Enhanced electrochemiluminescence sensor from tris(2,2'-bipyridyl)ruthenium(II) incorporated into MCM-41 and an ionic liquid-based carbon paste electrode

The electrochemiluminescence (ECL) of tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)(3)(2+)] ion-exchanged in the sulfonic-functionalized MCM-41 silicas was developed with tripropylamine (TPrA) as a co-reactant in a carbon paste electrode (CPE) using a room temperature ionic liquid (IL) as a binder. The sulfonic-functionalized silicas MCM-41 were used for preparing an ECL sensor by the electrostatic interactions between Ru(bpy)(3)(2+) cations and sulfonic acid groups. We used the IL as a binder to construct the CPE (IL-CPE) to replace the traditional binder of the CPE (T-CPE)--silicone oil. The results indicated that the MCM-41-modified IL-CPE had more open structures to allow faster diffusion of Ru(bpy)(3)(2+) and that the ionic liquid also acted as a conducting bridge to connect TPrA with Ru(bpy)(3)(2+) sites immobilized in the electrode, resulting in a higher ECL intensity compared with the MCM-41-modified T-CPE. Herein, the detection limit for TPrA of the MCM-41-modified IL-CPE was 7.2 nM, which was two orders of magnitude lower than that observed at the T-CPE. When this new sensor was used in flow injection analysis (FIA), the MCM-41-modified IL-CPE ECL sensor also showed good reproducibility. Furthermore, the sensor could also be renewed easily by mechanical polishing whenever needed.     

联吡啶钌电化学发光传感器测定海洛因

利用离子液体为粘合剂制作碳糊电极,采用高分子聚合法,合成包埋有Ru(bpy)2(dcbpy)2+的高分子聚合物,将钌聚合物掺杂于离子液体碳糊电极中,制作电化学发光传感器.结果表明,此传感器具有很好的电化学发光特性,与用石蜡油为粘合剂制作的电化学发光传感器相比,离子液体为粘合剂的电化学发光传感器检测三丙胺的检出限降低1个数量级.海洛因对电化学发光传感器的发光信号有很好的增强作用,基于此建立了高灵敏度检测海洛因的电化学发光分析法,海洛因浓度与电化学发光信号在2.0×10-9～2.0×10-5 mol/L范围内呈良好的线性关系,检出限为8×10-10 mol/L (S/N=3).将电化学发光传感器在5.0×10-9 mol/L海洛因溶液中采用线性循环电位连续扫描60圈,相对标准偏差小于2.2%.本方法用于血清中海洛因的检测,其回收率为94%～101%.     

在线紫外-可见光谱研究ITO导电玻璃电极上苯胺与对苯二胺的电化学共聚及其产物的表征

本文用在线紫外-可见光谱电化学的方法较详细地研究了在0.5M硫酸水溶液中苯胺、对苯二胺以及苯胺与对苯二胺混合体系在ITO导电玻璃电极上的电化学聚合和共聚合的过程。苯胺与对苯二胺在ITO导电玻璃上发生了电化学共聚合,在0.5M硫酸水溶液的纯苯胺和苯胺与对苯二胺共聚时的循环伏安曲线以及其对应的在线紫外-可见光谱表明对苯二胺的加入除了发生共聚外,也使聚合的速率明显加快;而且纯苯胺在循环伏安电化学聚合时在430nm处出现的吸收带因对苯二胺的加入而消失,说明对苯二胺的加入使聚合的机理与纯苯胺的聚合机理有明显不同,主要原因是苯胺产生的反应中间体可能很快与对苯二胺的阳离子自由基反应聚合。在导电玻璃ITO上的聚合物膜的反射傅立叶红外光谱表明,对苯二胺的加入可能产生了具有1,2取代模式结构,这说明了对苯二胺结合进入到聚合物中。这种共聚使得产物的表面形貌也发生了变化,聚合物扫描电镜图表明对笨二胺的加入有利于纤维状的表面形貌产生,纤维的直径可达到50nm粗细;同时用在线紫外-可见光谱研究了纯聚苯胺和共聚物随电位变化的电变色性质,结果表明在0v-0.6v之间共聚物与纯聚苯胺的在线紫外-可见光谱有明显的不同,且共聚物的电变色可逆性比纯聚苯胺好;同时SEM图也表明在0.8v电位下聚苯胺和共聚物表面形貌发生了团聚。     

