Preparation of Unconventional Dendrimers that Contain Rigid NH?Triazine Linkages and Peripheral tert‐Butyl Moieties for CO2‐Selective Adsorption

Three unconventional dendrimers that contained rigid NH? triazine linkages and peripheral tert‐butyl moieties were prepared by using a convergent approach and characterized by ¹H and ¹³C NMR spectroscopy, mass spectrometry, and elemental analysis. Based on a thermogravimetric analysis study, these dendrimers were observed to display thermal stability at about 300 °C. The NH? triazine moiety, which possessed protonated and proton‐free nitrogen sites (like the imidazole unit), displayed the capture of polarizable CO₂ molecules through hydrogen‐bond and/or dipole–quadrupole interactions. In addition, the adsorption of various amounts of CO₂ and N₂ at different pressures suggests that the dendritic pores, which arise from the stacking of the middle co‐planar and rim protuberant dendrimers, G _n ‐N～N‐G _n (n=1–3), either swell or shrink at high pressure, thus indicating that these dendrimers may have a breathing ability.     

Facile Self‐Assembly Synthesis of PdPt Bimetallic Nanotubes with Good Performance for Ethanol Oxidation in an Alkaline Medium

PdPt bimetallic nanotubes were prepared by the self‐assembly of Pt and Pd on Te nanowires at room temperature. The morphologies of the as‐prepared PdPt nanotubes were investigated by scanning electron microscopy and transmission electron microscopy, and the results display a large amount of PdPt bimetallic nanotubes with a diameter of 10–20 nm and a length of several micrometers. The composition and structure of the nanotubes were characterized by X‐ray diffraction, high‐resolution transmission electron microscopy, scanning transmission electron microscopy, and energy spectrum analysis, and the results display uniform compositional distributions of both elements (Pd and Pt). The mechanism of the formation of the nanotube structure was supposed. The electrocatalytic performance of PdPt nanotubes were studied by cyclic voltammetry and chronoamperometry. Electrochemical results show that the as‐prepared PdPt nanotube catalysts have not only high activity but also good stability for ethanol oxidation in alkaline medium.     

Aluminum fluoride-18-labelled indocyanine green as a potential PET imaging agent for hepatic function reserve

Journal of Radioanalytical and Nuclear Chemistry - This study evaluated the potential of Al18F-labelled restrained complexing agent (RESCA)-ICG to assess hepatic function reserve on PET/CT imaging....     

过渡金属催化的1,2,3-三氮唑导向的C—H键官能团化反应研究进展

1,2,3-三氮唑化合物是一类具有重要生理活性的含氮杂环化合物, 其在医药、农药、材料科学等领域都具有广泛的应用. 不断开发基于三氮唑骨架的新型结构, 寻找新型高效的合成三氮唑衍生物的方法具有重要的意义和应用价值. 过渡金属催化的C—H键活化策略具有操作简便、效率高、三废少等优点, 是现代有机合成中高效构筑C—C键和C—X键的强大工具. 近年来, 过渡金属催化的三氮唑导向的C—H官能团化反应受到科学工作者的广泛关注, 该方法以不同结构的1,2,3-三氮唑作为导向基团, 在不同反应条件下通过直接活化C—H键来构建新的C—C键和C—X键, 高效合成复杂的三氮唑衍生物. 综述了近年来1,2,3-三氮唑导向下过渡金属催化的C—H键官能团化反应研究进展, 按照成键类型(碳-碳键、碳-杂键以及环化反应)对这些反应进行了梳理和总结, 并对今后该领域的发展进行了展望.     

Effect of Aluminum Alloy Surface Modification on Adhesion of the Modified Polyurethane Coating and Its Corrosion Protective Performance北大核心CSCD

The ordinary organic coatings on aluminum alloy usually encounter a problem of low adhesion to the substrate, which results in destruction and failure of the long-term protective performance of the anticorrosion systems. The surface modification of aluminum alloy is able to enhance the adhesion of organic coating on aluminum alloys, and to improve their protective performance. In this work, a combined surface modification of anodic oxidation and mussel adhesion protein/CeO2/3-aminopropyltriethoxysilane composite film (MCA) was developed on the aluminum alloy. The adhesion of modified polyurethane coated on the treated aluminum alloy and its corrosion protective performance were evaluated comprehensively by using contact angle, adhesion strength, electrochemical impedance spectroscopy (EIS), and scanning reference electrode technique (SRET). The measurements of EIS and SRET demonstrated that the MCA composite film on anodic oxidized Al possessed self-healing function and provided effective protection against early corrosion of aluminum alloy. The pull-off test showed that both anodic oxidation treatment and MCA composite film modification were able to increase the adhesion of modified polyurethane coating on aluminum alloy, and their combined action were supposed to remarkably enhance the adhesion strength up to 17.1 MPa. The reason for the improvement of adhesion was that the anodic oxidation treatment and MCA composite film modification could improve the surface roughness of aluminum alloy, and enhance the surface wettability and surface polarity, which is beneficent to enhance the bonding of the modified polyurethane coating to aluminum alloy surface. The EIS results showed that no any corrosion occurred for the modified polyurethane coating on the treated aluminum alloy during 65 d immersion in 3.5wt.% NaCl solution. The impedance value in low frequency range of the modified polyurethane coating always maintained at a high order of magnitude on the aluminum alloy treated by anodic oxidation and MCA composite film modification, showing an excellent protective performance of the coating system. The evaluation of Neutral Salt Spray (NSS) indicated that the modified polyurethane coating on the treated aluminum alloy owned superior corrosion protection performance, and the adhesion strength remained 13.1 MPa and no any corrosion was found at the scratch locations even after 1200 h of salt spray testing. It was concluded that combination of anodic oxidation and MCA composite film were capable of significantly improving the adhesion of modified polyurethane coating on aluminum alloy and providing long-term effective corrosion protection for aluminum alloy. © 2021 Authors. All rights reserved.     

