Supramolecular Sheet Co(Ⅱ) Complex Assembled by Hydrogen Bond

The title complex,[[Co(Py)2(H2O)2(NO3)2]]n(1)was synthesized by liquid/liquid diffusion method at room temperature.The complex crystallizes in monoclinic,space group P2(1)/C,with a=0.877 5(6)nm,b=1.171 5(8)nm,c=0.751 8(5)nm,V=0.739 3(9)nm3,C10H14CoN4O8,Mr=377.18,Dc=1.694 g/cm3,μ=1.210 mm-1,F(000)=386,Z=2,the final R=0.022 9 and wR=0.066 1 for 3 137 observed reflections(I>2σ(I)).In the structure of 1,the center atom of cobalt revealed a centrosymmetric,six-coordinate structure,with two Py ligands,two monoden...     

Impedance spectroscopy study on Mn_(1+x)Fe_(2-2x)Ti_xO_4(0≤x≤0.5) ferrites

The complex impedance spectroscopy and surface morphology of Mn1+xFe2-2xTixO4(0≤x≤0.5) system,prepared using a conventional solid state reaction technique,were investigated.The impedance spectroscopy measurements were carried out at room temperature in the frequency range of 42-5 MHz.The electrical processes in the samples were modeled in the form of an equivalent circuit made up of a combination of two parallel RC circuits attributed to grain and grain boundaries.The DC conductivity obtained by extrapolation of AC data using impedance spectroscopy and four-probe method increases at 10% doping of Ti ions.The energy-dispersive X-ray(EDX) pattern confirmed the homogeneous mixing of the Mn,Fe,Ti and O atoms in pure and doped ferrite samples.     

Synthesis,structure, DNA binding and cleavage activity of a new copper(II) complex of bispyridylpyrrolide

A copper-bispyridylpyrrolide complex [Cu(PDPH)Cl](PDPH = 2,5-bis(2′-pyridyl)pyrrole) was synthesized and characterized. The complex crystallizes in the orthorhombic system with space group Pccn, a = 0.9016(3) nm, b = 1.0931(4) nm, c =2.5319(8) nm, and V = 2.4951(15) nm3. The copper center is situated in a square planar geometry. The interaction of the copper(II)complex with calf thymus DNA(CT-DNA) was investigated by electronic absorption, circular dichroism(CD) and fluorescence spectra. It is proposed that the complex binds to CT-DNA through groove binding mode. Nuclease activity of the complex was also studied by gel electrophoresis method. The complex can efficiently cleave supercoiled p BR322 DNA in the presence of ascorbate(H2A) via oxidative pathway. The preliminary mechanism of DNA cleavage by the complex with different inhibiting reagents indicates that the hydroxyl radicals were involved as the active species in the DNA cleavage process.     

Characterization and Luminescence Properties of a New Europium(Ⅲ) Complex with a Macrocyclic Ligand

The title compound(13,27-dichloro-3,6,9,17,20,23-hexaazatricyclo-[23.3.1.111,15]-triaconta-l(29),2,9,11,13,15(30),16,23,25,27-decaene-29,30-diol-N3,N6,N9,O29,O30)-bis(nitrato-O,O)-Europium(Ⅲ) nitrate was prepared and characterized by elemental analysis,infrared spectra,electrospray mass spectrum and X-ray diffraction,respectively.The crystal of the complex crystallizes in the monoclinic system,space group C2/c with a=2.3737(2) nm,b=14.333(1) nm,c=19.388(2) nm,β = 91.804(1)°,Mr= 850.4,V= 6.5929(8) nm3,R= 0.0333,wR= 0.0936.At room temperature,excitation of the title complex gives rise to the characteristic luminescent emissions of the Eu3+ ion.     

A Novel Topological Index F and Its Correlation With Standard Formaton Enthalpies of AB_n(g) Molecules

The topological index F* is defined and obtained by the method of a non-dimensional unit calculation in which three matrices multiply with each other. These matrices represent the connective cases of atoms in a molecule, the structural features of atoms on top and the bonded cases of the adjacent atoms respectively. The standard formation enthalpies of ABn(g) molecules were correlated with F'* (A = C, Al, Si, Ti, Zr, B = F, Cl, Br, I, H, n=1 -4) and these correlation coefficients are all more than 0.96. Some molecules (e.g CH4, SiH4,etc. )can be preferably handled by F* but can not be dealt with by other topological indices. By contrast to traditional hydrogen suppressed graph, the contribution of hydrogen atoms to structures and properties of molecules is considered.     

