Chemistry and Significance of the Carbohydrate Moieties of Human Serum Glycoproteins

The glycoproteins exercise important biological functions as transport proteins, inhibitors, enzymes, hormones, complement factors, and immunoglobulins. Their chemistry is characterized by a number of rules. Thus only asparagine, threonine, or serine can carry the oligosaccharide groups; for the N-acylglycosylamine linkage involving asparagine, the grouping Asn-X-Thr or Asn-X-Ser is always present in the peptide chain. However, practically no agreement is found in the molecular weights of the glycoproteins, their carbohydrate contents, and the relative contents of the-various sugars. The biological significance of the carbohydrate fraction has not yet been explained, but some idea of the part played by the easily removable neuraminic acid is being formed.     

Syntheses,Structure Analyses and Thermal Stabilities of Two Schiff Base Metal Complexes

A Schiff base ligand 1‐salicylideneamino‐1,3,4‐triazole (L) was prepared. Two new complexes with Schiff base, [Zn(L)₂(SCN)₂] ( 1 ) and [Co₂(L)₅(SCN)₄]·H₂O ( 2 ) have been synthesized and structurally characterized. Complex 1 takes a mononuclear zinc structure and the coordination geometry of zinc atom exhibits a distorted tetrahedron, in which a zig‐zag chain is constructed through hydrogen bonding interactions. A 2D supramolecular network is formed through Π‐Π stacking between triazole planes and phenyl planes of adjacent chains, and a 3D supramolecular network is further constructed by these non‐covalent Π‐Π stacking interactions between the triazole planes of neighboring layers. Complex 2 takes a dinuclear structure with the bidentate‐bridging Schiff base ligands, and cobalt site exhibits a distorted octahedron. The lattice water molecules and neutral complex 2 units form a dimer with hydrogen bonding interactions. In addition, IR and thermal gravimetric analysis are presented.     

含三唑基希夫碱的锰配合物的合成及结构

合成了4-(4-氯苯基亚甲基)亚胺-1,2,4-三唑希夫碱配体(L),以及希夫碱的配合物[Mn(SO4)(H2O)2L]n,并对配合物进行了结构表征。该配合物是1个用硫酸根桥连而成的一维链状配位聚合物,相邻的链通过水分子和硫酸根的氢键相互作用形成了二维超分子结构。利用DSC技术测试了配合物和固体推进剂主要组分(HMX,NC,RDX)的二元混合体系的热分解行为。本文也对配合物做了元素,红外光谱分析。     

X-Ray Structure of Lagochirsidine and Di-o-cyclohexylidenelagochilin

The structures of two diterpenoids from the lagochiline group, lagochirsidine and di-o-cyclohexylidenelagochilin, were determined by x-ray structure analysis.     

粉末衍射技术解析青蒿素晶体结构方法学比对研究

以粉末X射线衍射技术(PXRD)表征有机物晶体结构为目的,选取我国第1个全新药物青蒿素(Artemisinin)验证粉晶解析有机物晶体结构方法的合理性。粉晶解析结果为正交晶系,P212121空间群,a=23.98223±0.01624,b=9.42480±0.00645,c=6.34589±0.00439,α=β=γ=90°,Z=4,V=1434.693;单晶解析结果为正交晶系,P212121空间群,a=23.9564(9),b=9.3224(5),c=6.3205(3),α=β=γ=90°,P212121,Z=4,V=1411.55(17)3;两者所确定分子非氢结构键长、键角、二面角的相关系数分别为0.9921、0.9833和0.9997,晶胞参数基本吻合,分子构型相似。结果表明,粉晶X射线衍射技术可以求得较为准确的青蒿素晶胞参数及晶胞内分子构型。     

用X射线研究煤中大分子的结构

煤的大分子结构可用化学方法和物理方法进行研究。在化学方法中,煤结构统计分析法占有重要地位,但其结果存在一定统计误差。本文研究了一系列不同级别煤的高角X射线散射强度,结果表明,随煤级别增高,煤大分子结构的X射线参数的变化是连续的。显然,这一工作对于研究煤中大分子的结构是很有意义的。     

X-Ray Structure and Proton NMR Study of a Hexacoordinated Lithium Complex

The structure of the lithium complex with1,3,5-tris[oxymethylene(N,N-dicyclohexyl)carboxyamido]cyclohexanehas been determined by the X-ray method.The compound is triclinic, space group P¯1,a = 15.623(3), b = 19.279(4),c = 19.295(4)Å = 102.32(3), = 92.45(3), = 105.67(3)0, V = 5436(2)Å3, Z = 4. Itscomposition is represented by the formulaC48H82N3O6LiI 0.5H2O. The lithium cationis encapsulated in a polar pseudo-cavity of six oxygen atoms of the ligandmolecule and displays a distorted trigonal prism coordination. The conformationof the ligand in the solid state complex has been compared with the conformationof the complex in solution determined by 1H-NMR measurements.Supplementary data relevant to this publication have been deposited with the British Library, No. SUP 82224 (21 pages).     

