Electrochemical preparation and performance of γ-MnO_2

The effects of the electro-deposition conditions on the crystal structure and the properties of electrolytic manganese dioxide(EMD) were investigated in this paper. The results show that EMD was γ-crystal, with sand-like rough interface. The optimal preparation conditions of EMD were 30 min deposition time, and p H=1.0 in Mn SO4-H2SO4 solution at 50 ?C. Surfactant(P1) was conducive to the uniform and stable surface of γ-Mn O2 film, the impedance and the specific surface area of the electrode modified with γ-Mn O2 increased by 21.4 times and 75.6 times, respectively. The redox reversibility and the resolution ratio of characteristic peaks with the modified electrode were significantly improved in the benzodiazepines electrochemical reaction. The achievement illustrated that the controllable synthesis of γ-Mn O2 film thickness was practical in electrochemical sensors, and the determination reliability of benzodiazepines was improved with γ-Mn O2 modified electrodes used in environment monitoring technology.

Chemical Conversion of a Coumarin Derivative Containing Arylhydrazono: Crystal Structures and Fluorescence Properties

An arylhydrazono-containing coumarin derivative(1) can undergo chemical conversions in two modes. When in the presence of Cu^(2+), a Cu^(2+)-promoted cyclization reaction was observed in aqueous acetonitrile and gives compound 2, while a ring-opening reaction occurs to give compound 3 in the absence of Cu^(2+). Both 2 and 3 were characterized by single-crystal X-ray diffraction. Compound 2 crystallizes in monoclinic C2/c space group with a = 26.606(5), b = 5.8142(12), c = 26.906(5) ?, β = 103.41(3)°, Z = 8, F(000) = 1696, μ = 0.186 mm^(-1), R = 0.0487 and wR = 0.1129. Compound 3 crystallizes in monoclinic P21/n space group with a = 9.917(2), b = 13.644(3), c = 15.912(3) ?, β = 95.38(3)°, Z = 4, F(000) = 896, μ = 0.182 mm^(-1), R = 0.0769 and w R = 0.1617. The spectroscopic studies show that compound 2 exhibits strong fluorescence emission.

A Proposed Stereochemical Mechanism for the Improved Preparation of Maleic Anhydride Cycloadduct of CLA

The fatty acid derivatives, prepared from renewable natural oils, can be used as highly promising and potential substitutes for petrochemicals. The study of process improvement and stereochemical mechanism for preparing these derivatives would be beneficial for their industrial production. Conjugated linoleic acid (CLA) containing 9cis-11trans (9c, 11t) and 10trans-12cis (10t, 12c) isomers was prepared from Salicornia herbacea seed oil. Maleic anhydride cycloadduct of CLA (MAC) was prepared by an improved process, and it was characterized by FTIR, 1H and 13C NMR, etc. A new method to calculate conformers-ratio of CLA or MAC was also developed. Furthermore, the stereochemical mechanism for the improved preparation of MAC was proposed primarily by the calculation method above. The following observations were made: 1) The yield of MAC could reach as high as 96.7% under mild reaction conditions and with an easy and efficient product separation;2) The trans-trans CLA in the s-cis conformation acted as a predominant reactant to Diels-Alder [4 + 2] cycloaddition of maleic anhydride, which was the main reaction occurred simultaneously with catalytic configurational isomerizations of CLA in one step;3) From all studied CLA conformers, the most stable conformation was the s-trans conformation of trans-trans CLA, while the s-cis conformation of trans-trans CLA had the most favorable structural parameters for cyclohexenyl ring formation;4) Four MAC conformers derived from 9c, 11t- and 10t, 12c-CLA, were obtained as final main products that were determined to be cis-cycloadducts;5) The endo/exo ratios of the cis- cycloadducts derived from 9c, 11t- and 10t, 12c-CLA, were 2.14:1 and 1.99:1, respectively;and 6) The results obtained from the calculation method above were in excellent accordance with those from our experiments.

Chemical Structure of Surfactant-Grafted Polyacrylamide Used in Oilfields

Surfactant-grafted Polyacrylamide (S-PAM) flooding is a new technique used in Daqiang Oil Field in China and also a novel way for improving the recovery efficiency of primary oil layer after polymer flooding. S-PAM flooding technology is perfected gradually with the proceeding of multiple polymer surfactant oil displacement tests. Test results showed that the S-PAM used in field was greatly different with conventional ones. Therefore, it is necessary to study the chemical structure of S-PAM. Aiming at making clear the chemical structure of S-PAM, this study characterized the two commonly used S-PAM in oil field through chemical analysis and Fourier infrared spectrometer detection and analyzed the main composition and chemical structure of the two S-PAM.

