呋喃取代三芳基三唑的单核铜配合物中共存两个不同的铜离子

分别以3-（2-吡啶基）-4-苯基-5-（2-呋喃基）-1，2，4-三氮唑（L¹）和3-（2-吡啶基）-4-（对氟苯基）-5-（2-呋喃基）-1，2，4-三氮唑（L²）作为配体，合成了2个新的单核铜配合物：trans-[Cu （L¹）₂（NO₃）₂]_0.5[Cu （L¹）₂（H₂O）₂]_0.5（NO₃）（1）和trans-[Cu （L²）₂（NO₃）₂]_0.5[Cu （L²）₂（H₂O）₂]_0.5（NO₃）·₂CH₃OH （2）。对它们进行了红外、元素分析、热重分析、单晶结构和粉末X射线衍射表征。2个配合物都属于三斜晶系，P1空间群。单晶结构表明，配合物1和2中均有2个不同的铜离子，且都处于一个扭曲的八面体[CuN₄O₂]配位环境，但在轴向上一个铜离子与2个水分子配位，另一个铜离子则与2个硝酸根配位。配体的吡啶氮原子和三氮唑的一个氮原子参与配位，而呋喃的氧原子不配位。配合物晶体中存在C—H…N、C—H…O、O—H…O氢键和C—H…π相互作用，从而连接单核配合物形成二维层状结构。     

外电场作用下寡聚苯分子导线的性质

利用Hartree-Fock 方法在6-31G*水平上对聚苯分子进行了计算研究. 分别从几何构型、分子轨道空间分布和分子轨道能级三个方面讨论了外电场对寡聚苯分子导线的影响, 给出了分子导线的性质与外电场的关系. 进一步, 连接硫原子于聚苯分子的两端, 并共价结合在金电极上. 利用非平衡格林函数方法对其在0-2.0 V 偏压下电子输运特征进行了深入研究.     

Microwave-assisted Synthesis and antifungal activity of coumarin[8,7-<Emphasis Type="BoldItalic">e</Emphasis>][1,3]oxazine derivatives

The synthesis of novel coumarin[8,7-e][1,3]oxazine derivatives through a microwave-assisted three-component one-pot Mannich reaction is described in this study. All the target compounds were evaluated in vitro for their antifungal activity against Botrytis cinerea, Colletotrichum capsici, Alternaria solani, Gibberella zeae, Rhizoctonia solani, and Alternaria mali. The preliminary bioassays showed that 5e, 5m, and 5s exhibited good antifungal activity and the most active compound was 5m with an \(\hbox {EC}_{50}\) value as low as 2.1 nM against Botrytis cinerea.     

Application of instantaneous nebulization dispersive liquid-phase microextraction combined with HPLC for the determination of chalcone and isoflavone in traditional Chinese medicines

A simple and rapid instantaneous nebulization dispersive liquid-phase microextraction method was developed, and combined with high-performance liquid chromatography for determination of the contents of seven analytes in traditional Chinese medicines. In this study, using the sprinkler device to achieve instantaneous synchronous dispersion and extraction, only one spray can rapidly achieve the concentration and enrichment of seven kinds of chalcone and isoflavones. The key factors affecting the extraction efficiency were optimized including the type and volume of extractant, the pH and salt concentration of the sample phase, and the number of dispersion. Under the optimal conditions, the enrichment factor of the target analytes ranged from 103.1 to 180.9, with good linearity and correlation coefficients above 0.9970. The limits of detection ranged from 0.02 to 0.15 ng/mL, with good accuracy (recoveries 91.1 to 108.9%) and precision (relative standard deviations 1.5–7.1%). This method has short extraction time (2 s), low organic solvent consumption and high enrichment effect, so it has a wide application prospects.     

Induced removal of dipalmitoyl phosphatidylcholine by the exclusion of fibrinogen from compressed monolayers at air/liquid interfaces

The induced removal of dipalmitoyl phosphatidylcholine (DPPC) by the exclusion of fibrinogen from mixed DPPC/fibrinogen monolayers at compressed air/liquid interfaces was analyzed. The surface pressure-area hysteresis curves of the monolayers at interfaces were obtained by a Langmuir trough. The hysteresis curves of equilibrium fibrinogen adsorption layers suggest that fibrinogen desorption during the area compression stage became significant at a higher bulk concentration of 1000 ppm. For mixed monolayers of DPPC with fibrinogen, the fibrinogen molecules were expelled from the interface upon compression due to the presence of insoluble DPPC molecules. The squeeze-out of fibrinogen molecules evidently removed a significant number of DPPC molecules from the interface, with the extent depending on fibrinogen surface concentration. During the subsequent area expansion stage, fibrinogen molecules entered the interface and participated in the rise of surface pressure. The induced loss of free DPPC molecules at the interface by the expelled fibrinogen molecules during the area compression stage was then evaluated from the hysteresis curves.     

