The effect of ethylene-vinyl acetate copolymer on the formation process of wax crystals and hydrates

Ethylene-vinyl acetate copolymer(EVA) as a kind of effective polymeric pour point depressant has been extensively used in the pipeline transportation of crude oil to inhibit wax deposition and improve the low temperature fluidity of crude oil. In this work, molecular dynamics simulations were performed to investigate the effect of EVA on wax-hydrate coexistence system to evaluate the application potentiality of EVA to the flow assurance of deep-sea oil-gas-water multiphase flow system. Our simulation results reveal that wax molecules gradually stretched and stacked from random coiling to a directional and ordered crystalline state during the process of wax solidification. The strong affinity of polar vinyl acetate side chains of EVA to neighboring water molecules made the EVA molecule prefer being in a curly state,which disrupted the ordered crystallization of surrounding wax molecules and delayed the solidification rate of wax cluster. In addition, it is found that EVA cocrystallized with wax molecules to form eutectic when the wax was fully solidified. The simulation results of hydrate nucleation and growth show that the EVA molecule displayed a two-sided effect on gas adsorption of wax crystals, which was the key factor that affected the nucleation and growth of hydrates in the methane-water system. The nonpolar hydrocarbon backbone of EVA increased the diffusion rate of methane and water, allowing more methane to diffuse to the surface of wax crystals, reducing the methane concentration in aqueous solutions and inhibiting the hydrate formation. On the other hand, the nonpolar vinyl acetate chains had a repulsive effect on methane, which reduced the adsorption area of methane on the eutectic surface and decreased the adsorption threshold value of the wax crystal. The excluded methane molecules would continue dissociating in the aqueous phase and participating in the nucleation and growth process of hydrates.Therefore, the probability of hydrate formation would be increased. It was worth noting that the inhibition performance of EVA on hydrate formation mainly played a significant role in the system with small wax crystal, while its hydrate promotion effect played a dominant role in the system with lager wax crystal. In summary, EVA could significantly inhibit both of the wax and hydrate deposition for the waxgas-water multiphase system with low wax content. When the wax content in the system was high, the role of EVA was mainly played in the alleviation of wax crystallization rather than the gas hydrates. The results of the present work can contribute to a better understanding of EVA on wax deposition and hydrate formation, and provide theoretical support of the potential industrial applications of EVA.

NON-ISOTHERMAL CRYSTALLIZATION OF ETHYLENE-VINYL ACETATE COPOLYMER CONTAINING A HIGH WEIGHT FRACTION OF GRAPHENE NANOSHEETS AND CARBON NANOTUBES

The effect of the different geometrical dimensionality of two dimensional graphene nanosheets （2D GNSs） and one dimensional carbon nanotubes （1D CNTs） on the non-isothermal crystallization of an ethylene-vinyl acetate （EVA） copolymer at high loading （5 wt%） was studied. Transmission electron microscopy indicated a homogeneous dispersion of GNSs and CNTs in EVA obtained by a solution dispersion process. Fourier-transform infrared spectroscopy and differential scanning calorimetry measurements showed that 1D CNTs and 2D GNSs acted as effective nucleating agents, with a noticeably increased onset crystallization temperature of EVA. A high weight fraction of nano-fillers slowed the overall crystallization rate of composites. At the same crystallization temperatute, the crystallization behavior of GNS/EVA composites was slowed compared to that of the CNT/EVA ones owing to larger nucleus barrier and activation energy of diffusion. Dynamic mechanical relaxation and rheology behavior of CNT/EVA and GNS/EVA composites demonstrated that the planar structure of the GNSs had an intensively negative effect on EVA chain mobility due to interactions between nano- fillers and polymer chains, as well as spatial restriction.

