稳态和动态荧光研究疏水缔合共聚物P(AM/POEA)的自缔合行为和聚集体

应用稳态和动态荧光光谱方法,包括荧光探针、标记荧光和荧光淬灭等研究了共聚物P(AM/POEA)在水溶液中的自缔合性质.这种共聚物由丙烯酰胺(AM)和少量疏水单体2-苯氧乙基丙烯酸酯(POEA)组成.实验结果表明这类共聚物的自缔合行为和聚集体结构主要取决于聚合物的链结构和浓度.由胶束共聚合方法得到具有多嵌段结构的共聚物,它们容易发生疏水缔合,并产生很强的增粘作用,而由普通共聚合方法得到的无规共聚物却没有这些性质.同时这类聚合物的缔合类型及其增粘能力也直接与共聚物中的疏水体含量相关,随疏水体含量增加,由于分子间和分子内缔合的竞争,出现粘度先增后降的现象.在荧光研究的基础上提出了多分子聚合物聚集体的结构模型,它随聚集体浓度增加,进一步形成多联聚集体和网状结构.同时还观察到聚集体中疏水体有序排列现象.     

分子内电荷转移化合物的光谱和光物理

近年来,分子内电荷转移化合物光物理行为的研究受到了广泛的注意,这是由于这类化合物分子的发光性能强烈地受其周围溶剂性质的影响.它们常被考虑作为研究溶剂-溶质间相互作用以及溶剂分子弛豫的有效探针化合物.Loutfy等曾对被束缚的及未被束缚的N,N-二甲基氨基苄叉二腈类化合物的光物理行为作过详细研究.指出它们的荧光量子产率和该类化合物分子的刚性以及和母体环境的粘度、温度及物理化学性质等密切有关,它们     

α-吡喃酮衍生物的合成及聚集荧光增强性质研究

设计合成了具有4个苯基取代的α-吡喃酮衍生物,研究了该化合物在溶液中的稳态光物理过程,以及在四氢呋喃/水混合溶剂中的聚集行为和发光性质.该化合物在良溶剂中几乎没有发光,而形成聚集体后发出明亮的蓝绿色荧光,荧光量子产率达17%,比溶液中增强了253倍.根据化合物的结构和低温荧光实验结果推断,聚集荧光增强主要是聚集体中分子...     

四苯乙烯衍生物与大环主体在主客体相互作用下的聚集诱导发光

具有聚集诱导发光性质化合物的发展不仅很大程度上解决了传统有机分子发色团在高浓度、固态或者薄膜等形式的聚集状态下荧光猝灭的问题,而且扩展了有机发色团在荧光探针、传感器以及细胞成像等方面的应用。其中,四苯乙烯及其衍生物作为具有聚集诱导发光性质的典型化合物已被广泛应用在材料化学、生物化学等相关研究领域。受此启发,超分子化学家也将这类具有聚集诱导发光性质的四苯乙烯及其衍生物作为研究对象引入到超分子化学的领域,特别是利用大环主体与四苯乙烯客体通过主客体相互作用有效地限制了荧光客体分子的分子内转动或运动,增强了这类超分子体系的发光强度,并为其在刺激响应性传感器、智能探针等方面提供了新思路。本文总结了近年来涉及四苯乙烯衍生物与大环主体通过主客体相互作用形成聚集诱导发光超分子体系的发展,并按照大环主体进行分类简要介绍其应用。     

多枝罗丹明酰肼类荧光探针的研究进展与应用

罗丹明以其良好的光稳定性、光物理性质和荧光效应得到了人们的极大重视。 基于罗丹明的螺环衍生物与被检测物质作用开环而产生荧光响应的特性,将两个或多个罗丹明母体单元构筑到包含特异性的识别单元的探针分子中,形成多枝的罗丹明酰肼类荧光探针,不仅可以弥补单分子探针的某些功能缺陷,而且可以使其具有更高灵敏度、更高选择性和可靠性,更加有利于分析检测。 本文着重从设计原理、识别性能、应用范围等方面介绍了多枝罗丹明探针在Hg2+、Cu2+、Fe3+和Al3+等离子检测中发展趋势,并展望了这类荧光探针在活细胞金属离子光学成像的应用前景。     

