创新型化学实验设计:AIE超支化聚碳酸酯的合成、表征及性质研究

通过对酯化反应、酯交换反应和聚集诱导发光概念的深入介绍以及不同合成超支化聚碳酸酯方法的比较分析,引导学生理解“传统孕育创新”的文化思想。以碳酸二乙酯和丙三醇为原料,通过简单的酯交换缩聚反应设计并合成具有聚集诱导发光效应的超支化聚碳酸酯,利用紫外-可见分光光度计、荧光分光光度计分别研究超支化聚碳酸酯的紫外吸收性能和荧光性能;通过透射电镜和激光粒度仪研究超支化聚碳酸酯的聚集形貌和大小以探索发光机理。整个实验教学从科学角度出发,从合成原理和发光机理的教学理论中让学生理解“传统孕育创新”的文化内涵,不仅可以培养学生对科研的热情和兴趣,还可以让学生掌握先进仪器的操作技能,培养学生综合实验能力和人文素养。     

苯乙炔配位聚合及光热性能研究——推荐一个绿色高分子化学综合实验

介绍一个绿色高分子化学综合实验.在水相中,苯乙炔通过有机铑配合物催化聚合得到聚苯乙炔,利用红外光谱仪、核磁共振仪、紫外-可见分光光度计、荧光光谱仪和热重分析仪对其结构和光热性能进行研究.本实验难度适中,可以通过溶剂为可变因素展开分析讨论,引导学生主动思考.实验内容涵盖高分子化学、应用波谱学和聚合物仪器分析与表征等知识点.本实验的实施不仅可提升学生的综合运用专业知识能力,还可培养学生系统的科研思维和环保意识.     

刚果红分光光度法测定血清蛋白质

1　引　　言蛋白质的定量测定在生物化学、药学及食品等学科中有重要意义 ,也是临床诊断疾病及检查治疗效果不可缺少的分析项目。蛋白质含量测定方法很多 ,目前研究最多、应用最广的为染料结合法 ,但未见有刚果红作显色剂测定蛋白质的报道。研究了刚果红与蛋白质反应的基本条件 ,建立了以刚果红测定蛋白质的分光光度分析法 ,用于实际人血清样品中总蛋白质的测定 ,取得了满意的结果。与经典的考马斯亮蓝法比较 ,本法简便灵敏 ,稳定性好 ,线性范围较宽 ,颇有实用意义。2　实验部分2 .1　主要仪器及试剂　Ｌａｍｂｄａ 3 5紫外 可见分光光度计 …     

二阶导数紫外吸收光谱测定复合氨基酸注射液中的色氨酸和苯丙氨酸的含量

复合氨基酸注射液是含有11种氨基酸及甘露醇的复方制剂。文献曾报导用二阶导数光谱测定蛋白质及天然物中的色氨酸;徐绪温等使用双波长分光光度计,用导数光谱法测定了复合氨基酸注射液中色氨酸,本文提出用二阶导数光谱直接测定色氨酸和苯丙氨酸含量的方法。实验方法 (一)仪器与试剂所用仪器为岛津UV-240型自记式紫外分光光度计OP1-1附件。氨基酸标准物均为广州侨光制药厂提供的日本进口试剂,按药典检定合格;甘露醇,分析纯。复合氨基酸注射液由广州侨光制药厂提供,为内含11种氨基酸及甘露醇的无菌水溶液,     

新型引发体系——Cu(Ⅲ)络离子引发聚合反应动力学的研究(Ⅰ)——丙烯酰胺自还原引发聚合反应

二过碘酸合铜(Ⅲ)络离子在小分子氧化反应动力学方面的研究已有报道。但用于自由基聚合反应方面的研究至今尚未见报道。本文系用膨胀计法研究了Cu(Ⅲ)为氧化剂、丙烯酰胺(简称AM)为还原剂引发AM聚合反应动力学,得到聚合速率方程及聚合物分子量,探讨了反应机理。 1 实验部分 1.1 仪器和试剂 超级恒温水浴(精度±0.1℃);测高仪;UV-3000分光光度计(日本津鸟);红外光谱仪(日立260-50),试剂除AM外,其它均为分析纯。     