Investigation of the Crystallization Kinetics of Zn(Met)(AcO)_2·H_2O in Mixed Solution of Water and Acetone by Microcalorimetry

The crystal growth process of Zn(Met)(AcO)2旽2O from the mixed solution of water and acetone has been investigated using a Calvet microcalorimeter. The heat produced and the rate of heat production during the crystal growth process at 298.15, 301.15, 304.15, 307.15 and 310.15 K have been measured. On the basis of experimental and calculated results, the thermodynamics parameters (the apparent activation enthalpy, the activation entropy, and the activation free energy), the rate constant and the kinetic parameters (the activation energy, the pre-exponential factor) during the crystal growth process have been obtained. The results show that the crystal growth proceeds in accordance with the Burton-Cabrera-Frank dislocation theory.

Synthesis and Crystal Structure of Tetraaquacopper(II) Bis(5-fluorouracil-1-acetate) Tetrahydrate

The title compound, [Cu（C6H4N2O4F）2（H2O）4].4（H2O） I, has been hydrothermally synthesized and structurally determined by single-crystal X-ray diffraction method. It crystallizes in monoclinic, space group P21/c with a = 8.3041（17）, b = 12.045（2）, c = 11.077（2） A, β = 92.567（3）°, V= 1106.8（4） A^3, Mr = 581.89, Z= 2, Dc = 1.746 g/cm^3, F（000） = 598,μ（MoKa） = 1.090 mm^-1, the final R = 0.0296 and wR = 0.0806 for 3195 observed reflections with Ⅰ 〉 2σ（Ⅰ）. In the centrosymmetric compound I, each Cu（Ⅱ） ion is coordinated by six O atoms from two 5-fluorouracil-1-acetate anions and four water molecules, forming a six-coordinated octahedral environment. N-H…O and O-H…O hydrogen-bonding interactions are observed in the structure, leading to the formation of a three-dimensional network.

Synthesis and Crystal Structure of an Acetate Radical Bridged Dinuclear Copper(Ⅱ) Complex

A new acetate radical bridged dinuclear copper（ Ⅱ ） complex [（C8H9NO2）2- Cu2（CH3COO）4] has been synthesized by the reaction of Cu（OAc）2 with pyridine-3-ethyl formate and further characterized by X-ray single-crystal diffraction. Crystal data for the title compound： triclinic system, space group Pí, with a = 8.1654（14）, b = 9.7010（16）, c = 9.9005（17） A, α = 83.266（2）, β = 78.887（2）, γ = 72.881（2）°, V= 733.9（2） A^3, Mr = 665.58, Z = 1, Dc = 1.506 g/cm^3, F（000） = 342,μ = 1.510 mm^-1, the final R = 0.0392 and wR = 0.1005. According to the structural determination, each unit of the title compound is composed of two Cu（ Ⅱ ） atoms, two pyridine-3-ethyl formate molecules and four acetate ions. Each Cu（Ⅱ） coordinates to oxygen atoms of acetate and nitrogen atoms of pyridine- 3-ethyl formate ligand to give a six-coordinate distorted octahedral geometry. It is worth mentioning that strong Cu-Cu bond can be observed in the title compound.

Synthesis,Characterization,X-ray Crystal Structure and Safener Activity of Chiral 2-(3-Methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl)-2-oxoethyl Acetate

The new title compound, chiral 2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）- 2-oxoethyl acetate, has been synthesized via reduction, cyclization and acylation reaction. The structure of the product has been confirmed by IR, 1H NMR, 13C NMR, LC-MS （ESI） and single-crystal X-ray diffraction. （R）-2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）-2-oxoethyl acetate crystallizes in monoclinic, space group P21/c with a = 11.867（2）, b = 8.4087（2）, c = 14.325（6） A^°, β = 117.59（2）°, Z = 4, V = 1266.9（6） A^°3, Dc = 1.307 g/cm^3, F（000） = 528, μ（MoKα） = 0.097 mm-1, R = 0.0453 and wR = 0.1237; （S）-2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）-2-oxoethyl acetate belongs to the triclinic system, space group P with a = 8.2647（17）, b = 8.7034（17）, c = 9.5479（19） A^°, α = 105.33（3）, β = 100.95（3）, γ = 105.14（3）°, Z = 2, V = 614.1（2） A^°3, Dc = 1.348 g/cm^3, F（000） = 264, μ（MoKα） = 0.10 mm-1, R = 0.0613 and wR = 0.1037. Both of the molecules prefer to form crystal packing through C–H…O hydrogen bonds.

