The further crystallographic refinement of trichosanthin at 2.7A resolution and the comparison among the three molecular structures in two crystal forms

The three-dimensional structure of trichosanthin at 2.7A resolution has been improved further, by refitting one of the C-terminal tails, adjusting 16 residues in the molecular surface regions, discarding some water molecules with high B values, and adjusting weights during the further refinement. The R-factor has been reduced to 18.5% and the r.m.s deviations from ideal geometry are also improved. The structures of the two molecules in the monoclinic asymmetric unit and the only molecule in the orthorhombic asymmetric unit are compared with one another. The main-chain structures for most of the residues in the three molecules are substantially the same. However, the courses of the three C-terminal tails are completely different, and the intermolecular interactions resulting from the particular packing of the molecules in the crystals account for the differences. The strand Be-2 and the preceding B-turn in small domain show large r.m.s. deviations among the three molecules and they are also involved in i     

Interlayer-type Crystal Structure of N-（1-Adamantyl） urea

1 INTRODUCTION In the context of supramolecular chemistry, mo- lecules are joined together by intermolecular interac- tions to form a supramolecule whose physical pro- perties largely depend on the orientation and packing of molecules in the crystal structures[1]. The adaman- tane is a kind of cage alkane with high symmetry and stable framework. Its derivatives are extensively applied in the fields of medicine, macromolecular materials, aviation and so on due to the unique structures and …     

Host-guest supramolecular chemistry at solid-liquid interface: An important strategy for preparing two-dimensional functional nanostructures

Supramolecular self-assembly,an important strategy in nanotechnology,has been widely studied in the past two decades.In this review,we have introduced the recent progress on construction of two-dimensional(2D)nanostructures by host-guest supramolecular chemistry at solid-liquid interface,and the interactions between the host assembly and the guest molecules are the major concerns.At first,the hydrogen bonds connected hybrid structures are discussed.And then we have paid a close attention on the surface-confined condensation reactions that has flourished recently in direct preparing novel nanostructures with increasing structural complexity.In the end,the cavity confinement of the 2D supramolecular host-guest architectures has been studied.On the basis of the above-mentioned interactions,a group of functional hybrid structures have been prepared.Notably,scanning tunneling microscopy(STM),a unique technique to probe the surface morphology and information at the single molecule level,has been used to probe the formed structures on highly oriented pyrolytic graphite(HOPG)surface.     

Structure and property of the hydrogen bonding complex between triazines and water

The study of the intermolecular interactions that drive the solvation of six-membered nitrogenated aromatic rings is of particular importance since they are known to constitute key building blocks of pro- teins and nucleotides[1―5]. The investigation of the 1:1 adduct of these molecules with water will be the first step in the understanding of such interactions. These molecules possess two different proton-acceptor sites: the ring π cloud and the lone pairs of electrons on the nitrogen atoms…     

DFT Study on the Effect of Hydrogen-bond Formation on the Adsorption of Aminotriazines on Graphene

DFT calculations have been performed to explore the aminotriazine adsorption on graphene surfaces.Relative energies,equilibrium geometries and electronic structures of monomer and dimer of aminotriazine molecules adsorbed at the surface were investigated and analyzed in details.It was found that the hydrogen atoms in the NH2 group of aminotriazine molecules are directed toward the graphene surface,and the adsorption energy increases as the NH2 group is added.The adsorbed aminotriazine molecules facilely form a dimer through the hydrogen bonding interactions,and the two aromatic rings of optimized structure of 2-amino-1,3,5-triazine(B) dimmer(denoted by B2) and melamine(D) dimmer(denoted by D2) are parallel to the graphene sheet.The large deviation of the averaged adsorption energy of B2 and D2 compared to monor adsorption may reflect the increase of π-π repulsion and the effect of hydrogen bond formation.The electronic structure analyses reveal that the formation of hydrogen bonds in melamine dimer has great influence on the adsorption mode at the graphene surface.     

