Novel 1,3-dipolar cycloaddition reactions of calix[4]bis(spirodienones): synthesis of isoxazolidine derived macrocycles

Calix[4]bis(spirodienones) can perform as either 4π or 2π components in cycloaddition reactions with various carbo- and hetero-dienophiles and with 1,2-benzoquinones leading to the formation of highly functionalized macrocycles. In this Letter we report, highly regio- and stereoselective 1,3-dipolar cycloaddition reactions of a bis(spirodienone) derivative of calix[4]arene with nitrones that provide easy access to isoxazolidine derived macrocycles in excellent yields. These isoxazolidine derivatives can be considered as direct precursors of 1,3-amino alcohols.     

Green synthesis and dye-sensitized solar cell application of rutile and anatase TiO2 nanorods

Journal of Solid State Electrochemistry - Nanorods (NRs) of TiO2 have biogenically been prepared, i.e., from the extract of Phellinus linteus mushroom. The presence of mixed anatase and...     

The role of proton mobility in determining the energy-resolved vibrational activation/dissociation channels of N-glycopeptide ions

Site-specific glycoproteomic analysis largely hinges on the use of tandem mass spectrometry (MS/MS) to identify glycopeptides. Experiments of this type are usually aimed at drawing connections between individual oligosaccharide structures and their specific sites of attachment to the polypeptide chain. These determinations inherently require ion dissociation methods capable of interrogating both the monosaccharide and amino acid connectivity of the glycopeptide. Collision-induced dissociation (CID) shows potential to satisfy this requirement, as the vibrational activation/dissociation of protonated N-glycopeptides has been observed to access cleavage of either glycosidic bonds of the glycan or amide bonds of the peptide in an energy-resolved manner. Nevertheless, the relative energy requirement for these fragmentation pathways varies considerably among analytes. This research addresses the influence of proton mobility on the vibrational energy necessary to achieve either glycan or peptide cleavage in a collection of protonated N-glycopeptide ions. While greater proton mobility of the precursor ion was found to correlate with lower energy requirements for precursor ion depletion and appearance of glycosidic fragments, the vibrational energy deposition necessary for appearance of peptide backbone fragments showed no relation to the precursor ion proton mobility. These results are consistent with observations suggesting that peptide fragments arise from an intermediate fragment which is generally of lower proton mobility than the precursor ion. Such findings have potential to facilitate the rational selection of CID conditions which are best suited to provide either glycan or peptide cleavage products in MS/MS based N-glycoproteomic analysis.     

自适应粒子群优化算法及其在注塑成型质量指标软测量中的应用

对粒子群优化算法(PSO)进行分析,提出了一种根据速度信息自适应调整参数的粒子群优化算法(APSO-VI),该算法经过大量测试函数上的模拟实验验证,并与PSO进行了比较。实验结果表明,该算法能克服基本PSO算法在求解高维、多峰等大规模复杂非线性优化问题时易陷入局部最优和不收敛的     

Study of ionomer blends based on a polyurethane cationomer and an acrylic anionomer

Polyurethane and polyurethane cationomers were synthesized using 2,3-dihydroxypyridine and 2,3-dihydroxypyridine hydrochloride as chain extenders. Poly(butyl methacrylate-co-methacrylic acid) was synthesized by free radical solution polymerization and was converted into its sodium salt. The polyurethane cationomer and the acrylic anionomer were blended in different proportions in N,N-dimethylformamide. Simple blends without ionic groups were also prepared. Miscibility enhancement in these systems was studied by means of differential scanning calorimetry and scanning electron microscopy.     

A host-guest optical sensor for aliphatic amines based on lipophilic cyclodextrin

A host-guest optical sensor for the determination of aliphatic amines as exemplified by octylamine is proposed. It is based on the reversible fluorescence enhancement of heptakis(2,6-di-O-isobutyl)-β-cyclodextrin(DOB-β-CD) hosting tetraphenylporphyrin (TPP) immobilized in poly(vinyl chloride) (PVC) membrane by aliphatic amine extracted from aqueous phase into membrane phase. The optimum membrane contained 1.15 wt % TPP, 6.15 wt % DOB-β-CD as sensing reagent and other membrane materials. The fluorescence enhancement of the membrane resulted from the formation of a stable three-component complex among DOB-β-CD, TPP, and aliphatic amines. With the optimum conditions described, the fluorescence response of the sensor to octylamine shows a good correlation with the theoretically derived equation in the range 1.0 × 10^–6 to 8.0 × 10^–4 mol/L. The response characteristics including reversibility, response time, reproducibility and lifetime and selectivity of this optical device are also discussed in detail. This sensor has also been applied for the determination of octylamine in water samples containing interferents with satisfactory recovery. Received: 21 November 1999 / Revised: 10 January 2000 / Accepted: 15 January 2000     

