Phytochemical Constituents from Ginkgo biloba Exocarp

Chemistry of Natural Compounds -     

Ag(111)表面Ag配位结构的分等级组装

表面辅助的金属有机纳米结构因其结构稳定性和潜在应用受到广泛关注。在金属有机纳米结构中,金属原子来源于外部沉积的金属或金属表面原子。外部沉积的金属原子种类多样,取决于目标纳米结构。然而,金属表面原子受限于表面科学常用的金、银和铜单晶金属表面。金属有机纳米结构大多包括Au配位或是Cu配位结构,而只有少量的用表面Ag原子构成。分子金属相互作用的进一步研究有助于预期纳米结构的精确控制形成。至于构建基元,有机分子通过M―C、M―N和M―O键与表面金属原子配位。末端炔反应或者乌尔曼耦合能够实现C―M―C节点的形成。Cu和Au原子能够与含有末端氰基或吡啶基官能团的分子配位形成N―M―N键。另外,表面Ag增原子能够通过Ag―N配位键与酞菁分子配位。然而,M―O配位键的相关研究较少。因此,我们计划使用末端羟基分子与Ag增原子配位形成金属有机配位纳米结构去研究O―Ag节点。我们通过扫描隧道显微镜利用4, 4’-二羟基-1, 1’: 3’, 1’’-三联苯分子(4, 4’-dihydroxy-1, 1’: 3’, 1’’-terphenyl,H3PH)和Ag增原子成功构筑了一系列二维有序纳米结构。在室温下,蒸镀的H3PH分子自组装形成由环氢键连接的密堆积结构。当退火温度提升到330 K,一种新的纳米结构出现了,该结构由O―Ag配位键和氢键共同作用形成。进一步地提升退火温度至420 K,蜂巢结构和共存的二重配位链出现,这两种结构中仅由O―Ag―O键构成。为分析金属分子反应路径和O―Ag―O键的能量势垒,我们对该体系进行密度泛函理论计算。计算结果显示,O―Ag键形成的能量势垒是1.41 eV,小于O―Ag―O节点1.85 eV的能量势垒。这也解释了分等级金属-有机纳米结构形成的原因。我们的实验结果提供了一种利用有机小分子和金属增原子来设计和构筑分等级二维纳米结构的有效方法。     

Synthesis and ethylene oligomerization behavior of trinuclear nickel complex with phosphorus dendrimer

Transition Metal Chemistry - A phosphorus dendrimer with multiple amino groups was synthesized via a two-step reaction with phosphonitrilic chloride trimer and 4-acetamidophenol. The trinuclear...     

1-丁基-3-甲基咪唑甲基磺酸盐水溶液中酚型木质素单体溶解的二维相关红外光谱分析北大核心CSCD

当离子液体(IL)水溶液—1-丁基-3-甲基咪唑甲基磺酸盐([C_(4)C_(1)im]CH_(3)SO_(3))的摩尔分数x_(IL)=0.20时,酚型木质素单体模型化合物2,6-二甲氧基苯酚(2,6-DMP)的溶解度最高。这一现象与木质素溶解规律相似。利用二维相关红外光谱(2D-IR)研究2,6-DMP在[C_(4)C_(1)im]CH_(3)SO_(3)水溶液中溶解过程,以帮助深入理解木质素在IL水溶液中溶解机制。以x_(IL)变量的2D-IR分析结果表明,x_(IL)=0.02~0.20条件下IL加入破坏水的弱氢键结构,IL阴阳离子以水合离子对形式存在,疏水性2,6-DMP与[C_(4)C_(1)im]+和CH_(3)SO_(3)−同时发生相互作用,促进2,6-DMP溶解;x_(IL)=0.20~1.0条件下,IL形成致密离子簇结构,不利于2,6-DMP与IL阴阳离子相互作用。以2,6-DMP摩尔分数(x_(DMP))为变量的分析结果表明,加入2,6-DMP对IL结构影响小,而对水的微观结构影响大。对于具有离子对结构的IL水溶液(x_(IL)=0.10),水优先与CH_(3)SO_(3)−作用;对于具有离子簇结构的IL水溶液(x_(IL)=0.60),水优先形成自缔合小水簇结构。IL水溶液微观结构影响IL-水与2,6-DMP之间相互作用和2,6-DMP溶解特性,同时2,6-DMP溶解也导致IL水溶液的微观结构变化。     

Preparation of biomass N-doped carbon dots and detection of tioproninEI北大核心CSCD

Nitrogen-doped carbon dots (N-CDs) were prepared by one-step hydrothermal synthesis with pomegranate seeds as the carbon source and urea as the nitrogen source. Observed by transmission electron microscopy (TEM), average particle size of N-CDs was 20 nm. Observed by atomic force microscopy (AFM), the thickness of N-CDs was 0. 6-1. 4 nm. Fourier transform infra-red (FT-IR) confirmed the presence of water-soluble functional groups such as amino groups on the surface of N-CDs. With the prepared N-CDs as the target fluorophore, Hg2 + can efficiently bind to the surface of N-CDs to form a complex, and achieve static quenching. The addition of tiopronin can bind the Hg2 + in the complex to make the Hg2 + detach from the surface of N-CDs and realize fluorescence recovery. The nano fluorescence switch constructed in this work is more accurate and sensitive than the traditional detection method. The optimum conditions were determined by optimizing the pH value, reaction time, the dosage of N-CDs and Hg2 +. The relative deviation (RSD) was 4. 7%, and the detection limit was 0. 2 μmol/L. The method was used to determine the content of tiopronin in human serum samples with the recoveries of 97. 2%-101. 3%. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

