煤化工废水中无机阴离子的检测方法研究

建立了离子色谱法同时分离检测煤化工废水中F~-、Cl~-、NO_3~-、NO_2~-、Br~-、SO_4~(2-)、PO_4~(3-)共7种无机阴离子浓度的分析方法。采用Ion Pac AS14离子色谱柱对煤化工废水进行分离,Na_2CO_3和NaHCO_3为淋洗液。结果表明,F~-、Cl~-、NO_3~-、SO_4~(2-)检出限分别为0.03、0.21、0.55、0.86 mg/L,加标回收率为95%～104%,相对标准偏差(RSD)小于3%。该方法具有灵敏度高、操作简便、结果准确、重现性好等优势,适合于煤化工废水中无机阴离子的检测。     

超瑞利散射测定偶氮分子的一阶超极化率

用超瑞利散射技术测定了双羟乙氨基-硝基偶氮苯和偶氮-水杨醛的5个偶氮化合物的一阶超极化率。2个双羟乙氨基-硝基偶氮苯由于有效的给体-受体组合,使其β值达到177×10-30esu和211×10-30esu;而2个偶氮-水杨醛席夫碱同时存在二维分子内质子转移和分子内电荷转移,β值分别为87×10-30esu和94×10-30esu。这些偶氮生色分子显现出光学非线性-透明性-热稳定性三者之间综合平衡的良好性能。     

缩酮席夫碱阴离子受体的合成、表征及阴离子识别研究

随着经济与科学技术的发展,阴离子对医药、生命科学、环境保护、农业生产和工业催化等领域的研究有着越来越重要的影响。因此,阴离子识别技术与阴离子受体的设计合成有着广阔的发展前景。合成了3种1,10-邻菲罗琳-5,6-二酮缩(硝基)苯肼席夫碱阴离子受体(R3-1、R3-2和R3-3),应用比色法和紫外-可见吸收光谱法研究了受体分子对阴离子的识别性能。结果表明,受体R3-1、R3-2和R3-3均对阴离子有一定的识别能力,其中R3-3的识别效果最好。分析R3-3的紫外-可见吸收光谱,计算得出R3-3对F~-、Ac O~-和H_2PO_4~-的结合常数Ka分别为6 956(R~2=0.985 9)、4 730(R~2=0.987 3)和3 754(R~2=0.978 7);检出限分别为2.88×10~(-6)mol/L(R~2=0.991 2)、7.7×10~(-6)mol/L(R~2=0.995 3)、1.47×10~(-5)mol/L(R~2=0.992 9)。     

罗丹明型Cu~(2+)比色探针的合成及识别

以偶氮苯水杨醛和罗丹明B-酰肼为原料,经缩合反应得到Cu~(2+)比色探针RAH,其结构经1HNMR、MS和元素分析进行表征。通过紫外-可见光谱法研究了RAH对金属离子的识别能力。结果表明,RAH在CH_3CN/Tris-HNO_3溶液中对Cu~(2+)具有高选择性识别能力,溶液由无色迅速转变为粉红色,说明与Cu~(2+)形成1∶1型配合物,结合常数为1.1×10~5dm~3/mol。     

F~-+CH_3(CH_2)_4OH→OH~-+CH_3(CH_2)_4F的S_N2异侧反应机理研究在有机合成中的应用

采用量子化学方法 CBS-QB3对F~-+CH_3(CH_2)_4OH体系的S_N2反应机理进行了理论研究。研究结果表明,标题反应的活化吉布斯自由能为202.44 k J·mol~(-1),反应不易进行;通过对比带有不同烷基链的F~-+CH_3OH体系,表明烷基链的增长明显增大了F~-+CH_3OH的能垒,从而抑制了反应的进行。     

