靛蓝-F-组合探针光度法检测非质子有机溶剂中的微量水

以靛蓝-F^-为组合探针,建立了非质子有机溶剂(DMSO、THF、DMF、二恶烷、乙腈)中微量水的比色检测新方法。结果表明,F^-加入靛蓝溶液后体系的颜色由蓝色变为黄绿色,进一步加入微量水之后,体系从黄绿色又变回蓝色,因而可作为一种变色探针实现对有机溶剂中微量水的裸眼识别检测。体系具有较高灵敏度,对DMSO、THF、DMF、二恶烷及乙腈中微量水的检测限分别为0.022%、0.043%、0.016%、0.34% 和0.015%。该方法实验操作简便、快速、灵敏、安全。实验结果表明,靛蓝与F^-的结合比为1:2。利用核磁滴定方法对机理进行了探讨。     

Universal Trends between Acid Dissociation Constants in Protic and Aprotic Solvents

pKa values in non-aqueous solvents are of critical importance in many areas of chemistry. Our knowledge is, despite their relevance, still limited to the most fundamental properties and few pKa values in the most common solvents. Taking advantage of a recently introduced computationally efficient procedure we computed the pKa values of 182 compounds in 21 solvents. This data set is used to establish for the first time universal trends between all solvents. Our computations indicate, that the total charge of the molecule and the charge of the acidic group combined with the Kamlet-Taft solvatochromic parameters are sufficient to predict pKa values with at least semi- quantitative accuracy. We find, that neutral acids such as alcohols are strongly affected by the solvent properties. This is contrasted by cationic acids like ammonium ions whose pKa is often almost completely independent from the choice of solvent.     

Quenching Mechanisms and Diffusional Pathways in Micellar Systems Unravelled by Time‐Resolved Magnetic‐Field Effects

Radical observation : Time‐resolved magnetic‐field effects yield a very detailed picture of electron‐transfer quenching in micelles and of the fate of the resulting radical‐ion pairs. The system xanthone/DABCO (A/D, see figure) permits a separation of the different static and dynamic quenching pathways and a distinction between bulk and surface diffusion.

     

Study of Partitioning and Solubilization of Some New Chalcones Between Aqueous and Micellar Phases

The partitioning behavior of four newly synthesized chalcones between aqueous and micellar phases of ionic surfactants (SDS and CTAB) was investigated using ultraviolet-visible spectroscopy. The simple absorption spectra were recorded to study the interaction between these drugs and surfactants (in the concentration range below critical micelle concentration to above critical micelle concentration). The absorption data is also used to determine the number of additive molecules incorporated per micelle of the surfactant. The partition coefficient (K_x) of additives between bulk water phase and the micellar phase was determined in the range of 5.52 × 10⁺⁴ to 5.06 × 10⁺⁵ at 298 K by differential spectroscopic method. The corresponding standard free energy of partition ΔG°_p obtained was in the range of ?27.05 kJmol^?1 to ?32.54 kJmol^?1. The relative solubility of additives between aqueous and micellar phases in different micellar concentrations was also estimated. The results showed that the chalcones are preferably soluble in cationic surfactant micelles.     

Infrared Spectroscopic Study of the Solvation of Tetramethylurea in Protic + Aprotic Mixed Solvents

The infrared spectra of tetramethylurea have been measured in mixtures of dimethylsulfoxide or acetonitrile with D₂O or deuterated methanol (CH₃OD). Marked solvatochroism is observed for bands associated with the C=O and C–N stretches of tetramethylurea, with the former moving to lower wavenumber, and the latter to higher, as the concentration of the protic component is increased. The C=O band shows four distinct absorbances, which are attributed to non-, mono, di-, and trihydrogen bonded tetramethylurea. The relative populations of the different hydrogen bonded species were determined from analyses of the C=O band shapes. It is found that the variations in the populations of the different hydrogen bonded species can be accounted for by a simple mass action treatment.     