基于光线传感器的手机光度计设计与应用

利用智能手机的光线传感器设计了一款简易光度计,并为其开发了安卓手机应用,可以在线查看样品信号,自动计算吸光度值。此款简易光度计采用了液相色谱紫外检测器的流通池作为样品吸收池,利用光纤传导光信号,可以大幅降低试剂使用量。进行一次测试只需要使用约200μL样品,有效降低了实验室废液回收量。利用该光度计对铁离子标准溶液进行测定,在测定浓度范围内,吸光度与样品浓度具有良好的线性拟合关系,其中R2=0.9991,可取代化学实验中的传统分光光度计。利用该光度计进行实验可以强化学生对仪器和实验原理的理解,有利于培养创新意识。     

开放性实验：聚乙烯亚胺修饰碳点的合成、纯化与表征

开放性实验是培养拔尖创新人才的有效手段。我们基于学生兴趣、科研热点和实验室条件,设计了实验方案。实验采用一步水热法,以柠檬酸(CA)为碳源,聚乙烯亚胺(PEI)为修饰剂,合成PEI修饰碳点(PEI-CDs)。首先,将CA、PEI在0.1 mol/L的盐酸中超声至完全溶解,混匀后转移到高压反应釜中,放入烘箱130℃反应2 h,制得PEI-CDs原液;然后将冷却至室温的原液旋转蒸发浓缩至2 mL,并用无水乙醇沉淀、洗涤;最后,将所得沉淀放入真空干燥箱,70℃干燥12 h得到PEI-CDs粉末。利用紫外-可见分光光度计、荧光分光光度计、红外光谱仪和透射电镜对所合成的PEI-CDs进行表征。结果表明,所采用的无水乙醇沉淀纯化方法简单、快速、经济、绿色,制得的PEI-CDs水溶性好,发光性能优异,大小均一,稳定性高。通过该开放性实验,学生不仅熟悉了大型仪器的使用,而且增强了科学研究的兴趣。     

分析化学创新设计性实验——基于响应面法优化中药挥发油提取工艺研究*

将响应面法与中草药挥发油提取研究有机融合并考察其抗氧化性能的创新设计性实验面向中药特色专业开设。通过考察料液比、浸泡时间和提取时间等工艺条件,让学生掌握分析化学、无机化学中的提取理论知识。通过对不同工艺条件的响应面分析,让学生掌握响应面优化法的原理及操作步骤。通过对挥发油抗氧化性能的研究,让学生掌握仪器分析中紫外分光光度计的使用。     

金属离子的高速液体色谱分光光度分析用高选择性高灵敏试剂

(一)前言用分光光度计或荧光分光光度计为检测器的高速液体色谱(HPLC),可以看作是带有前处理装置的通用式分光光度计或荧光分光光度计。因此,可以预料HPLC在用有机试剂的微量金属离子的分析中,将在灵敏度、选择性两方面作出划时代的贡献。从历史上看,金属络合物的液相分配色谱,一直在受气相色谱的中性分子的分离行为和经典的液相色谱的概念的影响开展着研究。即使到了HPLC时代,仍然在利用像双硫腙     

原子吸收法测定岩石中钾、钠的干扰问题

原子吸收法测定岩石中钾、钠的干扰问题,很少见到较详细的报导,由于实际工作需要,我们对此问题进行了实验研究。实验部分 1.仪器及测定条件:WYX-401型原子吸收分光光度计(沈阳分析仪器厂)。仪器使用条件列于表1.     

