Thermodynamic Properties and Relative Stability of Polyhydroxylated Dibenzo-p dioxins Calculated by Density Functional Theory

In this work, partial thermodynamic properties of polyhydroxylated dibenzo-p-dioxins (PHODDs) are calculated by density functional theory (DFT) with the Gaussian 03 program at the B3LYP/6-311G** level. By comparing the total energy Eθ values, it is found that two types of hydrogen bonds exist in PHODDs, one between a hydroxyl and the parent compound (dibenzop-dioxin) with bond energy of approximate 15.7 kJ/mol and the other between two ortho hydroxyl groups with higher bond energy of about 18.3 kJ/mol. Hydrogen bonds have an effect on the conformation stability. On the basis of evaluating the strength of these two types of hydrogen bonds, 75 most stable congeners are ascertained. The relations of calculated thermodynamic parameters (total energy Eθ, zero-point vibrational energy ZPE, correction value of thermal energy Ethθ, heat capacity at constant volume CVθ) with the number and position of hydroxyl substitution (NPHOS) are also discussed. The results show that the NPHOS models can be used to predict the thermodynamic properties for PHODD congeners. In addition, the values of molar heat capacities at constant pressure (Cp,m) from 200 to 1000 K for PHODD congeners are calculated, and the temperature dependence relation of Cp,m is obtained with the least-squares method.     

A new pseudo rubrene analogue with excellent film forming ability

A novel pseudo rubrene analogue,6,11-di(thiophen-2-yl)-tetracene-5,12-dione (DTTDO) was synthesized,in which two thienyl groups and two carbonyl groups replacing four phenyl groups in the rubrene molecule were connected to the backbone of tetracene.This compound was characterized by single crystal X-ray structure analysis,thermogravimetric analysis,absorption spectra and electrochemical measurements.Unlike rubrene,DTTDO exhibited excellent film forming ability by normal vacuum deposition,indicating its prom...     

Polyfluorenes containing pyrazine units:Synthesis,photophysics and electroluminescence

A series of conjugated copolymers of 9,9-dioctylfluorene and symmetrical pyrazine unit (BY) were synthesized by Suzuki copolymerization and were used as novel light-emitting materials in PLEDs.Efficient energy transfer was observed in both thin film and solution.Compared with the lowest occupied molecular orbital (LUMO) energy level of the polyfluorenes homopolymer (PFO),the lower LUMO energy levels of copolymers indicated that the introduction of the BY unit would be benefit to electron injection.The turn-...     

Multiple resonances with time delays in scale-free networks of Hodgkin-Huxley neurons subjected to non-Gaussian noise

The spiking behavior with varying time delay in scale-free networks of Hodgkin-Huxley neurons with non-Gaussian noise has been studied,and the effect of non-Gaussian noise on the delay-induced spiking behavior is discussed. It was found that multiple spatio-temporal resonances occur when the delay lengths are integer multiples of the spiking periods,and the resonances may be strengthened when the non-Gaussian noise is appropriate. This result shows that time delays can optimize the spiking temporal regulari...     

丙烯酰氯分子的气相光解动力学

利用时间分辨傅立叶变换红外(TR-FTIR)发射光谱研究了气相中CH2=CHCOCl分子的光解动力学.观测到振动激发的光解碎片分子CO(ν≤5),HCl(ν≤6),C2H2和相应的两个光解离通道:C-Cl键断裂和HCl消除通道.通过分析转动分辨的红外发射光谱得到CO和HCl的初始振转能量态分布,由此提出CH2=CHCOCl的气相光解机理并阐明了内转换等非绝热过程在影响反应途径中的关键作用.     

浊点萃取-火焰原子吸收光谱法测定荔枝和桂圆肉中痕量铜

建立以二乙基二硫代氨基甲酸钠(DDT℃)为配位剂、TritonX-114为表面活性剂的浊点萃取-火焰原子吸收测定荔枝和桂圆肉中痕量铜的方法.研究了溶液pH值、配位剂类型与浓度、表面活性剂类型与浓度、平衡温度和平衡时间等实验条件对浊点萃取效率的影响.在最优的实验条件下,该方法测定铜的检出限为0.8μg/L,相对于传统火焰...     

一维链状Cd(Ⅱ)配位聚合物的合成、晶体结构及荧光性质

由Cd(CH3COO)2、间苯二甲酸(H2L)和柔性含氮配体2,2′-二[2-(2-吡啶)苯并咪唑]乙醚(bpb)反应,得了一种新型配合物[Cd2( L)2 (bpb)],通过元素分析、红外光谱和X-单晶衍射等对配合物的结构进行了表征.结果表明配合物属单斜晶系,空间群P2/c,晶胞参数a=0.931 8(5),b=1....     

基于多尺度小波变换的红外光谱谱峰识别算法

传统的谱峰检测方法一般分为3个步骤:谱线平滑、基线校正和谱峰识别.现有的基于小波变换的峰值检测方法能较好地将基线校正和谱峰识别两个步骤融为一步.在此基础之上,本研究将谱线平滑也很好地融入到小波变换的峰值检测算法中,使整个峰值检测算法成为一个整体.在峰值提取时,原始谱图直接处理,不再是处理加工过的谱图,减小了谱峰检测结果...     

冷原子荧光光谱法测定南宁市邕江支流水域中无机汞和总汞

采用氢化物发生-冷原子荧光光谱法,测定了南宁邕江支流水域中无机汞和总汞.实验结果表明,南宁邕江支流水域中汞含量均小于国家规定的地表水Ⅰ类水域的标准,水质良好.同时对样品的测量检出限及方法回收率进行实验,结果表明在优化的实验条件下检出限为0.021 ng/L,相对标准偏差为2.24％,无机汞和总汞的加标回收率分别为90....     

纸芯片制作及其在化学发光法检测葡萄糖和尿酸中的应用

纸芯片是一类新型的个性化诊断器件,可快速、廉价、简便地进行多组分分析.采用光刻法制备了一维和二维纸芯片(μPADs),并对不同通道芯片检测所需的样品体积进行理论估算.同时利用葡萄糖氧化酶-葡萄糖反应产生过氧化氢诱导鲁米诺化学发光,在纸芯片上检测葡萄糖,线性范围为2.0×10-4～9.0×10-4mol/L,检出限为5....