Preparation of cellulose I nanowhiskers with a mildly acidic aqueous ionic liquid: reaction efficiency and whiskers attributes

Cellulose I nanowhiskers were prepared in relatively high yield (48 ± 2 %) by single-stage hydrolysis of microcrystalline cellulose with an aqueous solution of 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO₄). This reaction occurred under mildly acidic reaction conditions with an [H⁺]/[AGU] ratio of 0.24 mol/mol, i.e., 2 orders of magnitude lower than with concentrated sulfuric acid. The nanowhiskers exhibited small width and width distribution and also smaller length than nanowhiskers obtained with concentrated acid. With a relatively low content of sulfur they also exhibited higher thermal stability than whiskers obtained with concentrated sulfuric acid. The lower solvating power of the aqueous ionic liquid compared to that of concentrated sulfuric acid likely contributes to the greater hydrolysis efficiency in the present system.     

Ni2＋的引入对离子液体烷基化催化性能的影响

Thealkylationofisobutanewithbuteneisanim portantprocessforthe productionofhigh qualitypetroleum .In placeofconcentratedsulfuricacid ,Et3NHCl/AlCl3ionicliquidhasbeenusedinthereac tionwithfairlygoodeffect[1] ,butthereisstillabigdifferencecomparedwiththeresultsofconcentratedsulfuricacid .TheC8contentinthealkylatesobtainedwithconcentratedsulfuricacidwas 72 1% [2 ] ,butitwasonly 5 6 %withtheionicliquid .ThekeyreactioninthealkylationishydrogentransferfromC+8toC08[3] ,andthisisthemainreasonforth…     

Thermal degradation of polyaniline films prepared in solutions of strong and weak acids and in water - FTIR and Raman spectroscopic studies

Polyaniline (PANI) films were prepared in situ on silicon windows during the oxidation of aniline with ammonium peroxydisulfate in aqueous solutions of strong (0.1 M sulfuric) or weak (0.4 M acetic) acid or without any acid. In solutions of sulfuric acid, a granular PANI is produced, in solutions of weak acids or without any acid, PANI nanotubes are obtained. The thermal stability and structural variation of the corresponding films produced on silicon windows during treatment at 80 °C for three months were studied by FTIR and Raman spectroscopies. The morphology of the films is preserved during the degradation but the molecular structure changes. The results indicate that the spectral changes correspond to deprotonation, oxidation and chemical crosslinking reactions. The films of PANI salts loose their protonating acid. PANI bases are more stable than the salt forms during thermal ageing. The films obtained in water or in the presence of acetic acid are more stable than those prepared in solutions of sulfuric acid. The protonated structure is more prone to crosslinking reactions than deprotonated one. The molecular structure corresponding to the nanotubular morphology, which contains the crosslinked phenazine- and oxazine-like groups, is more stable than the molecular structure of the granular morphology.     

Enhanced electrochemiluminescence of luminol-O2 system at gold–hydrophobic ionic liquid|water interface

A hydrophobic thiol-functionalized ionic liquid (IL) was synthesized and immobilized tightly on a gold electrode surface via Au–S bond to construct a stable Au–IL|water interface. At the Au–IL|water interface, the electrochemiluminescence (ECL) of luminol-O₂ system was investigated. The ECL intensity of luminol-O₂ system at the Au–IL|water interface was much larger and more stable than that at Au|water interface. The enhanced ECL mechanism at the Au–IL|water interface was studied and discussed in details.     

