Structure, absolute configuration, and conformation of the antimalarial drug artesunate

The crystal and molecular structure of the antimalarial compound artesunate has been determined by direct methods. Crystals are orthorhombic, P2₁2₁2₁, a = 9.8371(12), b = 10.517(2), c = 18.7594(5) Å, Z = 4, D _c = 1.316 mg/mL. The molecule is comprised of a fused ring system containing a six-membered ring C which includes an oxygen bridge and a peroxy bridge. The 9-atom oxygen–carbon chain from O(5)—C(12)... to ... O(2)—C(6) displays a striking sequence of short, long, short, long ... bonds while these distances are all within the ranges of a normal single bond or partial double bond. It is proposed that this pattern is caused by the delocalization of the lone pair electrons on the oxygen atoms. The ring C has a distorted boat conformation and the C—O—O—C torsion angle is 46.3(2)°. Rings A and D have ideal chair conformations. Ring junctions A/B and A/D are cis junctions, B/D and C/D are trans. Packing of the molecules is stabilized by one strong hydrogen bond involving the hydroxyl group on the ester linkage and the oxygen atom of the lactone ring.     

Crystal structure and conformation of the antimalarial drug 5,7-methoxy-8-(3-methyl-1-buten-3-ol)-coumarin

The crystal and molecular structure of the antimalarial compound 5,7-methoxy-8-(3-methyl-1-buten-3-ol)-coumarin, C₁₆H₁₈O₅, M _r = 290.3 Da, has been determined from X-ray diffraction data. The material crystallizes in the monoclinic space group P2₁/c with 4 molecules per unit cell of dimensions a = 8.9044(9), b = 17.623(1), c = 10.175(1) Å, = 113.97(1)°, crystal density D _c = 1.322 g/cm³. The structure was determined using direct methods and refined by full-matrix least squares to a conventional R index of 0.066 for 2416 measured reflections and 206 parameters.The coumarin ring system is almost planar with the methoxy C atoms rotated slightly out of the coumarin mean plane. Apart from the terminal CH₃ groups C(12) and C(13), which are 1.184(3) Å above and –1.315(3) Å below the plane, the 3-methyl-1-buten-3-ol substituent is planar (rms deviation 0.009 Å) making an angle of 6.31(7)° with the phenyl ring. One intermolecular hydrogen bond is present in the crystal structure between O(5)–HO(5) and the symmetry related O(2) oxygen, generated by the symmetry operation (x, 1/2 – y, –1/2 + z).     

Structure,absolute configuration,and conformation of a fused complex cyclic carbohydrate from a cameroon plant extract (CAMT2)

The crystal and molecular structure of the natural product C₂₉H₃₈O₉, an extract from a Cameroonian plant, has been determined by direct methods. Crystals are orthorhombic, P2₁2₁2₁,a=24.571(4),b=16.398(3),c=13.778(4) Å,Z-8,D _c=1.270 mg/m³. The final R-factor for 2892 reflections withI>2(I) is 0.0531. The two molecules forming the asymmetric unit have very similar molecular geometry. each molecule comprising a nucleus of six fused rings B to G: where B=pyranyl, C=pyranyl, D=furanyl, E=cyclohexene, F=pyranyl, G=cyclohexyl. Ring B also has a furanyl side-group (ring A). The ring conformations in both molecules are: A (1/2-chair/envelope); B(envelope); C(envelope); D(1/2-chair); E(1/2-chair); F(envelope); G(chair). In the cyclohexene ring E the substitution pattern is 2-hydroxy 3-methyl 5-dimethyl. The two molecules in the asymmetric unit are linked by two OH...O hydrogen bonds to form the crystal structure.     

Crystal structure,conformation, and absolute configuration of (−)-menthyl-p-bromophenylglyoxylate

The crystal and molecular structure of (—)-menthyl-p-bromophenylglyoxylate has been studied by x-ray diffraction techniques using diffractometer data. Crystals of this compound are triclinic:a= 10.152(3),b=19.661(3),c = 9.220(3) Å, α = 92.45(2), β = 102.74(4), γ = 93.11(4) °, andZ = 4. The structure was refined by least squares toR = 0.064. All 88 hydrogen atoms were determined from electron density difference maps. The significant structural features are the following: (i) the four molecules are conformationally different from one another; (ii) the two > C=O groups of the glyoxylate are twisted with respect to each other across the central C-C bond by angles ranging from 92 ° to 111 °; (iii) the phenyl group is coplanar with the proximal > C=O group; and (iv) all four molecules exhibit a conformation in which the axial hydrogens on the cyclohexane rings eclipse the closer keto oxygen. The absolute configuration was determined by the anomalous dispersion method and is (1R, 3R, 4S).     

