Reversible Switching CuII/CuI Single Sites Catalyze High-rate and Selective CO2 Photoreduction

Herein, we first design a model of reversible redox-switching metal–organic framework single-unit-cell sheets, where the abundant metal single sites benefit for highly selective CO₂ reduction, while the reversible redox-switching metal sites can effectively activate CO₂ molecules. Taking the synthetic Cu-MOF single-unit-cell sheets as an example, synchrotron-radiation quasi in situ X-ray photoelectron spectra unravel the reversible switching Cu^II/Cu^I single sites initially accept photoexcited electrons and then donate them to CO₂ molecules, which favors the rate-liming activation into CO₂^δ−, verified by in situ FTIR spectra and Gibbs free energy calculations. As an outcome, Cu-MOF single-unit-cell sheets achieve near 100 % selectivity for CO₂ photoreduction to CO with a high rate of 860 μmol g⁻¹ h⁻¹ without any sacrifice reagent or photosensitizer, where both the activity and selectivity outperform previously reported photocatalysts evaluated under similar conditions.     

超分子作用构筑具有高光学不对称性的表面等离子纳米粒子手性组装体

《Science》杂志最近刊发了吉林大学刘堃团队关于手性纳米材料研究的重要进展: 通过超分子作用诱导金纳米棒与人胰岛淀粉样多肽之间共组装, 构筑具有类似于手性液晶结构的纳米螺旋超结构. 与单独的金纳米棒相比, 长程有序的纳米螺旋结构的手性各向异性因子(g-factor)提高了4600倍, 高达0.12. 该工作在液晶与手性无机纳米结构间建立了联系, 为构筑有机-无机光学活性结构提供了统一的设计原则, 并为淀粉样类疾病药物在复杂生物介质中的筛选开发了新方法.     

Two Coordination Polymers based on 2‐Ethyl‐1H‐imidazole‐4,5‐dicarboxylic Acid and 1,3‐Bis(4‐pyridyl)propane: Synthesis,Crystal Structures,and Photoluminescent Properties

Two coordination polymers, [Cd(Heidc)(bpp)]_n ( 1 ) and [Zn₃ (eidc)₂(bpp)(H₂O)₂] · 2H₂O}_n ( 2 ) (H₃eidc = 2‐ethyl‐4,5‐imidazole dicarboxylic acid, bpp = 1,3‐bis(4‐pyridyl)propane) were hydrothermally synthesized and characterized by elemental analysis, IR, spectroscopy single‐crystal X‐ray diffraction, and thermogravimetric analyses. Compound 1 features a 2D layer formed by C–H ··· π stacking interactions between adjacent chains, whereas compound 2 shows a 3D (8³)₂(8⁵.10)‐tfc framework constructed of the 2D (6,3) layer. The result demonstrates that the central metal atoms play a key role in governing the coordination motifs. Moreover, solid‐state properties such as thermal stabilities and photoluminescence of 1 and 2 were also investigated.     

阴离子型聚丙烯酰胺与阳离子表面活性剂的相互作用

采用自由基水溶液共聚法制备了带有负电荷的水溶性聚丙烯酰胺,研究了水溶液中聚合物与阳离子表面活性剂的相互作用及所导致的水溶性、黏度和流变学性质的变化,为进一步研究驱油提供了理论基础.     

羧基亚胺配体的合成及其促进Suzuki偶联反应的研究

合成了4种羧基亚胺配体并将其用于促进Suzuki偶联反应。通过考察配体结构、溶剂极性、碱强度和温度等因素对反应产率的影响,确定了羧基亚胺配体参与的钯催化Suzuki偶联反应的最佳条件为:催化剂的量为0.001(mol)%的Pd Cl2和0.002(mol)%的配体,以碳酸钾作碱,4m L乙醇水溶液(1∶1,体积比)作溶剂,反应温度为60℃,在空气条件下反应。结果表明,羧基亚胺配体能够有效促进Suzuki偶联反应;在合成的配体L1~L4中,具有适当的位阻和给电子基团的L2的催化活性最高,能够高效催化合成一系列联芳类化合物。     

Frame‐Guided Assembly of Amphiphiles

Frame‐guided assembly, a recently discovered strategy for amphiphilic assembly, is discussed as a strategy for constructing vesicle assemblies with programmed geometries and dimensions under identical surrounding conditions. The strategy is inspired by the cytoskeletal‐membrane protein–lipid bilayer structure and shows great potential in the understanding and controlling of the amphiphilic assembly process. Both the principles and basic requirements are discussed, along with recently reported examples. The prospects and potential investigations of frame‐guided assembly are also proposed.     

An Indoxyl‐Based Strategy for the Synthesis of Indolines and Indolenines

An indoxyl‐based strategy for the synthesis of indolines and indolenines via unprecedented aza‐pinacol and aza‐semipinacol rearrangements was developed. This method provides direct access to the core structures of several classes of indole alkaloids. The synthetic utility was demonstrated by the divergent synthesis of an array of functionalized polycyclic structures from a common intermediate and the formal total synthesis of the indoline natural product minfiensine. The reversed reactivity of indoxyl as a building block compared to that of indole offers a conceptually distinct disconnection strategy for indoline‐ and indolenine‐containing heterocycles and natural products.     

有限元分析中硬化弹塑性本构方程积分算法

基于增量段上的应变关于塑性拉氏乘子的变化率为常矢量的假定,导出一种精确有效的、对有限元分析中线性混合硬化弹塑性本构方程的积分算法。以精确算例和等误差分布图的形式检验了本文方法以及其他两种常用方法的精度。     

智能结构中光纤智能夹层力学特性的实验研究

根据光纤自诊断系统模块化、集成化要求,制作出光纤智能夹层,它可以铺设于复合材料结构表面或埋入复合材料结构内部。对智能夹层试件的轴向拉伸试验和层间拉伸试验表明,光纤智能夹层的埋入对复合材料结构的强度性能无显著影响,可以埋入复合材料结构内部并实施健康监测。试验还表明,在一定应变范围内,单膜交错光纤中光强—应变之间具有良好的线性关系,可以在埋入复合材料之前进行标定。     

Nanospherical Surface‐Supported Seeded Growth of Au Nanowires: Investigation on a New Growth Mechanism and High‐Performance Hydrogen Peroxide Sensors

In this paper, a novel strategy with a new growth mechanism for fast and large‐scale growth of Au long nanowires on high‐curvature SiO₂ nanospherical surfaces has been developed. The synthesis includes three steps, i.e., amino modification of SiO₂ nanospheres, Au seed loading on aminated SiO₂ nanospheres and subsequently, Au seed‐mediated nanowire growth on SiO₂ nanospheres. The prepared Au nanowires (Au NWs) (exhibit long length, high aspect ratio, and good flexibility, and can naturally form the dense nanowire film, which is promising as a stable conductive electrode. In addition, the effect of synthetic conditions such as reactant feeding order, Au seeds and SiO₂@Au seeds on the morphology of Au nanostructures (nanowires, nanoteeth, and nanoflowers) has been investigated. It is found that Au seeds and high‐curvature SiO₂ nanospherical surfaces are necessary conditions for the successful preparation of Au NWs and nanowire films. The different growth mechanisms for Au NWs and nanoteeth have been proposed and discussed. Moreover, the novel nonenzymatic H₂O₂ sensor based on Au NWs exhibits much enhanced performance such as higher sensitivity, stability, and selectivity, wider linear range and lower detection limit, compared with that of Au nanoparticles‐based H₂O₂ sensor.