Simultaneous construction of a polyether backbone and a variety of keto side chains by three‐component polycondensation: An improved method for the use of a variety of silyl enol ethers

For the synthesis of polyethers with a variety of keto side chains in a one‐step reaction, the three‐component polycondensation of dialdehydes, diol disilyl ethers, and silyl enol ethers of ketones was investigated. The method of monomer addition strongly affected the molecular weight of polymers and was optimized to yield high molecular weight polymers by model reactions. A variety of dialdehydes, diol disilyl ethers, and silyl enol ethers were polymerized in the presence of a catalytic amount of triphenylmethyl (trityl) perchlorate in CH₂Cl₂ at −78 °C according to the method of monomer addition. This polymer synthesis was unusual in that it concurrently constructed both the polyether backbone and the keto side chains from three starting compounds. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 179–188, 2000     

Structural analysis of Gd6FeBi2 from single‐crystal X‐ray diffraction methods and electronic structure calculations

The crystal structure of the gadolinium iron bismuthide Gd₆FeBi₂ has been characterized by single‐crystal X‐ray diffraction data and analyzed in detail using first‐principles calculations. The structure is isotypic with the Zr₆CoAl₂ structure, which is a variant of the ZrNiAl structure and its binary prototype Fe₂P (Pearson code hP9, Wyckoff sequence g f d a). As such, the structure is best viewed as an array of tricapped trigonal prisms of Gd atoms centered alternately by Fe and Bi. The magnetic‐ordering temperature of this compound (ca 350 K) is much higher than that of other rare‐earth metal‐rich phases with the same or related structures. It is also higher than the ordering temperature of many other Gd‐rich ternary phases, where the magnetic exchange is typically governed by Ruderman–Kittel–Kasuya–Yosida (RKKY) interactions. First‐principles calculations reveal a larger than expected Gd magnetic moment, with the additional contribution arising from the Gd 5d electrons. The electronic structure analysis suggests strong Gd 5d–Fe 3d hybridization to be the cause of this effect, rather than weak interactions between Gd and Bi. These details are of importance for understanding the magnetic response and explaining the high ordering temperature in this material.     

利用钆配合物调节激基复合物发光颜色的一种有机发光二极管

报道一种可用钆配合物[Gd（DBM）3bath]调节电致发光（EL）颜色的有机发光二极管（OLED）。该有机发光二极管是在空穴传输层（m-MTDATA）和电子传输层（TPBI）之间插入-薄层Gd（DBM）3bath。随着Cd（DBM）3bath厚度增加,二极管的发光颜色呈现出绿色（主峰525nm）-黄色-橙色（主峰593rim）变化。该二极管的电致发光主要来自界面激基复合物的发射而不是来自各有机功能层;而发光颜色的变化是由于两种激基复合物发射的相对强度的改变。     

Tuning Glutamine Binding Modes in Gd‐DOTA‐Based Probes for an Improved MRI Visualization of Tumor Cells

Three new magnetic resonance imaging probes that target glutamine transporters have been synthesized. They consist of a Gd‐DOTA‐monoamide moiety (DOTA=1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid) linked through a six carbon atom chain to a vector represented by a glutamine residue bound through α‐carboxylic, γ‐carboxamidic, or α‐amino functionalities. Their uptake by HTC (rat hepatocarcinoma) and healthy rat hepatocytes has shown that the system containing the glutamine vector bound through the α‐carboxylic group displays a markedly higher affinity for tumor cells. The observed behavior is rationalized in terms of the exploitation of an additional glutamine transporter active in hepatic tumor cells.     

Ionic Liquid‐Based Routes to Conversion or Reuse of Recycled Ammonium Perchlorate

New, potentially green, and efficient synthetic routes for the remediation and/or re‐use of perchlorate‐based energetic materials have been developed. Four simple organic imidazolium‐ and phosphonium‐based perchlorate salts/ionic liquids have been synthesized by simple, inexpensive, and nonhazardous methods, using ammonium perchlorate as the perchlorate source. By appropriate choice of the cation, perchlorate can be incorporated into an ionic liquid which serves as its own electrolyte for the electrochemical reduction of the perchlorate anion, allowing for the regeneration of the chloride‐based parent ionic liquid. The electrochemical degradation of the hazardous perchlorate ion and its conversion to harmless chloride during electrolysis was studied using IR and ³⁵Cl NMR spectroscopies.     

