Palladium‐catalyzed Suzuki–Miyaura coupling with aryl and heteroaryl bromides using N,N,N′,N′‐tetra(diphenylphosphinomethyl)‐1,2‐ethylenediamine

An easily prepared tetraphosphine N,N,N′,N′‐tetra(diphenylphosphinomethyl)‐1,2‐ethylenediamine (1) combined with PdCl₂ affords an efficient catalytic system for Suzuki cross‐coupling of aryl and heteroaryl bromides. A high turnover number of 750 000 is obtained with the catalyst loading as low as 1 ppm. This catalyst system exhibits good stability and longevity. In this study, a broad scope of substrates is investigated and satisfactory yields are obtained. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis of Hirtellanine B,an Isoflavonoid with Potent Antiproliferative Effects in Cancer Cells

We reported the first total synthesis of hirtellanine B, using oxidative coupling for the key reactions, which resulted in a high yield. The antiproliferative activity of hirtellanine B against Jurkat cells, Raji cells and K562 cells were also investigated. It was found that hirtellanine B could induce G2/M arrest and apoptosis in human lymphoid/leukemia tumor cells.     

Rare‐Earth Nanoparticles with Enhanced Upconversion Emission and Suppressed Rare‐Earth‐Ion Leakage

Upconversion emissions from rare‐earth nanoparticles have attracted much interest as potential biolabels, for which small particle size and high emission intensity are both desired. Herein we report a facile way to achieve NaYF₄:Yb,Er@CaF₂ nanoparticles (NPs) with a small size (10–13 nm) and highly enhanced (ca. 300 times) upconversion emission compared with the pristine NPs. The CaF₂ shell protects the rare‐earth ions from leaking, when the nanoparticles are exposed to buffer solution, and ensures biological safety for the potential bioprobe applications. With the upconversion emission from NaYF₄:Yb,Er@CaF₂ NPs, HeLa cells were imaged with low background interference.     

A Guest‐Dependent Approach to Retain Permanent Pores in Flexible Metal–Organic Frameworks by Cation Exchange

Two anionic metal–organic frameworks were successfully prepared based on pre‐designed flexible multicarboxylate ligands and indium cations. Owing to the flexibility of the bridging organic linkers, which could not themselves sustain the frameworks, both of the frameworks showed thermal instability and shrinkage after removal of guest solvent molecules. Inspired by bamboo, we used a guest‐dependent approach to tune the permanent porosity of the MOFs. In this approach, several tetraalkyammonium cations of different sizes were introduced into the channels by cation exchange to act as partitions and to support the main frameworks. This approach significantly enhanced the stability of the framework and its permanent porosity. Moreover, the gas‐adsorption properties (such as gate sorption, hysteresis, and selectivity) of the MOFs were also modulated by the judicious choice of guest cations.     

Chiral Recognition of Penicillamine Enantiomers Based on DNA‐MWNT Complex Modified Electrode

Double‐stranded DNA and multiwalled carbon nanotube (MWNT) complex modified glassy carbon electrodes (DNA‐MWNT‐GCE) were employed to discriminate penicillamine (PA) enantiomers. Cyclic voltammetry, electrochemical impedance spectroscopy, atomic force microscopy and ultraviolet‐visible spectroscopy were used to characterize the enantioselective phenomenon. The results indicated that the binding effect between L ‐PA and DNA‐MWNTs was stronger than that of D ‐PA and DNA‐MWNTs. In addition, the influencing factors of the modified electrodes were systematically investigated. The modified electrodes exhibited a linear response towards PA enantiomers from 1.0×10^?1 to 1.0×10^?8 mol L^?1 and detection limits of 3.1×10^?9 and 3.3×10^?8 mol L^?1 for L ‐PA and D ‐PA, respectively.     

一维轴向有机无机异质结肖特基二极管的制备及性能研究

一维有机无机杂化材料的制备一直以来是难点问题, 其不同组分间协同产生的新颖性能及广泛应用前景, 使其成为近年来研究热点. 通过多孔氧化铝模板辅助分步电化学沉积方法, 成功设计和制备了有机导电聚合物聚3,4-乙撑二氧噻吩[poly(3,4-ethylenedioxythiophene), PEDOT]和无机金属银(Ag)的分段式纳米线. 使用扫描电子显微镜(SEM)和透射电子显微镜(TEM)对其形貌和结构进行了表征. 采用顶端接触上电极的方式, 研究了单根PEDOT纳米线和单根PEDOT-Ag异质结纳米线的伏安特性曲线. 结果表明, 单根异质结纳米线展现出肖特基二极管行为, 正向开启电压为0.3 V, 反向击穿电压为1.5 V, 正向开启后电流达到微安数量级.     

LaFe1-xCuxO3的光催化性及正电子湮没研究

研究LaFeO3及微量掺铜LaFeO3的光催化活性,利用正电子湮没谱分析掺杂的影响,发现随着掺杂百分比的增加,正电子寿命逐渐下降达到一最小值,然后又上升;而光催化活性随掺杂百分比的增加逐渐上升达到最大值,然后下降。结果表明：LaFeO3掺杂后光催化活性得以提高;正电子湮没技术是研究点阵缺陷结构的有效方法之一。     

Synthesis of an orange anthrathiophene pigment isolated from a Japanese bryozoan

A short, regiospecific synthesis of the naturally occurring anthrathiophene 1 from naphthazarin (7) is described.     

Pd(PhCN)(2)Cl(2)/P(t-Bu)(3): a versatile catalyst for Sonogashira reactions of aryl bromides at room temperature

[reaction: see text] Pd(PhCN)(2)Cl(2)/P(t-Bu)(3) serves as an efficient and a versatile catalyst for room-temperature Sonogashira reactions of aryl bromides.     

Infinite Three-Dimensional Coordination Polymers: Synthesis and Structures of [Cd (4,4'-bpy)2 (H2O)2]n (pic)2n, [Zn (4,4'-bpy)2 (H2O)2 ]n-(pic)2n (H2O)2n, and [Zn (4,4'-bpy)2 (H2O)2]n (4,4'-bpy)n (H2O)n (pic)2n

Recently, a new research realm in crystal engineering of supramolecular architecturesassembled by means of coordinate covalent bonding', hydrogen bonding', or other weakintermolecular interactions= has been rapidly expanding in order to rationally developnew classes of functional materials with cavities or pores. These types of compoundsmay exhibit interesting topological structures and the clathrations of the cavity structuresmay have many potential properties such as catalysis', electrical co…