Micellar Solubilization and In Vitro Release of Silymarin in the self-Aggregates of an Amphiphilic Derivative of Chitosan

Summary: The amphiphilic derivatives of chitosan, (2-hydroxyl-3-butoxyl)-propylcarboxymethyl-chitosan (HBP-CMCHS), can form micelles with the inner core of hydrophobic segments and the outer shell of hydrophilic segments. The typical poor water-soluble drug silymarin was solubilized in the HBP-CMCHS micellar by physical entrapped method. Results showed that the solubilizing capacity was enhanced by increasing the concentration of HBP-CMCHS with the same dosage of silymarin. Silymarin-loaded micellar system of HBP-CMCHS was characterized by TEM and DLS. TEM photograph revealed that the micelles were spherical and silymarin was solubilized in the cores of the spherical polymeric micelles. DLS showed that after solubilization the size of the micelles became bigger. In vitro tests showed that silymarin was slowly released from micellar solution and the release lasted up to 40 h by means of the dialysis method.     

Development of Microdroplet Generation Method for Organic Solvents Used in Chemical Synthesis

Recently, chemical operations with microfluidic devices, especially droplet-based operations, have attracted considerable attention because they can provide an isolated small-volume reaction field. However, analysis of these operations has been limited mostly to aqueous-phase reactions in water droplets due to device material restrictions. In this study, we have successfully demonstrated droplet formation of five common organic solvents frequently used in chemical synthesis by using a simple silicon/glass-based microfluidic device. When an immiscible liquid with surfactant was used as the continuous phase, the organic solvent formed droplets similar to water-in-oil droplets in the device. In contrast to conventional microfluidic devices composed of resins, which are susceptible to swelling in organic solvents, the developed microfluidic device did not undergo swelling owing to the high chemical resistance of the constituent materials. Therefore, the device has potential applications for various chemical reactions involving organic solvents. Furthermore, this droplet generation device enabled control of droplet size by adjusting the liquid flow rate. The droplet generation method proposed in this work will contribute to the study of organic reactions in microdroplets and will be useful for evaluating scaling effects in various chemical reactions.     

Spectroscopic Ellipsometry Characterisation and Estimation of the Hamaker Constant of Cellulose

Calculations of Hamaker constants using Lifshitz theory require the availability of accurate dielectric data, especially in the visible-ultraviolet region. We present spectroscopic ellipsometry data on well-defined cellulose films of a limited thickness range (100–140 layers) deposited on an oxidised and hydrophobised silicon substrate. The spectral data, representing measurements from a perpendicular orientation to the fibre deposition direction, was used for estimates of the necessary spectral parameters, i.e. the oscillator strengths and characteristic frequencies in the UV-range. Our calculations show that cellulose has a relatively low Hamaker constant in air (58 zJ) and water (8.0 zJ). The implications for the surface energy estimates of cellulose and colloidal interactions between cellulose and various types of fillers and coating colours are indicated.     

己基取代的1,4-二(2-噻吩基)苯并[c]哒嗪合成与光谱性质研究

本文设计并合成了一系列含氮原子的缺电子芳香片段,包括以苯并哒嗪作为核心、以富电子噻吩衍生物作为共轭延长链的有机共轭小分子1,4-二(2-噻吩基)苯并[c]哒嗪(5a)、1,4-二[2-(3-己基噻吩基)]苯并[c]哒嗪(5b)和1,4-二[2-(5-己基噻吩基)]苯并[c]哒嗪(5c).通过紫外光谱和荧光光谱研究,证明在共轭体系中的不同位置引入烷基链,可以有效影响化合物的能隙,调节化合物的光电性质.     

固相微萃取-气相色谱法测定食品包装材料中残留有机溶剂

提出了一种以固相微萃取与气相色谱-氢火焰联用技术为基础的测定食品包装材料中15种常用有机溶剂(苯类、醇类、酮类、酯类等)的方法。选择聚二甲亚砜作为固相微萃取的萃取相,采用DB-624毛细管色谱柱进行分离。在优化的试验条件下,15种有机残留溶剂在20min内能很好地分离,15种溶剂的测定下限(10S/N)为0.08～0.69μg.dm-2。加标回收率为60.0%～115.0%,相对标准偏差(n=5)为2.17%～8.34%。     