共存阴离子对纳米零价铁去除水中砷和硒的影响

纳米零价铁广泛用于水中砷和硒的去除。以含有类金属离子As(Ⅲ/Ⅴ)、Se(Ⅳ/Ⅵ)及共存阴离子SO_4~(2-)、PO_4~(3-)、NO_3~-、HCO_3~-、Cl~-、F~-的模拟废水为研究对象,采用纳米零价铁进行去除处理,探讨了6种共存阴离子对纳米零价铁去除As(Ⅲ/Ⅴ)和Se(Ⅳ/Ⅵ)的影响。结果表明,共存阴离子对纳米零价铁去除As(Ⅲ/Ⅴ)和Se(Ⅳ/Ⅵ)的影响有所不同;水中共存的SO_4~(2-)、PO_4~(3-)、NO_3~-、HCO_3~-、Cl~-、F~-对纳米零价铁去除Se(Ⅳ)基本无影响;PO_4~(3-)、HCO_3~-的共存对纳米零价铁去除Se(VI)有明显的抑制作用;PO_4~(3-)(5 mmol·L~(-1))和HCO_3~-(100 mmol·L~(-1))对As(Ⅲ)的去除产生了抑制作用;NO_3~-(5 mmol·L~(-1))、Cl~-(50 mmol·L~(-1))、F~-(50 mmol·L~(-1))可促进纳米零价铁对As(Ⅴ)的去除,PO_4~(3-)的共存会抑制纳米零价铁对As(Ⅴ)的去除。     

若干无机阴离子对酸性磷酸酯酶活性的影响

本文研究了若干无机阴离子对酸性磷酸酯酶(EC3.1.3.2)活性的影响.发现F~-、IO_3、SCN~-、SO_4~(2-)和H_2PO_4~-在10~(-4)～10~(-1)mol/L时,该酶的活性将受到不同程度的抑制.它们的抑制类型均为可逆性抑制.     

KF/K_2CO_3/γ-Al_2O_3催化合成香豆素-3-羧酸

以水杨醛和丙二酸二乙酯为原料,KF/K_2CO_3/γ-Al_2O_3为催化剂,催化合成香豆素-3-羧酸乙酯,再经皂化、酸解环合合成香豆素-3-羧酸.考察了催化剂用量、水杨醛与丙二酸二乙酯摩尔比、反应时间等因素对香豆素-3-羧酸收率的影响.结果表明,KF/K_2CO_3/γ-Al_2O_3具有良好的催化活性,较佳工艺条件为:水杨醛4.88 g(0.04 mol),n(水杨醛),n(丙二酸二乙酯)=1:1.25,KF/K_2CO_3/γ-Al_2O_3 2.0 g(KF 3.74 mmol),无水乙醇20 mL,反应1.5 h,香豆素-3-羧酸的平均收率达到92%以上.     

离子色谱法测定环境空气中F~-、Cl~-、NO_2~-、NO_3~-、SO_4~(2-)五种水溶性阴离子

建立了离子色谱法测定环境空气中水溶性阴离子。F~-、Cl~-、NO_2~-、NO_3~-、SO_4~(2-)五种水溶性阴离子的方法检出限分别为0.010 ug/m~3、0.010 ug/m~3、0.005 ug/m~3、0.010 ug/m~3、0.025 ug/m~3,精密度(RSD,n=6)为0.1%～5.4%,实际样品测定样品加标回收率在82.4%～103%。实验结果表明,该方法准确可靠、灵敏度好,适用于环境空气中五种水溶性阴离子的分析测定。     

用高压气体吸脱附-微量热联用法对CO2和CH4在煤上吸附热力学的研究

为了从热力学角度揭示CO_2和CH_4在煤上的竞争吸附实质,为驱替理论提供热力学参考,利用高压气体吸脱附-微量热联用仪,通过容量法测定30℃,40℃,50℃温度下CO_2和CH_4在煤上的吸附等温线,同时计算等量吸附热和极限吸附热,并测定了CO_2和CH_4在煤上的吸附热。结果表明:CO_2和CH_4吸附等温线均属于Ⅰ型吸附等温线,且均符合Langmuir吸附模型;温度升高,CO_2和CH_4在煤上的吸附量均减小;相同条件下,CO_2在煤上的吸附量明显高于CH_4的吸附量,表明CO_2更容易吸附于煤上。CO_2和CH_4在煤上的等量吸附反映出煤吸附CO_2和CH_4的过程均为物理吸附。同时CO_2在煤上的等量吸附热高于CH_4的等量吸附热,说明CO_2分子与煤分子之间作用力强于CH_4与煤分子之间的作用力,极限吸附热和实验测得的吸附热也显示了同样结果,从热力学角度阐释了CO_2和CH_4在煤体表面竞争吸附的实质。     

基于噻吩光电小分子的合成和性能

基于丁氧基苯并硒二唑为电子受体, 噻吩为电子给体的有机共轭分子通过斯蒂尔偶联反应制得, 并对其进行结构表征和光电性能测试。结果表明:核磁共振¹H谱和¹³C谱检测结果与理论一致;在乙腈溶液和聚甲基丙烯酸甲酯薄膜中, 共轭分子有较宽的紫外吸收波长(237～464nm);荧光测得在红光区域有很强的激发峰, 表明该分子是一种理想的红光材料;共轭分子(2.26～2.33eV)属于窄带隙, 在电化学测试中表现出稳定的氧化还原曲线。以上结论表明该共轭分子在有机光电材料领域有潜在的应用价值。     