人工智能发现活性分子背景下天然药物化学教学的转型与发展*

人工智能(AI)在活性分子发现及药物筛选方面的应用日趋深入,革新了传统发现天然药物的方式,重构了药物发现及设计的格局。这就要求天然药物化学人才熟练掌握天然药物化学基础知识、具备多学科交叉分析问题能力以及培养和树立与时俱进的逻辑思维。为顺应人工智能时代发展要求,天然药物化学教学需要构建AI参与天然药物发现教学体系、提供AI参与天然药物发现的直观教学、筛选优秀网络教学资源引导学生自主学习,同时培养学生在AI参与天然药物发现中的思考能力。     

泡腾辅助液相微萃取/高效液相色谱法检测蜂蜜中7种喹诺酮类药物

以密度小于水且具有可切换亲水性的壬酸作为萃取剂,通过加入Na2CO3和H2SO4改变溶液pH值,使壬酸完成从疏水性到亲水性再到疏水性的转换,同时利用原位产生的CO2鼓泡加大接触面积,完成对分析物的萃取,建立了基于可切换亲水性溶剂的泡腾辅助液相微萃取（EA－LPME－SHS）/高效液相色谱－荧光检测法（HPLC－FLD）测定蜂蜜中7种喹诺酮类药物（QNs）的分析方法。最佳提取条件如下：萃取剂为200 μL壬酸;pH调节剂为400 μL 2.0 mol/L Na2CO3和300 μL 2.0 mol/L H2SO4;提取时间为1.5 min。结果表明,5种喹诺酮类药物在2.0～200 μg/L范围内呈良好线性（诺氟沙星和环丙沙星为2.0～100 μg/L）,相关系数（r2）为0.999 5～0.999 9;在10、100、500 ng/g加标水平下,7种待测药物的回收率为62.8%～117%,日内（n = 3）和日间（n = 6）相对标准偏差（RSD）不大于6.2%,检出限为3.0 ng/g,定量下限为10 ng/g。该方法的提取过程均在注射器内完成,无需离心即可实现相分离,具有绿色环保、操作简便、省时等特点。     

Multi-functional Photoelectric Sensor Based on a Three-fold Interpenetrated Cd(II) Coordination Polymer for Sensitively Detecting Different Ions

Athree-fold interpenetrated cadmium coordination polymer[Cd₃(BTC)₂(H₂O)₉]·2H₂O(CP 1)(H₃BTC=1,3,5-benzenetricar-boxylic acid) was selected and synthesized to investigate its photoelectric properties. CP 1 showed excellent sensitivity for Cr₂O₇^2- and Fe³⁺, low limit of detection(LOD:0.39 µmol/L for Cr₂O₇^2- and 1.72 µmol/L for Fe³⁺) and stability as electrochemical sensor. More importantly, fluorescence sensing studies indicated that CP 1 exhibits sensing activity for Fe³⁺, Fe²⁺, and MnO₄^- with good cyclic stability and selectivity. Low LOD and high-sensitivity capability of CP 1 make it a potential multifunctional photoelectric sensor.     

Fabricating UCNPs-AuNPs Fluorescent Probe for Sensitive Sensing Thiamphenicol

Anovel fluorescent probe has been constructed based on fluorescence resonance energy transfer(FRET) between upconversion nanomaterials(UCNPs) NaYF₄:Yb,Er and gold nanoparticles(AuNPs). The fluorescent "off-on" switching was formed for the detection of thiamphenicol(TAP) in egg samples. The fluorescence of UCNPs can be quenched to a certain degree by AuNPs. After adding TAP, the AuNPs generated aggregation and the fluorescence of UCNPs was recovered. The synthesized amination UCNPs and AuNPs were characterized by Fourier transform infrared spectroscopy(FTIR), UV-Vis, X-ray diffraction(XRD), energy dispersive spectrometer(EDS), and transmission electron microscope(TEM) techniques for observation and confirmation. As a model target, the detection of TAP has two linear ranges in the buffer solution within 0.01-0.1 μmol/L and 0.1-1 μmol/L using this fluorescent probe. The detection limit was obtained to be 0.003 μmol/L(S/N=3), which is favorable for trace analysis. The recovery of TAP from 98.2% to 105.3% was obtained, and the relative standard deviation(RSD) was from 2.5% to 4.3%. Furthermore, the method established in this study based on the UCNPs auto-low background fluorescence has high selectivity and strong ability to eliminate interference, which is beneficial to analyzing complex samples.     

基于Zynq的不规则物体体积测量系统的设计与实现

为解决工业生产中原始物料体积的快速、准确测量与分级问题,设计了一种以Zynq-7000可扩展处理平台为核心的基于机器视觉的不规则物体体积测量系统。该系统通过摄像头采集物料图像,结合ARM与FPGA技术,并使用Vivado开发软件在ZyBo开发平台中进行了软硬件协同设计,最终实现了不规则物体体积测量算法的硬件加速。实验结果表明该系统可以准确的计算出不规则物体的体积,并能够达到工业生产的实时性要求,这将有效地提升原始物料分级的准确性,提高企业的经济效益和社会效益。