Preparation of Nano-TiO_2 Doped with Cerium and Its Photocatalytic Activity

Cerium-doped titanium dioxide nano-powders were prepared through the sol-gel method and the compound samples were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and UV/Vis diffuse reflectance spectra （DRS）. The photocatalytic activity was evaluated by photocatalytic degradation of phenol in water. The results of XRD, TEM, and DRS show that pure TiO2 and Ce-doped TiO2 powder crystallines are a mixture of anatase and rutile; the doping can retard the development of the grain size of TiO2 and decrease the diameter of TiO2 from more than 20 nm of pure TiO2 to about 10 nm; the doped TiO2 can improve the light absorption of TiO2 and suitable doping content tends to move the DRS spectrum of TiO2 towards visible light, but too much doping is not good for the light absorption ability. The results of the photocatalytic experiments show that doping with Ce content of 0.08%～0.4% can increase the photocatalytic activity of TiO2; however, doping with Ce content of 0.5%～2.5% can significantly decrease the photocatalytic activity of TiO2. The favorite doping content is 0.4% in the range of our experiments.

One-pot synthesis and characterization of a new, branched polycarbosilane bearing allyl groups

A highly branched polycarbosilane bearing allyl groups has been prepared by a one-pot synthesis with chloromethyltrichlor-osilane, chloromethylmethyldichlorosilane and allyl chloride as the starting materials. The resultant polymer, with the approximate formula [SiH1.2(CH3)0.71(CH2CH=CH2)0.09CH2]n, has been characterized by 1H, 13C, and 29Si NMR, GPC, TG and elemental analysis. It could be cross-linked thermally at 170℃in the absence of oxygen. Pyrolysis of the polymer gave a ceramic with a yield of about 70%.

The Kinetics of the Esterification of Free Fatty Acids in Waste Cook- ing Oil Using Fe2（SO4）3/C Catalyst

The esterification of free fatty acids(FFA) in waste cooking oil with methanol in the presence of Fe2(SO4)3/C(ferric sulfate/active carbon) catalyst was studied.The effects of different temperature,methanol/FFA mole ratio and amount of catalyst on the conversion of FFA were investigated.The results demonstrated that under optimal esterification conditions the final acid value of the resultant system can be reduced to ～1(mg KOH)·g-1,which met fully the requirements in post-treatment for efficient separation of glycerin and biodiesel.The kinetics of the esterification were also investigated under different temperatures.The results indicated that the rate-control step could be attributed to the surface reaction and the esterification processes can be well-depicted by the as-calculated kinetic formula in the range of the experimental conditions.

Effect of preparation methods on the structure and catalytic performance of Fe–Zn/K catalysts for CO2 hydrogenation to light olefins

Potassium promoted iron–zinc catalysts prepared by co-precipitation method(C–Fe–Zn/K),solvothermal method(S–Fe–Zn/K)and hydrothermal method(H–Fe–Zn/K)could selectively convert CO_2to light olefins,respectively.The physicochemical properties of the obtained catalysts were determined by SEM,N_2physisorption,XRD,H_2-TPR,CO_2-TPD and XPS measurements.The results demonstrated that preparation methods had great influences on the morphology,phase structures,reduction and adsorption behavior,and hence the catalytic performance of the catalysts.The samples prepared by hydrothermal and co-precipitation method generated small uniform particles and led to lower specific surface area.In contrast,microspheres with larger specific surface area were formed by self-assembly of nanosheets using solvothermal method.ZnFe_2O_4was the only detectable phase in the fresh C–2Fe–1Zn/K,S–3Fe–1Zn/K and S–2Fe–1Zn/K samples.ZnFe_2O_4and ZnO co-existed with increasing Zncontent in S–1Fe–1Zn/K sample,while ZnO and Fe_2O_3could be observed over H–2Fe–1Zn/K sample.All the used samples contained Fe_3O_4,ZnO and Fe_5C_2.The peak intensity of ZnO was strong in the AR-H–2Fe–1Zn/K sample while it was the lowest in the AR-C–2Fe–1Zn/K sample after reaction.The formation of ZnFe_2O_4increased the interaction between iron and zinc for C–2Fe–1Zn/K and S–Fe–Zn/K samples,causing easier reduction of Fe_2O_3to Fe_3O_4.The surface basicity of the sample prepared by co-precipitation method was much more than that of the other two methods.During CO_2hydrogenation,all the catalysts showed good activity and olefin selectivity.The CO selectivity was increased with increasing Zncontent over S–Fe–Zn/K samples.H–2Fe–1Zn/K catalyst preferred to the production of C_5^+hydrocarbons.CO_2conversion of 54.76%and C_2~=–C_4~=contents of 57.38%were obtained on C–2Fe–1Zn/K sample,respectively.