RbCl和CsCl水溶液结构的X射线散射及经验势结构精修模拟

采用X射线散射法研究了RbCl和CsCl水溶液的结构,利用基于经验势的结构精修(EPSR)方法获得了溶液中的水合Cl^-、Rb⁺、Cs⁺、离子缔合及本体水的对径向分布函数、配位数分布及空间密度分布(3D结构)等结构信息。在水溶液中,Cl^-具有相对稳定的6水合结构,其水合距离为0.321 nm,外加阳离子对其水合作用的影响不明显。7.3 ± 1.4个水分子与Rb⁺水合,其特征水合距离为0.297 nm,8.4 ± 1.6个水分子与Cs⁺水合其水合距离为0.312 nm。Cs⁺不具有第二水合层,而Rb⁺表现出了更强的水合能力,具有较明显的第二水合层。Cl^-、Rb⁺及Cs⁺常被认为是“结构破坏”型离子。从微观角度来看这种所谓的“结构破坏”主要体现在破坏了本体水分子的第二水合层保持四面体构型的趋势。RbCl和CsCl水溶液中部分存在着Rb-Cl和Cs-Cl直接接触离子对,在1.0 mol·dm^-3的溶液中Rb-Cl及Cs-Cl的特征距离分别为0.324和0.336 nm,溶剂分割离子对的距离则都在0.6 nm左右。相对于Cs⁺,Rb⁺与Cl^-离子之间表现出了更强的缔合能力。     

X-Ray Study of the Electronic Structure of Copper(II) Acetylacetonate

The Cu(acac)₂ complex was investigated by X-ray emission and XANES spectroscopy using synchrotron radiation. Structural data for the complex were obtained in chloroform solution and C₂F matrix. The experimental spectra and their fitting on a single scale of binding energies point to possible relaxation effects. As shown by model quantum-chemical calculations, the structure and energy position of the LUMOs constructed from the vacant metal 4p, 5p AOs strongly depends on the nature of the nearest environment.Original Russian Text Copyright © 2004 by L. N. Mazalov, S. V. Trubina, E. S. Fomin, I. M. Oglezneva, G. K. Parygina, N. V. Bausk, and I. K. Igumenov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 844–851, September–October, 2004.     

用热重分析与X-射线衍射法探究中国花鲈耳石的微结构

为表征中国花鲈耳石的微结构,应用数码照相机、热重分析仪与X-射线衍射仪对中国花鲈耳石的外观形貌、化学组成与晶体结构进行记录及表征。结果显示:中国花鲈耳石为较厚的宽叶形,表面有不同大小的晶状突,边缘有叶形晶状突,内弯面有中央突,弯曲背面有嵴突及几乎贯穿整个耳石的主凹槽;TGA曲线分为晶体间隙水的挥发,有机质和无机盐的灰化与分解,碳酸钙热分解为氧化钙等三个平台,化学组成中碳酸钙含量为97.92%,水、有机质和其它无机盐含量为2.08%;XRD晶体结构属于稳定性较差的含很少量第二相的霰石。组成与结构的表征有助于鱼类耳石的化学生物学分类数据库的建立,也丰富了耳石的研究内涵。     

Automation of Structure Analysis. Part II. Automation of the Evaluation

The extent to which it is possible to automate the determination of a structure from the data collected with automatic measuring equipment is discussed. The development of the automatic evaluation is synchronous with that of digital computer program.—Even the simple calculation of structure factors from the intensities (i.e. the analysis of the geometrical and physical intensity factors) takes several weeks when the many thousand reflections are processed “manually”, i.e. with a desk calculator. A large electronic computer, on the other hand, executes these calculations in a few seconds. Nevertheless, even the largest computers available at present are too small for many of the complex steps in the calculation and for the quantity of data involved. Evaluation methods which, owing to long computing times, can at present only be tested on relatively simple structures will become more attractive with the advent of machines with computing times in the nanosecond range. For corrigendum see DOI: 10.1002/anie.196605112     