Hydrothermal synthesis,crystal structure and properties of inorganic-organic hybrid materials based on diphosphopentamolybdate

The compound of diphosphopentamolybdate { [Cu（en）（Hen）]2[P2Mo5O23] }·3H2O [en=ethylenediamine] had been obtained from the hydrothermal method and characterized by single crystal X-ray diffraction, elemental analysis, FT-IR, and thermogravimetric analysis The structure consist of [P2Mo5O23]^6- clusters anions, complex [Cu（en）（Hen）]^3＋ cations and crystallization water molecules, which are held together to a two-dimensional framework The most interesting feature of the compound is that two nitrogen atoms are both coordinated with Cu（ Ⅱ ） in one ethylenediamine molecule, for the other ethylenediamine molecule, only one nitrogen atom is towards Cu（ Ⅱ） and the other nitrogen atom is protonated and formed Hen^＋.     

Structures and Properties of La_(0.8)Sr_(0.2)MnO_(3+σ)~(-z) SBA-15(z=0, 1, 2, 4) Perovskite Catalysts

Mesoporous La_(0.8)Sr_(0.2)MnO_(3+σ)/z SBA-15(z = 1, 2, 4) perovskite oxides were synthesized via hard-templating with ordered mesoporous silica SBA-15 as the template. The as-prepared samples were characterized by XRD, SEM, AFM, BET, and XPS and the catalytic activity was tested for CO oxidation. The wide-angle XRD patterns showed that La_(0.8)Sr_(0.2)MnO_(3+σ) perovskite was formed. The SEM and AFM analyses exhibited that La_(0.8)Sr_(0.2)MnO_(3+σ) by hard-templating method had much smaller particle size(18 nm) than that(40 nm) by the sol-gel method. The perovskite-type oxides La_(0.8)Sr_(0.2)MnO_(3+σ)/z SBA-15(z = 1, 2, 4) also displayed a higher BET surface area from 70 to 143.7 m~2/g and a disordered mesostructure from nitrogen sorption analysis, as well as a small-angle XRD pattern. Moreover, the La_(0.8)Sr_(0.2)MnO_(3+σ)/z SBA-15(z = 1, 2, 4) perovskite exhibited a much higher activity in CO oxidation than the conventional La_(0.8)Sr_(0.2)MnO_(3+σ) perovskite. Further analysis by the means of XPS techniques indicated that the existence of high content of O_(ads)/O_(latt) species contributed to the high activity.     

Chemical Synthesis and Magnetic Properties of Nanocrystalline (La_(0.67-X)Gd_X)Sr_(0.33)MnO_3 Using Amorphous Molecular Alloy as Precursors

A new route to synthesize nanosized crystalline of(La 0.67–X Gd X )Sr 0.33 MnO 3 (X=0.05,0.10, 0.15,0.20)perovskite-type complex oxides at calcination temperature of 600-1000°C using the amorphous molecular alloy as precursors was reported.The precursor could be completely decomposed into complex oxide at temperature below 500°C according to the TGA and DTA results.XRD demonstrates that the decomposed species is composed of perovskite-type structure at calcination temperature of 600°C for 2 h.The particle size that depends on the calcination temperature of the precursor is in a range of 30-120 nm as determined by transmission electron microscopy(TEM).This method is effective and can be easily quantitatively controlled to synthesize nanosized perovskite-type complex oxides.The magnetic properties of(La 0.67–X Gd X )Sr 0.33 MnO 3 nanocrystalline were preliminary studied.     

Crystal Structure of a New Compound :Na_(2.1)Ba_(0.9)Cu_(0.1)Nb_(4.9)O_(14.3)

Single crystal of a new compound Na2.1Ba0.9Cu0.1Nb4.9O14.3 was synthesised for the first time. The crystal structure has been determined by single crystal X-ray diffraction and the final R value is 0. 0559. The compound crystallizes in a tetragonal unit cell [a = 12. 442(3) A and c = 3. 954 A ]with space growp P4/mbm and Z=2. The compound is in tetragonal tungsten-bronze type structure but some oxygen vacancies exist in the structure. The structure of the compound consists of NbO6 octahedra and octahedra (Nb, Cu)O6 to form triangle, quadrilateral and pentagonal tunnels. The quadrilateral tunnels are occupied by Na atoms. More than 1/2 pentagonal tunnels are occupied by Na atoms and less than 1/2 that are occupied by Ba atoms. Cu2 replaces Nb5 to form different-valence isomorpism.     

