显色剂结构与胶束增敏作用的关系 II: Cadion, Cadion 2B的比较

本文从表明活性剂对Cd(II)-Cadion 和Cd(II)-Cadion 2B作用的不同, 研究了有机显色剂分子结构与胶束增敏作用的关系, 发现在无表面活性剂存在时,Cd(II)-Cadion 2B的灵敏度高于Cd(II)-Cadion, 当加入适量表面活性剂后, Cadion体系的增敏效应有如下顺序: SDBS〉混合表面活性剂〉SDS。阳离子表面活性剂无增敏效应。以Triton X-100为例, 分别测定了显色剂及其配合物所在胶束微环境中的D~e~f~f在胶束中的分配系数, 还另用分光光度法和析相法探求增溶位。结果表明: (1)具有两亲结构的被增溶物增溶于胶束的栅状层, 其能否进入栅状层及进入栅状层的深浅, 决定于被增溶物分子的横断面的大小和两亲结构明显程度。(2)在胶束栅状层, 受"刚性不对称微环境"的作用产生增敏作用。(3)从研究Cd(II)-Cadion和Cd(II)-Cadion 2B的分子结构表明: Cd(II)-Cadion 2B的横断面大于Cd(II)-Cadion, 而两亲结构又比Cd(II)-Cadion 不明显, 这是Cd(II)-Cadion 2B胶束增敏率小于Cd(II)-Cadion的主要原因。     

显色剂结构与胶束增敏作用的关系 Ⅱ.Cadion,Cadion 2B的比较

本文从表面活性剂对Cd(Ⅱ)-Cadion和Cd(Ⅱ)-Cadion 2B作用的不同,研究了有机显色剂分子结构与胶束增敏作用的关系,发现在无表面活性剂存在时,Cd(Ⅱ)-Cadion 2B的灵敏度高于Cd(Ⅱ)-Cadion,当加入适量表面活性剂后,Cadion体系的增敏效应有如下顺序:SDBS>混合表面活性剂>SDS。阳离子表面活性剂无增敏效应。以Triton X-100为例,分别测定了显色剂及其配合物所在胶束微环境中的_(off),在胶束中的分配系数,还另用分光光度法和析相法探求增溶位。结果表明:(1)具有两亲结构的被增溶物增溶于胶束的栅状层,其能否进入栅状层及进入栅状层的深浅,决定于被增溶物分子的横断面的大小和两亲结构明显程度。(2)在胶束栅状层,受“刚性不对称微环境”的作用产生增敏作用。(3)从研究Cd(Ⅱ)-Cadion和Gd(Ⅱ)-Cadion 2B的分子结构表明:Cd(Ⅱ)-Cadion 2B的横断面大于Cd(Ⅱ)-Cadion,而两亲结构又比Cd(Ⅱ)-Cadion不明显,这是Cd(Ⅱ)-Cadion 2B胶束增敏率小于Cd(Ⅱ)-Cadion的主要原因。     

胶束增敏显色反应机理的研究——由显色剂所处微环境的D_(eff)推测其增溶位

本文根据Cardinal等建立的方法,研究了含芳环的有机显色剂在不同表面活性剂胶束微环境中的有效介电常数D_(eff_)推测其增溶位,并探索了测定时的条件,为确定显色剂在胶束中的增溶位提供了定量参数,为深入研究胶束增敏机理提供了线索。     

有机试剂的分子结构与胶束增敏的关系: TAMB2-(2-噻唑偶氮)-5-二甲氨基苯甲酸和BTAMB2-(2-苯骈噻唑偶氮)-5-二甲氨基苯甲酸的比较研究

本文以TAMB和BTAMB为探针试剂, 考查了有表面活性剂胶束存在时有机试剂的亲水-疏水程度对金属-有机试剂配合物增敏效应的影响, 研究了两体系的光度性质, 显色剂及镍-显色剂配合物在各不同胶束中的分配情况, 并用析相、核磁共振、萃取及动力学试验等手段比较了两个试剂及配合物的特点和差异。结果表明, 试剂的“两亲"结构对配合物能否被增敏至关重要, 而试剂憎水性或亲水性过强, 均不利于配合物被增敏, 仅当具有“两亲"结构时, 配合物同时感受胶束“刚性不对称微环境"中两端不同作用力,配合物才会有较大增敏现象出现。     