Solubilization of bilirubin by cholate micelles. Spectroscopic and gel permeation studies

The interactions of bilirubin with bile salts have been studied using fluorescence, circular dichroism and¹H NMR methods. Enhancement of bilirubin fluorescence and induction of optical activity in bilirubin in the presence of cholate has been observed. Fluorescence enhancement is pronounced above the critical micelle concentration, while induced CD bands are detectable even in the premicellar region. Dehydrocholate and deoxycholate did not cause a fluorescence increase, but induced CD bands were observed for bilirubin in these cases. Gel permeation chromatography on Sephadex G-50 yielded a single bilirubin-cholate species at alkaline pH, while two species were obtained at neutral pH.¹H NMR and CD spectral characterizations of these complexes are reported. A 4∶1 cholate-bilirubin mixture has been analysed by difference (nuclear Overhauser effect) NOE spectroscopy. Observation of strong, negative NOE, both intermolecular and intramolecular leads to the conclusion that specific methyl groups on bilirubin and cholate are proximal in the mixed micelle.     

Revisiting the Physicochemical Properties and Applications of Deep Eutectic Solvents

Recently, deep eutectic solvent (DES) or ionic liquid (IL) analogues have been considered as the newest green solvent, demonstrating the potential to replace harsh volatile organic solvents. DESs are mainly a combination of two compounds: hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD), which have the ability to interact through extensive hydrogen bonds. A thorough understanding of their physicochemical properties is essential, given their successful applications on an industrial scale. The appropriate blend of HBA to HBD can easily fine-tune DES properties for desired applications. In this context, we have reviewed the basic information related to DESs, the two most studied physicochemical properties (density and viscosity), and their performance as a solvent in (i) drug delivery and (ii) extraction of biomolecules. A broader approach of various factors affecting their performance has been considered, giving a detailed picture of the current status of DESs in research and development.     

Measurement of Solubilization Location in Micelles Using Anchored Aggregation-Induced Emission Donors

Solubilization locations play a critical role in developing advanced surfactants and improving solubilization power in micelle-based applications. However, the current polarity-based techniques for measuring solubilization locations could come to conflicting conclusions. The key challenge is the unpredictable polarities in the micellar microenvironment. Now, an approach that is independent of micellar polarities is used to measure solubilization locations by covalently linking tetraphenylethylene (TPE) to the alkyl chain end of cationic surfactants. The solubilization locations of solubilized acceptors in the TPE-cored spherical micelles were accurately measured by calculating the Förster resonance energy transfer distance between anchored TPE donors and solubilized acceptors. Solubilization locations of solubilized substances in the micellar interior and at the micellar surface depend on their size and hydrophobicity, respectively.     

水杨酸-2′-乙基己基酯在胶束中的增溶位点

考察了阳离子、非离子和阴离子表面活性剂存在下水杨酸-2′-乙基己基酯(EHS)的吸收光谱和激发态分子内质子转移(ESIPT)荧光光谱.结果表明,EHS可增溶在胶束中,2′-乙基己基碳链朝向胶束内核,而水杨酸基朝向胶束-水界面;胶柬环境有利于EHS分子对紫外光的吸收和分子内氢键的形成,从而使ESIPT荧光显著增强,激发态分子以发射可见光和非辐射去活化方式衰减;并根据EHS和表面活性剂分子的结构和大小,解释了EHS分子在胶束中的结合位点,荧光猝灭和酯水解的光谱测量进一步为此结合位点提供了佐证.     

顶空气相色谱法测定食品添加剂中15种有机溶剂残留量

建立了顶空气相色谱法同时测定食品添加剂中甲苯、甲醇、正己烷等15种有机溶剂残留量的分析方法。选择N,N-二甲基甲酰胺对不同食品添加剂中的有机溶剂进行提取,将样液转移至顶空瓶中密封,顶空进样测定。对提取溶剂、提取方式、平衡时间和平衡温度等进行了优化。结果表明,15种有机溶剂分离良好,各残留溶剂在相应浓度范围内呈良好的线性关系,相关系数不小于0.999 8,定量下限为10.0 mg/kg(三氯甲烷和吡啶为20.0 mg/kg),回收率为90.6%~109.1%,相对标准偏差为0.1%~7.2%。该方法灵敏度高,重现性好,适用于食品添加剂中甲苯、甲醇、正己烷等15种残留溶剂的检测分析。     