Supramolecular Engineering Strategy to Construct BODIPY-Based White Light Emission Materials

Two kinds of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyads BDP-OH containing 4-hydroxystyrene groups and BDP-PY bearing pyridinyl units were prepared. In addition, a naphthalene derivative NAP-PY modified by pyridinyl moieties substituent was made. The above three dyads could be used to construct white-light emission (WLE) material by a supramolecular engineering strategy due to their three primary colors of blue, green and red. The supramolecular correlations between the hydroxyl group of BDP-OH and the pyridinyl groups of NAP-PY and BDP-PY were confirmed by ¹H NMR titration, 2D NOESY and FTIR. A fluorescence monitor application was carried out based on the realization of WLE. This work might be useful for designing other WLE supramolecular systems and image display.     

Growth and optical properties of Pr<Superscript>3+</Superscript>:KLu(WO<Subscript>4</Subscript>)<Subscript>2</Subscript> laser crystal: a candidate for red emission laser

A Pr³⁺:KLu(WO₄)₂ crystal with dimension of 30 × 30 × 15 mm³ was grown in the K₂W₂O₇ flux. A slice was cut from the crystal, and the polarized absorption and fluorescence spectra were measured at room temperature. Based on the J-O theory, the oscillator intensity parameters Ω _t (t = 2, 4, 6), spontaneous emission probabilities and branch ratios were estimated and good results had been obtained. Furthermore, the crystal has a relatively large emission cross-section in the region of 615–630 nm with the highest value of 14.5 × 10^?20 cm², which indicates that the crystal is good for the application in red emission laser. The emission decay time for ¹D₂ and ³P₀ multiplets was discussed. By adapting the I-H model to fit the emission decay curves, the lifetime for ¹D₂ at 607 nm and ³P₀ at 615 nm are 19.72 μs and 8.95 μs, respectively. Then the corresponding fluorescence quantum efficiencies of the two multiplets reach 83.7 % and 87.9 %, respectively. All the studies illustrate that this crystal is potential in red emission laser application.     

溶胶-凝胶法制备Pb(Zr1?xTix)O3复合梯度薄摸以及介电与热释电特性

"在Pt/Ti/SiO2/Si基片上用溶胶-凝胶法生长制备了PZT(Pb(Zr1-xTix)O3)复合梯度铁电薄膜． 薄膜最终结构由6层组成,"向上"梯度薄膜在Pt底电极上的第一层从PbZrO3开始,顶层是PZT(50/50),即第一层是PbZrO3,第二层PZT90/10 (10%Ti),第三层是PZT80/20,第四层PZT70/30,第五层PZT60/40,第六层PZT50/50．每一层与此相反的是"向下"梯度PZT薄膜．用X射线衍射、俄歇电子能谱和阻抗分析来研究梯度薄膜的结构与介电特性．600     

铜修饰微电极阵列硝酸根检测（英文）

许多水域含有过量的硝酸根,会诱发许多问题。采用微机电系统工艺,制备出一种基于铂叉指微电极阵列的硝酸根离子(NO-3)检测微传感电极。通过电化学恒电位沉积法在铂叉指微电极阵列上修饰,得到多孔、簇状铜敏感膜。采用线性扫描伏安电化学检测方法,考察该微传感电极对NO-3的响应性能,在0~2mg/L浓度范围内,线性度为0.999,灵敏度为-3.15μA·L·mg-1。在相同沉积修饰条件下,叉指微电极比同等敏感面积(1mm2)的圆盘微电极表现出更强的催化活性和更高的灵敏度,分析其原因,认为主要是叉指微电极的结构和边缘效应造成的。     

AgI Microplate Monocrystals with Polar {0001} Facets: Spontaneous Photocarrier Separation and Enhanced Photocatalytic Activity

Elucidating the facet‐dependent photocatalytic activity of semiconductor photocatalysts is important in improving the overall efficiency of photocatalysis. Furthermore, combining facet control with selective deposition of oxidation and/or reduction cocatalysts on specific faces of semiconductor photocatalysts is potentially an effective strategy to synergistically optimize the functionality of photocatalysts. In the present study, high‐purity wurtzite‐type β‐AgI platelet microcrystals with polar {0001} facets were prepared by a facile polyvinylpyrrolidone‐assisted precipitation reaction. The polar‐faceted AgI microplates were used as archetypes to demonstrate preferential diametric migration (i.e., effective separation) of photogenerated electrons and holes along the c axis. Such vectorial electron–hole separation stems from the asymmetric surface structures, which give rise to distinct photoexcited reaction behaviors on the ±(0001) polar facets of wurtzite‐type semiconductors. Furthermore, on selective deposition of Ag and MnO_x (1.5<x<2) cocatalysts on the reductive (0001) and oxidative (000$\bar 1$ ) facets, respectively, photocatalytic activity of the AgI microplates in degrading organic pollutants was dramatically enhanced thanks to the broad light‐absorption range, strong dye‐adsorption ability, and effective spatial separation of photocarriers.