Effect of the graphitic degree of carbon supports on the catalytic performance of ammonia synthesis over Ba-Ru-K/HSGC catalyst

A series of high surface area graphitic carbon materials （HSGCs） were prepared by ball-milling method. Effect of the graphitic degree of HSGCs on the catalytic performance of Ba-Ru-K/HSGC-x （x is the ball-milling time in hour） catalysts was studied using ammonia synthesis as a probe reaction. The graphitic degree and pore structure of HSGC-x supports could be successfully tuned via the variation of ball-milling time. Ru nanoparticles of different Ba-Ru-K/HSGC-x catalysts are homogeneously distributed on the supports with the particle sizes ranging from 1.6 to 2.0 nm. The graphitic degree of the support is closely related to its facile electron transfer capability and so plays an important role in improving the intrinsic catalytic performance of Ba-Ru-K/HSGC-x catalyst.     

A New Terbium（III） Coordination Compound with 2-Thiophenecarboxylic Ligand： Synthesis and Crystal Structure①

A new coordination compound with formula [Tb（2-TC）3（DMF）]n （1, 2-TC = 2-thio- phenecarboxylic ligand and DMF = dimethylformamide） was synthesized by solvothermal method. The structure of compound 1 was determined by single-crystal X-ray diffraction analyses, and characterized by elemental analyses, IR and powder X-ray diffraction. Structure analysis reveals compound 1, exhibiting a one-dimensional chain structure, crystallizes in triclinic space group P21/c, with a = 9.2751（19）, b = 16.490（3）, c = 15.865（5） A, β = 118.98（2）°, V= 2122.7（9）A3, D,. = 1.916 g/cm3, Mr= 612.45 （C18H15NO7S3Tb）, F（000） = 1196,μ（MoKa） = 3.67 mm-1, Z = 4, R = 0.0616 and wR = 0.0962 for 3865 observed reflections （I 〉 2o（I））, and R = 0.1092 for all data. Meanwhile, the photoluminescent properties of compound 1 were also investigated in the solid state at room temperature.     

Syntheses,Crystal Structures,and Properties of a New Lead(Ⅱ) Complex Involving Holo-and Hemidirected Coordination Spheres with 3,5,6-Tris(2-pyridyl)-1,2,4-triazine Ligand

[Pb(TPT)(μ-I)2PbI2(μ-I)2Pb(TPT)] 1(TPT is the abbreviation of 3,5,6-tris(2-pyridyl)-1,2,4-triazine ligand) has been synthesized and characterized by elemental analysis, IR, 1HNMR spectroscopy and studied by thermal and electrochemical properties as well as X-ray crystallography. The single-crystal X-ray data show two different kinds of Pb2+ ions in 1 with coordination numbers of six, Pb1 = PbI6, and five, Pb2 = PbN3I2, with holodirected and hemidirected coordination spheres, respectively. The supramolecular features in 1 are negotiated through the weak but directional Pb···I, C–H···N and C–H···I interactions and aromatic π-π stacking interactions.     

A New Cadmium（II） Coordination Polymer Constructed by 2-（2-Chloro-6-fluorophenyl）-lH-imidazo[4,5-f] [1, 10]phenanthroline and 1,2,3-Benzenecarboxylate： Synthesis,Structure and Luminescence

A new Cd（II） coordination polymer, namely, [Cd3（1,2,3-BTC）2（L）2]·2.25H2O （1, L = 2-（2-chloro-6-fluorophenyl）-1H-imidazo[4,5-A][1,10]phenanthroline and 1,2,3-BTC = 1,2,3-ben- zenetricarboxylate）, has been synthesized under hydrothermal conditions. The compound was characterized by single-crystal X-ray diffraction. It crystallizes in triclinic, space group Pī with α = 11.650（2）, b = 12.240（2）, c = 19.760（4） A, α = 72.01（3）, β = 77.11（3）, γ = 83.48（3）°, V = 2609.4（9） A3, Z = 2, C56H31Cd3Cl2F2N8O14.25, Mr = 1489.99, Dc = 1.896 g/cm3, F（000） = 1466, μ（MoKa） = 1.401 mm^-1, R = 0.0401 and wR = 0.1104. Compound 1 shows a 1D chain structure, and the neigh- boring 1D chains of 1 are joined together by π···π interactions to result in a 2D supramolecular layer. In addition, the luminescent property of 1 has been studied in the solid state at room temperature.     

Effect of Molecular Weight on the Properties of Poly（butylene succinate）

Poly（butylene succinate） （PBS） with different molecular weight was synthesized from 1, 4-butanediol and succinic acid by direct melt condensation. The synthesized PBS was identified by IH-NMR and FTIR spectrometry. The molecular weight was calculated from the intrinsic viscosity, and its value was between 20000 and 70000. The crystallization behavior and crystal morphology as function of molecular weight were investigated by DSC and PLM, respectively. The mechanical properties and hydrolytic degradation behaviors related with change of molecular weight were also studied in this work. The results demonstrated that the properties of PBS were determined by both molecular weight and crystallization properties （crystallinity as well as crystal morphology）. Our work is important for the design and preparation of PBS with proper molecular weight for its practical application.     