X-RAY STUDIES ON THE STRUCTURE OF DES-PENTAPEPTIDE INSULIN AT 2.4 RESOLUTION——THE DPI MOLECULE AND ITS STRUCTURAL RELATIONSHIP WITH INSULIN

The structure of the monomeric insulin analogue des(B26—B30) insulin is presented.; A detailed comparison with the 2Zn insulin structures shows that while there are some large changes in the structure, the basic secondary structural units maintain their integrity. The DPI structure is broadly similar to molecule Ⅰ in the 2Zn structure, and in this respect is like other crystal forms of insulin. In addition to changes on the surface of the structure there are some subtle but extensive changes in the heart of the molecule. The molecules are closely packed in the crystal with many and varied contacts, including a complex network of protein-cadmium interactions and a considerable number of water mediated contacts. The molecular surface has an unusually large number of hydrophobic groups which tend to cluster in a thick band running around the protein. The crystal structure is well ordered, indeed the clarity of some side chains and the definition of the water molecules is superior to that found in the mor     

Structural Characterization of an Exopolysaccharide from the Myxobacterium Sorangium Cellulosum NUST06

The large amounts of extracellulular matter produced by myxobacteria were composed of EPS and proteins that demonstrated as required factor for cell-cell cohesion1. There were few reports on the structure and bioactivities of the EPS in myxobacteria and all focus on myxobacterial extracellular matter were their role in myxobacteria social interactions2. Studies of the chemical structure of these molecules, constituent identification, and chemical and physical properties are essential for u…     

Synthesis,Crystal Structure and Antitumor Activity of Tectochrysin-6-sulfonate

In order to enhance water-solubility and biological utilization rate of tectochrysin,sodium 5-hydroxyl-7-methoxyflavone-6-sulfonate(1) was synthesized and its structure was identified on the basis of 1 H NMR,FT-IR and elemental analysis.5-Hydroxyl-7-methoxyflavone-6-sulfonate was assembled with Ni(II) or Mn(II),hexaquanickel(II) bis(5-hydroxyl-7-methoxyflavone-6-sulfonate) tetrahydrate(2) and hexaquamanganese(II) bis(5-hydroxyl-7-methoxyflavone-6-sulfonate) tetrahydrate(3) were obtained and characterized by IR spectroscopy.The crystal structures of 2 and 3 were determined by X-ray single-crystal diffraction analysis.The results showed that 2 and 3 are isomorphous crystals and crystallize in monoclinic crystal system,space group C2/c.In 2 and 3,the supramolecular structures are organized into hydrophilic and hydrophobic regions.Hydrophilic regions are generated by O–H???O hydrogen bonds among sulfonate groups,latticed water molecules and coordinated water molecules.The π-π stacking interactions assemble the flavone skeletons into columns and these columns form hydrophobic regions.The sulfonate groups play an important role as a bridge of the hydrophilic and hydrophobic regions as well as the inorganic and organic components.Three-dimensional networks of 2 and 3 are furnished by extensive array of hydrogen bonds,π-π stacking interactions and electrostatic interactions.The anti-proliferative activities of 1~3 in vitro against human leukemia cells K562 and human lung cancer cells A549 were evaluated by the standard MTT assay.The pharmacological activity results showed that the introduction of sulfonic acid groups enhanced the antitumor activity of tectochrysin.     

Ni（bpy）（H2O）（V2O6）和[Ni（bpy）2]2（V6O17）的水热合成与晶体结构

用NiCl2·6H2O,2,2＇-联吡啶（bpy）,NH4VO3,WO3在443K下通过水热反应法得到了两种多钒酸镍配合物Ni（bpy）（H2O）（V2O6）（1）和[Ni（bpy）2]2（V6O17）（2）．单晶X射线衍射结果表明化合物（1）属于正交晶系,空间群为Pcα2（1）,晶胞参数为0=0．91704（18）nm,b=1．0519（2）nm,c=1．4336（3）nm,V=1．3830（5）nm^3,Z=4;化合物（2）属于单斜晶系,空间群为P2（1）／c,晶胞参数为α=1．5467（3）nm,b=1．4740（3）nm,c=1．0457（2）nm,β=91．99（3）°,V=2．3826（8）nm^3,Z=4．化合物（1）由2,2’-联吡啶修饰的二维[Ni（V2O6）（H2O）]∞电中性层构成,而化合物（2）则由2,2＇-联吡啶修饰的、呈正弦波浪状的[Ni：（V6O17）]∞二维电中性层构成．     

两个具一维水链的镧系配位聚合物的合成与晶体结构(英文)

