined to R = 0.034 with anisotropic displacement parameters using 2530 reflections with F > 3σ(F). The idealized formula of the mineral (Z = 3) is Na₈(H₃O)₅(K,Ce,Sr)₂Ca₆Zr₂Ti_1.2(Fe,Mn)_0.6Si₂₆O₇₂(OH)₂Cl · 4H₂O. At the ratio Zr: Ti ~ 2: 1, titanium atoms lie in four sites and are not predominant in any of them. Another distinguishing feature of the mineral is the structural separation of chemical elements, such that K, Sr, and Ce cations and H₃O groups are randomly distributed between four split sites to form polyhedra with different volumes. The isomorphism of Zr and Ti in eudialyte-group minerals is discussed.     

Crystal Growth from Silica Gels and Single Crystal Structure of Bariumchromate

Rhombic single crystals of bariumchromate were grown in silica gels up to 1.5 mm in size. The influence of the initial pH-value of the gel and the kind and concentration of reactants are studied. The crystal structure has been determined. The compound crystallizes in space group Pnma, with cell dimensions a = 9.113(4) Å, b = 5.528(3) Å, c = 7.336(4) Å and Z = 4. The structure was refined to R = 0.062 on the basis of 364 reflections. Every barium atome, centered in a distorted archimedian antiprism, is coordinated to 8 oxygen atoms each belonging to a chromate tetrahedron. Interatomic distances and bond angles were calculated.     

Crystal Structure of Urate Oxidase from Bacillus Subtilis 168

Crystallography Reports - Urate oxidase catalyzes the oxidative degradation of uric acid to allantoin via peroxide formation by a radical recombination mechanism. Here the crystal structure of...     

New Data on the Isomorphism in Eudialyte-Group Minerals. IХ: Blocky Isomorphism at Key Sites. Crystal Structure of Fe-Deficient Eudialyte from the Khibiny Massif

Crystallography Reports - The crystal structure and crystallochemical features of Fe-deficient manganese-rich eudialyte from the Khibiny massif (Kola Peninsula) have been investigated by X-ray...     

New Data on the Isomorphism in Eudialyte-Group Minerals. VIII: Crystal Structure of the Fe2+-Analog of Feklichevite,a Potentially New Mineral from the Khibiny Massif

Crystallography Reports - A potentially new calcium-rich eudialyte-group mineral from the Khibiny massif has been investigated by X-ray diffraction (XRD) analysis. The trigonal unit-cell parameters...     

晶体生长时的固液相结构变化分析

晶体的溶解、熔化以及结晶成核生长时的固液相原子结构是怎样变化的,晶体生长时的生长基元是原子还是原子团.本文根据各种材料液相结构的最新研究结果,提出不饱和配位结构转换模式,并以此模式对各种常见晶体材料从溶解、熔化到结晶生长时的液态母相结构变化以及晶体成核过程进行了描述和分析,认为晶体生长时的界面结构和液相结构十分接近,溶解、熔化主要是晶体表面的不饱和配位原子(离子)转换到液相结构的过程,晶体生长主要是液相中的不饱和配位原子(离子)转换到固液生长界面的位错位置,使配位结构更饱和的过程.随着液相过饱和度的增大,液相结构单元的原子数越来越多,吸附到晶体生长界面若来不及转换回液相,就形成新的位错生长中心,形成晶体生长缺陷.     

Crystal Structure of Rabdoternin A

Abstract  

Rabdoternin A is a natural diterpenoid isolated from Rabdosia rubescen and its crystal structure was determined by X-ray single crystal diffraction. The compound compactly packs in an orthorhombic unit cell in the P2₁2₁2₁ space group with unit cell dimensions a = 7.9200(10) ?, b = 11.2411(14) ?, c = 20.474(2) ?, V = 1822.8(4) ?³ and Z = 4. Two intermolecular hydrogen bonds assemble the title compound into infinite two-dimensional networks along (001) plane.     

Crystal and Molecular Structure of Rhaponticin from Rheum hotaoense

Abstract  

Rhaponticin was isolated from the rhizome and root of Rheum hotaoense C.Y. Cheng et C.T. Kao and its crystal structure was determined by single crystal X-ray diffraction. The compound compactly packs in a triclinic unit cell in the P1 space group with unit cell dimensions a = 5.1240(12) ?, b = 7.0453(17) ?, c = 14.535(4) ?, α = 83.182(3)°, β = 89.212(3)°, γ = 68.956(3)°, V = 1486.0(2) ?³, Z = 1, D _calcd = 1.436 Mg m⁻³ and F(000) = 222. The atoms of the stilbene moiety are nearly coplanar, and the dihedral angle between ring (C2–C7) and ring (C10–C15) is 9.0°. The O–H⋯O hydrogen bonding interactions link the molecules into a complicated 3D framework.     

Crystal Structure of Microclusters of Silver

Finding the crystallographic structure of clusters is a crucial and challenging problem. The properties like lattice concentration, unusual crystal symmetries etc. of metal clusters have been studied recently. We report here a 15% lattice concentration for silver clusters produced by Bredig's method.     

Extraction and Crystal Structure of Fucosterol

Crystallography Reports - The compound of fucosterol (C29H48O), an active phytosterol present in many edible marine algae, has been characterized by X-ray diffraction and extensive nuclear magnetic...     

Crystal and Molekular Structure of Piperidinium-acet-p-Cl-anilide-chloride

Piperidinium-acet-p-Cl-anilide-chloride crystallizes in the triclinic space group P 1 with 2 formula units C₁₃H₁₈ON₂Cl₂ in the unit cell. The lattice constants are a = 10.471 Å, b = 12.545 Å, c = 6.149 Å, α = 72.14°, β = 105.70° and γ = 105.21°. Bond lengths, bond angles and the conformational flexibility were determined by X-ray structure analysis. The crystal structure contains dimeres consisting of drug molecules connected by hydrogen bonds.     

A New Crystal Structure of Clarithromycin

Abstract A new crystal structure of clarithromycin single acetonitrile solvate designated “Form III” was first determined by single crystal X-ray diffraction. The compound crystallized in the monoclinic system, P2 ₁ space group with a = 10.644(2) ?, b = 18.099(4) ?, c = 11.628(2) ?, α = γ = 90°, β = 95.38(3)°, V = 2230.1(8) ?³, Z = 2, D _c = 1.175 g/cm³, μ = 0.087 mm⁻¹, F(000) = 860, R ₁ = 0.034, wR ₂ = 0.062, S = 0.875, (Δ/σ)_max = 0.001 for 2,709 observed reflections (I > 2σ (Ι)). Form III of clarithromycin, contrary to Form I, is more thermodynamically stable than Form II used currently on the market. Graphical abstract A New Crystal Structure of Clarithromycin Jian-Hua Liang, Guo-Wei Yao A crystal structure of clarithromycin single acetonitrile solvate was first determined by single crystal X-ray diffraction.