Effect of ac electrodeposition conditions on the growth of high aspect ratio copper nanowires in porous aluminum oxide templates

The effect of several deposition parameters on the uniformity of copper electrodeposition through the alumina barrier layer into porous aluminum oxide templates grown in sulfuric or oxalic acid was systematically investigated. A fractional factorial design of experiment was conducted to find suitable deposition conditions among the variables: frequency, voltage, pulsed or continuous deposition, electrolyte concentration, and barrier layer thinning voltage. Continuous ac sine wave deposition conditions yielded excellent uniformity of pore-filling but damaged the porous aluminum oxide templates when deposition was continued to grow bulk copper on the surface. Pulsed electrodeposition yielded comparable uniformity of pore-filling and no damage to the porous aluminum oxide templates, even when bulk copper was deposited on them. Further optimization of pulsed deposition conditions was accomplished by comparing square and sine waveforms and pulse polarity. Pulsed square waveforms produced better pore-filling than pulsed sine waveforms. For sine wave depositions, the oxidative/reductive pulse polarity was more efficient than the commonly used reductive/oxidative pulse polarity. For square wave depositions into sulfuric acid grown pores, the reductive/oxidative pulse polarity produces more uniform pore-filling, likely as a result of enhanced resonant tunneling through the barrier layer and reoxidation of copper in faster filling pores.     

pH- and ionic strength-controlled cation permselectivity in amine-modified nanoporous opal films

The influence of pH and ionic strength on permselective transport in nanoporous opal films prepared from 440 nm silica spheres was investigated by cyclic voltammetry in aqueous and acetonitrile solutions. Three-layer opal films were deposited from a 1.5 wt % colloidal solution of silica spheres onto 25-microm-diameter Pt microdisk electrodes shrouded in glass. The films were chemically modified by immersing them in a dry acetonitrile solution of 3-aminopropyl triethoxysilane. When the surface amino groups of the modified opal films are protonated and there is little or no supporting electrolyte present in solution, the flux of cationic redox species through the opal membrane is blocked because of electrostatic repulsion. The permselectivity is pH-dependent and can be modulated by adjusting the Debye screening length within the nanopores of the opal by changing the ionic strength of the contacting solution.     

Evidence for enhanced capacitance and restricted motion of an ionic liquid confined in 2 nm diameter Pt mesopores

The organised nanostructure of mesoporous platinum deposited from the H(I) phase of a lyotropic liquid crystal template contains a regular, hexagonal array of uniform nanometre diameter cylindrical pores. This structure is ideally suited to the investigation of the interfacial capacitance and properties of ionic liquids confined within small pores of the type found in the high surface area electrodes favoured for supercapacitors and batteries. Cyclic voltammetry experiments for BMIM-PF(6) show a large capacitance for the mesoporous Pt electrode, confirming that the ionic liquid fills the 2 nm pores. The value of the specific capacitance, normalised to the total surface area, for the ionic liquid within the pores is approximately twice as large as the corresponding value at a flat Pt surface. Impedance measurements, using a small amplitude perturbation, give a value for the capacitance about one order of magnitude less than that from cyclic voltammetry where the amplitude of the perturbation is much larger. The impedance measurements show that the conductivity of the ionic liquid within the pores is at least three orders of magnitude lower than that in the bulk indicating highly restricted mobility for the ions in these narrow pores. The implications of these results for applications in supercapacitors and batteries are discussed.     

BF3.2CF3CH2OH (BF3.2TFE), an efficient superacidic catalyst for some organic synthetic transformations

BF3.2CF3CH2OH complex was found to be a very effective superacidic catalyst comparable in acid strength to at least that of 100% anhydrous sulfuric acid for various acid-catalyzed organic transformations such as isomerizations, rearrangements, ionic hydrogenation of various ketones, and aromatics with triethylsilane and nitration of aromatics with metal nitrate. Studies of the pivalaldehyde-methyl isopropyl ketone rearrangement and the benzopinacol to phenanthrene transformation suggest that the complex has an acidity comparable to that of 100% anhydrous sulfuric acid. The structure and properties of the 1:2 boron trifluoride-trifluoroethanol complex have been further studied using NMR (1H, 13C, 19F, 11B) and DFT calculations at the B3LYP/6-311++G//B3LYP/6-31G level.     