Simultaneous determination of 1H-1H and 1H-13C residual dipolar couplings in a chiral liquid crystal solvent using a natural abundance HSQC experiment

A high-resolution, phase-sensitive, natural abundance F2-coupled 1H-13C HSQC (F2HSQC) NMR experiment was developed to measure simultaneously both (n)D(HH) and 1D(CH) residual dipolar couplings (RDCs) of small molecules present in a chiral polypeptide liquid crystal solvent system composed of poly-gamma-benzyl-L-glutamate (PBLG) in CDCl3. Because this is an indirect-detection NMR experiment, the relatively small amount of sample (7.5 mg in this study) and short acquisition times (5 h) that are required make this HSQC experiment well suited for samples that are either limited in solubility or in quantity or require short analysis times. The F2HSQC experiment can be performed without any specialized equipment or sample modification and can enhance our ability to measure RDCs accurately and rapidly in polypeptide liquid crystal solvents.     

双相角结构不变量与Harker作图法在柯卡因卤化物结构相角计算中的联合应用

结合Hauptman的概率式与Harker作图法计算了不同条件下柯卡因卤化物的结构相角,分析了模拟的实验误差对相角精度的影响,为使用真实实验数据进行计算提供了参考依据。     

Vibrations of a single adsorbed organic molecule: anharmonicity matters!

Vibrational spectroscopy is a powerful tool to identify molecules and to characterise their chemical state. Inelastic electron tunnelling spectroscopy (IETS) combined with scanning tunnelling microscopy (STM) allows the application of vibrational analysis to a single molecule. Up to now, IETS was restricted to small species due to the complexity of vibration spectra for larger molecules. We extend the horizon of IETS for both experiment and theory by measuring the STM-IETS spectra of mercaptopyridine adsorbed on the (111) surface of gold and comparing it to theoretical spectra. Such complex spectra with more than 20 lines can be reliably determined and computed leading to completely new insights. Experimentally, the vibrational spectra exhibit a dependence on the specific adsorption site of the molecules. Theoretically, this dependence is only accessible if anharmonic contributions to the interaction potentials are included. These joint experimental and theoretical advances open new perspectives for structure determination of organic adlayers.     

Improved excitation uniformity in multiple‐quantum NMR experiments of mixtures

Multiple‐quantum ¹H NMR spectroscopy has been finding a renewed interest for its possible applications in the analysis of mixtures of small molecules, due to its simplification properties. A crucial aspect of this application of multiple‐quantum NMR is the sensitivity of the spectrum intensity to the molecular structure and to the parameterization of the experiment, which could result in the missing of some components. We demonstrate that a general scheme to overcome this drawback consists in varying the experiment parameterizations over a small number of values, selected according the values of the couplings and the relaxation rates. Copyright © 2013 John Wiley & Sons, Ltd.     

Effects of gas molecules on nanofluidic behaviors

Most previous studies on nanofluidic motions were focused on liquid-solid interactions, with the important role of gas phase being ignored. Through a molecular dynamics simulation, we show that the gas-liquid interaction can be an indispensable factor in nanoenvironments. Gas molecules in relatively large nanochannels can be dissolved in the liquid during pressure-induced infiltration, leading to the phenomenon of "nonoutflow". By contrast, gas molecules tend to form clusters in relatively small nanochannels, which triggers liquid defiltration at a reduced pressure. The results qualitatively fit with the observations in a high-pressure-resting experiment on nanoporous silica gels.     

Selective 1D HCH experiment: a fast NMR tool that connect protons belonging to different spin systems

A selective 1D version of the HCH experiment (selHCH) is proposed for the efficient and fast correlation between protons belonging to different spin systems. The experiment consists of two consecutive, doubly selective heteronuclear J(CH) transfer steps that can individually be optimized. As any conventional proton-selective 1D experiment, the successful application of a frequency-selective 180° pulse on a well-isolated proton is the only practical requirement. The resulting clean selHCH spectrum probes to be an excellent complement to the conventional selTOCSY experiment to trace out proton-proton J connectivities through transparent non-protonated carbons or heteroatom centers. Several selHCH examples on small molecules are provided showing the improvements with respect to the selTOCSY experiment.     