Synthesis and Properties of a One-Dimensional Mixed-Ligand Cd(Ⅱ) Complex with Helical Structure

The title complex,[[Cd(Him)(OH-BDC)(H2O)2]·3H2O]n(1) (Him is imidazole,OH-H2BDC is 5-hydroxyisophthalic acid),was synthesized by liquid/liquid diffusion method at room temperature.The complex crystallizes in orthorhombie,space group P212121,with a = 0.671 6(7),b = 1.380 6(2),c =1.7421(2) nm,V = 1.615 2 (3) nm3,C11 H18 CdN2O10,Mr = 450.67,Dc = 1.853 g/cm3,μ =1.407 mm-1,F(000) = 904,Z = 4,the final R1 = 0.020 9 and wR 2 = 0.045 3 for 3 211 observed reflections (Ⅰ＞ 2σ (Ⅰ)).In the structure of 1,the OH-BDC ligands exhibiting bis-bidentate coordimtion mode bridge the adjacent Cd centers to form a one-dimensional helical chain and the second ligand Him acting as terminal ligands are attached to the helical chain.It is notable that a series of complicated hydrogen bonds (e.g.,N-H ...O,O-H...O) exist in the structure,which link neighboring helices into a three-dimensional supramolecular architecture.An observed intense blue luminescence with an emission band peaking at 390 nm for 1 may be resulted from ligand-to-metal charge transfer (LMCT).     

Microstructure and dielectric properties of BaTi_4 O_9 (f)/0.64 BaTi_4 0_9+0.36 BaPr_2 Ti_4 O_(12) composites

The microstructure, dielectric properties and chemical state of Ti element on BaTi_4O_9 (f)/(0.64 BaTi_4O_9-0.36BaPr_2Ti_4O_(12)) composites sample surface were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), LCR meter method and X-ray photoelectron spectroscopy (XPS). The results show that the system is composed of BaTi_4O_9 and BaPr_2Ti_4O_(12) two phases. Pr ions are distributed in the BaWi_4O_9 grains and the segregation of Pr ions was observed on the grain boundaries of BaTi_4O_9/BaTi_4O_9. The content of Ti~(3+) and Ti~(2+) decrease in the BPT system composites due to the addition of BaTi_4O_9 fibers, which improved the dielectric properties of the system. BPT10 sample with 10% BaTi_4O_9 fibers, has the best dielectric properties in the system, its ε_r = 64, tan δ= 1×10~(-4)(at 1 MHz) , and it may be a potential candidate for microwave dielectric ceramics.     

Structures and magnetic properties of nanocomposite CoFe_2O_4-BaTiO_3 fibers by organic gel-thermal decomposition process

The nanocomposite xCoFe2O4-(1-x)BaTiO3(x=0.2,0.3,0.4,0.5,molar fraction) fibers with fine diameters and high aspect ratios(length to diameter ratios) were prepared by the organic gel-thermal decomposition process from citric acid and metal salts.The structures and morphologies of gel precursors and fibers derived from thermal decomposition of the gel precursors were characterized by Fourier transform infrared spectroscopy,X-ray diffractometry and scanning electron microscopy.The magnetic properties of the nanocomposite fibers were measured by vibrating sample magnetometer.The nanocomposite fibers consisting of ferrite(CoFe2O4) and perovskite(BaTiO3) are formed at the calcination temperature of 900 ℃ for 2 h.The average grain sizes of CoFe2O4 and BaTiO3 in the nanocomposite fibers increase from 25 to 65 nm with the calcination temperature from 900 to 1 180 ℃.The single fiber constructed from these nanograins of CoFe2O4 and BaTiO3 has a necklace-like morphology.The saturation magnetization of the nanocomposite 0.4CoFe2O4-0.6BaTiO3 fibers increases with the increase of CoFe2O4 grain size,while the coercivity reaches a maximum value when the average grain size of CoFe2O4 is around the critical single-domain size of 45 nm obtained at 1 000 ℃.The saturation magnetization and remanence of the nanocomposite xCoFe2O4-(1-x)BaTiO3(x=0.2,0.3,0.4,0.5) fibers almost exhibit a linear relationship with the molar fraction of CoFe2O4 in the nanocomposites.     