发光ZnSalen配合物在分子荧光成像中的应用进展

荧光分子探针的设计、合成以及应用是分子荧光成像领域重要的化学问题.本文从Znsalen配合物的基本性质出发,概述了Znsalen配合物结构与功能的关系,特别是其发光性质与分子结构及分子聚集状态的相关性及应用.针对Znsalen配合物的发光性质,展示了其应用于分子荧光成像和活细胞中分子事件监测的研究进展.这些最新研究表明,Znsalen配合物探针的细胞毒性低(利于活细胞成像)、发光效率高(适用于单、双光子成像)、发光可调(通过配体的修饰和分子聚集状态的调节),有望作为一类重要的发光金属荧光探针实现在分子荧光成像中的应用.     

光化学在自组装结构调控与探测中的应用

利用光照引发的光化学变化,作为一种通过宏观手段向微观系统提供能量和外加刺激的理想手段,在分子自组装研究中起到了重要的作用.通过光化学变化可以实现对分子自组装结构从分子结构到微观结构,再到宏观性质的多层级调控.反之,通过其他手段调节聚集体的组装结构和分子排列,也可以控制改变聚集体的发光情况.此外,分子荧光探针为认识纳米尺度的分子自组装结构的微观环境提供了有力的支持,是研究自组装结构中不可取代的重要表征手段.本文就光化学手段对分子自组装结构的调控与探测,以及自组装结构对发光分子的光学性质的影响等方面进行了介绍.     

罗丹明6G的溶液状态和荧光特性的研究

罗丹明6G的荧光性质和它的分子聚集态研究是一个重要的科研领域,所得之k_d值表明水溶液中形成罗丹明6G的双聚体。本文提出用荧光法测定k_d聚合常数,该法用于测定罗丹明6G的溶液状态.实验结果表明罗丹明6G双聚体解聚的某些规律,当单体与双聚体平衡趋于单体时,荧光灵敏度就会增加。     

多雌酚酮化合物的合成

近年来对具有生理活性物质的多分子聚集体的研究引起了人们的广泛关注.为了研究这种聚集体形式对药物性质的影响,本文报道了以聚乙二醇为链的多雌酚酮化合物的合成.     

基于罗丹明的重金属和过渡金属阳离子荧光分子探针研究进展

介绍了近五年来以罗丹明为母体的重金属和过渡金属阳离子荧光分子探针领域的研究进展.文中按照荧光团和识别基团之间连接臂的不同对国内外各研究组的工作进展进行归类总结,并对探针设计的思路、探针的性质和应用给出了简要介绍.     

长链烷氧取代金属卟啉的合成及催化性能研究

本文报道了一类长链烷氧取代金属卟啉化合物3的合成.研究了由化合物3与表面活性剂:十二烷基三甲基溴化铵所形成的混合胶束体系作为仿细胞色素P-450加氧酶模拟物对苯乙烯环氧化的催化活性.结果表明:在胶束体系中长链烷氧取代金属卟啉的催化效率优于对称四甲苯基金属卟啉,由此证实:混合胶束中,疏水内核提供的模拟酶的疏水微环境,在苯乙烯环氧化反应中起着重要作用.     

A MICROEMULSION COSURFACTANT WITH EXCELLENT WATER SOLUBILIZATION AT HIGH OIL CONTENT

Medium chain length alkyl amines were found to be more effective cosurfactants for microemulsion formation than are medium chain length alcohols at high hydrocarbon levels with sodium doecyl sulfate as the surfactant. Both aromatic and short chain aliphatic hydrocarbons were studied. By contrast, the amines were found virtually Ineffective with quaternary anmoniutn salts whereas the alcohols showed good performance. This suggests the possibility that complementarity of function between surfactant and cosurfactant may be a desirable feature of a microemulsion system at high hydrocarbon levels.     