有机试剂的分子结构与胶束增敏的关系: TAMB2-(2-噻唑偶氮)-5-二甲氨基苯甲酸和BTAMB2-(2-苯骈噻唑偶氮)-5-二甲氨基苯甲酸的比较研究

本文以TAMB和BTAMB为探针试剂, 考查了有表面活性剂胶束存在时有机试剂的亲水-疏水程度对金属-有机试剂配合物增敏效应的影响, 研究了两体系的光度性质, 显色剂及镍-显色剂配合物在各不同胶束中的分配情况, 并用析相、核磁共振、萃取及动力学试验等手段比较了两个试剂及配合物的特点和差异。结果表明, 试剂的“两亲"结构对配合物能否被增敏至关重要, 而试剂憎水性或亲水性过强, 均不利于配合物被增敏, 仅当具有“两亲"结构时, 配合物同时感受胶束“刚性不对称微环境"中两端不同作用力,配合物才会有较大增敏现象出现。     

离子型-非离子型混合表面活性剂对显色反应作用的研究及其应用——Ⅱ.反应微环境对协同增敏作用的影响

前文报导了阳离子-非离子混合表面活性剂对Cd-PAR和Al-CAS显色体系的协同增敏作用以及所观察到的一些现象,并进一步提出了协同增敏作用的主要内在原因可能由于混合胶束形成的看法。许多作者认为胶束体系能提供珍贵的反应介质,改变被增溶物的微环境,而阳离子型-非离子型混合胶束的形成是有多种力的作用下两种胶束的重新组合,因此被增溶物的微环境必将相应改变。     

镉的高灵敏显色体系研究及表面活性剂作用机理

本文以2-氯-4-硝基苯重氮氨基偶氮苯(CNDAA)为显色剂, 研究了镉的高灵敏显色体系及表面活性剂的作用机理。研究结果表明: 对于Cd(II)-CNDAA配合物, 非离子型、阴离子型及阴-非混合型表面活性剂对此有显著的增溶增敏作用, 并以Cd(II)-CNDAA-SF显色体系建立了光度法测定微量镉的高灵敏新方法, 并对几种测定方法进行了比较, 筛选出显色条件宽容、选择性好的体系。该体系用于铝合金样品中镉的测定, 结果满意。另外, 还提出了Cd(II)-CNDAA配合物的结构, 对表面活生剂对体系的作用作了描述, 并阐明了试剂的酸性离解常数(pK~a)与显色酸度以及方法的选择性三者之间的关系。     

非离子表面活性剂的结构对络合物吸收光谱的影响

本文用分光光度和核磁共振两种实验方法研究非离子表面活性剂(记作n-Sf)胶束对漂蓝6B(ECAB)及其金属络合物的增溶增敏作用。n-Sf对金属络合物的增溶增敏作用发生在胶束的极性部分与非极性部分的交界处,故n-Sf分子中的烷基链与聚氧乙烯链是否直接相联,会影响到金属-ECAB络合物的吸收光谱形状、λ_(max)和ε值。n-Sf胶束增溶ECAB,会抑制ECAB的酸式离解。     

离子缔合物增溶剂的研究 Ⅳ.缔合物分子结构的影响

同一非离子表面活性剂胶束对不同离子缔合物的作用,主要取决于离子缔合物及其中两个对离子的憎水性强弱,由此引起在胶束中增溶位置的不同。只有对组成离子缔合物的两个对离子憎水性很强且基本相似的体系,才可用非离子表面活性剂为增溶荆;有时还同时发生增敏作用。聚乙烯醇、明胶、阿拉伯胶等大分子物质,由于氢键作用及空间稳定作用,可作为大多数离子缔合物休系的分散剂,但增敏作用不强。     

显色反应中表面活性剂增溶及增敏机理的现状及分析(续)

(四)光度分析中胶束增敏机理研究的现状自从表面活性剂在光度分析中得到应用以来,关于表面活性剂的增敏机理曾经进行了广泛的研究。但是,表面活性剂究竟以什么形式参与增敏作用这一基本问题至今尚未取得比较一致的看法。目前,主要流行以下三种观点:(1)以胶束形式参与增敏作用,但与染料分子相互作用的是胶束中的表面活性剂分子,(2)以表面活性剂的单分子形式参与增敏作用,而极性端的电荷起着决定性的作用,(3)CMC值以前,表面活性剂以单分子形式增敏,而在CMC值以后则以胶束形式增敏,即单分子和胶束均有增敏作用。     