Synthesis,Structure and Photoluminescent Property of a Cd-organic Complex [Cd(L)_2(pbda)]_n

A new complex,[Cd(L)2(pbda)]n(1,L = 3-(2-pyridyl)-4-(p-methoxyphenyl)-5-(2-thienyl)-1,2,4-triazole,H2pbda = 1,4-benzenedicarboxylic acid),has been hydrothermally prepared and characterized by single-crystal X-ray diffraction,IR spectroscopy,elemental analysis and PXRD.The complex crystallizes in monoclinic,space group P21/c with a = 8.2929(9),b = 21.668(2),c = 10.9940(11) ,β = 90.242(2)o,V = 1975.5(4) 3,Z = 2,C44H32N8O6S2Cd,Mr = 945.30,Dc = 1.589 g/cm3,μ = 0.721 mm-1,S = 1.097,F(000) = 960,the final R = 0.0590 and wR = 0.1045 for 3846 observed reflections(I > 2σ(I)).In the title complex,the rigid bridging pbda2-ligands utilize oxygen atoms of carboxylate groups to coordinate with Cd(II) atoms to form one-dimensional chains which are further interlinked into a three-dimension framework via the intermolecular weak interactions.Photoluminescence study revealed that complex 1 exhibits strong fluorescent emission band in the solid state at room temperature.

Synthesis, Structure and Luminescent Property of a New Zn(Ⅱ) Coordination Polymer Based on 1,3,5-Benzenetricarboxylate and 4,4'-Bipyridine Ligands

A new Zn(II) coordination polymer [Zn3(BTC)2(4,4'-bpy)(CO)2]n(1, H3 BTC =1,3,5-benzenetricarboxylic acid, 4,4'-bpy = 4,4'-bipyridine) has been prepared through urothermal reaction of zinc nitrate hexahydrate with 1,3,5-benzenetricarboxylic acid and 4,4'-bipyridine, and characterized by elemental analysis, IR spectroscopy, TGA and powder XRD, and its crystal structure was determined by single-crystal X-ray diffraction analysis. The title compound crystallizes in the monoclinic system, space group C2/c, with a = 10.262(3), b = 18.838(5), c =15.083(4) A, β = 99.203(4)o, V = 2878.3(14) A3, C30H14Zn3N2O14, Mr = 822.54, Z = 4, Dc = 1.898g/cm3, μ = 2.561 mm-1, F(000) = 1640, R = 0.0363 and w R = 0.0932 for 2828 observed reflections(I> 2σ(I)). X-ray analysis shows that the asymmetric unit of the title compound contains two crystallographically unique Zn(II) atoms which are connected by BTC3- ligands and 4,4'-bpy coligands to form a 3D framework with 1D channels. The solid luminescence of ligand and the title complex was also studied at room temperature.

Synthesis,Characterization and Fluorescence Properties of Europium,Terbium Complexes with Biphenyl-4-Carboxylic Acid and o-Phenanthroline

Two series of solid complexes of europium and terbium with biphenyl 4-carboxylic acid and phen were synthesized and characterized in this report. Their elemental analysis, molar conductivities and TG-DTA studies indicate that the complexes have the composition of Eu(phen)L3·1/2H2O, Eu0.5RE0.5(phen)L3·1/2H2O; Tb(phen)L3·H2O and Tb0.5RE0.5(Phen)L3·1/2H2O. (RE=Y3+, La3+ and Gd3+; L=biphenyl 4-carboxylic acid; phen=o-Phenanthroline). The studies of their IR, UV 1H NMR and molar conductivities demonstrate that biphenyl 4-carboylic acid is bounded with RE(Ⅲ) ion. Rare earth ions coordinate with two nitrogen atoms of phen molecules directly in these rare earth complexes. The fluorescence spectra and fluorescence lifetimes of the rare earth complexes show that the fluorescent intensity and lifetime of a series of europium complexes are longer than those of the series of terbium complexes as having the some ligands. There are better fluorescent intensity and lifetime of hetero-nuclear rare earth complexes than homo-nuclear rare earth complexes for europium complexes. The fluorescence emission intensity of Eu3+ is raised by inert fluorescent rare earth ions (Y3+, Gd3+ and La3+), but in Tb3+ hetero-nuclear rare earth complexes the intensity of Tb3+ ions are quenched by the inert fluorescent rare earth ions.