Reinvestigation of the Crystal Growth of “L-Proline Succinate” and “L-Threonine Zinc Acetate” Showing Use of Infrared Spectra for Product Identification

Reinvestigation of the growth of L-proline succinate (1) (Paramasivam and Ramachandra Raja, Journal of Crystallization Process and Technology, 2 (2012) 21 - 24;Balamurugaraj et al., Journal of Material Physics and Chemistry 1 (2013) 4 - 8) and L-threonine zinc acetate (2) (Puhal Raj and Ramachandra Raja, Photonics and Optoelectronics, 2 (2013) 56 - 64) is reported. Slow evaporation of an aqueous solution containing equimolar quantities of L-proline and succinic acid (for 1) and L-threonine and zinc acetate (for 2) results in the fractional crystallization of succinic acid (in the first case) and L-threonine (in the second case) and not any novel organic non-linear optical (NLO) crystals. In this paper, the usefulness of infrared spectra for correct product characterization is demonstrated.

LYOTROPIC AND THERMOTROPIC LIQUID CRYSTALL INE TRIALKYL CELLULOSES OBTAINED DIRECTLY FROM CELLULOSE ACETATE IN DIMETHYL SULFOXIDE

Highly substituted n-atkyl celluloses with sidechains 3 to 10 carbon atoms long have been prepared from cellulose acetate, sodium hydroxide and n-alkyl bromides with dimethyl sulfoxide as solvent. Synthetic conditions of n-alkyl celluloses were studied with respect to reaction temperature, time and yield. The molecular structure of the n-alkyl celluloses, which were obtained as white powders or as sticky, soft and birefringent solids at room temperature, was investigated by IR and NMR spectra and elemental analysis. The highly substituted n-alkyl celluloses all exhibited both therotropic and lyotropic liquid crystalline cholesteric phases in some non-polar solvents. The metting behavior and solubility of the n-alkyl celluloses were examined.

A Novel Two-dimensional Lead(Ⅱ) Coordination Polymer Based on Dinuclear Lead(Ⅱ) Unit Containing(5-Chloro-quinolin-8-yloxy) Acetate

A novel two-dimensional lead（II） coordination polymer 1, [C11H7Cl2NO3Pb]n, has been prepared by solvothermal reaction of new bridging ligand（5-chloro-quinolin-8-yloxy）acetic acid（HL） with PbCl2, and its structure was characterized by IR, elemental analysis, TG-DTA and single-crystal X-ray diffraction analysis. The crystal is of monoclinic system, space group P21/c with a = 16.7603（7）, b = 8.6907（4）, c = 8.4745（3）A, β = 101.1110（11）°, C11H7Cl2NO3 Pb, Mr = 479.27, V = 1211.25（9）A3, Z = 4, Dc = 2.628 g/cm^3, F（000） = 880, μ = 14.367 mm^-1, R = 0.0173 and wR = 0.0508. The asymmetric unit contains one lead（II） cation, one（5-chloro-quinolin-8-yloxy）acetate（L） ligand and a chloride ion. The PbII center is hepta-coordinated in a distorted pentagonal bipyramidal geometry. The coordination sphere of the Pb atom is completed by two oxygen atoms and one nitrogen atom of the same L ligand, two bridging chloride ions and two bridging oxygen atoms of two adjacent L ligands. Two PbII centers are linked by the two L ligands to form a C2-symmetric dimer unit with a planar [Pb2O2] ring. Each dimer unit acts as a secondary building unit（SBU） and links adjacent four dimer units by the chloride atoms and oxygen atoms of carboxylate groups of L, forming a two-dimensional array. Such two-dimensional layers are packed through intermolecular C–H…Cl hydrogen bonds into a three-dimensional supramolecular structure. When the dimer unit is viewed as a 4-connected node, 1 is simplified as a 4-nodal 2-D network with square lattices of the diagonal lengths to be 6.079（1）A. The fluorescence emission peak of complex 1 appears near 407 nm.

