通过宽线固体核磁共振氢谱研究半晶高分子的相结构

宽线固体核磁共振氢谱（¹H NMR）是一种研究半晶高分子相结构的经典方法.本文以半晶聚乙烯的宽线固体¹H NMR谱为例，探讨了通过Gaussian/Sinc、Gaussian和Lorentzian函数组合对宽线固体¹H NMR谱图进行拟合的方案，并根据半晶聚乙烯的相结构成分对拟合得到的各信号成分进行归属.并在此基础上探讨了各个相结构中分子链运动与信号线型的相关性，以及利用宽线固体¹H NMR谱测量半晶高分子结晶度存在的困难.     

Synthesis,properties and mechanism of photodegradation of core–shell structured upconversion luminescent NaYF4:Yb3+,Er3+@BiOCl

Microspherical bismuth oxychloride (BiOCl) can only utilize ultraviolet (UV) light to promote photocatalytic reactions. To overcome this limitation, a uniform and thin BiOCl nanosheet was synthesized with a particle size of about 200 nm. As results of UV–visible diffuse reflectance spectroscopy showed, the band gap of this nanostructure was reduced to 2.78 eV, indicating that the BiOCl nanosheet could absorb and utilize visible light. Furthermore, the upconversion material NaYF₄ doped with rare earth ions Yb³⁺ and Er³⁺ emitted visible light at 410 nm following excitation with near‐infrared (NIR) light (980 nm), which could be utilized by BiOCl to produce a photocatalytic reaction. To produce a high‐efficiency photocatalyst (NaYF₄:Yb³⁺,Er³⁺@BiOCl), BiOCl‐loaded NaYF₄:Yb³⁺,Er³⁺ was successfully synthesized via a simple two‐step hydrothermal method. The as‐synthesized material was confirmed using X‐ray diffraction, scanning electron microscopy, X‐ray photoelectron spectroscopy as well as other characterizations. The removal ratio of methylene blue by NaYF₄:Yb³⁺,Er³⁺@BiOCl was much higher than that of BiOCl alone. Recycling experiments verified the stability of NaYF₄:Yb³⁺,Er³⁺@BiOCl, which demonstrated excellent adsorption, strong visible‐light absorption and high electron–hole separation efficiency. Such properties are expected to be useful in practical applications, and a further understanding of the NIR‐light‐responsive photocatalytic mechanism of this new catalytic material would be conducive to improving its structural design and function.     

Preparation and solution properties of a novel cationic hydrophobically modified polyacrylamide for enhanced oil recovery

Abstract

A novel cationic water-soluble monomer allyldimethylisooctylammonium bromide (ADIAB) containing a short-chain alkane was synthesized successfully. This monomer was copolymerized with acrylamide and sodium acrylate to produce hydrophobically modified polyacrylamide (HMPAM) using solution polymerization without surfactants. The structures of monomer ADIAB and HMPAM were characterized with infrared spectroscopy and nuclear magnetic resonance spectroscopy. Influence of preparation condition on viscosities of products was studied. The aqueous solution viscosity of the terpolymer was also investigated as functions of concentration, temperature and salinity. The results showed that when the temperature exceeds the 60?°C and NaCl concentration exceeds about 2000?mg/L, the temperature and salt tolerance characters of terpolymer were demonstrated. The enhanced oil recovery tests were initially carried out using homogeneous sandpack models.     

基于衣康酸配体构筑的两个锌配合物的合成、结构和荧光性质

通过水热法合成了两种锌配位聚合物{[Zn(ic)(bip)]·2H₂O}n (1)和[Zn(ic)(bpe)]n (2)(H₂ic=衣康酸,bip=3,5-二(1-咪唑基)吡啶,bpe=1,2-二(4-吡啶基)乙烯),并通过X射线单晶衍射和元素分析对其结构进行了表征.配合物1和2均为含有一维金属-羧酸链的二维(4,4)格子层结构.此外,对它们的热重、粉末X射线衍射和固体荧光性能进行了考察.与配体bip相比,1的发射光谱发生了明显的蓝移(~78 nm),可能归因于配体到金属的电荷转移;2显示与游离的bpe配体相似的荧光性质,轻微的红移可能是因为与金属离子之间的配位作用导致的.     

具有类白钨矿结构的KGd（MoO4）2的晶体结构和能带结构

以Gd₂O₃、K₂CO₃、MoO₃为原料,采用高温熔盐法,合成了一个含钾的稀土钼酸盐KGd（MoO₄）₂。通过X射线单晶衍射法测定了它在室温下的晶体结构,并测定了它的光学性质。结构分析表明它属于三斜晶系,空间群为P1,a=0.52923（6）nm,b=0.69210（6）nm,c=1.06889（7）nm,α=75.79（8）°,β=76.79（5）°,γ=67.60（4）°,Z=2,R₁（alldata）=0.0258。结构中的K和Gd原子位于各自的晶体学位置,不存在调制结构的现象。此外,我们用得到的晶体学数据,通过密度泛函理论研究了化合物的能带结构、态密度、介电常数,其结果和实验数据相吻合。     

Two Pillared-layer Co(Ⅱ) Metalorganic Frameworks Displaying Pore Modulation by Rodlike Ligands