以Ln2O3(Ln=Nd和La),2,2′-联吡啶-3,3′-二羧酸(bpdc),4,4′-联吡啶(bpy)为原料,采用溶剂热法合成了2个具有二维骨架结构的无机-有机杂化材料[Nd2(bpdc)3(H2O)2]·bpy·4H2O(1)和[La2(bpdc)3(H2O)4]·4H2O(2),通过IR和X-射线单晶衍射分析等手段对其结构进行了表征。晶体1属于单斜晶系,C2/c空间群,晶胞参数a=3.3104(7)nm,b=0.74812(15)nm,c=1.9848(4)nm,β=104.75(3)°。晶体2属于单斜晶系,C2/c空间群,晶胞参数a=2.6749(5)nm,b=0.71165(14)nm,c=2.0542(4)nm,β=92.70(3)°。在这2个配位聚合物中,晶体中的结晶水沿着b轴呈现一维无限有序排列,将化合物中二维的金属有机骨架通过氢键相连进而形成了三维超分子结构。     

手性3,5-二甲基-2-芳基-2-吗啉醇盐酸盐的合成及其晶体结构

以(S)-2-氨基丙醇为手性源与α-溴-3-氯苯丙酮反应, (R)-2-氨基丙醇为手性源与6-甲氧基-2-(2-溴丙酰基)萘反应, 分别合成了手性纯化合物(2R,3R,5S)-3,5-二甲基-2-(3-氯苯基)-2-吗啉醇盐酸盐(4a)和(2S,3S,5R)-3,5-二甲基-2-(6-甲氧基-2-萘基)-2-吗啉醇盐酸盐(4b), 利用X射线单晶衍射仪测定了两化合物的晶体结构和两化合物的空间结构, 并初步分析两化合物空间结构, 化合物4a晶体属正交晶系, 空间群为P2₁2₁2, 晶胞参数为: a＝0.8718(2) nm, b＝0.7883(2) nm, c＝2.0247(6) nm, Z＝4, V＝1.3915(7) nm³, D_c＝1.328 g/cm³, F(000)＝584, R₁＝0.0399, wR₂＝0.0797, S＝1.042. 化合物4b晶体属正交晶系, 空间群为P2₁2₁2₁, 晶胞参数为: a＝0.71035 (9) nm, b＝0.77703(10) nm, c＝2.9820(4) nm, Z＝4, V＝1.6318(4) nm³, D_c＝1.318 g/cm³, F(000)＝688, R₁＝0.0520, wR₂＝0.1108, S＝0.994.     

三维超分子化合物[Ni（DMF）6]2[SiMo12O40]·H2O的合成、晶体结构及表征

合成了一个新的三维超分子化合物[Ni（DMF）6]2[SiMo12O40]·H2O,通过红外光谱、X射线单晶衍射和热重分析等手段对其结构进行了表征．单晶结构解析结果表明,标题化合物属于三方晶系,船空间群,晶胞参数为：a=1．5902（4）nm,b=1．5902（4）nm,c=3．2281（17）nm,V=7．069（4）nm^3,Z=3,Dc=1．994g／cm^3,μ=2．032mm^-1．F（000）：4146,R1=0．0516,ωR2=0．1453．配合物中镍离子采用6配位的八面体配位构型,晶体堆积中通过多种分子间氢键作用形成三维网状结构．     

Dawson结构α-H6P2W18O62·3(CH3)2NH·H2O的合成、表征和晶体结构

由二甲胺与H6P2W18O62·nH2O合成了电荷转移化合物α-H6P2W18O62·3(CH3)2NH·H2O.单晶结构解析结果表明晶体属单斜晶系,空间群为P21/c,晶胞参数a=1.2964(3)nm,b=1.3621(3)nm,c=4.155 9(8)nm,β=90.02(3)°,V=7.338(3)nm3,Z=4.标题化合物具有可逆光色性.热分析表明,化合物阴离子在430.5℃左右分解.     

聚金属氧酸盐[(C4H9)4N]6[PMo12O40]2·0.5H2O的晶体结构

在乙腈-水混合溶剂中培养得到了聚金属氧酸盐[(C4H9)4N]6[PMo12O40]2.0.5H2O的单晶.X射线衍射结构分析表明,该晶体属于单斜晶系,C2/c空间群,晶胞参数:a=4.996(10)nm,b=1.411(3)nm,c=2.633(5)nm,β=114.804(4)°,V=16.844 nm3,Z=1,R1=0.0843,wR2=0.2546.化合物分子由两个多阴离子[PMo12O40]3-,6个四丁基胺阳离子[n-Bu4N]+和0.5个结晶水组成.     