A Novel Topological Index F^＊ and Its Correlation with Standard Formaton Enthalpies of ABn（g） Molecules

The topological index F^* is defined and obtained by the method of a non-dimensional unit calculation in which three matrices multiply with each other.These matrices represent the connectine cases of atoms in a molecule,the structural features of atoms on top and the bonded cases of the adjacent atoms respectively.The standard formation enthalpies of ABn(g) molecules were correlated with F^*(A=C,Al,Si,Ti,Zr,B=F,Cl,Br,I,H,n=1-4)and these correlation coefficients are all more than 0.96 .Some molecules(e.g CH4,SiH4,etc)can be preferably handled by F^* but can not be dealt with by other topological indices.By contrast to traditional hydrogen suppressed graph,the contribution of hydrogen atoms to structures and properties of molecules is considered.     

Synthesis and crystal structure of a nitrogen-rich compound: 3,5-diazido-1,2,4-triazole

The compound of 3,5-diazido-1,2,4-triazole was synthesized by the reaction of 2,5,2',5'-tetrachloro-1,1'-azo-1,3,4-triazole with sodium azide at 50 ℃.Its crystal structure was determined by single-crystal X-ray diffraction.It crystallizes in monoclinic,space group Cc with a=1.212 4(2) nm,b=2.342 4(5) nm,c=0.804 74(16) nm,β=125.56(3)°,V=1.859 3(6) nm3,Z=4,C2HN9,Mr=151.04,Dc=1.62 g/cm3,F(000)=912 and μ(MoKa)=0.129 mm-1,the final R=0.039 7 and wR=0.087 4.X-ray analysis indicates a stronger intermolecular hydrogen bonding,leading to the formation of a trimmer,containing a nine-membered cyclic ring with graph-set R33(9) in the compound.     

Effects of electric pulse on microstructure of Al-Si alloy in liquid and solid states

In order to investigate the change in liquid microstructure of Al-Si alloy treated by electric pulse (EP), X-ray diffraction tests with liquid A1-Si alloy and ZL109 alloy treated or not by EP were carried out. The results show that the number of Al-Si atomic clusters decreases and that of Al-Al and Si-Si atomic clusters increases for the treated samples. The tests with ZL109 alloy indicate that a large amount of primary crystal Si appears in the solidified microstructure after treated by EP. It is found that EP can change the microstructure of liquid metal by affecting the probability of electrons appearing in different atoms (Al and Si) in the liquid metal.The combining force of different atoms decreases relatively, and that of the same atoms increases, which is the main reason of re-ducing the atomic cluster with different atoms (Al-Si) and increasing the atomic cluster with the same atoms (Al-Al, Si-Si). The in-creasing of the atomic cluster with the same atom cluster resulted in the increasing of Si activity and the higher point of eutectics in the phase diagram. It makes a lot of primary silicon appeared in ZL109 alloy.     

Liquid structure of pure iron by X-ray diffraction

The liquid structure of pure iron at 1540, 1560 and 1580℃ was studied by X-ray diffraction. The results show that near the melting point there is a medium-range order structure that fades away with the increasing temperature. The average nearest distance of atoms is almost independent of the melts temperature, but the average coordination number, the atom cluster size and the atom number in an atom cluster all decrease with the increasing temperature of the melt. Near the melting point there are a lot of atom clusters in the pure iron melt. The atom cluster of pure iron has the body-centered cubic lattices, which are kept from the solid state. And the body-centered cubic lattices connect into network by occupying a same edge. The atoms in the surrounding of the atom clusters are arranged disorderly.     

