黄酮类天然产物13C NMR数据的计算机检索和辅助解析(Ⅱ)黄酮类天然产物的13C NMR数据规律及其在智能解析中的应用

本文通过对大量的黄酮类化合物¹³C NMR图谱的分析和研究,总结了不同类型的黄酮类化合物的¹³C NMR图谱特征及化学位移规律.对影响黄酮类化合物结构骨架上不同位置碳原子化学位移的因素进行了分析,建立了用于黄酮类天然产物¹³C NMR图谱智能解析的知识库.     

Pachysandra型生物碱13C NMR谱的研究

文献中未报道过Pachysandra型生物碱的¹³C NMR数据,在研究这类化合物的化学结构的基础上,本文系统地研究了Pachysandra型生物碱的¹³C NMK谱,完整归属了化学位移数据,探讨了¹³C NMR规律和特征。     

苯基哌嗪衍生物的NMR波谱研究

通过¹H NMR、¹³C NMR、及HMBC、HSQC、¹H-¹H DQFCOSY等2D NMR方法对新合成的10个苯基哌嗪衍生物类抗高血压药物进行结构鉴定, 并对这些化合物的¹H NMR和¹³C NMR信号进行了全归属. 初步探讨了取代基对分子¹³C化学位移的影响.      

羰基化合物分子距边矢量与其13C NMR δC的关系

通过对155个羰基化合物中羰基碳原子的¹³C NMR谱与其分子距离-边数矢量(MDE)、立体效应参数(γ 效应)关系的研究，发现羰基化合物羰基碳的¹³C NMR谱化学位移可表示为：
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δ_C=a+bμ₅₁+cμ₅₂+dμ₅₃+eμ₅₄+fγ
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此式不仅在一定程度上表明了羰基化合物¹³C NMR谱化学位移与其分子结构信息之间的关系，同时也提供了一种计算羰基化合物¹³C NMR化学位移的新方法，并对解析和预测其¹³C NMR谱提供了理论依据.      

8种苯并[h]喹啉的13C NMR归属

报道了8种新的苯并[h]喹啉的¹³C NMR谱.应用¹³C NMR等谱确定了这8种新化合物的分子结构,并对全部谱峰进行了归属,初步探讨了分子结构对¹³C NMR化学位移的影响.     

取代喹啉的13C NMR研究

报道了14种新的取代喹啉的¹³C NMR谱.应用¹³C NMR等谱确定了这14种新化合物的分子结构,并对全部谱峰进行了归属,初步探讨了分子结构对¹³C NMR化学位移的影响.     

新型萘酰亚胺衍生物的13C NMR研究

报道了四种新的萘酰亚胺衍生物的¹³C NMR谱. 应用¹H、¹³C、DEPT、HMQC、HMBC 等谱确定了这四种化合物的分子结构,并对全部谱峰进行了归属,探讨了分子结构对¹³C NMR化学位移的影响.     

3-卤代喹啉的13C NMR研究

报道了11种新的3-卤代喹啉的¹³C NMR谱.应用¹³C NMR等谱确定了这11种新化合物的分子结构,并对全部谱峰进行了归属,初步探讨了分子结构对¹³C NMR化学位移的影响.     

2-环烷基苯腈的13C NMR研究

报道了7种新的2-环烷基苯腈的¹³C NMR谱.应用¹³C NMR等谱确定了这7种新化合物的分子结构,并对全部谱峰进行了归属,初步探讨了分子结构对¹³C NMR化学位移的影响.     

4-环烷基苯腈的13C NMR研究

报道了5种新的4-环烷基苯腈的¹³C NMR谱.应用¹³C NMR等谱确定了这5种新化合物的分子结构,并对全部谱峰进行了归属,初步探讨了分子结构对¹³C NMR化学位移的影响.     

An Easy and Efficient Fluorescent Method for Detecting Aldehydes and Its Application in Biotransformation

Water-soluble aldehydes (acetaldehyde, propionaldehyde) and non-water-soluble aldehydes (butyraldehyde and phenylacetaldehyde) were easily detected by an efficient fluorescent method with 5-aminofluorescein as probe. Under optimal detection conditions, 5-aminofluorescein could selectively respond to aldehydes with high sensitivity in comparison with other carbonyl compounds like ketones and acids. Thus, the proposed method was used to monitor microbial oxidation and succeeded in trapping transiently-produced aldehydes during biotransformation of primary alcohols by Gluconobacter oxydans.     

A multi-component reaction (MCR) approach to the synthesis of highly diverse polymers with polypeptide-like features

A new strategy for the combinatorial synthesis of new materials has been developed through the consecutive application of an Ugi 4CC reaction and a ring-opening metathesis polymerization (ROMP) reaction. Norbornenyl aldehydes and carboxylic acids could be used in the Ugi MCR to give highly diverse monomers that were converted to the corresponding polymers by exposure to the second-generation Grubbs' catalyst. These polymers have structural features reminiscent of polypeptides and the process could be extended to the preparation of chiral materials.     

Application of Parahydrogen-Induced Polarization to Unprotected Dehydroamino Carboxylic Acids

One focus of current nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) investigation is the hyperpolarization of biologically relevant substrates. In this study, the application of parahydrogen-induced polarization (PHIP) to amino carboxylic acids was enabled by protonation of the amino group as well as of the carboxylic acid. Due to the donor character of these functional groups, they usually act as ligands at the active catalytic sites. To enable parahydrogenation, blocking of the catalytic sites by the functional groups has to be avoided. In a new approach, this was realized via protonation of the starting material. For the first time PHIP spectra of allylglycine, vigabatrin and γ-amino-butyric acid (GABA) were generated. The feasibility of the hydrogenation of amino carboxylic acids without using a protection group supersedes the deprotection reaction usually required. Hence, hydrogenation after protonation of the substrate opens the class of free dehydroamino carboxylic acids to PHIP.     

