CRYSTAL AND MOLECULAR STRUCTURE OF IPOHARDINE PICRATE, C_(15)H_(16)NO·C_6H_2N_3O_7

<正> INTRODUCTION. Ipomoea Hardwickii Hemsl (Ⅰ) belongs to Convolvulaceae, and its seed may be used as an anodyne. Ipoharine and Ipohardine were obtained by Reinickate method from the aqueous solution of Ⅰ. The structure of the title compound has been determined by X-ray crystal structure analysis. The structure of the cation (C_(15)H_(16)NO)~+ is reported here for the first time.     

QUANTUM CHEMICAL CALCULATIONS ON THE ELECTRONIC STRUCTURE AND SPECTRA OF[Mo_3O_4-nSn]~(4+)(n=O-4)CLUSTER CATIONS

The electronic structure and spectra of [Mo3O4-nSn]~(4+)(n=0-4)cations were calculated by means of INDO/CI quantum chemistry method toaccount for the experimental data of their spectra in water solutions.     

THEORETICAL STUDIES ON THE STRUCTURES AND REACTIVITY OF SILYLENOIDS (Ⅰ)——STRUCTURES AND ISOMERIZATION OF SILYLENOID H_2SiLiCl

The structures of silylenoid H_2SiLiCl have been studied by RHF/3-21G gradient method. Three equilibrium states and two isomerization transition states are located. The electronic energy, Mulliken populations, dipole moments and frontier molecular orbitals (FMO) of every structure and the isomeric barriers are also given and analyzed. Further single point calculations on the 3-21G optimum geometries were performed using 6-21G basis set. The calculations show that three-membered ring structure of H_2SiLiCl is the most stable and detectable, and the "classical" tetrahedral form is not the local minimum on the potential energy surface.     

Non-Isothermal Decomposion Kinetics of Supermolecule Compound [Eu(C_(10)H_9N_2O_4)(C_(10)H_8N_2O_4)(H_2O)_3]_2·phen·4H_2O

Europium(Ⅲ) compound with 2-oxopropionic acid salicyloyl hydrazone (C_(10)H_(10)N_2O_4,H_3L) and 1,10-phenan-throline (C_(12)H_8N_2,phen) has been prepared.A yellow prismatic crystal of the compound was obtained,and themolecule crystallized in the triclinic space group P-1.There are two 9-coordinated complex molecules in everystructure unit,where every Eu atom is coordinated by three water molecules and two tridentate C_(10)H_(10)N_2O_4 ligands,forming two stable pentacycles.The coordination polyhedron around Eu~(3+) was described as a single cap squareantiprism.In the crystal cell,there are one free 1,10-phenanthroline and four water molecules.The thermaldecomposition of the compound and its kinetics were studied by non-isothermal thermogravimetry.The Kissinger'smethod and Ozawa's method were used to calculate the activation energy value of the first-step decomposition.Thestages of the decompositions were identified by TG-DTG-DSC curve.The non-isothermal kinetic data were ana-lyzed by means of integral and differential methods.The possible reaction mechanism and the kinetic equationswere investigated by comparing the kinetic parameters.     

Theoretical studies of adsorption property on Ir_4/MgO and Ir_4/γ-Al_2O_3

The adsorption properties of atomic and molecular species on Ir4/MgO and Ir4/γ-Al2O3 have been systematically studied by means of planewave density functional theory(DFT)calculations using the periodic boundary conditions.The binding energies of these species were ordered as follows:H2O相似文献   

Photocatalytic Activities for Water Splitting of RuO_2-loaded MGa_2O_4（M=Zn,Ni） with d~（10） Configuration

MGa2O4(M=Zn,Ni) rods with similar crystallinity and BET surface area were prepared via a facile template-engaged reaction.The photocatalytic activities for water splitting of RuO2-loaded MGa2O4(M=Zn,Ni) were investigated under high-pressure Hg lamp.RuO2-loaded ZnGa2O4 catalyst exhibited much higher photocatalytic activity than RuO2-loaded NiGa2O4.Factors affecting the photocatalytic activities of RuO2-loaded MGa2O4(M=Zn,Ni) were discussed.It was suggested that the electronic structure of oxide semiconductor was a predominant factor of the photocatalytic behavior for RuO2-loaded MGa2O4(M=Zn,Ni).     