Synthesis,Crystal Structure and Antitumor Activity of a Novel Zn(Ⅱ)Complex with 2-(Nicotinoyloxy)acetic Acid Ligand

A novel Zn（Ⅱ） complex, [ZnL2（H2O）4]·H2O（1, HL = 2-（nicotinoyloxy）acetic acid）, was synthesized using Zn（OAc）2·2H2O and 2-（nicotinoyloxy）acetic acid as raw materials. Its structure has been elucidated by elemental analysis, IR and single-crystal X-ray diffraction. The structural analysis revealed that complex 1 crystallizes in triclinic, space group P1 and the Zn（Ⅱ） atom is six-coordinated with two N atoms from two different 2-（nicotinoyloxy）acetate anion ligands and four O atoms from coordinated water molecules. Complex 1 forms a 3D network structure by O–H···O hydrogen bonds. The antitumor activities of 2-（nicotinoyloxy）acetic acid ligand and its Zn（Ⅱ） complex were evaluated against human lung adenocarcinoma A549 cells, human hepatoma SMMC-7721 cells and human colon carcinoma Wi Dr cells.

Synthesis,Structure and DFT Calculations of a Novel Copper(Ⅱ)Complex Based on Tert-butyl 2-[N-(tert-butyloxycarbonylmethyl)-2-picolyamino]acetate

A novel copper（Ⅱ） complex with tert-butyl 2-[N-（tert-butyloxycarbonylmethyl）-2-picolyamino]acetate（ampy） was synthesized and structurally characterized by elemental analysis, FT-IR spectrum, electrospray ionization-mass spectrometry, UV-vis spectrum and single-crystal X-ray diffraction, respectively. A mononuclear copper（II） complex with ampy, [Cu（ampy）Cl2]（1）, was formed irrespective of the metal-to-ligand molar ratios（[Cu2＋]：[ampy] = 0.5：1, 1：1, and 2：1） as a single product. Complex 1 crystallizes in the orthorhombic system, space group Pbca with a = 12.343（2）, b = 18.928（3）, c = 20.058（4） A, V = 4686.1（14） A3, Z = 8, Dc = 1.3349（4） g/cm3, F（000） = 1920, S = 1.016, R = 0.0693 and w R = 0.1721 for 3151 observed reflections with I 〉 2σ（I）. X-ray diffraction analysis reveals that the central copper（II） ion is bound by pyridyl N, tertiary amine N and carbonyl O atoms of the quadridentate ampy as well as two Cl anions, constructing a slightly distorted octahedral geometry. Complex 1 further constructs a stable 3D supramolecular architecture by intermolecular C–H…Cl hydrogen bonds. In addition, the molecular geometry was calculated by density functional theory（DFT/B3LYP） method with the basis sets（6-31＋G（d,p） for H, C, N, O and Cl atoms, and LANL2 DZ for Cu atom, respectively）. The calculated results show that the optimized geometrical parameters are in good agreement with the experimental data. Natural bond orbital（NBO） analysis and frontier molecular orbitals（FMOs） analysis were investigated at the same level.

Preparation,Crystal Structure,Thermal Decomposition and Explosive Properties of K_2(tza)_2(H_2O) (tza=Tetrazole-1-acetic Acid)