长链烷氧取代金属卟啉的合成及催化性能研究

本文报道了一类长链烷氧取代金属卟啉化合物3的合成。研究了由化合物3与表面活性剂:十二烷基三甲基溴化铵所形成的混合胶柬体系作为仿细胞色素P-450加氧酶模拟物对苯乙烯环氧化的催化活性。结果表明:在胶束体系中长链烷氧取代金属卟啉的催化效率优于简单对称四甲苯基金属卟啉,由此证实:混合胶束中,疏水内核提供的模拟酶的疏水微环境,在苯乙烯环氧化反应中起着重要作用。     

Polymeric sulfated surfactants with varied hydrocarbon tail: I. Synthesis, characterization, and application in micellar electrokinetic chromatography

The influence of surfactant hydrocarbon tail on the solute/pseudostationary phase interactions was examined. Four anionic sulfated surfactants with 8-, 9-, 10-, and 11-carbon chains having a polymerizable double bond at the end of the hydrocarbon chain were synthesized and characterized before and after polymerization. The critical micelle concentration (CMC), polarity, and aggregation number of the four sodium alkenyl sulfate (SAIS) surfactants were determined using fluorescence spectroscopy. The partial specific volume of the polymeric SAIS (poly-SAIS) surfactants was estimated by density measurements and capillary electrophoresis (CE) was employed for determination of methylene selectivity as well as for elution window. The CMC of the monomers of SAIS surfactants decrease with increase in chain length and correlated well when fluorescence method was compared to CE. The physicochemical properties (partial specific volume, methylene selectivity, electrophoretic mobility, and elution window) increased with an increase in chain length. However, no direct relationship was found between the aggregation number and the length of hydrophobic tail of poly-SAIS surfactants. These polymeric surfactants were then used as pseudostationary phases in micellar electrokinetic chromatography (MEKC) to study the retention behavior and selectivity factor of 36 benzene derivatives with different chemical characteristics. Although variation in chain length of the polymeric surfactants significantly affects the retention of nonhydrogen bonding (NHB) benzene derivatives, these effects were less pronounced for hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD) benzene derivatives. Therefore, hydrophobicity of poly-SAIS surfactants was found to be a major driving force for retention of NHB derivatives. However, for several benzene derivatives (NHB, HBA, and HBD) significantly higher selectivity factor was observed with longest chain polymeric surfactant (e.g., poly(sodium 10-undecenyl sulfate), poly-SUS) compared to shorter chain polymeric surfactant (e.g., poly(sodium 7-octenyl sulfate), poly-SOcS). In addition, the effect of the surfactant hydrophobic chain was also found to have some impact on migration order of NHB, HBA, and HBD benzene derivatives.     

Amperometric method for determining the degree of complexation of polyelectrolytes with cationic surfactants

The complexation of sodium polystyrene sulfonate with monovalent cationic surfactants at a microsized liquid/liquid interface has been studied using electrochemistry. The method is based on measurement of surfactant ion transfer across the interface between two immiscible electrolyte solutions (ITIES). The complexation of various cationic surfactants (alkylpyridinium- and trimethylammonium-) with oligosized polystyrene sulfonate was measured. Binding isotherms were used to determine the degree of binding as a function of the surfactant chain length and type of head group. It was found that the hydrophobicity of the surfactant was the predominant factor. The effect of the polyelectrolyte chain length on the binding mechanism was studied using cetylpyridinium chloride as a complexing agent. It was found that binding affinity, as well as cooperativity of the binding process, decreases with decreasing polyelectrolyte chain length. Thermodynamics of surfactant binding was measured using titration microcalorimetry. The thermodynamic data obtained show that the enthalpy of surfactant binding is not dependent on polymer chain length, but an increase in chain length makes the binding process entropically more favorable.     

Dependence of Colloidal Forces Between Bitumen and Silica on the Chain Lengths of Ammonium Surfactants

Effects of ammonium surfactants with different hydrocarbon chain lengths (C8, C12, C16, and C18) on the colloidal forces between bitumen and silica were studied by atomic force microscopy. The results showed that the chain length of the ammonium surfactants had a significant impact on both the long-range interaction and adhesion forces. With the addition of surfactants with relative short chains of C8 and C12 in the solutions, the long-range repulsive force decreased or even became strong attractive force, while it became repulsive again in solutions of surfactants with long chains of C16 and C18. It was further observed that addition of Ca²⁺ in various surfactants solutions would either depress or enhance the colloidal interactions based on the surfactant chain lengths. It was believed that variation of the interaction behaviors resulted from the mono-layer or bilayer adsorption of various surfactant molecules on the negatively charged surfaces of bitumen and silica, which affected the surface wettability and the surface charge characteristics and then greatly changed the colloidal interactions. The findings indicated that, to have a high bitumen recovery and good froth quality, the surfactant type and concentration of the di-valent metal ions in the oil sand processing slurry must be well considered.     