富氮杂环配位超分子化合物的合成、结构及光谱特征

以2,6-二(5-甲基-1H-吡唑-3-基)吡啶(简写为H2L)为第一配体,以均苯四甲酸和乙酸为第二配体,合成了2个新的配位超分子化合物[Ni(H2L)2]·(Me O-H2BTA)2(1)和Mn(H2L)(Ac)2(2)(H4BTA∶均苯四甲酸,HAc∶乙酸),并由元素分析、红外光谱、紫外-可见光谱以及X射线单晶衍射等对其进行了表征,分析了其光谱及结构特征。晶体结构分析表明,化合物1属于正交晶系,Pbcn空间群,a=0.95747(8)nm,b=1.99273(13)nm,c=2.50175(13)nm,α=90°,β=90°,γ=90°,V=4.773 3(6)nm3,Z=4;化合物2属于单斜晶系,Cc空间群,a=1.11300(13)nm,b=2.0239(2)nm,c=0.97308(12)nm,α=90°,β=118.555(16)°,γ=90°,V=1.9253(4)nm3,Z=4。     

Hydrothermal Synthesis and Crystal Structure of [（CH3CH2）4N]4[（La12（OH）12MoO29）],A Novel Cluster Compound with a MoO5 Hexahedron Center surrounded by La—O Octahedron

IntroductionRecently,the molecular designs of polyox-ometalates( POM) with basic oxometal clusterbuilding blocks are of great interest[1,2 ] . Hy-drothermal synthesis,with the characteristic ofone- pot reaction,provides a convenient method toobtain novel structures of POM compounds[3— 6] . Inthe Ln/Mo/O system ( Ln=rare earth) ,somecompounds containing La and Mo elements havebeen reported[7— 17] . However,these compoundshave all been synthesized under the highly restrict-ed synthetic co…     

2，3－二苯基－1，4，6－三氮杂二环[3.3.1]－2－壬烯单盐酸盐的合成及晶体结构

在ZrOCl_2的存在下,二乙烯三氨与联苯甲酰在甲醇中回流得到2,3－二苯基 －1,4,6－三氮杂二环[3.3.1]－2－壬烯单盐酸盐。对其进行了~1H NMR,IR和 UV-vis谱表征及X射线单晶衍射结构分析。晶体属单斜晶系,P2_1/c空间群,晶胞 参数为：a=1.69341(6)nm,b=0.77564(3)nm,c=1.21000(4)nm,β=96.1880(10)° ,Z=4,D_c=1.319g·cm~(-3)。该化合物是一非平面型具有部分不饱和键的氮杂桥 二环化合物,两个六元环中,与苯环连接的六元环为半椅式构型,另一六元环为椅 式构型。     

氧化-4-吡啶甲酸桥联的一维链状三丁基锡配合物的合成与晶体结构

利用双三丁基氧化锡与氧化-4-吡啶甲酸(HOCOC5H4NO)以物质的量比1∶2反应,合成了有机锡配合物[Bu3Sn(OCOC5H4NO)]n。通过元素分析、红外光谱和核磁共振氢谱对其结构进行了表征,用X射线单晶衍射测定了它的晶体结构。结果表明,该配合物晶体属单斜晶系,空间群为C2/c,晶胞参数a=2.002 8(9)nm,b=1.224 7(6)nm,c=1.913 6(12)nm,β=119.145(6)°,Z=8,V=4.166(4)nm3,Dc=1.365 g.cm-3,μ=1.239 mm-1,F(000)=1 760,R=0.052 9,wR=0.192 1,GOF=1.013。在配合物中锡原子由氧化-4-吡啶甲酸桥联为五配位的畸变的三角双锥构型。氧化-4-吡啶甲酸配体中N-O基团中的氧原子和另一配体中的羧基氧原子与中心锡原子配位,形成无限一维链状有机锡配合物。该配合物具有良好的热稳定性和较高的抗肿瘤活性。