The Determination of Trace Amounts of Cadmium in Rice Samples by Dual-wave Length Spectrophotometry——cd(Ⅱ)-Cadion 2B-Tween 40 System

The optimal conditions of the Cd(Ⅱ)-Cadion 2B-Tween 40 system have been studied.In the alkaline medium of NaOH,a red Cd(Ⅱ)-Cadion 2B-Tween 40 complex forms with e510nm=9.80×104 The Ka ofCadion 2B and Surface tension in the system was estimated.It was proved that K was increased and the reagent species with absorption maximum at 605nm formed.Using the dual-wave length method at 510?605nm the apparent molar absorptivity for cadmium measured was 2.60×10 The molar ratio of cadmium to Cadion 2B is estimated to be 1:3 as estimated by the molar ratio method and continuous variation method.The Beer's law is obeyed in 0~6μg Cd/25ml.Using the proposed method with TEA,IDA and CIT masking mixture,the Cd content in rice samples was determined with satisfactory results.     

Spectrophotometric study of the reaction of Hg(II) with cadion A and cadion 2B

The reaction between Hg(II) and Cadion A and Cadion 2B has been studied. Methods are suggested for the determination of Hg(II) in the 0.1-4 ppm range with Cadion A and in the 0.2-8 ppm range with Cadion 2B. Of the 49 ions studied only Hg(I), Sn(II), Br(-), I(-), MnO(-)(4), EDTA, SCN(-), CN(-) and S(2-) interfere. The combination ratios and instability constants of the Hg-Cadion complexes were determined. The structural formulae of the complexes were deduced from the infrared spectra and elemental and thermogravimetric analyses.     

离子型-非离子型混合表面活性剂对显色反应作用的研究及其应用III.显色剂在胶束相的分配系数

The distribution constants of PAR and Chrome Azurol S between micellar and aqueous phases, for cetyltrimethylammonium bromide and its mixtures with nonionic surfactants at a particular acidity were determine The relation between the distribution constants and the sensitivity of the color reaction was studied. An increase of the distribution constant of the ligand in the micellar phases is one of the main causes of the synergic sensitizing effect of mixed ionic-nonionic surfactants on color reaction. The mechanism of the synergic sensitizing effect of mixed surfactants on color reactions is discussed further.     

Phosphorylation of Pyrimidinophane in the Reversed Micellar Solutions of Cationic and Nonionogenic Surfactants

Reactions of a macrocycle containing three pyrimidine fragments and N,N′-bis(2-methylthio-6-methylpyrimidin-4-yl)-hexamethylenediamine with p-nitrophenyl bis(chloromethyl)phosphinate in the micellar solutions of cetyltrimethylammonium bromide, polyethyleneglycol-600 laurate and their mixture in chloroform was investigated spectrophotometrically. Catalytic activity of micelles depends on their structure, concentration of surfactants, molar fraction of the latter in solution, and structure of the nucleophilic reagent.     

Synthesis and analytical properties of the polymerized surfactant pposa

A new low-polymer surfactant, poly(propylene oxide)--stearyldimethylammonium chloride (PPOSA) has been synthesized. It contains a polyglycol main chain and quaternary ammonium branched chains. Investigation of the surface-active properties of PPOSA showed that as a sensitizing and solubilizing reagent for spectrophotometric analysis it possesses some of the characteristics of both cationic and non-ionic surfactants. The surfactant shows a sensitizing effect superior or equal to that of classical surfactants commonly used in analytical chemistry. Use of PPOSA leads to development of some excellent micellar spectrophotometric procedures for determining trace metals.     

Dual-wavelength spectrophotometric determination of cadmium with cadion

Cadmium has been determined by dual-wavelength spectrophotometry with cadion, p-nitrobenzenediazoaminobenzene-p-azobenzene, and a non-ionic surfactant, Triton X-100. Cadion and its cadmium chelate are dissolved in a micellar solution of the surfactant. The absorbance difference at the wavelength of maximum absorption of the cadmium chelate (477 nm) and that of cadion (566 nm) is measured. A combination of triethanolamine, iminodiacetate and citrate is very effective for masking other ions. Cadmium in zinc metal can be determined without prior separation.     