羧酸羧基中17O-NMR化学位移的研究

提出了计算羧酸羧基¹⁷O-NMR化学位移的公式：δ_cal=253.0+Δα+Δβ+Δγ,通过线性回归法确定了17种取代基参数.经回归检验表明该公式计算结果置信度为99.5%,与实验值的偏差Δδ在5.0以内羧酸的羧基¹⁷O-NMR化学位移计算值在95%以上.     

Role of oxygen functional groups for structure and dynamics of interfacial water on low rank coal surface: a molecular dynamics simulation

Molecular dynamics simulations were employed to study the effects of oxygen functional groups for structure and dynamics properties of interfacial water molecules on the subbituminous coal surface. Because of complex composition and structure, the graphite surface modified by hydroxyl, carboxyl and carbonyl groups was used to represent the surface model of subbituminous coal according to XPS results, and the composing proportion for hydroxyl, carbonyl and carboxyl is 25:3:5. The hydration energy with ?386.28 kJ/mol means that the adsorption process between water and coal surface is spontaneous. Density profiles for oxygen atoms and hydrogen atoms indicate that the coal surface properties affect the structural and dynamic characteristics of the interfacial water molecules. The interfacial water exhibits much more ordering than bulk water. The results of radial distribution functions, mean square displacement and local self-diffusion coefficient for water molecule related to three oxygen moieties confirmed that the water molecules prefer to absorb with carboxylic groups, and adsorption of water molecules at the hydroxyl and carbonyl is similar.     

X-ray photoelectron study of the oxidative modification of proteins

The effect of temperature and various modifiers on the shape of the X-ray photoelectron spectra of protein (mink albumin) is studied. Metal-containing multiwalled carbon nanotubes and NiO nanoparticles are used as modifiers. The studies are carried out using an X-ray electron magnetic spectrometer. It is shown that modification by copper-containing multiwalled carbon nanotubes improves the thermal stability of the protein to 523 K. In the case of the oxidative destruction of the protein, carboxylic groups COOH and NH groups are decomposed, and the formation of carbonyl groups takes place, which depends on temperature or the presence of metal catalysts.     

发光型主体分子胍基芘识别二羧酸根阴离子

在质子性溶剂甲醇中，发光型主体分子胍基芘通过氢键与二羧酸根阴离子结合，自组装形成2：1的主客体超分子复合物，本文采用前表面反射荧光检测，通过跟踪主体分子结合客体前后芘的激基二聚体与单体荧光强度比值的变化，研究了胍基芘对不同酸根数目，不同取代位置的苯取代羧酸盐，磺酸盐，长链二羧酸盐以及双羧基氨基酸的识别能力和识别选择性，结果表明，胍基芘对二羧酸根阴离子的识别能力与客体分子中两个羧基间的距离，分子的平面构型以及取代基的种类密切相关，1，2，4，5－苯四甲酸根的识别效果远远好于其他二羧酸根阴离子。     

Effect of sulphuric–nitric acid mixture composition on surface chemistry and structural evolution of liquid‐phase oxidised carbon nanotubes

Liquid phase functionalisation of carbon nanotubes is carried out via a H₂SO₄ + HNO₃ mixture, and the effect of the sulphuric to nitric acid volume ratio (1:3–3:1) is systematically investigated by means of complementary techniques, observing the expected progressive downgrade of the crystalline quality, along with the increase of oxygenated functionality concentration. In addition, in contrast with common expectations, the results obtained demonstrate that the concentration of carboxylic groups (acids and anhydrides) never exceeds that of all other functionalities (lactones, phenols, quinones/carbonyls and sulphonic groups) introduced by chemical oxidation. Only by using equal volumes of sulphuric and nitric acids the concentrations of carboxylic and non‐carboxylic groups become comparable. Raman analysis reveals that a change in the sample homogeneity accompanies the variations of the relative proportions of the various oxygenated groups, by the typology of which the vibration modes of carbon pairs and carbon rings appear to be affected to different extents. Copyright © 2012 John Wiley & Sons, Ltd.     

Surface characterisation of carbon fibre recycled using fluidised bed

X-ray photoelectron spectroscopy (XPS) was used to investigate the surface of carbon fibres recycled using a high-temperature fluidised bed. The interfacial shear strength of the recycled carbon fibres with epoxy resin was examined using a micro-droplet test. The corresponding as received carbon fibres were used as control samples. It was shown that the recycling process converted some of the surface hydroxyl groups into carbonyl and carboxylic groups due to the effect of heat in atmosphere of air. The overall O/C ratio was not changed significantly. The interfacial shear strength with epoxy resin was not affected by the change of surface oxygen composition. It was also shown that surface texture may play a dominant role in interfacial bonding performance.     

Fluorescent Studies of Salicylaldehyde and Other Related Carbonyl Compounds for the Selective and Sensitive Detection of Zinc(II) Ions in Aqueous Solution

Salicylaldehyde was found to have a high selectivity for zinc ions with simultaneous enhancement of fluorescence in aqueous buffer solution at optimum pH 8.5. The stoichiometry of the complex was determined to be 1:1 with a K(a) value of 3.4 × 10(4) M(-1) at 298 K. The fluorescence of the complex is not affected by common anions and Zn(2+) binds preferentially to salicylaldehyde in the presence of alkali, alkaline earth and heavy metal cations (Hg(2+), Cd(2+), Cr(3+) and Ni(2+)). This property is not observed with related phenolic compounds bearing a carbonyl group such as esters, amides, carboxylic acids and ketones.