钴( Ⅱ)与1,3-间苯咪唑及间苯二甲酸根构筑的两个配位聚合物的合成、晶体结构及性质

以间苯咪唑(1,3-bib)和间苯二甲酸(H2MPA)为配体,在温和的水热条件下,合成了Co( Ⅱ)的2个配位聚合物{[Co(1,3-bib)(MPA)(H2O)2]·H2O}n(1)和{[Co2(1,3-bib)2(MPA)2]·5H2O}n(2),分别用X-射线单晶衍射、元素分析、IR和热重等手段对它们进行了表征,结果表明,配位聚合物1为1D层状结构,属于正交晶系,Pnma空间群;配位聚合物2为双核2D结构,属于三斜晶系,P1空间群。在室温下研究了它们的光学性质。     

2,2-二甲基-1-[5-二茂铁基-3-(三氟甲基)-1H-吡唑-1-基]丙-1-酮的合成及其电化学性质

以乙酰基二茂铁为原料,经3步反应合成了一个新型的二茂铁衍生物——2,2-二甲基-1-[5-二茂铁基-3-(三氟甲基)-1H-吡唑-1-基]丙-1-酮(4),其结构经1H NMR,ESI-MS,元素分析和X-射线单晶衍射表征。4属单斜晶系,P2(1)/c空间群,晶胞参数a=7.805 6(4),b=20.906 1(11),c=11.124 6(6),β=93.820(2)°,V=1 811.33(17)3,Z=4,Dc=1.482 g·cm-3,μ=0.872 mm-1,R1=0.034 8,wR2=0.089 2。采用循环伏安法研究了4的电化学性质。结果表明:4有一对可逆的氧化还原峰,Epa=0.640 V,Epc=0.482 V,ΔE=153 m V。     

界面扩张流变法研究C12mimBr对Gemini12-2-12在空气/水界面聚集行为的影响

采用界面扩张流变技术研究了季铵盐偶联表面活性剂C₁₂-(CH₂)₂-C₁₂·2Br (Gemini12-2-12)及其与离子液体表面活性剂溴化1-十二烷基-3-甲基咪唑(C₁₂mimBr)复配体系的动态界面张力、扩张流变性质和界面弛豫过程等, 探讨了C₁₂mimBr 对C₁₂mimBr/Gemini12-2-12 混合体系界面性质的影响及C₁₂mimBr 对Gemini12-2-12界面聚集行为影响的机制. 结果表明, 随着离子液体表面活性剂的不断引入, 体系界面吸附达到平衡所需的时间逐渐缩短, 扩张模量和相角明显降低, 界面吸附膜由粘弹性膜转变为近似纯弹性膜; 同时, 界面及其附近的弛豫过程也发生显著变化, 慢弛豫过程消失, 快弛豫过程占主导地位, 且离子液体浓度越高, 快弛豫的贡献越大. 这些界面性质的变化主要归因于离子液体表面活性剂C₁₂mimBr参与界面形成及两表面活性剂在界面竞争吸附的结果. 少量离子液体表面活性剂C₁₂mimBr 的加入可以填补疏松的Gemini12-2-12 界面上的空位, 形成混合界面吸附膜. 随着C₁₂mimBr 含量的增加, 嵌入界面的C₁₂mimBr 分子数不断增多, 导致界面上相互缠绕的Gemini12-2-12烷基链“解缠”, 在体相和界面分子扩散交换的过程中“解缠”的Gemini12-2-12分子从界面上解吸回到体相, 与此同时, C₁₂mimBr 分子相对较小的空间位阻及较强的疏水作用促使其优先扩散至界面进而取代Gemini12-2-12分子, 最终界面几乎完全被C₁₂mimBr分子所占据.     

MgH2+20%(w)MgTiO3复合材料的吸/放氢性能

为了降低MgH₂的吸放氢温度, 提高其吸放氢动力学性能, 本文通过球磨方法制备了MgH₂+20%(w)MgTiO₃复合储氢材料, 并研究了其储氢性能. X射线衍射(XRD)结果表明, MgTiO₃在与MgH₂球磨过程中生成Mg₂TiO₄和TiO₂, 并且Mg₂TiO₄和TiO₂在体系的吸放氢过程中保持稳定, 能够对MgH₂的吸放氢过程产生催化作用. 程序升温脱附和吸/放氢动力学测试结果表明, 添加MgTiO₃后MgH₂的初始放氢温度从389 ℃降至249 ℃.150 ℃下的吸氢量从0.977%(w)提高到2.902%(w), 350 ℃下的放氢量从2.319%(w)提高到3.653%(w). 同时, MgH₂放氢反应的活化能从116 kJ·mol^-1降至95.7 kJ·mol^-1. 与MgH₂相比, MgH₂+20%(w) MgTiO₃复合材料的热力学与动力学性能均有显著提高, 这主要是由于球磨和放氢过程中原位生成的TiO₂和Mg₂TiO₄具有良好的催化活性.     