CRYSTAL STRUCTURE OF 18-TUNGSTODIVANADATE ANION IN Na_2H_2[H_2V_2W_(18)O_(62)].12H_2O

The structure of Na_2H_2[H_2V_2W_(18)O_(62)]12H_2O has been determined by x-rayanalysis.The crystals are trigonal,space group R3m,with cell parametersa=37.613(11),c=12.972(7)A,V=15901(13)A~3,and Z=9.The structure model wasrefined by full-matrix least square to R=0.065 for 1702 reflections with F>4σ(F).The existence of the[H_2V_2W_(18)O_(62)]~(4-)heteropolyanion in the crystals has beenconfirmed.It is composed of two VO_4 tetrahedra and eighteen WO_6 octahedralinked to gve the Dawson-type structure.     

A Density Functional Study of Small （NiTi）x Clusters with x=1-3

Systematic studies on the geometry, electronic structure and vibrational properties of small (NiTi)x clusters with x=1-3, within the framework of the density functional theory, were performed in this work. The electronic structure analyses were used to investigate the bonding between the early-late(EL) transition metals in their alloy. The results of our calculations have been used to predict (NiTi)x clusters structure for the ground state and confirm that s-electron density is transferred from Ti atoms to Ni atoms followed by the back donation of electrons through the d-orbital. The study provides a fragment approach based on the isolobal analogy that NiTi molecular fragments play a significant role in forming clusters.     

Mn-Na2WO4/SiO2催化剂表面活性中心结构的DFT研究

Mn Na2WO4/SiO2 is one of the best catalysts for oxidative coupling of methane.To investigate the nature of active centers and the reaction mechanism,the structure of possible metal sites formed by tungsten and manganese over the silica surface were studied using molecular simulation method and ab initio DFT calculations.Silica support exists in the catalyst as 岐瞔ristobalite and its (111) face exposes preferentially to the surface.The calculated results show that tungsten interacts with the silica surface by three or one bridge oxygen atoms to form tetrahedral [WO4],and manganese interacts with single bridge oxygen to form dispersed [MnO4] or exists as oxide clusters.The nature of the molecular orbitals and the electronic structure suggest that the tetrahedral [WO4] site with single bridge oxygen is the most probable active center responsible for methane activation.     

Preparation and Characterization of Cu_3V_2O_7(OH)_2·2H_2O Hollow Spheres from Na_2V_6O_16·3H_2O Nanobelts

Monoclinic Cu3V2O7(OH)2·2H2O(copper polyvanadate) hollow spheres were prepared with Na2V6O16· 3H2O nanobelts as V-precursor by hydrothermal method. The purity and structure of the products were characterized by X-ray powder diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy, Raman spectroscopy, thermogra-vimetric analysis(TGA) and X-ray photoelecton spectroscopy(XPS). The morphology and size were observed by scanning electron microscopy(SEM). We found that the Kagomé staircase-structural copper...     

ROLE OF MoO_3 AND La_2O_3 PROMOTERS IN Ni-CATALYZED METHANATION REACTIONS OF CO

A series of catalysts containing nickel were prepared by impregna-tion.The activity,heat resistance and sulfur resistance of catalysts were inves-tigated using catalytic microreactor.The experimental results show that the Ni/γ-Al_2O_3 catalysts containing molybdenum or lanthanum possess higher activity,better heat resistance and sulfur resistance than Ni/γ-Al_2O_3 catalyst.The sur-face behaviour of catalysts and the role of molybdenum or lanthanum in Ni-Mo-La/γ-Al_2O_3 system have been studied by XRD,TEM,XPS and TPY.It hasbeen shown that the addition of molybdenum or lanthanum can increase theconcentration of nickel atoms on the surface of catalysts,make the crystallinegranule of nickel smaller,increase the number of active centers of nickel andaffect the electronic structure of nickel.All these avtions will improve thecatalytic activity and surface behaviour of catalllysts.     