Characterization of catechol‐containing natural thermosetting polymer “urushiol” thin film

Urushi (oriental lacquer) is made from the sap of Rhus vernicifera and consists mainly of the catechol derivative urushiol. Thermal curing of urushiol, unlike other catechol derivatives, is possible because of the unsaturated double bonds in the long hydrocarbon side chain. We described here a simple, efficient method to produce a thermally cross‐linked urushi thin film using iron(II) acetate as the additive. The cured thin films showed robust, flexible feature as confirmed by strain‐induced elastic buckling instability for mechanical measurements (SIEBIMM) and bulging experiments. In contrast, a thin film of poly(dopamine) that is a typical catechol derivative without long hydrocarbon side chain showed brittleness. The long hydrocarbon side chain of urushiol plays an important role for both thermal processability and superior mechanical properties of the material. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3688–3692     

Diffusion of isolated surface-active molecules at the air/water interface

Fluorescence correlation spectroscopy was applied to study the diffusion of isolated surface-active molecules at air/water interfaces. Rhodamine 6G was used as a surface-active fluorescent tracer. Results show that the diffusion coefficient of the Rhodamine 6G at the interface is about 2.5 times higher than in the bulk. Effects of Rhodamine 6G concentration and added SDS or CTAB surfactants have been studied. Diffusion of Rhodamine 6G at the interface is slowed down at surfactant concentration corresponding to a mean distance between molecules of 10 and 40 nm, indicating a long-range interaction.     

Effect of Surfactants on the Behavior of Chromium in Analytical Flame Atomic Absorption Spectrometry

The behavior of surfactants of different natures and chain lengths was studied in flame atomic absorption spectrometry (FAAS) analyses. The variations of absorbance, which arise as a consequence of the surfactant addition to aqueous solutions of Cr(VI) or Cr(III), were measured. Depressions were observed below the critical micelle concentration (CMC), whereas enhancements were observed above the CMC. These depressions are more significant when the surfactant is opposite in charge to the analyte and the longest surfactant chain is used. A mechanism that enables explanation of the effects of a surfactant on FAAS is also suggested. This mechanism is based on the preferential orientation of surfactant molecules to the surface of nebulized droplets.     

Probing the impact of advanced melting and advanced adsorption phenomena on the accuracy of pore size distributions from cryoporometry and adsorption using NMR relaxometry and diffusometry

The penetration of compressed CO(2) in hydrocarbon and fluorocarbon regions of concentrated surfactant mesophases are interpreted from differences in the CO(2)-processed pore expansion of mesoporous silica thin films templated by three surfactants containing varying degrees of hydrocarbon and fluorocarbon functionality. Ordered silica thin films are synthesized for the first time using the 16-carbon (C(16)) partly fluorinated surfactant, 11,11,12,12,13,13,14,14,15,15,16,16,16-tridecafluorocetyl pyridinium bromide (HFCPB), as a templating agent. Silica films templated with surfactants containing a 8-carbon (C(8)) fluorocarbon tail (3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl pyridinium chloride (HFOPC)) and a 16-carbon (C(16)) hydrocarbon tail (cetyl pyridinium bromide (CPB)) and HFCPB (C(16)) are processed in compressed CO(2) (69-172 bar, 25 °C and 45 °C) during synthesis. CO(2) processing results in significant pore expansion for films templated with both fluorinated surfactants, while pore expansion is negligible for the hydrocarbon templated material suggesting that preferential CO(2) penetration occurs in the 'CO(2)-philic' fluorocarbon segments of the surfactant template. The effect of substrate surface energy on the final uniformity of the dip-coated films is studied by varying the substrate from unmodified glass to a fluorocarbon-capped substrate. The ability to create dip-coated thin films on low surface energy substrates through favorable interaction of surfactant template tail with the substrate surface functional groups is demonstrated.