原位微区同步辐射X射线荧光和近边吸收谱研究铅耐受细菌吸附-转化铅机理

为了从微观水平研究细菌生物吸附及转化铅机理,利用原位微区同步辐射X射线荧光(μ-SRXRF)及X射线吸收近边结构谱( XANES)研究云南兰坪铅锌矿区农田土壤样品中筛选的铅耐受性细菌吸附铅的分布特征及铅形态转化规律。土壤中具有铅耐受性的菌株主要为Arthrobacter sp.属(节杆菌属),采用μ-SRXRF对其吸附铅的含量进行快速简单直接分析,部分细菌吸附铅的含量高达5925μg/g,富集系数达14.8。XANES结果表明,细菌吸附 Pb 后存在形态为 PbS、(C17 H35 COO)2Pb 和 Pb5(PO4)3Cl 分别占58.0％,22.2％和19.8％,与培养基本身以有机态为主的Pb形态有明显差异,表明培养基中铅被细菌吸附后有向硫化物转化的趋势,这为研究重金属生物有效性的影响因素提供了实验参考。     

Single-Crystal X-Ray Diffraction Studies of Oligonucleotides and Oligonucleotide–Drug Complexes

Nucleic acids constitute the library of genetic information for all living organisms. They also play a regulatory role in many biological events concerned with the utilization of genetic information. The double-helical model of DNA, proposed by Watson and Crick in 1953, suggested the structural basis for its biological role, but this insight into nucleic acid structures seems to have generated as many questions as it has provided answers. Experimental studies, in particular fiber diffraction work, yielded a wealth of information on the conformational flexibility of nucleic acids and on the importance of interactions with water and cations. Major advances in synthetic organic chemistry, with implications for molecular biology, propelled nucleic acid research forward in the late 1970s. The availability of milligram quantities of synthetic oligonucleotides of defined sequence and high purity paved the way for detailed and accurate structural analysis using single-crystal X-ray diffraction methods and, in more recent times, NMR spectroscopy. This article is a detailed survey of the structural results generated by crystallographic techniques as applied to DNA, RNA, and nucleic acid–drug complexes over the period 1979–1990. The appendix lists important definitions used in the characterization of oligonucleotide structures.     

四种新型柔性吡啶基配合物的合成、结构及配体构象与配合物结构的关系

合成了柔性配体3-吡啶甲酸-1,2-乙二酯(3-pyridinecarboxylic acid 1,2-ethanediyl ester,pcaede),并将其分别与Co盐和Hg盐进行组装,得到4个新配合物[Co(pcaede)2Cl2.2CH3CN.H2O]n(1),[Co(pcae-de)2Cl2.H2O]n(2),[Hg(pcaede)I2]n(3)和[Hg(pcaede)Br2]n(4),对其进行了元素分析、红外光谱及X射线单晶结构分析.配合物1和2为含有孔道的一维链状结构,配合物3是1D内消旋螺旋链,配合物4则是锯齿形1D链状结构.研究结果显示,孔道中填充的溶剂分子和平衡阴离子对配合物的组装有显著的影响.此外对4个配合物中配体的构象进行了理论计算.     

温度对液态水结构的影响：中子及X射线散射研究

采用中子散射和X射线散射研究了液态水在298～373 K温度范围内的结构,通过偏径向分布函数(PDF)、配位数分布(CN)、角分布(ADF)及空间密度分布(SDF)等讨论了温度对液态水结构的影响。整体来看,液态水具有"不规则四面体"氢键网络的短程有序结构,该有序度可延续到第三水合层。液态水分子的第一水合层中,围绕中心水分子约有4.8个水分子,然而其中仅有约3.3个水分子与中心水分子通过氢键相键合,约1/3进入到第一水合层的水分子并未与中心水分子直接键合,也正是这些间隙水分子的存在加剧了液态水结构的复杂性。温度对液态水的有序度存在一定的影响,在298～373 K的有限温度变化范围内,温度对液态水中氢键的键长、键角分布及第一水合层SDF的影响不大。从298K升温到373K,O(W)-O(W)距离仅增加0.03?,氢键数目也仅有微小减少,温度对第二和第三水合层的影响则要显著很多。     

Synthesis,Crystal Structure and Properties of a Pentanuclear Carboxylato-Bridged Complex Containing a Cu3Y2 Core

