Catalytic silylation of secondary alcohols by pyridine N-oxide derivative

The reaction of t-butyldiphenylsilyl (TBDPS) chloride with secondary alcohols was catalyzed by pyrrolidinopyridine N-oxide (PPYO) in the presence of diisopropylethylamine (DIPEA) at room temperature, giving the corresponding TBDPS ethers in high yields.     

两个基于4-(1H-1,2,4-三氮唑)苯甲酸的稀土配位聚合物的合成、晶体结构及荧光性质(英文)

以4-(1H-1,2,4-三氮唑)苯甲酸为配体,采用水热法合成了2种稀土配位聚合物[Tb(tbc3)(H2O)3]n(1)和{[Nd(tbc3)(H2O)3]·H2O}n(2)(Htbc=4-(1H-1,2,4-三氮唑)苯甲酸)。运用X-射线单晶衍射法对该配位聚合物进行了结构测定,并对其进行了元素分析、红外光谱、TG及荧光光谱表征。单晶结构表明,配位聚合物1为三斜晶系,空间群P1,配位聚合物2属于单斜晶系,空间群为P21/c。配位聚合物1和2均为一维链结构,均通过非共价键作用形成三维超分子构造。     

Electrochemical sensor based on f-SWCNT and carboxylic group functionalized PEDOT for the sensitive determination of bisphenol A

A simple,sensitive,and reliable method for the voltammetric determination of bisphenol A(BPA) by using carboxylic group functionalized single-walled carbon nanotubes(f-SWCNT)/carboxylic-functionalized poly(3,4-ethylenedioxythiophene)(PC4) complex modified glassy carbon electrode(GCE) has been successfully developed.The electrochemical behavior of BPA at the surface of the modified electrode is investigated by electrochemical techniques.The cyclic voltammetry results show that the as-prepared electrode exhibits strong catalytic activity toward the oxidation of BPA with a well-defined anodic peak at 0.623 V in PBS(0.1 mol/L,pH 7.0).The surface morphology of the 3D network of composite film is beneficial for the adsorption of analytes.Under the optimized conditions,the oxidation peak current is proportional to BPA concentration in the range between 0.099 and 5.794 μmol/L(R~2 = 0.9989),with a limit of detection of 0.032 μmol/L(S/N = 3).The enhanced performance of the sensor can be attributed to the excellent electrocatalytic property of/-SWCNT and the extraordinary conductivity of PC4.Furthermore,the proposed modified electrode displays high stability and good reproducibility.The good result on the voltammetric determination of BPA also indicates that the asfabricated modified electrode will be a good candidate for the electrochemical determination and analysis of BPA.     

A Novel L‐Cysteine Electrochemical Sensor Using Sulfonated Graphene‐poly(3,4‐Ethylenedioxythiophene) Composite Film Decorated with Gold Nanoparticles

By exploiting the electrostatic interaction between positively charged 3,4‐ethylenedioxythiophene cation radicals and negatively charged sulfonated graphene (SG) sheets, we prepared a poly(3,4‐ethylenedioxythiophene)‐sulfonated graphene (SG‐PEDOT) composite film by a one‐step electrochemical process. The composite was further decorated with gold nanoparticles (AuNPs) and employed as an electrode material for the detection of L ‐cysteine (Cys). The SG‐PEDOT composite film is shown to provide a rough surface for the electrodeposition of AuNPs and to improve substrate accessibility and interaction with Cys. Moreover, the AuNPs‐decorated composite exhibits better electrocatalytic performance than that of a SG‐PEDOT composite only. Under optimum experimental conditions, the amperometric current of the sensor is linearly related to the concentration of Cys in the 0.1 to 382 µM range, and the detection limit is 0.02 µM (at S/N=3). The modified electrode displays favorable selectivity, good stability and high reproducibility. The method was successfully applied to the detection of Cys in spiked human urine.     

Study on the Cracking Mechanism of 1,1,2-Trichloro-1,2,2-trimethyldisilane Catalyzed by Aluminum Chloride

The cracking mechanism of 1,1,2-trichloro-l,2,2-trimethyldisilane catalyzed by aluminum chloride is investigated by DFT and MP2 methods. The reactants decompose in two ways, which are competing response. The reaction pathways are both by three steps. And the two reaction channels were both exothermic reaction. The heat of the overall reaction was –293.372 kJ·mol-1. The rate determining steps are the third and first steps, respectively. The Standard Gibbs Free Energy Change is the same, –297.55 kJ·mol-1. The Standard Equilibrium Constant is 1.354 × 1052. The theoretical productivity is high under normal temperature and pressure. The theoretical results agreed well with the experimental data.     