Effect of continuous magnetic field on the growth mechanism of nanoporous anodic alumina films on different substrates

The effects induced by an external homogeneous magnetic field on the oxide film growth on aluminum in aqueous solutions of oxalic and sulfuric acid and on surface morphology of the alumina films were studied. Aluminum films of 100 nm thickness were prepared by thermal evaporation on SiO₂/Si and glass-ceramic substrates. The pore diameter for oxalic acid alumina films on the SiO₂/Si substrate decreased by 0.8 nm, the interpore distance by 5.9 nm, and cell diameter by 6.9 nm if a magnetic field of 0.5 T was applied. When aluminum was anodized in sulfuric acid on the same substrate, the significant changes in parameters of porous structure of alumina, which were similar to the ones in oxalic acid, are firstly observed in stronger magnetic fields (of 0.7 T). On the basis of data obtained in this study and of previous investigation on the negative space charge and thermally activated defects in anodic alumina, we concluded that the intensity of the magnetic field is associated with energy of electron traps and that the changes of cell diameter characterize the trap concentration. The energy of electron traps in oxalic acid alumina films was proved to be smaller than the one in films formed in sulfuric acid, but the concentration of traps was of the same order of magnitude. When the substrate was replaced with the glass-ceramic one, the pore diameter in oxalic acid alumina films increased to ca. 17.6 nm.     

Glucose sensing by electrogenerated chemiluminescence of glucose-dehydrogenase produced NADH on electrodeposited redox hydrogel

In this work, we report a new sensing approach based on electrogenerated chemiluminescence (ECL) in an electrodeposited redox hydrogel using glucose dehydrogenase as a model system. The ECL-hydrogel films were electrodeposited by potential cycling of a PBS solution containing [poly(4-vinylpyridine)Ru(2,2'-bipyridine)(2)Cl(-)](+/2+). The film was easily prepared in a rapid, reproducible and well-controlled one-step procedure. The deposited hydrogel film is permeable to water-soluble chemicals and biochemicals, like enzyme substrates and coenzymes. Electrochemistry and ECL of NADH were studied at the level of the hydrogel film. Results indicate that ECL emission occurs at a relatively low anodic potential compared to the classical Ru(bipy)(3)(2+) complex. This is an important advantage since the measurements performed with the ECL hydrogel are thus less sensitive to interfering species. An ECL oxidative-reductive mechanism is presented for the ECL-hydrogel. Then we showed that the intensity of the ECL of NADH produced by the enzymatic activity varies with the enzyme substrate concentration. Such sensing approach combines enzymatic selectivity with the ECL advantages at low oxidation potential.     

吗啡啉功能化酸性离子液体的合成、表征及其催化酯化性能

制备和表征了三种新型质子酸离子液体: 吗啡啉硫酸氢盐([Hnhm]HSO4)、4-甲基吗啡啉硫酸氢盐 ([Hnmm]HSO4)和SO3H-功能化的4-(3-磺丙基)吗啡啉硫酸氢盐([C3SO3Hnhm]HSO4). 以氯乙酸(CAA)和乙醇合成氯乙酸乙酯的酯化反应考察了它们的酸性和催化活性, 并与1-(3-磺酸基)丙基-3-甲基咪唑硫酸氢盐、1-(3-磺丙基)吡啶硫酸氢盐、1-(3-磺丙基)-2-吡咯烷酮硫酸氢盐等三种具有不同氮杂环的SO3H-功能化酸性离子液体以及浓硫酸相对照. 结果表明, 上述SO3H-功能化离子液体对酯化反应的催化性能比非SO3H-功能化的[Hnhm]HSO4和[Hnmm]HSO4都高, 等同甚至优于浓硫酸. 当反应条件为: n(EtOH)∶n(CAA)∶n([C3SO3Hnhm]HSO4)＝1.3∶1∶0.2, 反应温度80 ℃, 反应时间3 h, 酯收率可达93.4%. 而且离子液体经真空干燥重复使用9次, 催化活性仍无明显下降. 以[C3SO3Hnhm]HSO4催化乙酸和不同醇的酯化反应获得较高的酯收率和选择性, 离子液体跟酯产物均能自动分相. 还考察了SO3H-功能化酸性离子液体对奥氏体316不锈钢的腐蚀性. 尽管SO3H-功能化离子液体与硫酸的酸性相近, 但对钢试样的腐蚀率不到硫酸的1/3.     