Abstract

Preparation and isolation of a pentanuclear mixed metal complex having the formula [Cu₃Y₂(Cl?CH₂COO)₁₂(H₂O)₈] · 2H₂O was accomplished by the reaction of a mixture of copper(II) nitrate and yttrium nitrate with sodium chloroacetate in aqueous solution. The structure of the complex was determined by X-ray crystallography. It consists of linear centrosymmetric pentanuclear molecules with a four-coordinate copper atom at the inversion site and the other two copper atoms having a 4 + 1 coordination geometry at both ends. Two yttrium atoms separate the three copper atoms. Each yttrium atom is bridged to the neighbouring terminal copper atom by four carboxylato ligands in a syn-syn fashion forming a dimer with the Y…Cu distance being 3.5311(8) Å. Each dimer is then linked to the central copper atom via a carboxylato bridging ligand in a syn-anti fashion. Two other carboxylato ligands coordinate to the central copper to complete its planar coordination. The apical site of each terminal copper atom is occupied by a water molecule. The eight-coordinate geometry of each yttrium atom is completed by three water molecules. Bridging and the monodentate carboxylato ligands were characterized by IR analysis. TG studies confirmed the numbers of coordinated and lattice water molecules.     

Syntheses and crystal structures of azafulleroid and aziridinofullerene bearing silyl or germyl benzene

Addition of silyl and germylmethyl azides (1) to fullerene C₆₀ at 50 °C through [2+3] cycloaddition led to the formation of the triazoline adducts (2). Subsequently, heating 2 at 100 °C in the solid state, caused N₂ extrusion producing two different isomers, [5,6]-azafulleroid (3) and [6,6]-aziridinofullerene (4). The ¹³C NMR spectrum of 3 had an absence of resonances in the aliphatic region for the fullerene C₆₀ cage, showing a fulleroid with C_S symmetry. In contrast, 4 exhibited one sp³ resonance in the aliphatic region for the fullerene C₆₀ cage, indicative of an aziridinofullerene with C_2V symmetry. However, MALDI-TOF mass characterization was hampered because ion peaks corresponding to the bis-adduct are detected in positive ion mode measurements, whereas the ion peaks [M−N₂]⁻ for 2a as well as [M]⁻ for 3a and 4a are observed in negative ion measurements. In an effort to obtain X-ray data, silyl and germylphenyl groups were introduced to form intermolecular complexes with fullerene C₆₀. The X-ray structures of 3c and 3d revealed a strong enhancement of homoconjugation in the bridged annulene moiety based on POAV analysis. The X-ray structures of 3c,d and 4c were confirmed with the detection of silyl and germylphenyl-C₆₀ interactions, similar to dimethoxyphenyl-C₆₀ interactions.     

X-Ray Crystal Structure of Four Inclusion Complexes of the Novel Host Gossindane: An Oxidation Product of Gossypol

Gossindane, the oxidation product of gossypol, demonstrates inclusion properties towards four solvents chosen accidentally. The crystal data of these complexes with ethanol (I), ethylacetate (II), dichloromethane (III) and water (IV) are: (I): C26H30O6· 2C2H5OH, monoclinic, P2/c, a = 8.687(2) Å, b = 10.986(3) Å, c = 14.778(3) Å = 110.94° V = 1317 Å3, Z = 2, R = 0.069, N = 1368; (II): C26H30O6· 0.5C4H8O2, monoclinic, P21/c, a = 8.960(2) Å, b = 21.937(5) Å, c = 14.712(3) Å, = 111.98(2)°, V = 2681 Å3, Z = 4, R = 0.083, N = 2653; (III): C26H30O6· CH2Cl2, monoclinic, P21/c, a = 8.886(2) Å, b = 21.778(6) Å, c = 14.996(4) Å, = 111.31(3)°, V = 2704 Å3, Z = 4, R = 0.131, N = 1580; (IV): C26H30O6·2H2O, monoclinic, C2/c, a = 29.422(9) Å, b = 6.720(2) Å, c = 27.525(9) Å, = 117.43(2)°, V = 4830 Å3, Z = 8. R = 0.096, N = 2240.In the solvates H-bonded host molecules form bilayers with very similar structures and a nearly hydrophobic surface. Guest molecules are placed in channels formed between these bilayers and may be H- bonded to host molecules (ethanol). In the hydrate two water molecules using their H-bonding capacity incorporate gossindane molecules into bilayers.