Iron-mediated AGET ATRP of styrene and methyl methacrylate using ascorbic acid sodium salt as reducing agent

Atom transfer radical polymerization of styrene(St) and methyl methacrylate(MMA) in bulk and in different solvents using activators generated by electron transfer(AGET ATRP) were investigated in the presence of a limited amount of air using FeCl3·6H2O as the catalyst, ascorbic acid sodium salt(AsAc-Na) as the reducing agent, and a cheap and commercially available tetrabutylammonium bromide(TBABr) as the ligand. It was found that polymerization in THF resulted in shorter induction period than that in bulk and in toluene for AGET ATRP of St, while referring to AGET ATRP of MMA, polymerization in THF showed three advantages compared with that in bulk and toluene: 1) shortening the induction period, 2) enhancing the polymerization rate and 3) having better controllability. The living features of the obtained polymers were verified by chain end analysis and chain-extension experiments.     

Investigation of Hydrolysis in Poly（ethylene terephthalate） by FTIR-ATR

The hydrothermal aging of poly(ethylene terephthalate)(PET) was investigated at 70 95 °C. A new method to investigate the hydrolysis degree of PET by Fourier transform infrared spectroscopy(FTIR) was proposed. The spectra during the hydrothermal aging were measured using attenuated total reflection accessory(ATR). Peak resolving of carbonyl regions was performed, and the ratio of two groups of bands representing carboxylic acids and esters respectively were calculated to show the hydrolysis degree of ester groups in PET. The acid/ester ratio shows exactly the same trend as the average chain scission number per unit mass at various temperatures and thus can be used as a parameter to characterize the hydrolysis and random chain scission of PET. This method related to the hydrolysis mechanism directly, is simple, fast and convenient compared to the traditional methods such as viscometry, end-group titration and size exclusion chromatography(SEC). It may also be useful in hydrolysis characterization of other polyesters.     

Microstructure characterization of short-chain branching polyethylene with differential scanning calorimetry and successive selfnucleation/annealing thermal fractionation

A series of the copolymers of ethylene with 1-hexene(M1–M9) synthesized by metallocene catalyst Et[Ind]2ZrCl2/MAO was studied by differential scanning calorimetry and successive self-nucleation and annealing(SSA) thermal fractionation. The distribution of methylene sequence length(MSL) in the different copolymers was determined using the SSA method. The comonomer contents of samples M4 and M5 are 2.04 mol% and 2.78 mol%, respectively. Both M4 and M5 have low comonomer content and their MSL distribution profiles exhibit a monotonous increase trend with their MSL. The longest MSL of M5 is 167, and its corresponding molar percent is 43.95%, which is higher than that of M4. Moreover, the melting temperature(Tm) of M5 is also higher than that of M4. The comonomer contents of samples M7, M8, and M9 are 8.73 mol%, 14.18 mol% and 15.05 mol%, respectively. M7, M8, and M9 have high comonomer contents, and their MSL distribution profiles display unimodality. M7 has a lower peak value of 33 and a narrow MSL distribution, resulting in a Tm lower than that of M8 and M9. The MSL and its distribution are also key points that influence the melting behavior of copolymers. Sometimes, MSL and its distribution of copolymers have a greater impact on it than the total comonomer contents, which is different from traditional views.     

两种异马来二氰基二硫烯镍(II)-取代苄基喹啉鎓盐的制备及其光谱性质和晶体结构

以甲醇为溶剂,将异马来二氰基二硫烯酸钾[K2(i-mnt)]和六水氯化镍分别与溴化4-溴苄基喹啉盐([4-BrBzQl]Br)或溴化4-硝基苄基喹啉盐([4-NO2BzQl]Br)直接反应,得到两种新的离子对配合物[4-BrBzQl]2[Ni(i-mnt)2](1)和[4-NO2BzQl]2[Ni(i-mnt)2](2);测定了其红外光谱和紫外-可见光谱,并利用X射线衍射表征了配合物1的晶体结构.结果表明,配合物[4-BrBzQl]2[Ni(i-mnt)2]为三斜晶系,P-1空间群,其每个不对称单元含半个[Ni(i-mnt)2]2-阴离子和1个[4-BrBzQl]+阳离子,晶体中的阴、阳离子通过静电作用和C-H…S、C-H…N氢键作用形成网络结构.     

CM⁃Phos配体在钯催化交叉偶联反应中的应用

本文综合评述了近年来2-[2-(二环己膦基)苯基]-1-甲基-1H-吲哚(CM-Phos)膦配体及其衍生物在钯催化的交叉偶联反应中的应用, 主要根据不同种类的交叉偶联反应进行系统性分述, 并对该领域的发展前景进行了展望.