A Novel Fluorescence Probe 9-（4-（1,2-diamine）benzeneN 1-phenyl）acridine for Nitric Oxide Determination

A novel fluorescent probe 9-(4-(1,2-diamine)benzene-N1-phenyl)acridine(DABPA) was synthesized for the detection of nitric oxide(NO) and characterized by IR, 1H-NMR and EI-MS spectroscopy. Based on a photoelectron transfer mechanism, the fl uorescence intensities of DABPA were investigated with the different concentrations of NO. Under the optimal experimental conditions, the fl uorescence intensity of DABPA had a good linear relationship(R2=0.9977) with NO concentration in the range from 1×10-7 to 1.5×10-6 mol/L with a detection limit of 1×10-8 mol/L. The cytotoxicity induced by DABPA was evaluated by the MTT(3-(4,5-dimethylthiazol-2-yl)-2,5diphenyl tetrazolium bromide) assay for biological application. Furthermore, the probe DABPA had also been successfully applied to real-time image NO produced in PC12 cells in the presence of L-arginine.     

Complex Precipitation Mechanism of Ti-Nb-V Microalloyed Bainitic Base High Strength Steel

The addition of high Ti(0.1%) in microalloyed bainitic high strength steel was designed, and the precipitation morphology of steels with different Ti, Nb, and V contents was studied by utilizing transmission electron microscopy(TEM). Based on the classical nucleation-crystal growth theory and the Johnson-Mehl-Avrami equation, the precipitation thermodynamic and kinetic model of second phase particles in austenite was established in the form of(Nbx,Vy,Tiz)C, and the complex precipitation mechanism of second phase particles was emphatically studied. The experimental results show that the complex precipitation particles could be divided into two categories: the coarser particles with about 100 nm grain size and the independent complex precipitation particles in the form of(Nb,V,Ti)C with 35-50 nm grain size. The latter has a better precipitation strengthening effect, and the calculated PTT curve shows a typical "C" shape. When the deformed storage energy is 3 820 J?mol~(-1), the fastest precipitation temperature of calculated PTT curve is 925 °C, and the calculated result is essentially consistent with experimental values. The increase of Ti content increased the nose point temperature and expanded the range of fastest precipitation temperature.     

Fluorescence Properties of Eu~(3+) Doped in Na_5Lu_9F_(32) Single Crystals

Eu~(3+) ion doped cubic Na_5Lu_9F_(32) single crystals with high quality were synthesized by a modified Bridgman method by using a high 70-90 ℃/cm temperature gradient for cross solid-liquid interface. The optical spectroscopic investigations of the obtained single crystal were reported for the absorption, excitation and emission. The experimental results show that a strong red emission at 609 nm attributing to the ~5D_0→~7F_2 transition of Eu~(3+) doped Na_5Lu_9F_(32) single crystals can be obtained under the excitation of 394 nm light and reach the maximum when the Eu~(3+) doping concentration is 4 mol% in present research. The local covalent is enhanced and symmetry is reduced with the increase of Eu~(3+) concentrations inferring from the strength parameters Ω_2 and Ω_4 calculated by their measured emission spectra. The CIE chromaticity coordinates of the 4 mol% Eu~(3+) doped Na_5Lu_9F_(32) single crystals are calculated as(x=0.626, y=0.3736), which are close to the NTSC standard values for red(x=0.67, y=0.33). The experimental results reveal that the single crystal can be used as potential red phosphors under near ultraviolet(NUV) light excitation.     

Mechanism of Cathode Process of B(Ⅲ) in LiF-NaF-KBF_4 Meltby Electrochemical Titration Technique

The mechanism of cathode process of B(Ⅲ) at molybdenum and platinum electrodes in LiF-NaF-KBF4melt was studied and the transferred electron number of the reaction was calculated by means of cyclic voltammetry.The effect of adsorption of electroactive component on the electrochemical response (e. g., the voltammetric i─Ecurves) was analyzed and discussed. The "electrochemical spectra" for linear sweep voltammetry was used to elucidate the electrode reaction accompanied by a following transform process. The results show that the reduction ofB(Ⅲ) to B(0) proceeds in reversible one step three-electron reaction and the cathode process of B(Ⅲ) is affected byproduct adsorbed strongly at the electrode surface. It is assumed that the reduction and deposition of B(Ⅲ) at molybdenum and platinum electrodes proceed in two kinds of mechanism： (1) B(Ⅲ)＋ 3e = Bads→ B (surface diffusiondeposition mechanism) and (2) B(Ⅲ) ＋ 3e = B (direct deposition mechanism).