A new energetic compound based on the tetrazole-1-acetic acid （tza） and potassium（I） salt, K2（tza）2（H2O）, was synthesized and characterized by elemental analysis and FT-IR spectrum. Its crystal structure was determined by single-crystal X-ray diffraction analysis. The results show that the crystal belongs to the orthorhombic system, space group Pna21 with a = 1.11972（17） nm, b = 0.46647（7） nm, c = 2.5158（4） nm, V = 1.3140（3） nm3, K2C6H8N8O5, Mr = 350.40 g·mol-1, Dc = 1.771 g·cm^-3, μ（MoKα） = 0.759 mm^-1, F（000） = 712, Z = 4, R = 0.023 and wR = 0.0527 for 2961 observed reflections （I 〉 2σ（I））. The K（I） cation is six-coordinated with four O atoms from three carboxylate groups, one O atom from one H2O molecule and one N atom from tetrazolyl ring, in which each tza is coordinated in a tridentate chelating bridging coordination mode. The thermal decomposition mechanism of the title complex was studied by DSC and TG-DTG techniques. Under nitrogen atmosphere at a heating rate of 10 K·min-1, the thermal decomposition of the complex contains one main exothermic process between 191.7 and 243.8 ℃ in the DSC curve. Its combustion heat was mensurated by oxygen bomb calorimetry. The non-isothermal kinetics parameters were calculated by the Kissinger＇s method and Ozawa-Doyle＇s method, respectively. The sensitivity properties of K2（tza）2（H2O） were also determined with standard methods, which was very sensitive to flame.

Synthesis and Crystal Structure of 6-Bromo-piperonal-dimethyl-acetal

The title compound (C10H11BrO4, Mr = 275.10) was synthesized and its crystal structure has been determined by single-crystal X-ray diffraction. The crystal is of monoclinic, space group P21/n with a = 7.2960(8), b = 12.209(1), c = 12.568(1) ? b = 98.120(2)? l = 0.71073 ? m(MoKa) = 3.700 mm-1, V = 1108.3(2) 3, Z = 4, Dc = 1.649 g/cm3 and F(000) = 552. The structure was solved by direct methods and refined by full-matrix least-squares methods. R = 0.0375 and wR = 0.0864 for 1598 reflections with I > 2s(I). X-ray diffraction reveals that there exist two rings in the molecule, and the dihedral between them is 177.5?

Synthesis and Crystal Structure of an Anionic Linear Trinuclear Copper(Ⅱ) Complex Containing 2-Thenoyltrifluoroacetonato and Acetato Ligands

A novel anionic trinuclear linear copper（II） complex {[Et3NH][Cul.5（CH3COO）- （TTA）3] } 2 （1, TTA = 2-thenoyltrifluoroacetonate） has been synthesized in a direct reaction involving copper（]l） acetate monohydrate, TTA and excess triethylamine base in dichloromethane solvent. Green colored X-ray quality crystals of 1 were grown from n-hexane solvent at room temperature. The data were collected at 100 K. Compound I crystallizes in the monoclinic P21/n space group （a = 11.2141（8）, b = 19.0965（13）, c = 17.3680（14） A, β = 90.225（2）°, V= 3719.3（5） A3, Mr = 1840.14, Dc = 1.643 Mg/m3, F（000） = 1866, μ = 1.129 mm^-1 and Z = 2）. The asymmetric unit of 1 contains two copper atoms, one of which lies on a crystallographic inversion center with 50% occupancy.

Synthesis and Crystal Structure Analysis of 2-(3,5-Di-tert-butyl-2-hydroxyphenyl)-2-(3,4- dimethylphenyl) Acetic Acid Dimethylamine Salt

A new compound 2-（3,5-di-tert-butyl-2-hydroxyphenyl）-2-（3,4-dimethylphenyl） acetic acid dimethylamine salt （[NH2（CH3）2][C24H31O3]） was synthesized and structurally determined. It is of monoclinic system, space group P21/c with a = 14.731（2）, b = 10.1185（10）, c = 17.065（2） A^°, β = 98.293（10）° ,Z = 4, V = 2517.0（6）A^°^3, Dc = 1.091 g/cm^3, F（000） = 904 and Mr= 413.58. The dihedral angle defined by two benzene rings is 98.23°.