Fault-tolerant topology in the wireless sensor networks for energy depletion and random failure

Nodes in the wireless sensor networks(WSNs) are prone to failure due to energy depletion and poor environment,which could have a negative impact on the normal operation of the network. In order to solve this problem, in this paper, we build a fault-tolerant topology which can effectively tolerate energy depletion and random failure. Firstly, a comprehensive failure model about energy depletion and random failure is established. Then an improved evolution model is presented to generate a fault-tolerant topology, and the degree distribution of the topology can be adjusted. Finally, the relation between the degree distribution and the topological fault tolerance is analyzed, and the optimal value of evolution model parameter is obtained. Then the target fault-tolerant topology which can effectively tolerate energy depletion and random failure is obtained. The performances of the new fault tolerant topology are verified by simulation experiments. The results show that the new fault tolerant topology effectively prolongs the network lifetime and has strong fault tolerance.     

Characterization of the transient species generated by the photoionization of Berberine: A laser flash photolysis study

Using 266 nm laser flash photolysis it has been demonstrated that Berberine (BBR) in aqueous solution is ionized via a mono-photonic process giving a hydrated electron, anion radical that formed by hydrated electron react with steady state of BBR, and neutral radical that formed from rapid deprotonation of the radical cation of BBR. The quantum yield of photoionization is determined to be 0.03 at room temperature with KI solution used as a reference. Furthermore utilizing pH changing method and the SO₄⁻ radical oxidation method, the assignment of radical cation of BBR was further confirmed, the pK_a value of it was calculated, and the related set up rate constant was also determined.     

Isolation and chemotaxonomic significance of stenine- and stemoninine-type alkaloids from the roots of Stemona tuberosa

One new stenine-type alkaloid,tuberostemonine D(1),together with five known stenine-type alkaloids(2–6) and two known stemoninine-type alkaloids(7 and 8),were isolated from the roots of Stemona tuberosa.Their structures were elucidated by extensive spectroscopic methods(IR,UV,MS,1D and 2D NMR),and the structure of 1 was further confirmed by X-ray diffraction analysis.First simultaneous isolation of stenine- and stemoninine-type alkaloids not only added a new chemical type and increased the chemical diversity of Stemona tuberosa,but also provided chemotaxonomic clues for the close relationship between genera Stemona and Stichoneuron,and favored retaining them in the same family.     

‘‘Amano' lipase DF-catalyzed efficient synthesis of 2,20-arylmethylene dicyclohexane-1,3-dione derivatives in anhydrous media

A simple and efficient method was developed for the synthesis of 2,20-arylmethylene dicyclohexane-1,3-dione derivatives via the Knoevenagel–Michael cascade reactions of aromatic aldehydes and 1,3-cyclic diketones catalyzed by ‘‘Amano' lipase DF, which expands the application field of enzyme catalytic promiscuity. This protocol provides several advantages over the traditional chemical synthesis, such as simple work-up procedure, high yields(up to 94%) and environmental friendliness.     

顶空气相色谱-质谱联用法分析粪便中挥发性脂肪酸

建立了一种快速分析粪便中挥发性脂肪酸(Volatile fatty acids,VFAs)的顶空气相色谱-质谱联用法(Headspace gas chromatography-mass spectrometry,HS-GC/MS)。粪便样品用6%H3PO4溶液按1∶2(m/V)混悬后密封于顶空进样瓶中,直接进行HS-GC/MS检测。顶空振荡室加热温度为80℃,振荡加热时间30 min,顶空进样针温度为80℃,不分流进样1 mL;采用DB-FFAP毛细管柱(30 m×0.25 mm×0.25μm),进样口温度为250℃,升温程序(初始温度50℃保持1 min,以10℃/min升至200℃),载气(高纯氦)流速为1.0 mL/min;使用电子轰击(Electron impact,EI)离子源,电子能量为-70 eV,离子源温度为250℃,传输线温度为280℃,电子倍增器电压为0.95 kV,全扫描模式,扫描范围m/z 33~200。结果表明,本方法能够应用于人及大鼠粪便中挥发性脂肪酸的分析,通过NIST标准谱库检索,采用对照品比对以及质谱数据解析的方法,在人的粪便样品中检测到9种挥发性脂肪酸:乙酸、丙酸、异丁酸、丁酸、异戊酸、戊酸、异己酸、己酸、庚酸;在大鼠粪便中检测到8种挥发性脂肪酸:乙酸、丙酸、异丁酸、丁酸、异戊酸、戊酸、己酸、庚酸。通过峰面积归一化法,计算得到乙酸、丙酸、丁酸的相对百分含量约占挥发性脂肪酸总量的85%。本方法简单、灵敏,可用于人和大鼠粪便中挥发性脂肪酸的快速检测。