Calix[4]arenes as Molecular Platforms for Magnetic Resonance Imaging (MRI) Contrast Agents

The novel amphipilic conjugate of a calix[4]arene with four Gd–1,4,7,10‐ tetra(carboxymethyl)‐1,4,7,10‐tetraazacyclododecane (DOTA) chelates has potential as a magnetic resonance imaging contrast agent, both in its monomeric and in its micellar form. The system, illustrated here with its nuclear magnetic relaxation profile, shows good relaxivities, thanks to its high rigidity.

     

钐钆共掺杂荧光配合物的合成及在潜手印显现中的应用

以2-噻吩甲酰三氟丙酮(TTA)为第一配体,邻菲罗啉(o-Phen)为第二配体,利用共沉淀法合成一系列钐钆共掺杂荧光配合物,并优化了该系列荧光配合物的合成条件(反应温度、体系pH、稀土离子相对含量).将最优条件合成的Sm0.5 Gd0.5 TTA3(o-Phen)荧光配合物粉末用于常见光滑非渗透性客体表面潜在手印的显现...     

多孔纳米CoFe2O4的制备及其对高氯酸铵的热分解催化性能

采用胶晶模板法制备出具有三维多孔结构的纳米CoFe₂O₄。利用X射线衍射仪(XRD)、傅里叶变换红外(FT-IR)光谱仪、扫描电镜(SEM)、透射电镜(TEM)和N₂吸附-脱附对样品的晶型和形貌结构等进行表征,采用差示扫描量热法(DSC)对比研究多孔纳米CoFe₂O₄和球形纳米CoFe₂O₄对高氯酸铵(AP)的热分解性能的影响,并考察这两种催化剂对AP催化热分解的动力学参数。结果显示,制备出的多孔纳米CoFe₂O₄样品具有典型的尖晶石结构,孔径约200 nm;比表面积明显高于40 nm球形CoFe₂O₄,达到55.646 m²·g^-1。DSC测试结果表明：多孔纳米CoFe₂O₄的加入促进了AP的热分解,最高使AP的高温分解峰温降低91.46℃,能量释放最高达1120.88 J·g^-1,是纯AP分解放热量的2.3倍;多孔纳米CoFe₂O₄具有较高的比表面积,能提高催化反应的接触面积,使AP的高温分解峰温度更低,反应活化能较小,从而表现出比球形纳米CoFe₂O₄更高的催化活性。此外,对多孔纳米CoFe₂O₄催化AP的热分解机理进行初步探索,纳米多孔催化剂对气态中间产物的作用促进了AP的热分解。     

离子色谱法测定葡萄酒中的高氯酸盐

建立了离子色谱测定红酒中高氯酸盐的分析方法。以4种葡萄酒为典型样品,测定了其中的高氯酸盐含量。使用Metrosep A Supp5阴离子分析柱（150 mm×4.0 mm）进行分离,柱温为40℃,流动相为1.0 mmol/L碳酸钠水溶液-丙酮（85：15,v/v）,流速为0.8 mL/min。结果表明,高氯酸盐在0.1~10 mg/L内具有良好的线性关系,相关系数为0.9998,方法回收率大于86.0%,相对标准偏差小于2.6%。该方法前处理方便快捷、检测灵敏度高,可满足红酒中高氯酸盐含量的测定。     

光响应负载型脯氨酸的合成及其在水相中催化不对称羟醛缩合反应的应用

应用RAFT聚合法合成了含脯氨酸、香豆素及聚乙二醇的光响应负载型催化剂(P),其结构经¹H NMR和元素分析表征。紫外光谱分析表明：在紫外光照前后, P的结构会发生变化。催化性能测试结果表明：P在紫外光照前后均能实现水相中催化环己酮和4-硝基苯甲醛之间的羟醛缩合反应,收率65%~76%, dr>93/7, ee>95%。