Synthesis,Characterization and Crystal Structure of the Dimeric Organotin Compound:{[n-Bu_(2)Sn(O_(2)CCH_(2)CS_(2)NC_(4)H_(8))]_(2)O}_(2)

The title compound,{[n-Bu_(2)Sn(O_(2)CCH_(2)CS_(2)NC_(4)H_(8))]_(2)O}_(2),has been synthesized by the reaction of(tetrahydro-pyrrodithiolocarbamoylthio)acetic acid with the di-n-bubyltin oxide in1∶1molar ratio.The complex has been characterized by elemental analysis,IR and NMR.The crystal structure of it has been determined by X-ray single crystal diffraction.And the results showed that the crystal belongs to triclinic system with space group P1and some crystal parameters:a=1.2202(9)nm,b=1.3158(10)nm,c=1.3804(10)nm,α=111.215(9)°,β=99.357(9)°,γ=96.075(10)°,V=2.006(2)nm 3,Z=1,F(000)=908,μ=1.489mm^(-1),D c=1.474g·cm^(-3),R_(1)=0.0375,wR_(2)=0.0839.The complex has a centrosymmetric dimer structure mode with a four-membered central endo-cyclic Sn_(2)O_(2)unit in which two bridged oxygen atoms both connect with an exo-cyclic tin atom which has a distorted octahedron.Each of the endo-cyclic tin atoms exhibits a distorted trigonal bipyramid coordination geometry with an additional weak coordination carboxylate oxygen.Four carboxylate ligands are divided into two types.And two of them are bidentate and connecting to each of exo-cyclic tin atoms by using both oxygen atoms,whereas the others bridge to each pair of exo-and endo-cyclic tin atoms utilizing one oxygen atom only.CCDC:220513.

Synthesis,Structure,and Surface Photo-electric Properties of a New Zn(Ⅱ)Coordination Complex Constructed from 2-(1H-benzotriazol-1-yl)acetic Acid and 1,10-Phenanthroline Ligands

A new binuclear Zn^Ⅱ coordination complex,Zn2（bta）（phen）2（Cl）3（1,Hbta = 2-（1Hbenzotriazol-1-yl）acetic acid and phen = 1,10-phenanthroline）,has been synthesized and characterized by single-crystal X-ray diffraction,IR spectroscopy,elemental,and photoluminescent analysis.Complex 1 crystallizes in triclinic system,space group P1 with a = 9.3040（19）,b = 10.694（2）,c =16.841（3） A°,α = 101.18（3）,β = 105.77（3）,γ = 91.72（3）°,V= 1575.8（5） A°3,C（32）H（22）Zn2Cl3N7O2,Mr =773.66,Dc = 1.631 g/cm^3,Z = 2,F（000） = 780,μ = 1.820 mm^-1,the final R = 0.1238 and wR =0.1131.X-ray diffraction analyses indicate that 1 displays two crystallographic independent Zn^Ⅱmetal centers with a distorted tetragonal pyramidal（ZnN4O） and a tetrahedral（ZnNCl3） geometries,respectively.The phen serves as a common N,N＇-bidentate ligand,and the bta^- as a unique N,O-bridged ligand in 1.In the crystal,1 forms a stable 3D supramolecular architecture by trifurcated hydrogen bonding C-H…C1 interactions and C-H…π,π…π stacking.1 showed photo-electric conversion properties.

Synthesis, Structure and Thermal Behaviors of a Magnesium(Ⅱ) Complex with Tetrazole-1-acetic Acid

A new complex of magnesium with tetrazole-l-acetic acid （tza） has been synthe- sized and characterized by elemental analysis and FT-IR spectrum. Single-crystal X-ray diffraction analysis determined the molecular formula as Mg（tza）2（H20）4. The crystal belongs to the triclinic system with Pi space group, and a = 6.133（2）, b = 6.488（2）, c = 10.0127（7） A, a = 77.282（10）, fl = 91.558（1）, ）, = 76.002（8）°, Y = 349.0（2）A3, Z = 1, C6HI4MgNsOs, Mr = 350.56, Dc = 1.668 g.cm-3, F（000） = 182,μ = 0.189, S = 1.000, the final R = 0.0294 and wR = 0.0785 for 1128 observed reflections with I 〉 20-（I）. In this molecule, the tza ion exhibits an infrequent monodentate coordination mode. The magnesium center is hexa-coordinated to a slightly distorted octahedral configuration by six oxygen atoms from two tza ligands and four coordinated water molecules. DSC and TG-DTG analyses were applied to assess the thermal decomposition behavior. The kinetic parameters of the exothermal peak were calculated by non-isothermal reaction kinetics. The values of critical temperature of thermal explosion, △S≠, △H≠ and △G^≠, were obtained as 596 K, -42.25 J mo1^-1 K^-1, 296.43 kJ mol^-1 and 323.53 kJ mol1, respectively.