POSS‐based fluorinated azobenzene‐containing polymers: Photo‐responsive behavior and evaluation of water repellency

The photoresponsive polyhedral oligomeric silsesquioxanes (POSS) based fluorinated azobenzene‐containing polymers were prepared and characterized by NMR, FT‐IR, GPC, XRD, TG and UV–Vis spectra. The thermal property of the polymers was improved by the introduction of POSS cage. The trans‐cis photoisomerization of the polymers in solution was similar to that of the fluorinated azobenzene monomer and in accordance with the first‐order reaction kinetics equation within the first 250 seconds UV irradiation. The cotton fabrics coated with the polymers showed excellent water repellency and possessed switchable wettability under UV irradiation. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43540.     

Molecular structure modulated properties of azobenzene-substituted polydiacetylene LB films: Chirality formation and thermal stability

Langmuir-Blodgett (LB) films of three novel azobenzene-substituted diacetylene monomers (DA1, DA2 and DA3) were fabricated and their optical and chiroptical properties were investigated in detail by ultraviolet-visible (UV-vis) spectra and circular dichroism (CD) spectra. Achiral DA1 molecules could form chiral LB films through overcrowded packing of the azobenzene moiety, while achiral DA2 and DA3 molecules not. When exposed to left-or right-handed circular polarized UV light (CPUL), striking left- or right-handed (opposite) CD signals for azobenzene chromophores and polydiacetylene chains were observed for the polymerized DA1 (PDA1) and DA2 (PDA2) LB films. However, DA3 LB films could hardly be polymerized in this case, and only striking opposite CD signals for azobenzene chromophores could be observed. It was demonstrated that the intermolecular steric hindrance and irregular arrangement of azobenzene chromophores were not favorable for the topo-polymerization and chirality formation of polydiacetylenes backbone. Further, the effects of thermal treatment on the supramolecular chirality of above three LB films were studied. Strong collective noncovalent interactions (π-π stacking) were believed to be responsible for the thermal stability of chiral supramolecular assemblies.     

Anodic synthesis of polyaniline coatings onto fe sheets

Aniline Black coatings were obtained on Fe anodes by electrolyzing a basic solution of aniline in a water—methanol medium. Allylamine (an inhibitor of Fe corrosion), although not essential to the process, imparts better efficiency to it. The deposited polymers contain 15–20% azobenzene and exhibit semiconductor properties. The three nitroaniline isomers need a more efficient corrosion-inhibition system. They may be polymerized to adherent films in the presence of both allylamine and K₂CrO₄.     

A Photoswitchable Trivalent Cluster Mannoside to Probe the Effects of Ligand Orientation in Bacterial Adhesion

We have recently demonstrated, by employing azobenzene glycosides, that bacterial adhesion to surfaces can be switched through reversible reorientation of the carbohydrate ligands. To investigate this phenomenon further, we have turned here to more complex—that is, multivalent—azobenzene glycoclusters. We report on the synthesis of a photosensitive trivalent cluster mannoside conjugated to an azobenzene hinge at the focal point. Molecular dynamics studies suggested that this cluster mannoside, despite the conformational flexibility of the azobenzene-glycocluster linkage, offers the potential for reversibly changing the glycocluster's orientation on a surface. Next, the photoswitchable glycocluster was attached to human cells, and adhesion assays with type 1 fimbriated Escherichia coli bacteria were performed. They showed marked differences in bacterial adhesion, dependent on the light-induced reorientation of the glycocluster moiety. These results further underline the importance of orientational effects in carbohydrate recognition and likewise the value of photoswitchable glycoconjugates for their study.     

