磷化淀粉的合成及其与聚磷酸铵协效阻燃聚乳酸的性能研究

利用9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)和马来酸酐(MA)对淀粉进行改性得到磷化淀粉(DOPOMASt),通过红外光谱(FTIR)、核磁共振谱(1H-NMR)和X射线光电子能谱(XPS)确定其结构.利用DOPOMASt作为碳源,与聚磷酸铵(APP)复配后通过熔融共混制备了阻燃聚乳酸(PLA)...     

How do molecular interactions affect fluorescence behavior of AIEgens in solution and aggregate states?

Molecular interactions are crucial in diverse fields of protein folding,material science,nanotechnology,and life origins.Although mounting experimental research controls luminescent behavior by adjusting molecular interactions in light-emitting materials,it remains elusive to correlate microscopic molecular interactions with macroscopic luminescent behavior directly.Here,we synthesized three red luminogens with subtle structural variation and investigated the influence of molecular interactions on their luminescent behavior in solution and aggregate states.Our results indicate that strongπ-πand D-A interactions in both dilute solution(between luminogen and solvent molecules)and aggregate(between luminogens)states cause the redshift in emission,while weak interactions(e.g.,Van der Waals,C–H…π,and C–H…F interactions)enhance the quantum yield.This work provides a thoughtful investigation into the complicated influence of various molecular interactions on luminescent behavior.     

无机与有机混合物的含量分析——以探究鼻可乐成分为例

在化学实验课堂上,以生活中常见药品作为实验对象更能激发起学生对化学学习的兴趣。鼻可乐是一种常见的市售洗鼻剂,主要成分为氯化钠、柠檬酸与柠檬酸钠,是一种典型的无机物与有机物的混合体系。本文设计了对鼻可乐的组成进行定量分析的方法,并且通过实验验证其合理性,以期为鼻可乐成分分析实验进入高校分析化学实验课堂提供指导方法。学生通过该实验不仅能掌握恒重坩埚、沉淀滴定等实验基本操作方法,而且能更好地理解定量分析数据的方法。     

Fire retarded polyurethane foam composites based on steel slag/ammonium polyphosphate system: A novel strategy for utilization of metallurgical solid waste

A series of FR-RPUF composites were prepared by a one-step water foaming process with ammonium polyphosphate (APP) and steel slag (SS) as flame retardants. Thermogravimetric analysis (TG), limiting oxygen index (LOI), UL-94 vertical combustion test, microscale combustion calorimetry (MCC), TG-Fourier transform infrared spectrometry (TG-FTIR), scanning electron microscopy (SEM), Raman spectra and FTIR were used to investigate the thermal stability, flame retardancy, combustion performance, gas phase products, and char residue morphology of FR-RPUF composites. TG test results showed that the initial decomposition temperature (T_-5wt%) and char residue rate at 700°C of RPUF/APP/SS composites were significantly enhanced by the addition of APP and SS, and the thermal stability of the composites was improved. Flame retardant test results confirmed the significantly increased LOI values of RPUF/APP/SS composites with V-0 rating. TG-FTIR also confirmed the obviously decreased release of toxic gases and flammable gases in the combustion of RPUF/APP/SS composites. SEM and Raman spectra of char residues for the composites suggested that APP/SS system improved the compactness and graphitization degree of char layer for RPUF/APP/SS composite. The above researches provide a new strategy for the utilization of SS in fire safety engineering.     

Enantioselective Synthesis of Chiral Carboxylic Acids from Alkynes and Formic Acid by Nickel-Catalyzed Cascade Reactions: Facile Synthesis of Profens

We report a stereoselective conversion of terminal alkynes to α-chiral carboxylic acids using a nickel-catalyzed domino hydrocarboxylation-transfer hydrogenation reaction. A simple nickel/BenzP* catalyst displayed high activity in both steps of regioselective hydrocarboxylation of alkynes and subsequent asymmetric transfer hydrogenation. The reaction was successfully applied in enantioselective preparation of three nonsteroidal anti-inflammatory profens (>90 % ees) and the chiral fragment of AZD2716.     