表面活性剂在非极性有机溶剂中的自组装

本文总结了表面活性剂在非极性有机溶剂中复杂反相聚集的研究进展。首先突破了表面活性剂在非极性溶剂(油)中溶解的难题,通过设计合成大头基的新表面活性剂,或引入合适添加剂使之与表面活性剂头基相互作用,由此增大头基有效尺寸,这些均能有效促进表面活性剂形成核-壳完整的聚集体,进而带动表面活性剂分散(溶解)在非极性溶剂中。基于聚集体带动溶解的思路,建立了制备表面活性剂/油均相溶液的直接溶解方法,讨论了制备方法的关键要素,它比文献常用的甲醇预溶解法方便且有效。列举了若干典型的表面活性剂/环己烷均相体系,以此评述了聚集体带动溶解的方法,也展现了丰富多样的反相聚集形貌,讨论了表面活性剂头基尺寸对聚集结构的影响。     

水杨酸-2’-乙基己基酯在胶束中的增溶位点

考察了阳离子、非离子和阴离子表面活性剂存在下水杨酸-2’-乙基己基酯(EHS)的吸收光谱和激发态分子内质子转移(ESIPT)荧光光谱. 结果表明, EHS可增溶在胶束中, 2’-乙基己基碳链朝向胶束内核, 而水杨酸基朝向胶束-水界面; 胶束环境有利于EHS分子对紫外光的吸收和分子内氢键的形成, 从而使ESIPT 荧光显著增强, 激发态分子以发射可见光和非辐射去活化方式衰减; 并根据EHS和表面活性剂分子的结构和大小, 解释了EHS分子在胶束中的结合位点, 荧光猝灭和酯水解的光谱测量进一步为此结合位点提供了佐证.     

Spectroscopic and Quantum Mechanical Studies of Substituted Anilines and their Charge-Transfer Complexes with Iodine in Different Solvents

Summary. Equilibrium constants and molar extinction coefficients for 1:1 charge-transfer complexes between 2-hydroxyaniline (HA), 5-chloro-2-hydroxyaniline (CHA), and 4-bromo-2,6-dimethylaniline (BMA) as donors and iodine, as a typical σ-acceptor were determined spectrophotometrically in chloroform, dichloromethane, and carbontetrachloride solutions. Spectral characteristics and formation constants are discussed in terms of donor molecular structure and solvent polarity. The stoichiometry of the complexes was established to be 1:1. For this purpose, optical data were subjected to the form of the Rose-Drago equation for 1:1 equilibria. Electronic absorption spectra of the studied anilines were measured in different solvents. Spectral data were reported and band maxima were assigned to the appropriate molecular orbital transitions (π–π^* and n–π^* electronic transition). Solvent effects on the electronic transitions were discussed. Optimized geometry of the studied anilines was obtained at B3LYP/6-31 + G(d). The effect of the electronic factors of the substituents on the geometrical parameters of the ring has been explored. Geometrical values of the ring deviate from the regular hexagonal ring. Intramolecular H-bonds in HA and CHA have been computed at B3LYP/6-31 + G(d) and MP2/6-31 + G(d) levels. The H-bonding distance was calculated to be 2.105 ? in HA and 2.127 ? in CHA. Abstracted from her M.Sc. thesis     

顶空毛细管气相色谱法测定非那雄胺中有机溶剂的残留量

建立了顶空毛细管气相色谱法测定非那雄胺中二氯甲烷和氯仿两种有机溶剂残留量的方法,并讨论了平衡温度、平衡时间、盐效应对测定的影响。分析结果表明:该法可将两种残留有机溶剂完全分离,具有较好的线性(相关系数分别为0.999 7和0.999 8),检出限为3.2μg/L和0.094μg/L,测定结果的相对标准偏差分别为1.33%和0.89%,样品回收率分别为94%和96%。