聚丙烯酰胺纳米复合水凝胶研究进展

传统化学交联的聚丙烯酰胺(PAM)水凝胶由于力学性能较弱,其应用范围受到很大限制。与之相比,采用纳米复合技术制备的PAM纳米复合(NC)水凝胶,不仅大幅提高了力学性能,而且在溶胀率等方面也有明显的提高。本文结合该领域近年来的研究进展,将PAM NC水凝胶分为纯物理交联和化学物理交联相结合两类,重点讨论了NC水凝胶在力学性能方面的研究结果,对溶胀率等其它方面的性能也进行了综合论述。     

Improving the impact property and heat‐resistance of PLA/PC blends through coupling molecular chains at the interface

The influences of both the molecular structure and the melt viscosity differences between Poly(lactic acid) (PLA) and polycarbonate (PC) on the interpenetration of molecular chains at the interface were investigated by comparing the dynamic mechanical properties and morphologies of the as‐prepared PLA/PC solution‐casting blends with those of their corresponding annealed (180°C, 8 h) samples or PLA/PC melt blends. Additionally, two chain extenders containing epoxy groups (ADR and TGDDM) were used to improve the interfacial strength. Subsequently, the interpenetration of PLA and PC molecular chains at the interface was also surveyed. Finally, the effects of the morphology formed by after adding ADR or TGDDM on the impact property, and heat resistance were discussed. The results showed that there was no interpenetration of molecular chains at the interface in PLA/PC melt blends because of the serious hindrance of the molecular structure and the melt viscosity differences. Although the interfacial strength achieved significant increase after adding ADR or TGDDM, the increase of the interfacial strength should be caused by the connection of ADR or TGDDM molecules with PLA and PC molecules at the interface through chemical bonds rather than the entanglements of PLA and PC molecular chains because of no interpenetration of PLA and PC molecular chains at the interface. Thus, the morphology formed after adding ADR or TGDDM is still the type of complete phase separation, which may be the most suitable morphology for achieving high impact and heat resistance PLA/PC blends because these two properties strongly depend on the crystallinity of PLA phase. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and magnetic properties of organic multilayer films based on the layer‐by‐layer assembly

Two polymers containing pyridine rings were prepared by free‐radical polymerization and confirmed by Fourier transform infrared and ¹H NMR spectra. The preparation of four multilayer films that were obtained by self‐assembly of the polymer and the transition metal neutralized polyelectrolyte on PE substrate was described. UV–vis spectra and atomic force microscopy images were applied to characterize these films and indicate the uniform assembling process. The driving force for building up the multilayer films was identified by infrared spectroscopy to be the coordination interaction. The magnetic behavior was examined as a function of magnetic field strength at 30 kOe and as a function of temperature (5–300 K). All films display strong soft ferromagnetic properties and higher than those of the bulk materials. The magnetic results show that the layer‐by‐layer self‐assembling approach is beneficial to the ordered alignment of adjacent paramagnetic spins and induces better magnetic phenomena. Copyright © 2015 John Wiley & Sons, Ltd.     