H_2O_2-Promoted Size Growth of Sulfated TiO_2 Nanocrystals

Anatase nanoparticles modified by sulfate groups were synthesized using hydrothermal method. The particles were controlled to large sizes by simply adjusting the amount of H2O2, in which HOO^- ions replaced the surface sulfate groups and reduced the steric effect to promote the grain growth. The size-induced microstructural changes of the as-prepared nanoparticles were characterized using powder XRD, FT-IR, TG. and UV-vis analyses. The sulfate groups existed on anatase surface in unidentate and bidentate coordination forms. With the particle size reduction, bandgap energies of the as-prepared anatase nanoparticles decreased, and the desorption temperature of sulfate groups shifted towards lower temperatures.     

SYNTHESIS AND CRYSTAL STRUCTURE OF HETEROPOLY MOLYBDOSILICIC LANTHANIDE K_(10)H_3[Pr(SiMo_(11)O_(39))_2]·18H_2O

The intensity data of the title complex were collected at a low temperature of -90℃. Thecompound crystallizes in the monoclinic space group P2_1/n, a = 17.504(2), b = 27.323 (5),c = 21 .616(4)A, β= 104.49 (2)°, Z=4. The structure was solved by Patterson and Fouriertechniques and refined by least- squares to an R = 0.088 for 8320 independent reflections.The central Pr ion is bonded to eight oxygen atoms from two molybdosilicic heteropolyligands to form a square antiprism. The Pr- O average distance is 2.44 (2)A. Both molyb-dosilicic heteropoly ligands are of a defective α- Keggin structure.     

STUDIES ON LANGMUIR-BLODGETT FILM OF METAL COMPLEXES(Ⅰ)-PREPARATION AND CHARACTERIZATION OF THE LB FILM OF N-HEXADECYL PYRIDINIUM TETRAKIS(1-PHENYL-3-METHYL-4-BENZOYL-PYRAZOL-5-ONE)EUROPIUM,C_5H_5NC_(16)H_(33)Eu(PMBP)_4

The LB film of the title complex was prepared by dropping a benzene solution of the title complex on the surfaceof water subphase at 25±1℃.The film was deposited in Z type on various hydrophilic pretreated substrates ofquartz,CaF_2 and electronic conductive glass for different purposes.The π-A curve of the film shows that thecross section per molecule is 125 ~2,which indicates that the alkyl chain of the molecule is basically perpendiculalto the surface of the substrate.UV,IR spectra and transmission electronic microscopy of the film were also obtained.     

Density Functional Theory Study on Organic Dye Sensitizers Containing Bis-dimethylfluorenyl Amino Benzofuran

The geometries, electronic structures, polarizabilities and hyperpolarizabilities, as well as the UV-Vis spectra of the two organic dye sensitizers containing bis-dimethylfluorenyl amino benzofuran were studied via density functional theory （DFT） and time-dependent DFT. The features of electronic absorption spectra were assigned on account of the agreement between the experiment and the calculations. The absorption bands in visible region are related to photoinduced electron transfer processes, and the dimethylfluorenyl amino benzo[b]furan groups are major chromophore that contributed to the sensitization of photo-to-current conversion. The role of vinylene group in geometry, electronic structure and spectra property is analyzed according to the comparative study of the dyes.     