CMC系列高分子表面活性剂的胶束形态

高分子表面活性剂分子量高 ,分子中兼具亲水和疏水链段 ,在选择性溶剂水中同小分子表面活性剂一样 ,可形成疏水链段为核心、亲水链段为外壳的胶束结构 ,但高分子量又使其表现出许多不同于低分子表面活性剂的形态特征 ,如胶束的多种形态、尺寸分布多分散性等等 ,而这些形态特征对高分子表面活性剂的界面活性、增粘、乳化等性能有决定性的影响．结构规整的嵌段或接枝共聚物在选择性溶剂中的分子聚集形态已有研究 ［１,２］,亲水亲油性的高分子表面活性剂在水溶液中由于结构复杂、水溶液中氢键作用及静电作用力等因素造成的困难 ,因而研究较少…     

Interaction of amphiphilic block copolymer micelles with surfactants

An out line and summary of literature studies on interactions between different types of amphiphilic copolymer micelles with surfactants has been given. This field of research is still emerging and it is difficult presently to make generalisations on the effects of surfactants on the copolymer association. The effects are found to be varied depending upon the nature and type of hydrophobic (hp) core and molecular architecture of the copolymers and the hydrocarbon chain length and head group of surfactants. The information available on limited studies shows that both anionic and cationic surfactants (in micellar or molecular form) equally interact strongly with the associated and unassociated forms of copolymers. The beginning of the interaction is typically displayed as critical aggregation concentration (CAC), which lies always below the critical micelle concentration of the respective surfactant. The surfactants first bind to the hydrophobic core of the copolymer micelles followed by their interaction with the hydrophilic (hl) corona parts. The extent of binding highly depends upon the nature, hydropobicity of the copolymer molecules, length of the hydrocarbon tail and nature of the head group of the surfactant. The micellization of poly(ethylene oxide) (PEO)–poly(propylene oxide) (PPO)–poly(ethylene oxide) was found to be suppressed by the added surfactants and at higher surfactant concentrations, the block copolymer micelles get completely demicellized. This effect was manifested itself in the melting of liquid crystalline phases in the high copolymer concentrations. However, no such destabilization was found for the micelles of polystyrene (PS)–poly(ethylene oxide) copolymers in water. On the contrary, the presence of micellar bound surfactant associates resulted in to large super micellar aggregates through induced intra micellar interactions. But with the change in the hydrophobic part from polystyrene to poly(butadiene) (PB) in the copolymer, the added surfactants not only reduced the micellar size but also transformed cylindrical micelles to spherical ones. The mixtures in general exhibited synergistic effects. So varied association responses were noted in the mixed solutions of surfactants and copolymers.     

Effect of recognized and unrecognized salt on the self-assembly of new thermosensitive metal-chelating surfactants

New functional thermoreversible metal complexing surfactants consisting of a chelating amino acid residue grafted to the tip of a nonionic surfactant [alkyl poly(oxyethylene) CiEj] or in a branched position are studied. Nonionic surfactants are thermoreversible and exhibit a clouding phenomenon associated with phase separation of micelles. The functional molecules retain both the surface-active properties and the characteristic thermoreversible behavior. Because of the hydrophilic contribution of the chelating group (acetyl lysine), the cloud point and the area at the air-water interface are higher for functional surfactants than for nonionic precursors. These new surfactants have efficient complexing properties toward metal ions and are more efficient than the mixture of the corresponding nonionic surfactant and the acetyl lysine ligand solubilized in micelles. This reveals the synergistic effect obtained by the covalent link between the two functions. Addition of a bulky group on classical amphiphilic structures modifies markedly the packing constraints at the origin ofmicellar structures. Small-angle X-ray or neutron scattering results, modeled jointly on the absolute scale, demonstrate the influence of unrecognized lithium nitrate (LiNO3) as well as specifically recognized uranyl nitrate [UO2(NO3)2] salts on micellar structure and phase boundaries. The determination of the micellar shape variations induced by a recognized salt, that is, a decrease of the polar headgroup, allows the rationalization of uncommon synergistic effects on the cloud point variation: increase with lithium nitrate, no decrease in the presence of uranyl nitrate, and a very large decrease when these two salts are present together.