载体表面酸碱性质对无碱水溶液中Au催化的甘油氧化反应产物选择性的调控作用

甘油(GL)是一种重要的生物平台分子,通过催化选择氧化反应将其转化为具有高附加值化学品是可持续发展化学化工的重要课题之一.以Au为催化剂的GL水相选择氧化反应可以生成甘油酸(GLA)、二羟基丙酮(DHA)、羟基丙二酸(TTA)、羟基乙酸(GCA)和乳酸(LA)等多种产物.通常,该反应需要碱(NaOH)存在时才能进行,产物往往以GLA为主(选择性40%-70%),副产物主要有GCA, TTA和草酸(OA).一般认为,可溶性碱(OH-)是通过夺取GL分子中羟基上的质子而诱发反应的.尽管在Au催化的反应体系中从未检测到有甘油醛(GLD)生成, GLD和/或DHA被认为是该反应的中间物种.本课题组前期工作表明,氧化物(TiO2, Al2O3, ZrO2, CuO等)负载的纳米Au催化剂能够在无碱(无外加OH-)水溶液中选择性催化GL氧化生成DHA(而不是GLA).因此, OH-的存在与否很可能会改变水溶液中Au催化剂上GL氧化反应的途径.本文试图回答当GL的水溶液中不存在NaOH时, Au催化剂载体的表面酸碱性质是否也会对GL氧化反应的选择性产生调控作用.我们选用Mg/Al比(x)不同的MgO-Al2O3样品为Au催化剂的载体,以尿素为沉淀剂,采用沉积沉淀法制备了相应的Au/MgO-Al2O3(x)催化剂样品.采用X射线衍射、电感耦合等离子体-原子发射光谱仪、透射电镜以及N2吸附-脱附等温线等对MgO-Al2O3(x)和/或Au/MgO-Al2O3样品的物相、元素组成、Au颗粒大小以及比表面积等进行了表征分析;采用NH3和CO2程序升温脱附(TPD)分别对MgO-Al2O3(x)载体表面的酸、碱性进行了测定. NH3-TPD和CO2-TPD结果表明,随着Mg/Al比x从0增加至4.8, MgO-Al2O3(x)的表面酸量从0.94降到0.20μmol/m2,而其表面碱量却从0.05剧增至0.80μmol/m2.因此,载体中MgO含量越多或Mg/Al比越大,其酸性越弱而碱性越强.在无碱水溶液中的催化反应结果表明, Au/MgO-Al2O3(x)上GL氧化反应的主要产物为DHA, GLA以及GCA等.随着x值(催化剂表面碱性)不断增大,产物DHA的选择性从约80%下降到10%左右,而GLA的选择性却从约4%增加至约50%.当载体为酸性最强的Al2O3(x =0)时,产物DHA的选择性为最高(80%).由此可见,载体表面的酸碱性质决定了无碱水溶液中Au催化剂上的GL氧化产物的分布. 此外,当保持Au粒子的尺寸基本不变(如3.1或6.6 nm左右),而改变载体的酸碱性质时, Au/MgO-Al2O3催化GL氧化反应的活性(TOF)可相差8-9倍.本文还通过改变Au/MgO-Al2O3样品焙烧温度,制备了表面酸碱性质相同而颗粒大小不同的三个Au/MgO-Al2O3(0.2)催化剂,考察了Au粒径对GL氧化反应选择性的影响.在这三个催化剂上, Au颗粒的平均尺寸分别为2.8,3.2和6.6 nm, GL氧化反应的产物选择性近乎相同(DHA和GLA的选择性分别为65%和15%左右),但平均尺寸为6.6 nm Au粒子的催化活性(TOF)是3.2 nm Au粒子的1.6倍,2.8 nm Au粒子的2.7倍.因此,本文建立了载体表面酸碱性质与无碱水溶液中GL氧化产物选择性之间的关系,通过改变载体表面酸碱性质实现了对无碱水溶液中Au催化剂上GL氧化反应选择性的调控.尽管载体酸碱性质和Au粒子尺寸都对Au/MgO-Al2O3催化剂的本征活性有重要影响,但载体酸碱性质的影响更显著.     

Structural,Electronic and Optical Properties of the Monoclinic α-CoV_2O_6

First-principles calculations based on density functional theory are performed to investigate the structural,electronic and optical properties of monoclinic α-Co V2O6.Firstly,the geometry structures obtained by geometry optimization are consistent with the experimental values.Then,the energy band structure is studied using both GGA and GGA+U methods.It is found that the on-site Coulomb repulsion of the Co 3d orbital plays a key role in describing the electronic properties of α-Co V2O6,and is necessary to open the energy band gap.According to the partial density of states(PDOS),significant Co–O and V–O hybridizations are observed in the valence and conduction bands,respectively.Furthermore,the Co–O and V–O bonds are found to have significant covalent characters.Below the absorption threshold ~1.9 e V,no absorption can be detected.However,there exists a strong and wide absorption band in the energy range from 1.9 to 11 e V.Such novel optical properties imply that the α-Co V2O6 may have some potential optical applications.     

Synthesis,Crystal Structure and Properties of a New Cd(Ⅱ) Complex Based on Mixed 5-Hydroxy-isophthalic Acid and 1-(1H-imidazol-4-yl)-3-(4H-tetrazol-5-yl)benzene Ligands

A new coordination polymer [Cd2(5-IPA)(HL)2(H2O)2]·4H2O(1) was prepared under hydrothermal conditions based on 5-hydroxy-isophthalic acid(5-H2IPA) with multi-N-donor ligand 1-(1H-imidazol-4-yl)-3-(4H-tetrazol-5-yl)benzene(H2L). The complex was characterized by IR spectroscopy, TGA, X-ray powder and single-crystal diffraction. It crystallizes in the monoclinic system, space group C2/c with a = 23.6291(18), b = 9.9847(8), c = 17.7244(14) ?, β = 124.6180(10)?, V = 3441.4(5) ?3, Z = 4, C28H30N12O11Cd2, Mr = 935.44, Dc = 1.805 g/cm3, μ = 1.313 mm-1, S = 1.055, F(000) = 1864, the final R = 0.049 and w R = 0.1315 for 2985 observed reflections(I 2σ(I)). The central metal Cd(II) atoms with octahedral coordination geometry are six-coordinated by three oxygen and three nitrogen atoms. The HL- ligands from the deprotonated H2 L connect Cd(II) atoms to form two-dimensional(2D) double-layer fes networks which are further pillared by 5-IPA2- ligands into a rare binodal(3, 4)-connected three-dimensional(3D) architecture with a(4·6·8)(4·62·83) fsc-3,4-C2/c topology. Solid state luminescent property and sorption property of 1 have been investigated.