药物化学中的大分子效应※

药物种类按照分子量来划分可以分为小分子药物(自然提取或化学合成的)和大分子药物(生物制剂). 尽管目前小分子药物仍然是市场的主流, 但其研发增速趋缓, 而大分子药物在药物研发中的地位日渐突显, 并被预期在未来药物市场中占据越来越高的份额. 除了生物制剂大分子药物, 将小分子药物与天然或合成大分子结合制备得到的化学合成大分子药物, 近年来受到药物研究者们越来越多的关注. 由于大分子具有丰富的骨架结构及空间构架, 其所特有的骨架效应、多价效应, 以及通过分子组装而产生的聚集效应和靶向效应等, 能够为药物化学的设计带来更多新的可能. 有鉴于此, 本综述将简略介绍药物化学设计中的大分子效应, 重点讨论合成大分子的骨架效应、多价效应、聚集效应和靶向效应等为药物化学设计所带来的新性能. 通过对药物化学中大分子效应所带来的优势、问题和重要研究进展的探讨, 以期能够推动化学合成大分子药物的发展, 为药物化学设计提供新的思路.     

-电感耦合等离子体质谱法测定硅锰冶炼渣中8种金属元素

实验采用HCl-HNO₃-HF-HClO₄混合酸为消解体系对样品进行前处理,加入1.0 mL盐酸羟胺溶液(100 g/L)溶解残渣,选择合适的同位素,以¹⁰³Rh为内标测定Cr、Co、Ni、Cu、Zn和Cd,以¹⁹³Ir为内标测定Tl和Pb,建立了电感耦合等离子体质谱(ICP-MS)法测定硅锰冶炼渣中8种重金属元素的方法。实验发现,样品前处理选择HCl∶HNO₃∶HF∶HClO₄=5∶5∶5∶1,并在复溶阶段加入1.0 mL盐酸羟胺溶液(100 g/L)可以完全消解样品,实验采用KED模式和干扰系数校正法消除质谱干扰,样品中待测元素的测定结果不受基体成分的干扰。通过绘制校准曲线及测定流程空白,各元素校准曲线的相关系数均大于0.9999,方法检出限为0.006~0.19 mg/kg,方法定量限为0.018~0.57 mg/kg。对硅锰渣实际样品进行测定,各元素的相对标准偏差(RSD,n=11)在0.83%~4.1%,加标回收率为94.7%~106%;经过人员比对实验,相对偏差为-4.54%~4.24%。测定结果稳定可靠,能满足硅锰冶炼渣中8种微量金属元素含量的分析检测要求。     

C60离子束撞击固体表面的坍塌与沉积(II)扫描隧道显微研究

Mass-selected C60 beam produced by laser ablation was accelerated and bombarded the (0001) surface of highly oriented pyrolitic graphite and (111) surface of gold single crystal. The samples were characterized by STM. The STM images showed that, the deposited species collapsed and formed planar structure on the solid surface, but the collapsed species were not dissociated and well oriented on the surface. Both positive and negative C60 ions were observed in the desorption mass spectra, confirming that the species collapsed on the solid surface are still the C60 clusters.     

Robust nickel silicate catalysts with high Ni loading for CO2 methanation

CO₂ is the main component of greenhouse gases and also an important carbon source. The hydrogenation of CO₂ to methane using Ni-based catalysts can not only alleviate CO₂ emissions but also obtain useful fuels. However, Ni-based catalysts face one major problem of the sintering of Ni nanoparticles in the process of CO₂ methanation. Thus, this work has synthesized a series of efficient and robust nickel silicate catalysts (NiPS−X) with different nickel content derived from nickel phyllosilicate by the hydrothermal method. It was found that the Ni loading plays a critical role in the structure and catalytic performance of the NiPS−X catalysts. The catalytic performance gradually increases with the increase of Ni loading. In particular, the highly dispersed NiPS-1.6 catalyst with a high Ni loading of 34.3 wt% could obtain the CO₂ conversion greater than 80%, and the methane selectivity was close to 100% for 48 h at 330 °C and the GHSV of 40,000 mL g⁻¹ h⁻¹. The excellent catalytic property can be assigned to the high dispersion of Ni nanoparticles and the strong interaction between the active component and the carrier, which is derived from a unique layered silicate structure with lots of nickel phyllosilicate and a large number of Lewis acid sites.