Structure and absolute configuration of enhydrin bromohydrin

X-ray study of enhydrin bromohydrin, C₂₃H₂₉BrO₁₀, reveals that the crystal has space groupP2₁2₁2₁ with cell parametersa =10.08,b = 26.97, andc = 8.94 Å. There are four molecules in the unit cell. The structure was solved by direct methods, with three-dimensional CuK diffractometer data to = 75 °, and refined by block-diagonal least squares to anR index of 11.4% for 2254 reflections. The molecule is a germacronolide sesquiterpene having acis sterochemistry at the C(1), C(10) double bond and atrans configuration at the epoxide ring, C(4)-O-C(5). The absolute configuration established on the basis of the anomalous scattering of CuK. radiation by the bromine atom shows that the asymmetric atoms have the 4R, 5R, 6S, 7S, 8S, 9S, 20S, and 22S configurations.     

Configuration,conformation and crystal structure of rabdosianin b

Rabdosianin B, 7,20‐epoxy‐7β‐hydroxy‐1α,6β,11α,15β‐tetraacetoxy‐ent‐kaur‐16‐ene, C₂₈H₃₈O₁₀, was the first isolated from Isodon henryi. It consists of three six‐membered rings A, B, C and one five‐membered ring D. The fused‐ring system A, B and C are in chair, boat and chair conformations, respectively, and ring D is in an envelope conformation, on the basis of NMR and X‐ray diffraction analysis. The crystal of rabdosianin B is in orthorhombic crystal system with space group P2₁2₁2₁, lattice constants: a = 9.969(1) Å, b = 15.400(3) Å, and c = 17.624(3) Å, Z = 4. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,characterization and magnetic behaviour of a linear chain poly(oxomolybdophosphate) compound

A new linear chain compound, [Cu(en)₂][Cu(en)₂(H₂O)_1.5][Cu(en)₂(H₂O)₂]_0.5[{Cu(en)₂}₅{HP₂Mo₅O₂₃}₃] · 6.5H₂O ( 1 ) (en = ethylenediamine), has been synthesized under mild hydrothermal conditions, and characterized by elemental analysis, IR, thermogravimetric analyses, magnetic susceptibility measurements and single‐crystal X‐ray diffraction. The crystals are monoclinic, C2/c, a = 42.509(2) Å, b = 25.542(2) Å, c =22.1011(14) Å, β = 102.5940(10)º, V = 23419(3) ų, Z = 8. The crystal structure of 1 features Cu‐bearing cations that are both free as well as being coordinated to the poly(oxomolybdophosphate) groups formed a linear chain that runs along the b axis. Magnetic studies show that the complex is antiferromagnetic. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Structure and absolute configuration of 9-desoxy-9-chloroquinine,C20H23N2OCl

The title compound crystallizes in the orthorhombic space groupp2₁2₁2₁a=8.674(1),b=8.944(1),c=23.255(4) Å,Z=4. The structure was solved by direct methods, and refined by full-matrix least squares toR=0.047 for 1472 observed reflections. Determination of the absolute configuration [S at C(9)] enabled a discrepancy in the literature concerning the stereochemical outcome of the reaction between SOCl₂ and quinine to be resolved.     

Crystal structure,absolute configuration and stereochemistry of nupharidine hydrobromide

An X-ray diffraction study of nupharidine hydrobromide has been carried out in order to obtain an unequivocal solution to the question of the N-oxide configuration. Nupharidine hydrobromide (C₁₅H₂₄BrNO₂) crystals are orthorhombic, space groupP2₁2₁2₁ withz = 4. The unit cell constants at 22 ± 3 ° area = 13·419(2),b = 13·668(4),c = 8·731(2) Å (CuK₁, = 1·54051 Å). Three-dimensional intensity data, to the limit 2 = 145 ° for CuK₁, were measured on a GE XRD-490 automatic diffractometer equipped with Ni-Co balanced filters for monochromatization. The crystal structure was solved by the heavy-atom method and refined by least squares to anR of 0·06 for 1960 reflections.X-ray analysis clearly established that (a) the quinolizidine N-oxide system is built of twocis-fused chairs, (b) the methyl and the furan substituents occupy the equatorial position and (c) the absolute configuration indicated by the chemical methods is in agreement with the X-ray work. The stereochemical aspects of the Polonovski elimination reaction in the conversion of (+) nupharidine to ⁶-dehydrodeoxynupharidine has been studied in the light of these X-ray results.     