Direct Electrochemistry and Electrocatalysis of Myoglobin with Ionic Liquid through Multilayers Film on Carbon Ionic Liquid Electrode

Multilayers of myoglobin (Mb) with ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMIM]BF₄) was assembled on carbon ionic liquid electrode (CILE) based on the electrostatic attraction between the negatively charged Mb and the positively charged imidazolium ion of IL. The CILE was fabricated with 1‐ethyl‐3‐methylimidazolium ethylsulfate ([EMIM]EtOSO₃) as the modifier, which exhibited imidazolium ion on the electrode surface. Then Mb molecules were assembled on the surface of CILE step‐by‐step to get a {IL/Mb}_n multilayer film modified electrode. UV‐Vis adsorption and FT‐IR spectra indicated that Mb remained its native structure in the IL matrix. In deaerated phosphate buffer solution (pH 7.0) a pair of well‐defined quasi‐reversible redox peaks appeared with the apparent formal potential (E^0′) as ‐0.212 V (vs. SCE), which was the characteristic of Mb heme Fe(III)/Fe(II) redox couples. The results indicated that the direct electron transfer of Mb was realized on the modified electrode. The {IL/Mb}_n/CILE displayed excellent electrocatalytic ability to the trichloroacetic acid reduction in the concentration range from 2.0 to 22.0 mmol/L with the detection limit of 0.6 mmol/L (3σ). The proposed method provides a new platform to fabricate the third generation biosensor based on the self‐assembly of redox protein with ILs.     

Biosorption studies of uranium (VI) on cross-linked chitosan: isotherm,kinetic and thermodynamic aspects

The cross-linked chitosan (CS) gels synthesized by using glutaraldehyde (GLA), epichlorohydrin (EC), and ethylene glycol diglycidyl ether (EGDE) as cross-linkers respectively were used to investigate the adsorption of U(VI) ions in an aqueous solution. The pure chitosan (PCS) and the cross-linked chitosan gels were characterized by FTIR and SEM analysis. The kinetic, thermodynamic adsorption and adsorption isotherms of U(VI) ions onto unmodified and modified cross-linked chitosan were studied in a batch adsorption experiments. The effect of pH, contact time and temperature on the adsorption capacity were also carried out. At the optimum pH, the maximum adsorbed amount of PCS, GLACS, ECCS and EGDECS were 483.05, 147.05, 344.83 and 67.56 mg/g, respectively. The uranium (VI) adsorption process of PCS and ECCS followed better with pseudo-second-order kinetic model, while GLACS and EGDECS followed pseudo-first-order kinetic model well. The results obtained from the equilibrium isotherms adsorption studied of U(VI) ions were analyzed in two adsorption models, namely, Langmuir and Freundlich isothms models, the results showed that the Langmuir isotherm had better conformity to the equilibrium data. The thermodynamic parameters such as enthalpy (ΔHo), entropy (ΔSo), and Gibbs free energy (ΔGo) showed that the adsorption process was both spontaneous and endothermic.     

Facile electrosynthesis and thermoelectric performance of electroactive free-standing polythieno[3,2-b]thiophene films

Polythieno[3,2-b]thiophene (PTT) was electrosynthesized by facile anodic oxidation of thieno[3,2-b]thiophene (TT) in three systems: boron trifluoride diethyl etherate (BFEE), acetonitrile (ACN), and dichloromethane solutions. The onset oxidation potential of TT in BFEE was determined to be 0.62?V vs. Ag/AgCl, which was much lower than those in ACN and dichloromethane solutions. PTT films exhibited excellent electrochemical property, high thermal stability, good redox activity, and stability. Free-standing PTT films with good mechanical property can be obtained from BFEE solution, whose structure and morphology were characterized by FT-IR, UV?Cvisible spectra, and scanning electron microscopy. With an electrical conductivity of 1.5?S?cm^?1 and a Seebeck coefficient of 85???V?K^?1 at 306?K, the as-prepared free-standing PTT films showed a certain thermoelectric property. The dimensionless figure-of-merit of PTT films was estimated to be 2.3?×?10^?3 at 306?K, which was much higher than those of some organic thermoelectric materials reported previously. All these results indicated that PTT films may have potential applications in the thermoelectric field.     

表面解吸常压化学电离质谱快速鉴别樟木制品

采用自行研制的表面解吸常压化学电离质谱(SDAPCI-MS),在无需样品预处理的情况下,对樟木制品及普通木材进行检测,在正离子模式及m/z 90～400范围内获得其化学指纹图谱,并通过主成分分析(PCA)方法对所获指纹谱图信息进行分析,进而对不同样品进行鉴别。结果表明,SDAPCI-MS能够对樟木表面多种特征化学成分(樟脑,香叶醇等)进行解吸电离,快速获得樟木的化学指纹谱图,并能够对目标组分做多级串联质谱鉴定。结合PCA方法,可对不同品质、不同种类的木材样品进行区分。结果表明,本方法灵敏度高,分析速度快(单个样品分析时间小于3 min),可望应用于珍贵木材快速无损分析及品质鉴定。     

单光子电离质谱法用于不同品牌真假酒的快速鉴别

利用单光子电离飞行时间质谱法(SPI-TOF-MS),结合主成分分析(PCA),在无需样品预处理的条件下,建立了快速准确鉴别酒(包括白酒和劲酒)类样品真假的方法。同时,利用光电子电离质谱法(PEI-TOF-MS)对SPI-TOF-MS的准确度和可靠性进行了验证。结果表明,本方法不仅能快速实现对茅台等5种不同品牌酒的真假区分,还可以对影响酒的品质的特征物质进行分析和鉴定。与其它离子化技术(如EI,PEI,ICP等)相比,SPI作为一种"软"电离源,更容易产生分子离子峰,图谱更简单。因此,本方法有望应用于市场上酒类饮品的真假鉴别及品质的鉴定,对于快速筛选伪劣酒类产品有着重要的应用价值。