Preparation of Au/CeO_2 catalyst and its catalytic performance for HCHO oxidation

Aqueous precipitation and deposition-precipitation method were used to prepare CeO2 supports and Au/CeO2 catalysts, respectively. The effect of preparation condition of support on the catalyst activity was investigated. The catalytic combustion of HCHO was considered as the probe reaction for comparing the catalyst activity. The BET, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and Temperature-programmed reduction (TPR) were carried out to analyze the influence factor on the catalysts activity. The results showed that the addition of dispersant and use of microwave in the support preparation procedure could be beneficial for enhancing the interaction of supports and gold species and thus improved the catalytic activity. The total conversion temperature for HCHO was 146 °C over AC400. With the modification during supports preparation process, the catalytic activity increased with total conversion temperature decreasing to 98 °C. The results of XPS indicated that Au0 and Au+1 species coexisted in these catalysts and the activity of catalyst correlated with Au+1/Au0 ratio. Temperature-programmed reduction results demonstrated that the reduction peak appeared between 100–170 °C with the inducing of gold. The dependence of activity on the reduction peak temperature implied that ionic gold was catalytic activity component for HCHO oxidation.

Adsorption Thermodynamics and Diffusion Kinetics of PX over Na Y Zeolite Synthesized by In-Situ Crystallization from Kaolin Microsphere

Para-xylene was chosen as the probe molecule to study adsorption thermodynamics and diffusion kinetics on NaY zeolite and composite structured NaY zeolite synthesized by in-situ crystallization from kaolin microsphere(designated as Na Y/kaolin composites) separately, using a high precision intelligent gravimetric analyzer(IGA). The adsorption isotherms showed normal Langmuir type-Ⅰ behaviors. The increased adsorption heat with an increasing p-xylene coverage supported a mechanism of phase transition, diffusion and re-arrangement of p-xylene molecules during the adsorption process. The rearrangement seemed to be most pronounced at an adsorption loading of 2.13 and 2.29 mmol/g for Na Y zeolite and Na Y/kaolin composites respectively. Compared with Na Y zeolite, a 2—3 times higher in the diffusion coefficient of p-xylene was observed on Na Y/kaolin composites when the pressure was more than 50 Pa. Temperature-programmed desorption(TPD) of p-xylene on two samples from room temperature to 450 ℃ at a special loading has also been investigated by IGA. Results showed only single desorption peak appeared for Na Y zeolite, indicating that adsorption can only occur in the super-cage structure. Comparably, there were two different peaks for in-situ synthesized Na Y zeolite, corresponding to the two thermo desorption processes in both super-cage structure and the channels provided by kaolin, respectively.Key words:

Synthesis,Structure and Spectral Properties of a Novel Triaryl Substituted Triazole and Its Co(Ⅱ) Complex

The new compound 3-(2-pyridyl)-4-(p-methoxyphenyl)-5-(2-thienyl)-1,2,4-triazole L was synthesized and characterized by elemental analysis,IR,1H NMR,13C NMR,MS,UV and photoluminescent spectra.The complex CoL2(NCS)2 was prepared by the reaction of ligand L with Co(SCN)2,and its structure was characterized by single-crystal X-ray diffraction,IR,UV,elemental analysis and MS.The complex crystallizes in monoclinic,space group P21/n with a=13.7639(19),b=7.6641(11),c=18.409(3),β=101.549(3)o,V = 1902.6(5) 3,Z=2,C38H28CoN10O2S4,Mr=843.87,Dc=1.473 g/cm3,μ=0.720 mm-1,S=1.075,F(000)=866.0,the final R=0.0825 and wR=0.2149 for 2566 observed reflections(I>2σ(I)).In the crystal structure,the cobalt atom adopts a distorted octahedral environment with two NCS-ions in the axial positions and two bidentate chelating L ligands in the equatorial plane.The extended 2D network of the complex is formed by intermolecular C-H…N hydrogen bonds together with π-π stacking interactions.