Synthesis and characterization of polyurethane–polyvinylbenzyl chloride multiblock copolymers and their cationomers using a polyurethane macroiniferter

Polyurethane iniferter prepared from isocyanate end capped prepolymer and 1,1,2,2-tetraphenyl-1,2-ethanediol, has been used to polymerize vinylbenzyl chloride to obtain polyurethane-polyvinylbenzyl chloride multiblock copolymers. Formation of the block copolymers proceeds with increase in both molecular weight and conversion with increasing polymerization time showing that the polymerization proceeds via a “living” radical mechanism. The block copolymers so obtained were converted into their cationomers by the treatment of triethylamine. The block copolymers and their cationomers have been characterized by FTIR, FTNMR, TGA, and DSC studies. The effect of thermal energy on the molecular weight of the macroiniferter in the absence of monomer has been studied in order to understand the mechanism of formation of the block copolymers. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1237–1244, 1997     

Tetraphenylethane iniferters. II. Toluene diisocyanate-based polyurethane iniferter for “living” radical polymerization of acrylonitrile

A novel polyurethane iniferter, synthesized from equal moles of toluene diisocyanate and 1,1,2,2-tetraphenyl-1,2-ethanediol, was used to polymerize acrylonitrile to assess whether it proceeded via a “living” radical polymerization mechanism. From the kinetic results, the rate of polymerization could be expressed as R_pα[BPT]^0.96[AN]^1.64. The increase of number-average molecular weight with increase of both conversion and polymerization time, the bimodal molecular weight distribution in gel permeation chromatography and the increase of molecular weight in the post-polymerization of polyacrylonitrile confirm that the present tetraphenylethane-based polyurethane iniferter follows a “living” radical polymerization mechanism. © 1996 John Wiley & Sons, Inc.     

Thermophysical and Spectroscopic Studies of Pure 1-Butyl-3-methylimidazolium Tetrafluoroborate and Its Aqueous Mixtures

Intermolecular interactions in the aqueous mixtures of the room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF₄]), have been studied. The thermophysical properties: density ρ, speed of sound u, specific conductivity κ and refractive index n _D have been measured over the whole composition range at different temperatures (293.15–323.15 K) and are discussed. The results from thermophysical measurements are explained with the help of spectroscopy. In order to interpret the nature of molecular interactions occurring between [BMIM][BF₄] and water molecules, as well as to identify the moieties in which interactions are taking place, ¹H, ¹³C NMR and FT-IR spectra of the solutions have been studied. Excess molar volume V ^E, excess molar isentropic compressibility $ K_{S}^{\text{E}} $ , partial molar excess volume $ V_{i}^{\text{E}} $ , partial molar excess isentropic compressibility $ K_{S,i}^{\text{E}} $ , deviation in specific conductivity ?κ, and deviation in refractive index ?R have also been determined and analyzed to have a better understanding of the interactions taking place between the different components. Additionally, the excess ultrasonic speed u ^E and excess isentropic compressibility $ k_{S}^{\text{E}} $ , in terms of volume fractions, have been calculated and analyzed. It has been observed that temperature has a significant effect on the thermophysical properties of the studied system. Spectroscopic measurements confirm the disruption of ion-pair interactions of [BMIM][BF₄] and hydrogen-bonded network of water in the aqueous mixture of [BMIM][BF₄].     

近红外差谱法选择信息区提高同分异构体预测模型准确度

以短波近红外光谱法定量检测了二甲苯三种同分异构体混合溶液中各自的体积相对含量。分别采用全光谱、截取具有高相关系数的波段和差谱法选择光谱差异大的波段三种不同的建模方式建立偏最小二乘回归 (Partial L east- Squares Regression)预测模型并对被预测样品进行了相互验证 (Cross Validation)。实验表明 ,采用差谱法选择光谱差异大的波段建立的预测模型显著地克服了同分异构体光谱之间的相似性 ,其预测准确度优于前两者。