The aniline-to-azobenzene oxidation reaction on monolayer graphene or graphene oxide surfaces fabricated by benzoic acid

The oxidation of aniline to azobenzene was conducted in the presence of either monolayer graphene (EG) or graphene-oxide-like surface, such as GOx, under ultra-high vacuum conditions maintaining a 365-nm UV light exposure to enhance the oxidation reaction. The surface-bound products were investigated using micro Raman spectroscopy, high-resolution photoemission spectroscopy, and work function measurements. The oxygen carriers present on the GOx surfaces, but not on the EG surfaces, acted as reaction reagents to facilitate the oxidation reaction from aniline to azobenzene. Increasing the aniline concentration at 300 K confirmed that the exchange ratio from the aniline to the azobenzene was enhanced, as determined by the intensity ratio between the aniline- and azobenzene-induced N 1 s core-level spectra. The work function changed dramatically as the aniline concentration increased, indicating that the aniline on the GOx surface conveyed n-type doping characteristics at a low coverage level. A higher aniline concentration increased the p-type doping character by increasing the azobenzene concentration on the GOx surface. A comparison of the oxidation reactivity of aniline molecules on the EG or GOx surfaces revealed the role of the oxygen carriers on the GOx surfaces in the context of catalytic oxidation.     

Optical properties of some new azo photoisomerizable bismaleimide derivatives

Novel polythioetherimides bearing azobenzene moieties were synthesized from azobismaleimides and bis-2-mercaptoethylether. Kinetics of trans-cis photoisomerization and of thermal conversion of cis to trans isomeric forms were investigated in both polymer solution and poly(methyl methacrylate) doped films using electronic absorption spectroscopy. Thermal recovery kinetics is well described by a two-exponential relation both in solution and polymer matrix, while that of low molecular weight azobismaleimide fit a first-order equation. The photoinduced cis-trans isomerization by visible light of azobenzene chromophores was examined in solution and in polymer films. The rate of photoinduced recovery was very high for azobismaleimides.     

Preparation of nano‐ and microparticles through self‐assembly of azobenzene‐pendent ionomers

The particle formation of azobenzene‐containing ionomers, through self‐assembly, in aqueous media (THF/H₂O solvent) was studied. The ionomers were synthesized by copolymerization between azobenzene‐pendent methacrylate and methacrylic acid. It was revealed by UV–vis spectra and light scattering measurements that the extent of H‐aggregation of the azobenzene units first decreased, and then increased with increasing volume fraction of H₂O of the solvent. The H₂O fraction at which the extent of H‐aggregation began to increase became lower, when the copolymers contained more azobenzene units. Colloidal particles were prepared by slow addition of various concentrations of aqueous NaOH to the copolymer THF solutions. The hydrodynamic diameters of the particles obtained by the procedures were several hundreds of nanometer. When the azobenzene unit content in the copolymer was smaller, the diameters of the particles became smaller. When the colloidal particles dispersions were cast on a carbon sheet and dried, the particles aggregated and formed larger spherical particles, with diameters of several micrometers. The size of the particles obtained by the drying process became smaller, when higher concentrations of aqueous NaOH solutions were used. Therefore, the particle sizes were controlled by the azobenzene units content in the copolymers and the concentration of aqueous NaOH solutions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3913–3918, 2006     

Photochromism of liquid crystalline dendrimer with azobenzene terminal groups in solution

The photochromism of a liquid crystalline dendrimer (LCD) with 36 hexyloxyazobenzene terminal groups in solution was described in this paper. The molar absorption coefficient, quantum yield, photoisomerization, photo back-isomerization, thermal back-isomerization and activation energy of LCD in solution are studied by UV/Vis absorption spectra. The results indicate that the photochromism, photo and thermal back-isomerization of LCD in chloroform (CHCl₃) and tetrahydrofuran (THF) solutions are in accordance with the first order kinetics. The photochromism rate constants of LCD are 10⁻¹ s⁻¹, it is 10⁷ times larger than that of side-chain liquid crystalline polymers (LCP) containing the same azobenzene moieties. These results indicate that the dendritic structure does not significantly affect the photoisomerization activity of the azobenzene unit in its periphery. The k_t/k_c of LCD is less than that of azobenzene unit shows that the LCD has better photo-reversibility. So the liquid crystalline dendrimer has potential applications.     

偶氮苯改性聚乙烯醇的研究

通过三聚氯氰的氯原子和聚乙烯醇的羟基之间脱氯化氢的反应,用含有2个偶氮苯的三聚氯氰衍生物改性聚乙烯醇（PVA）1788。红外光谱和核磁共振分析表明,在二氧六环和水混合溶剂中可以将偶氮苯成功接枝到PVA上,PVA中约每12个羟基就有1个发生反应。含有偶氮苯的PVA可以溶解在水和二甲亚砜中。其紫外可见吸收光谱与偶氮苯相似,并表现出偶氮苯的典型光致异构现象。