Structure-direct assembly of hexagonal pencil-like ZnO group whiskers

Hexagonal ZnO group whiskers synthesized from Zn(NH₃)₄²⁺ precursor at 145°C in a structure-directing template solvent (2.5% v/v alcohol) show strong photoluminescence at 409 and 420 nm. FE-SEM and TEM observation reveals that the ZnO group whiskers consist of uniform pencil-like whiskers with the diameter of around 1.5 μm and the length of up to 6 μm.     

手性高效液相色谱法测定1—（6‘—甲氧基萘）乙醇不对称氢酯基化反应

在自制的硅基纤维素－三（３，５－二甲基苯基氨基甲酸酯）高效液相色谱手性固定相上（ＨＰＬＣ－ＣＳＰ），优化了１－（６＇－甲氧基萘）乙醇氢酯基化反应产物－萘普生甲酯手性分离的条件，测定了相应的一系列不对称氢酯基化反应产物的对映体过剩值（ｅ．ｅ．值）。结果表明，在ＣＤＭＰＣ－ＣＳＰ手性柱上用ＨＰＬＣ测定此类不对称催化反应的光学产率，评价催化剂体系的手性选择是一种非常理想的方法。     

主链含硅聚芳酯的合成及气体透过性能的研究

以双［对－酰氯苯基］二甲基硅烷和酚酞、四溴酚酞以及双酚Ａ为原料，合成了三种主链含硅聚芳酯，并对聚合物相关的物理性质进行了表征，制成了均质透明的薄膜．采用低真空法测定这些聚合物对Ｈ２、Ｏ２、Ｎ２、ＣＯ２、ＣＨ４的气体透过速率，并计算出气体透过系数、扩散系数、溶解系数、分离系数．从气体透过性能与聚合物分子结构关系的角度，按照气体透过的溶解－扩散机制，对聚合物的气体透过性能进行了研究，而且着重讨论了聚合物的堆积密度对气体扩散系数的影响，以及聚合物主链中极性链段的百分含量对气体溶解系数和溶解选择性的影响。     

BaCe1—xRExO3—0.5x的溶胶—凝胶法合成及离子导电性

用溶胶－凝胶法合成了系列钙钛矿结构的ＢａＣｅ１－ｘＲＥｘＯ３－０．５ｘ（ＲＥ＝Ｌａ，Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｄｙ，Ｈｏ，Ｅｒ和Ｙ）复合氧化物，通过ＸＲＤ和热分析对样品结构及生成过程进行了研究．测定了不同温度下样品的交流阻抗谱，讨论了稀土离子掺杂对ＢａＣｅＯ３电性质的影响．溶胶－凝胶法比固相反应法合成温度降低了６００～８００℃，稀土掺杂使ＢａＣｅＯ３离子导电率提高了１０～４０倍．     

Cover Picture: A Stepwise Annulation for the Transformation of Cyclic Ketones to Fused 6 and 7‐Membered Cyclic Enimines and Enones (Chin. J. Chem. 4/2019)

The cover picture shows a typical building within the Campus of Xiamen University displaying Chen Jiageng (Tan Kah Kee)'s style. Just like many beautiful buildings designed and constructed by human, Nature “designs and constructs” a huge number of useful molecules with fascinating structures called natural products. Many natural products possess a fused six or seven‐membered carbocyclic unity. On page 315–322, the Huang's group disclosed a three‐step “[2+n]” annulation method for the construction of fused six and seven‐membered carbocyclic enimines and enones. The method starts from simple cyclic ketones and terminal olefinic amides, and relies on both the Suzuki coupling reaction and the olefin‐amide based Friedel‐Crafts type acylating reaction, a method developed by Huang and coworkers.

     

Maximum spectrum of continuous wavelet transform and its application in resolving an overlapped signal

To estimate the number of peaks and to find the individual peak positions in an overlapped signal, a new method called maximum spectrum of continuous wavelet transform (MSCWT) was developed by extracting the maximum coefficients of continuous wavelet transform (CWT). The peak position in MSCWT was the same as that in its original signal. In this process, CWT was performed not on a single dilation but on an appreciation dilation range. To obtain such a range, a new criterion was introduced to choose a center dilation, which was used to form the dilation range. If Cdilation denoted the center dilation, the proper dilation range was [Cdilation -6 +/- 2, Cdilation +1 +/- 1]. The Mexican Hat function was an analytical wavelet. Utilizing the information of the peak number and the position detected by MSCWT, a fitting route was performed to recover the original signal. One simulated and four true overlapped signals, including high performance liquid chromatography (HPLC), ultraviolet-visible (UV) spectrum, and differential pulse voltammetric (DPV), were processed, and the results indicated that MSCWT could detect an overlapped peak number and position, and the curve fitting based on information of MSCWT had a higher accuracy. The proposed method was an efficient one in resolving different types of overlapped signals.     

高效离子排斥色谱法测定饮料中的糖精钠

提出了一种用高效离子排斥色谱法测定饮料中糖精钠的新方法。以ＩｏｎＰａｃ ＩＣＥ－ＡＳ ６柱为分离柱，０．１０ ｍｍｏｌ／ＬＨ２ＳＯ４＋甲醇（９＋１）为淋洗液，２０２ｎｍ波长下紫外检测。在１－１００ｍｇ／Ｌ范围内，糖精钠的含量与峰面积呈 良好线性关系。检出限为０．６０ｎｇ，灵敏度优于以往采用离子交换色谱－电导检测法的结果。在实验条件下，饮料 中常见有机酸以及其它人工合成甜味剂等均不产生干扰。方法用于饮料中糖精钠的测定，加标回收率为９８％～ １０５％。此外还比较了电导检测、紫外检测和经化学抑制系统后紫外检测等三种检测方式对测定灵敏度的影响。     

Inorganic electrides

Inorganic electrides are a novel kind of ionic compounds in which the anions are electrons confined in a complex array of cavities or channels and the cations are nanoscale arrays of alkali metal ions that provide charge balance. In electrides the donated electron behaves like a low-density correlated electron gas, whereby the dimensionality of the electron gas and its electronic and magnetic properties are determined by the topology of the cavities in the host matrix. Unlike traditional electrides, in which alkali cations are encapsulated within an organic cage, inorganic electrides are thermally stable. The current inorganic electrides based on alkali metal loaded zeolites can be designed as useful reduced-dimensionality materials. Inorganic electrides are powerful reducing agents, and they are able to reduce small aromatic molecules to the radical anions within the channels of the zeolite.     

非晶SiO2纳米灯笼的制备和表征

在1000 ℃用活性炭把二氧化锡粉末还原成单质锡, 锡作为催化剂, 硅片作为硅源同时作为收集衬底, 在硅片上制备出了非晶SiO2纳米灯笼. 灯笼的一端连在硅片上, 另一端为一个锡球, 中间是一些圆弧状的SiO2纳米线把两端相连. 纳米灯笼具有良好的对称性. 利用扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、选区电子衍射(SAED) 和HRTEM自带的能谱分析仪(EDS)对样品的表面形貌、微观结构和成分进行了分析研究. 结果表明, 灯笼中SiO2纳米线为非晶态, 结点是晶态锡, 结点表面覆盖一层非晶态的硅的氧化物. 结合实验条件对纳米灯笼的生长机理进行了讨论, 提出了纳米灯笼生长的一个模型.