Concerted Asynchronous Hula‐Twist Photoisomerization in the S65T/H148D Mutant of Green Fluorescent Protein

Fluorescence emission of wild‐type green fluorescent protein (GFP) is lost in the S65T mutant, but partly recovered in the S65T/H148D double mutant. These experimental findings are rationalized by a combined quantum mechanics/molecular mechanics (QM/MM) study at the QM(CASPT2//CASSCF)/AMBER level. A barrierless excited‐state proton transfer, which is exclusively driven by the Asp148 residue introduced in the double mutant, is responsible for the ultrafast formation of the anionic fluorescent state, which can be deactivated through a concerted asynchronous hula‐twist photoisomerization. This causes the lower fluorescence quantum yield in S65T/H148D compared to wild‐type GFP. Hydrogen out‐of‐plane motion plays an important role in the deactivation of the S65T/H148D fluorescent state.     

Transfer of Aryl Halide to Alkyl Halide: Reductive Elimination of Alkylhalide from Alkylpalladium Halides Containing syn‐β‐Hydrogen Atoms

β‐Hydride abstraction is a well‐accepted elementary step for catalytic cycles in organometallic chemistry. It is usually anticipated that alkylpalladium halides containing syn‐β‐hydrogen atoms will undergo β‐hydride abstraction to afford the Heck‐type products. However, this study discloses that the above general knowledge is only conditionally correct. Our experimental results demonstrate that the reductive elimination of alkylhalides from alkylpalladium halides containing syn‐β‐hydrogen atoms may surpass the β‐hydride abstraction or even become exclusive in certain cases.     

Neo‐Fused Hexaphyrin: A Molecular Puzzle Containing an N‐Linked Pentaphyrin

The first neo‐confused hexaphyrin(1.1.1.1.1.0) was synthesized by oxidative ring closure of a hexapyrrane bearing two terminal “confused” pyrroles. The new compound displays a folded conformation with a short interpyrrolic C???N distance of 3.102 Å, and thus it readily underwent ring fusion to afford a neo‐fused hexaphyrin with an unprecedented 5,5,5,7‐tetracyclic ring structure. Furthermore, coordination of Cu^II triggered a ring opening/contracting reaction to afford a Cu^II complex of an N‐linked pentaphyrin derivative. The roles of reactive N? C bonds in the porphyrinoid macrocycles were demonstrated.     

Effect of temperature on the morphologies and electrochemical properties of polyaniline-gold fibrillar nanocomposites

The polyaniline-gold (PANI-AuNPs) fibrillar nanocomposites were prepared via a simple one-pot synthesis route in ethylene glycol (EG) medium. The morphology of PANI-AuNPs was characterized by transmission electron microscopy (TEM), and their electrochemical properties were studied by CV, TAF and EIS measurement using an electrochemical workstation. The results show that the morphology of nanocomposites can be controlled by changing the temperature. The diameter of PANI-AuNPs composite nanofiber reduce from about 80 to 30 nm, and the size of AuNP also reduce from about 20 to 4 nm, with the rise of synthesized temperature. When the synthesized temperature is 10°C, the distribution of AuNPs is the best, and the amount of AuNPs dispersed in PANI is the most, as well as the electrochemical performance of PANI-AuNPs is the most excellent.     

气相色谱法测定不同水质中的二氯乙酸和三氯乙酸

采用气相色谱法测定水中二氯乙酸和三氯乙酸的含量。并且检测了地表水、海水、污水处理厂进口和化工废水等不同水质实际样品。水样中加入氯化钠,经硫酸酸化,甲基叔丁基醚萃取后,以硫酸-甲醇(20+80)溶液作为衍生试剂,衍生温度为50℃时,气相色谱-电子捕获检测器测定。在优化分离条件下,分流比为5比1,二氯乙酸和三氯乙酸具有良好的分离效果。二氯乙酸、三氯乙酸的检出限分别为0.21,0.14μg·L-1,加标回收率在97.4%~105%之间,测定值的相对标准偏差(n=6)小于6%。     

多组分烟用香精定量分析方法的研究进展

综述了近年来烟用香精、香料各组分化合物的定量分析方法的研究进展。面积归一化法、内标法、外标法和标准加入法等常用色谱定量分析方法主要用于烟用香精、香料中目标化合物或单个组分的测定;多标定量法、特征峰-内标定量法和多元校正法能深入剖析烟用香精复杂体系中各组分含量(引用文献48篇)。     

以3-硝基邻苯二甲酸根构建的环状双核Zn(Ⅱ),Cd(Ⅱ)配合物的合成及晶体结构(英文)

以3-硝基邻苯二甲酸和咪唑及2,2′-联吡啶为配体构筑了2种配合物[Zn2(npa)2(Im)4](1)和[Cd2(npa)2(2,2′-bipy)2(H2O)2]·2H2O(2)(npa2-=3-硝基邻苯二甲酸根,Im=咪唑,2,2′-bipy=2,2′-联吡啶)。用元素分析、红外光谱对其进行了表征,并用单晶X-射线衍射测定了配合物的晶体结构;测定了配合物1和2的热稳定性。2个配合物均为双核分子,具有M2C8O4十四元大环结构。配合物1的双核单元通过分子间氢键形成3D网络结构,配合物2的双核单元通过分子间氢键和π-π堆积形成2D层状结构。     

Turn-on fluorescence sensing of cyanide ions in aqueous solution简

A sensitive fluorescent probe, 2,2＇-bisbenzimidazole （L）, for CN has been developed. This structurally simple receptor displays great selectivity for the cyanide anion over other common inorganic anions in an aqueous environment. In addition, further study demonstrates the lower detection of the fluorescence response of the sensor to CN is in 10 9 mol/L range. Thus, the present probe should be applicable as a practical system for the monitoring of cyanide concentrations in aqueous samples.     

全印刷工艺制备聚合物OLED显示屏

详细探讨采用全印刷工艺,制备聚合物OLED显示屏的工艺流程和技术难点的克服。通过喷墨打印纳米银电子墨水制备金属阴极,完全避免了高温及真空工艺的使用。在显示屏制备过程中,我们成功研发由水/醇溶性共轭聚合物聚[9,9-二辛基芴-9,9-双(N,N-二甲基胺丙基)芴],与一种可固化的环氧树脂粘合剂共混形成的多功能缓冲层。此多功能缓冲层,一方面保护有机功能层,避免纳米阴电子墨水的侵蚀,另一方面提供必需的电子注入功能,使高功函银阴极可以有效地注入电子。通过研究表面能优化打印阴极的成型形貌,并克服工艺难点,所制得的96×3×64分辨率的单色和全彩色聚合物OLED显示屏无坏点/坏线,红、绿、蓝电流效率分别为0.62、4.38、0.93cd/A,色坐标分别为(0.63,0.37)、(0.39,0.57)、(0.18,0.16)。