Two novel compounds, {[Co2(epda)2(4,4-bpy)(H2O)2]·3H2O}n1 and {[Co2(epda)2(bpe)(H2O)2]3H2O}n2(H2epda=5-ethyl-pyridine-2,3-dicarboxylic acid, 4,4’-bpy=4,4’-bipyridine and bpe=1,2-di(4-pyridyl)ethylene) were solvothermally synthesized and characterized by elemental analysis, IR spectroscopy, therm ogravimetric analysis (TGA), and singlecrystal X-ray diffraction. Complex 1 is of monoclinic system, space group P21/c with a=13.344(5), b=14.724(5), c=8.267(3), β=105.840(4)°, V=1562.5(10)3, Dc=1.480 g/cm3, Mr=375.19, Z=4, F(000)=712, μ=1.121 mm-1, the final R=0.0512 and wR=0.1260 for 2890 observed reflections with I>2σ(I). 2 belongs to the monoclinic system, space group P21/c with a=14.224(4), b=14.726(4), c=8.287(2), β=99.696(4)°, V=1711.1(9)3 , Dc=1.402g/cm3, Mr=388.21, Z=4, F(000)=740, μ=1.027 mm-1 , the final R=0.0354 and wR=0.0862 for 12237 observed reflections with I>2σ(I). Both complexes present intimately related structures featuring infinite Co-carboxylate layers of [CoⅡ(epda)(H2O)]n pillared by 4,4’-bpy (or bpe) molecule to produce the microporous frameworks, unambiguously indicating that pore dimensions of the framework are regulated by the N,N’-donor pillars.     

滑动弧电极放电等离子体作用甲烷制C2烃的工艺

采用刀片式不锈钢电极放电反应器,以Ar气为稀释气,研究了等离子体作用下甲烷转化制C2烃的工艺条件。考察了CH4流量、高频电源输入电压和电极间距等参数对甲烷转化率、C2烃选择性、收率和反应表观能耗的影响。结果表明,增加CH4流量,表观能耗随之降低;当输入电压和电极间距较小时,甲烷转化率随输入电压和电极间距的增大而增大,但输入电压和电极间距过大时,C2烃收率明显下降,积碳严重。在CH4流量14 mL/min、Ar气流量60 mL/min、高频电源输入电压22 V、电流0.44 A、电极间距4 mm的优化条件下,甲烷最高转化率为43.1%,C2烃收率、选择性和表观能耗分别为40.1%、93.2%和2.41 MJ/mol。C2烃中不饱和烃的体积分数可达95%以上。     

Characterization of size‐segregated aerosols using ToF‐SIMS imaging and depth profiling

Size‐segregated particles were collected with a ten‐stage micro‐orifice uniform deposit impactor from a busy walkway in a downtown area of Hong Kong. The surface chemical compositions of aerosol samples from each stage were analyzed using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) operated in the static mode. The ToF‐SIMS spectra of particles from stage 2 (5.6–10 µm), stage 6 (0.56–1 µm), and stage 10 (0.056–0.1 µm) were compared, and the positive ion spectra from stage 2 to stage 10 were analyzed with principal component analysis (PCA). Both spectral analysis and PCA results show that the coarse‐mode particles were associated with inorganic ions, while the fine particles were associated with organic ions. PCA results further show that the particle surface compositions were size dependent. Particles from the same mode exhibited more similar surface features. Particles from stage 2 (5.6–10 µm), stage 6 (0.56–1 µm), and stage 10 (0.056–0.1 µm) were further selected as representatives of the three modes, and the chemical compositions of these modes of particles were examined using ToF‐SIMS imaging and depth profiling. The results reveal a non‐uniform chemical distribution from the outer to the inner layer of the particles. The coarse‐mode particles were shown to contain inorganic salts beneath the organics surface. The accumulation‐mode particles contained sulfate, nitrate, ammonium salts, and silicate in the regions below a thick surface layer of organic species. The nucleation‐mode particles consisted mainly of soot particles with a surface coated with sulfate, hydrocarbons, and, possibly, fullerenic carbon. The study demonstrated the capability of ToF‐SIMS depth profiling and imaging in characterizing both the surface and the region beneath the surface of aerosol particles. It also revealed the complex heterogeneity of chemical composition in size and depth distributions of atmospheric particles. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of Axial Ligands on the Molecular Configurations,Stability, Reactivity,and Photodynamic Activities of Silicon Phthalocyanines

To demonstrate the effect of axial ligands on the structure–activity relationship, a series of axially substituted silicon phthalocyanines (SiPcs) have been synthesized with changes to the axial ligands. The reactivity of the axial ligand upon shielding by the phthalocyanine ring current, along with their stability, photophysical, and photodynamic therapy (PDT) activities were compared and evaluated for the first time. As revealed by single‐crystal XRD analysis, rotation of the axial ? OMe ligands was observed in SiPc 3 , which resulted in two molecular configurations coexisting synchronously in both the solid and solution states and causing a split of the phthalocyanine α protons in the ¹H NMR spectra that is significantly different from all SiPcs reported so far. The remarkable photostability, good singlet oxygen quantum yield, and efficient in vitro photodynamic activity synergistically show that compound 3 is one of the most promising photosensitizers for PDT.