Molecular iodine in [bmim][BF4]: a highly efficient green catalytic system for one-pot synthesis of 1,3-oxathiolan-5-one

Aldehydes and mercaptoacetic acid are coupled in the presence of a catalytic amount of economical and non-toxic molecular iodine in [bmim][BF₄] ionic liquid under mild conditions to afford the corresponding 1,3-oxathiolan-5-one in excellent yields. Molecular iodine acts faster in ionic liquids when compared to conventional solvents such as DMSO, DMF, ethyl acetate, and acetonitrile. The recovered ionic liquids can be recycled in subsequent reactions with consistent activity.     

Influence of the solvent on the spreading of poly[(D,L-lactic acid)-co-(glycolic acid)] monolayers

 The properties of mono layers of poly[(D,L-lactic acid)-co-(glycolic acid)] (PLA/GA) are strongly conditioned by the nature of the solvent from which they are spread. In this work, we studied the properties of PLA/GA films deposited on water from acetonitrile (a poor spreading solvent) and chloroform (a good one), observing marked differences with regard to the influence of the pH, temperature and ionic strength of the subphase. These differences were attributed to the structure of PLA/GA at the air/water interface, being pre-determined by its structure in the bulk spreading solvent (closely coiled in acetonitrile, unfolded in chloroform). Viscosity measurements on acetonitrile and chloroform solutions of PLA/GA, and the calculation of the corresponding intermolecular expansion factor, α, confirmed that PLA/GA was better solvated by chloroform than by acetonitrile, in which intramolecular interactions between polymer segments, and thus coiling, will therefore have predominated over polymer–solvent interactions. Received: 14 October 1996 Accepted: 7 January 1997     

液相色谱－电致化学发光检测系统的检测性能研究

使用几种常见的反相液相色谱介质和４种多环化合物对液相色谱交流电致化学发光检测系统的性能进行了测试，结果表明：检测器对４种化合物的检测限均可达到２．０ｎｇ，线性范围达３个数量级。     

FeCl3-Catalyzed Pechmann Synthesis of Coumarins in Ionic Liquids

The synthesis of coumarin derivatives via Pechmann reaction using anhydrous FeCl₃ as Lewis acid catalyst in ionic liquid medium has been carried out. The best results were obtained (yields as high as 89%) with ionic liquids having bis(triflic)imide as a counteranion. The ionic liquid could easily be recovered and reused.     

Effects of pretreatments on crystalline properties and morphology of cellulose nanocrystals

Cellulose nanocrystals (CNCs) have drawn tremendous attention because of their extraordinary physical and chemical properties as well as renewability and sustainability. In this work, after a range of pretreatments, such as freeze-drying, ball-milling, mercerization, N-methylmorpholine-N-oxide dissolution and ionic liquid dissolution, various CNCs with different crystalline properties and morphologies were obtained by hydrolysis or oxidation. XRD and AFM were used to determine the influences of pretreatments on the crystalline properties and morphologies of CNCs. New methods, i.e., specific pretreatments followed by sulfuric acid hydrolysis or 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation, were developed to obtain sphere-like CNCs. It was found that sphere-like CNCs were more likely to be obtained from cellulose materials possessing high accessibility. Pretreatments produced cellulose with various crystallinities and polymorphs, and therefore changed the yields of CNCs and influenced their morphology. CNCs prepared by TEMPO oxidation generally had smaller size than the corresponding products obtained by sulfuric acid hydrolysis. In addition, for the dissolved/regenerated cellulose, TEMPO oxidation was a better method to yield sphere-like CNCs than sulfuric acid hydrolysis.