Syntheses and Crystal Structures of Two Nickel(Ⅱ) Complexes [Ni(dmpzm)_2(L)]Cl·nH_2O (L=HCO_2,OAc;n=2,3;dmpzm=1,1'-Methylenebis(3,5-dimethyl-1H-pyrazole))

Reactions of NiCl2-6H2O with dmpzm and formic or acetic acid at PH = 7 produced the two title compounds, [Ni（dmpzm）2（HCO2）]Cl·2H2O 1 and [Ni（dmpzm）2（OAc）]C2·H2O 2 （dmpzm = 1,1 ＇-methylenebis（3,5-dimethyl-lH-pyrazole））. 1 and 2 were characterized by elemental analysis, IR spectra, and thermogravimetric analysis. 1 crystallizes in the orthorhombic system, space group Pcca with a = 18.700（2）, b = 8.6843（9）, c = 18.098（2）A, V= 2939.1（5）A^3, Z = 4, Dc = 1.319 g/cm^3, T = 193 K, C23H37CINsNiO4, Mr = 583.75, F（000） = 1232, p（MoKa） = 0.792 cm^-1, S = 1.079, R = 0.0772 and wR = 0.1958 for 2265 observed reflections with I〉 2σ（I）. 2 crystallizes in the orthorhombic system, space group Pcca with a = 17.011（3）, b = 18.630（4）, c = 19.300（4）A, V = 6117（2）A^3, Z = 8, Dc = 1.337 g/cm^3, T= 193（2） K, C24H41C1N8NiO5, Mr = 615.79, F（000） = 2608, μ（MoKa） = 0.768 cm^-1, S = 1.059, R = 0.0518 and wR = 0.1109 for 5124 observed reflections with I 〉 2σ（I）. The Ni atoms in 1 or 2 are chelated by two dmpzm ligands and one formate or acetate anion, forming slightly distorted octahedral geometries. In the crystals of 1 or 2, intermolecular hydrogen bonding interactions result in the formation of 2D hydrogen-bonded frameworks.

Synthesis and Molecular Structure of Acetic Acid-3,5-diacetoxy-2-acetoxymethyl-6-(4-quinoxalin-2-yl-phenoxy)-tetrahydro-pyran-4-yl-ester

The title compound, acetic acid-3,5-diacetoxy-2-acetoxymethyl-6-（4-quinoxalin- 2-yl-phenoxy）-tetrahydro-pyran-4-yl-ester 8 （C28H28N2O10, Mr = 552.54）, has been synthesized and its crystal structure was determined by X-ray diffraction analysis. It crystallizes in monoclinic, space group P21, a = 10.060（8）, b = 5.648（4）, c = 24.11（2）A, β = 91.078（10）°, Z = 2, V= 1369.9（19）A^3, Dc = 1.339 g/cm^3,μ（MoKa） = 1.03 cm^-1, F（000） = 580.00, T =. 193.1 Kx-9 θmax = 25.03, （△/σ）max = 0.0000, Flack = -0.0（24）, the final R = 0.0680 and wR = 0.140 （w = 1/[0.0016Fo^2 ＋ 1.00000（Fo^2）]/（4Fo^2）） for 3126 observed reflections （1 〉 20（/））. The pyranoid ring adopts chair conformation in the sugar moiety, and all of the acetyl groups are in the e bond of the pyranoid ring, so the sugar moiety is very stable.