Structure and absolute configuration of 10-chloro-10-sulfinylcamphor,C10H13ClO2S

The structure of the title compound, C₁₀H₁₃ClO₂S, was determined by X-rays:M _r =232.72, monoclinic, space groupP2₁,a=6.4902(6),b=12.022(1),c=14.130(3) Å,=103.11(1)°,V _c =1073.7 ų,Z=4,D _x =1.44 Mg m^–3. MoK radiation (graphite crystal monochromator, =0.71069 Å),(MoK)=4.9 cm^–1,F(000)=342,T=293 K. Final conventionalR-factor=0.035 for 2221 observed reflections and 252 variables. The structure was solved usingDirdif. The absolute configuration of the structure is reported. The two independent molecules differ primarily in the orientation of the sulfine group with respect to the camphor moiety.On leave from the Department of Chemistry, University of Colorado, Boulder, Colorado 80309.     

非线性光学晶体BaBPO5的生长、结构研究

本文采用顶部籽晶高温溶液法,以Li4P2O7为助熔剂,生长了大尺寸BaBPO5单晶.进行了BaBPO5晶体的结构测定,结果表明该晶体属三方晶系,空间群:P3221,晶胞参数为a=b=0.71329(10)nm,c=0.70368(14)nm,α=β=90°,γ=120°, Z=3.该晶体结构中沿[001]方向存在BO4四面体链,每一个硼氧四面体用它的两个顶点分别与两个PO4四面体相连组成螺旋状的链.硼氧四面体、磷氧四面体和钡氧多面体结合在一起形成一个三维网络结构.同时,对BaBPO5的粉末倍频效应进行了研究.     

Crystal structure and conformation of frentizole, [1-(6-methoxy-2-benzothiazolyl)-3-phenylurea, an antiviral agent and an immunosuppressive drug

Crystals of Frentizole (from ethanol/water) are monoclinic, space group P2₁/c, with a = 11.187(4), b = 7.392(2), c = 32.727(6) Å, = 92.77(2)°, Z = 8, D _o = 1.47 g/cm³, and D _c = 1.472 g/cm³. There are two independent molecules in the crystallographic asymmetric unit with very different conformations. In molecule A the urea group is in the plane of the benzothiazole ring (0.9°) whereas in molecule B the dihedral angle between them is 4.4°. The dihedral angle between the planes of the phenyl group and the benzothiazole ring are ±157° and ±12°, respectively, in the two molecules. The molecules are linked by a pair of N–H···N hydrogen bonds involving the urea nitrogen and two other N–H···N bonds involving the urea nitrogen and the nitrogen of the benzothiazole group.     

晶体结构控制晶体形态的理论及应用

本文对比分析了研究晶体宏观形貌与内部结构关系的3种主要理论,即布拉维法则、周期键链理论和负离子配位多面体生长基元理论.提出利用布拉维法则,结合晶胞形状及结构中螺旋轴、滑移面的影响,可以更准确地分析晶体的习性,并据此对晶体习性进行了分类.     

Growth and crystal structure of the layered compound TlGaSe2

The semiconducting compound TlGaSe₂ was grown by solid state reaction technique. The crystal structure of this material was confirmed by single‐crystal X‐ray diffraction. TlGaSe₂ crystallizes in the monoclinic system with space group C2/c (No. 15), Z = 16 and unit cell parameters a = 10.779(2) Å, b = 10.776(1) Å, c = 15.663(5) Å, β = 99.993(6)°. The structural refinement converged to R(F) = 0.0719, R(F²) = 0.0652 and S = 1.17. The structure consists of a three‐dimensional arrangement of distorted TlSe₈ and GaSe₄ polyhedrons. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Single Crystal Growth,Structure and Physical Property of LiCoO2 and LiNiO2

Abstract

Single crystals of LiCoO₂ and LiNiO₂ have been successfully grown for the first time by a flux method. A single-crystal X-ray diffraction study confirmed trigonal symmetry, and their lattice parameters were a = 2.8161(5) Å and c = 14.0536(5) Å for LiCoO₂, and a = 2.8899(13) Å and c = 14.1938(17) Å for LiNiO₂, respectively. The cation distribution in Li_0.92Ni_1.08O₂ was determined to be (Li_0.74Ni_0.26)_3a[Li_0.18Ni_0.82]_3bO₂ with a final R value of 2.7% by a single-crystal X-ray structure analysis. LiCoO₂ proved to show a semiconducting behavior below room temperature by an in-plane electrical resistivity measurement using the single crystal specimen.     