Study of molecular interactions between lipids and proteins using dynamic surface tension measurements: a review

Molecular interactions between small molecules and proteins, such as binding of lipids to proteins, are of fundamental importance in various biological processes. A recently-developed method based on dynamic surface tension measurement is efficient and versatile in detecting such molecular interactions: Axisymmetric Drop Shape Analysis (ADSA) provides a tool for measuring the surface tension (γ) response to surface area changes. Through the analysis of the γ response pattern, surface competitive adsorption between small organic molecules and protein molecules can be detected. Surface squeeze-out of small molecules by proteins can also be observed. Molecular binding of lipids to proteins manifests itself in a modification of the γ response which is not compatible with a simple superposition of the two individual patterns. The specific binding can be studied in terms of dose effects and specificity.     

Multiplicity editing including quaternary carbons: improved performance for the 13C-DEPTQ pulse sequence

An improved version of the DEPTQ experiment yielding the signal and multiplicity information for all carbon types including the signals of quaternary carbons is proposed. It encompasses all the known advantages of the basic DEPT experiment. In comparison to the original version, signals of the sensitivity-limiting quaternary carbons are markedly increased: the initial 13C pulse may be adjusted to the Ernst angle, the NOE build-up period is prolonged by the split relaxation delay and a partial recovery of signal losses due to instrumental imperfections is achieved by the incorporation of composite adiabatic 13C refocussing pulses. Furthermore, pure absorption lineshapes for all carbon types are obtained with only one single scan. These attributes make this experiment attractive for 13C analysis of small molecules (including spectral editing), particularly in high-throughput analysis laboratories.     

Small molecule-dependent genetic selection in stochastic nanodroplets as a means of detecting protein-ligand interactions on a large scale

Background: Understanding the cellular role of a protein often requires a means of altering its function, most commonly by mutating the gene encoding the protein. Alternatively, protein function can be altered directly using a small molecule that binds to the protein, but no general method exists for the systematic discovery of small molecule ligands. Split-pool synthesis provides a means of synthesizing vast numbers of small molecules. Synthetic chemists will soon be able to synthesize natural product-like substances by this method, so compatible screening methods that detect the activity of minute quantities of molecules among many inactive ones will be in demand.Results: We describe two advances towards achieving the above goals. First, a technique is described that uses a simple spray gun to create 5000–8000 droplets randomly, each having a volume of 50–200 nanoliters. The individual ‘nanodroplets’ contain a controlled number of cells and many also contain individual synthesis beads. As small molecules can be photochemically released from the beads in a time-dependent manner, the concentration of ligands that the cells are exposed to can be controlled. The spatial segregation of nanodroplets prevents the mixing of compounds from other beads so the effects of each molecule can be assayed individually. Second, a small molecule-dependent genetic selection involving engineered budding yeast cells was used to detect intracellular protein-ligand interactions in nanodroplets.Conclusions: The technique described here should facilitate the discovery of new cell-permeable ligands, especially when combined with a positive selection assay that detects intracellular binding of small molecules to proteins. Using ‘anchored combinatorial libraries’, it may be possible to screen entire libraries of natural product-like molecules against the entire collection of proteins encoded within cDNA libraries in a single experiment.     

Problems,artifacts and solutions in the INADEQUATE NMR experiment

The INADEQUATE experiment can provide unequalled, detailed information about the carbon skeleton of an organic molecule. However, it also has the reputation of requiring unreasonable amounts of sample. Modern spectrometers and probes have mitigated this problem, and it is now possible to get good structural data on a few milligrams of a typical organic small molecule. In this paper, we analyze the experiment step by step in some detail, to show how each part of the sequence can both contribute to maximum overall sensitivity and can lead to artifacts. We illustrate these methods on three molecules: 1‐octanol, the steroid 17α‐ethynylestradiol and the isoquinoline alkaloid β‐hydrastine. In particular, we show that not only is the standard experiment powerful, but also a version tuned to small couplings can contribute vital structural information on long‐range connectivities. If the delay in the spin echo is long, pairs of carbons with small couplings can create significant double‐quantum coherence and show correlations in the spectrum. These are two‐ and three‐bond correlations in a carbon chain or through a heteroatom in the molecule. All these mean that INADEQUATE can play a viable and important role in routine organic structure determination. Copyright © 2010 John Wiley & Sons, Ltd.