SYNTHESIS AND CRYSTAL STRUCTURE OF [(η~5-C_5H_5)_2NdCl·OC_4H_8]_2

All attempts to prepare light lanthanide dicyclopeutadienyt chloride failed,due to the disproportionation reaction. The crystal complex of [(η~5-C_5H_5)_2NdCl.OC_4H_8]_2 was successfully prepared by the reaction of NdCl_3·2C_4H_8O with cyclopentadienyl sodium (molar ratio 1:1.8)in tetrahydrofuran at room temperatureThe composition of the title compound was determined by the methods of elemental analysis, infrared spectroscopy and photoelectron spectroscopy. The crystal structure of [(η~5-C_5H_5)_2NdCl·OC_4H_8]_2 was determined from single crystal X-ray diffraction. Data were collected at-60℃ under dry nitrogen atmosphere.The complex crystallizes in the monoclinic space group P2_1/c,with Z=2. Lattice parameters are: a=8.201(3), b=21.589(6),c=8.596(3),β=109.10(3)°.The structure was solved by Patterson and Fourier techniques and refined by least-squares to a final conventional R=0.0636 for 1680 reflections. There are two Nd atoms in the dimeric unit which are bridged asymmetrically by the two chlori     

STRUCTURE OF { CEu_2 (OOCCH_2NHCOCH_2NH_3)_4 (H_2O)_4]·(C1O_4)_6·4H_2O}_n

<正> {[Eu(OOCCH2NHCOCH2NH3)2(H2O)2]·(ClO4)3·2H2O}2,Mr = 1572,P21/n,a=12. 014(4),b=8. 910(5),c=22. 749(5)A ,β=91. 73(3)°,V = 2034 A3,Z=2,Dx=2. 15g·cm-3,λ(MoKa) = 0. 71073A,R=0. 060 for 3107 unique observed reflections (I≥3σ(I)). The complex cation is of one-dimensional chain structure in which the basic unit is a dinuclear complex and the gly-gly ligands are coordinated to metal atoms in two kinds of forms. The overall structure of the dinuclear unit is dioxo and dicarboxyl-bridged.     

INFRARED SPECTROSCOPIC STUDY OF STRUCTURE TRANSITION IN THE PEROVSKITE-TYPE LAYER COMPOUND: (n-C_9H_(19_NH_3)_2CuCl_4

Infrared spectra of (n-C_9H_(19)NH_3)_2CuCl_4 in three solid phases were investigated. It was found that the phase transition at T_(cl)(25℃) arises from the change of the interaction and packing structure of the chain. The phase transition at T_(c2)(34℃)is related to the change of a partial conformational order-disorder. The GTC or GTG' and small concentration of TG structure near CH_3 group exist in phase Ⅲ (above 38℃).     

CRYSTAL STRUCTURE OF COMPLEX OF ERBIUM(Ⅲ) AND QLYCINE,[Er(GLy)_2(H_2O)_4]_2(ClO_4)_6·4(C_4H_8O_2)

<正> The crystal structure of [Er(Gly)2 (HaO)4]2(ClO4)6.4(Dio) (Gly= NH2CH2COOH; Dio=dioxane) has been determined belonging to triclinic system with space group P1.The final R was 0.055. The carboxyl groups of Gly are associated to Er(Ⅲ) atoms to act as the bidentate bridging ligands.     

Graphene oxide–MnO_2 nanocomposite-modified glassy carbon electrode as an efficient sensor for H_2O_2

In this study, a new facile preparation method of nanocomposites consisting of graphene oxide and manganese dioxide nanowires(GO/MnO_2 NW_s) was developed. The morphology, structure and composition of the resulted products were characterized by transmission electron microscopy, X-ray diffraction and N_2 adsorption and desorption. The GO/MnO_2 nanocomposite was used as an electrode material for non-enzymatic determination of hydrogen peroxide. The proposed sensor exhibits excellent electrocatalytic performance for the determination of hydrogen peroxide in phosphate buffer solution(PBS, pH7) at an applied potential of 0.75 V. The non-enzymatic biosensor for determination of hydrogen peroxide displayed a wide linear range of 4.90 mmol L~(-1)–4.50 mmol L~(-1)with a correlation coefficient of 0.9992, a low detection limit of 0.48 mmol L~(-1) and a high sensitivity of 191.22μA(mmol L~(-1))~(-1)cm~(-2)(signal/noise, S/N = 3). Moreover, the non-enzymatic biosensor shows an excellent selectivity.