Carnosol. Crystal structure,absolute configuration,and spectroscopic properties of a diterpene

The structure and absolute configuration of naturally occurring Carnosol have been investigated by X-ray analyses. Crystal data are: orthorhombic P2₁2₁2;a=15.762(1),b=13.755(1),c=7.7747(7) Å,Z=4,V=1688.2 ų, andR=0.031 (2569 reflections). The absolute configuration is established at a significance level better than 0.995 according to HamiltonsR-factor test and is in accordance with that predicted experimentally by chemically means. Correlation of the solid-state IR pattern of the regions sensitive to hydrogen bonding (CO and OH stretching bands) with the X-ray crystal structure is excellent and shows, that even weak inter- and intramolecular hydrogen bonds may be unambiguously identified by IR spectroscopy. The variable-temperature nuclear magnetic resonance studies (NMR) show that the twinning of the signals from the isopropyl methyl protons cannot be due to hindered rotation but can be ascribed magnetic nonequivalence induced by the chiral centers.     

Crystal Structure of N2,N2-Dimethylacetamidinium N,N-Dimethylcarbamate

The title compound crystallizes in the monoclinic space group P2 1 /c with four formula units in a unit cell of dimensions a = 10.814(2), b = 8.400(2), c = 11.398(4) A, β = 110.86(2)°, V = 967.5(5) A³. The crystal structure is characterized by almost exactly planar [Me₂NC(NH₂)Me]⁺cations and [O₂CNMe₂ ]^- anions which are approximately perpendicular oriented to one another. The amidine N¹—C and N²—C bond lengths are significantly different (1.341(7) and 1.292(7) A, respectively) but the C—O distances of the carbamate anion are equal within experimental error (1.263(6) and 1.256(6) A). An essential feature of the crystal structure are N—H —O hydrogen bonds between cations and anions.     

新型铝硅酸盐磷光体的结构及性能研究

以凝胶燃烧法在相对较低温度下合成了长石型的蓝白色长余辉材料Sr0.94Al2Si2O8:Eu2+0.02,Dy3+0.04,并用X射线粉末衍射(XRD)、荧光分光光度计(FL)以及扫描电子显微镜(SEM)等技术对样品的物相结构、光谱性质、微观形貌及粒度等进行了分析表征.结果发现:尿素用量、点火温度、还原温度及时间、冷却方式等工艺条件均直接影响样品的晶体结构,进而影响其发光性质.长余辉性能最佳时产物属于六方晶系及单斜晶系的混晶;其激发峰是位于290～400nm处的宽带峰;发射峰是位于380～520nm处的宽带峰,由两个发光中心构成,390nm处的发射峰归属于Dy3+的 4H21/2→6H15/2跃迁,440nm处的发射峰归属于Eu2+的4f65d1→4f7跃迁.结合XRD分析,我们认为两种发光中心是由于样品中包含两种晶型,且两种晶型的发射中心不同,六方晶系的发射中心以Dy3+为主,而单斜晶系的发射中心以Eu2+为主.1200℃还原1h后强制冷却所得样品的颗粒较细,一次粒径大约为0.5μm.     

Crystal Structure Analysis of a New Coumarin Derivative

The title compound (6,6‐dimethyl‐cis‐6H,6aH,7H,12bH,13H‐bis[1]benzopyrano[4,3‐b:4',3'‐d]pyran‐13‐one) crystallizes in monoclinic space group P2₁ /c with Z = 4. The unit cell dimensions are a = 8.6231(2) Å, b =10.0260(2) Å, c = 19.8376(2) Å, and β = 102.1(1)°, V = 1674.51(5) ų , D_cal = 1.326 Mg/m³. The coumarin moiety is in the planar conformation, the dioxadecalin moiety is cis fused and within the dioxadecalin moiety both the rings are in half cahir/sofa conformations. The structure has many C‐H … O type interactions.     

Crystal structure and absolute configuration of the indole alkaloid arborescidine C

The structure and absolute configuration (3R, 17R) of the indole alkaloid arborescidine C were determined by x-ray diffraction. The six-membered ring assumes a half-chair conformation and the seven-membered ring has a twist-like conformation. The crystal packing is characterized by intermolecular hydrogen-bonding between the hydroxyl group and nitrogen atom N4 which leads to the formation of infinite chains of molecules along the a-axis of the crystal. The absolute configurations of two related indole alkaloids, arborescidine B and arborescidine D are inferred from the experimentally determined configuration of arborescidin C molecule. A comparison of the present structure with that of a related indole alkaloid akagerine showed significant conformational and configurational differences. Crystal data: C₁₆H₁₉N₂OBr, orthorhombic, P2₁2₁2, a = 10.3376(8), b = 15.461(4), c = 9.2094(9)Å, V = 1471.9(6)ų, Z = 4, D _calc = 1.510 g cm^–3, = 1.54178Å.