Preparation of Ni2P/Al-SBA-15 catalyst and its performance for benzofuran hydrodeoxygenation

The Al-doped Ni_2P/Al-SBA-15 catalyst with high hydrodeoxygenation(HDO) activity was synthesized by temperature programmed reduction at a relatively low reduction temperature of 400 °C. The as-prepared catalyst was characterized by X-ray diffraction(XRD), H_2 temperature-programmed reduction(H_2-TPR), X-ray photoelectron spectroscopy(XPS), transmission electron microscope(TEM), NH3 temperature programmed desorption(NH_3-TPD), N_2 adsorption–desorption and CO uptake. The effect of Al on benzofuran(BF) HDO performance was investigated. The result indicates that the incorporation of Al into the SBA-15 support can promote the formation of much uniform, smaller, highly dispersed Ni_2 P particles on the catalyst. The Al also contributes to suppress the enrichment of P and promote more exposed Ni sites on the surface. In addition, the incorporation of Al can enhance the acid strength. The total deoxygenated product yield over Ni_2P/Al-SBA-15 reached 90.3%, which is an increase of 19.4%, when compared with that found for Ni_2P/SBA-15(70.9%).

Synthesis of O-glycosylα-aryl nitrones

伪 - 芳基 nitrone 是 nitrones 的最有用的类型之一并且广泛地在最近的年里被探索了。然而，糖一半以前没被介绍进这些分子。我们这里在苯经由代替 N 的 hydroxylamine 和芳基醛 glycosides 的冷凝作用介绍了伪 - 芳基 nitrone O-glycosides 的有效合成。

Synthesis, Structure and Antimicrobial Activity of 9,9-Dimethyl-9,10-dihydrospiro[benzo[a]-xanthene-12,3'-indoline]-2',11(8H)-dione

One novel spiro-compound(C_(26)H_(21)NO_3) has been synthesized and characterized by means of NMR spectroscopy,elemental analyses and X-ray diffraction. The single crystal belongs to the monoclinic system,space group P21/c with a = 8.8039(7),b = 24.123(2),c = 10.0751(9) ?,β = 108.403(3)°,M3r = 395.44,V = 2030.3(3) ?~3,Z = 4,D_c = 1.294 g/cm,F(000) = 832.0,μ = 0.085 mm^(-1),R = 0.0801 and wR = 0.2228. The title compound shows good activities against Micrococcus tetragenus,Bacillus cereus,Bacillus subtilis,Staphylococcus aureus,S.albus and Escherichia coli.

Photocatalytic performance of TiO_2 catalysts modified by H_3PW_(12)O_(40), ZrO_2 and CeO_2

The binary composite photo-catalysts CeO2/TiO2, ZrO2/TiO2 and the ternary composite photo-catalysts H3PW12O40-CeO2/TiO2, H3PW12O40-ZrO2/TiO2 were prepared by sol-gel method. The catalysts were characterized by thermogravimetric-differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The photocatalytic elimination of methanol was used as model reaction to evaluate the photocatalytic activity of the composite catalysts under ultraviolet light irradiation. The effects of doped content, activation temperature, time, initial concentration of methanol and gas ffow rate on the catalytic activity were investigated. The results showed that after doping a certain amount of CeO2 and ZrO2, crystallization process of TiO2 was restrained, particles of catalysts are smaller and more uniform. Doping ZrO2 not only significantly improved the catalytic activity, but also increased thermal stability. Doping H3PW12O40 also enhanced the catalytic activity. The catalytic activities of binary and ternary composite photocatalysts were significantly higher than un-doped TiO2. The dynamics law of photocatalytic reaction over the binary CeO2/TiO2 and ZrO2/TiO2 catalysts has been studied. The activation energy 15.627 and 15.631 kJ/mol and pre-exponential factors 0.5176 and 0.9899 s-1 over each corresponding catalyst were obtained. This reaction accords to the first order dynamics law.

Ionic liquids functionalized β-cyclodextrin polymer for separation/analysis of magnolol

Ionic liquids functionalized β-cyclodextrin polymer,a mono-6-deoxy-6-(1.2-dimethylimidazolium)-(5-cyclodextrin iodide polymer(ILs-β-CDCP).was synthesized as a solid-phase adsorbent coupled with high-performance liquid chromatography for separating or analyzing magnolol in drug samples.The results showed that magnolol was adsorbed rapidly on ILs-β-CDCP and eluted with methanol.Under the optimum conditions,preconcemration factor of the proposed method was 12.The linear range,limit of detection(LOD).correlation coefficient(R) and relative standard deviation(RSD) were found to be 0.02-8.00 μg/mL,1.9 ng/mL,0.9992 and 2.76%(n=3,c=2.00 μg/mL),respectively.The interaction between ILs-β-CDCP and magnolol was studied through the inclusion constant,FTIR and TGA analysis.This proposed method has been successfully applied to the determination of magnolol in real samples.