光谱法分析乙丙共聚物的序列结构及链节比

用FTIR, 1 H NMR和 13 C NMR分析乙丙共聚物的序列结构与链节比. 通过对乙丙共聚物 1 H NMR, 13 C NMR和 13 C-1 H二维核磁共振谱的综合分析, 提出了与前人不同的归属, 并提出了不同位置碳原子积分面积相关性分析方法, 该方法避免了烦琐的理论计算, 可简便地得到乙丙共聚物的主要序列结构. 通过比较 1 H NMR和 13 C NMR计算乙丙共聚物中乙烯、 丙烯链节比, 表明可以用 1 H NMR代替 13 C NMR完成对乙丙共聚物中乙烯、 丙烯链节比的定量计算.     

核磁共振法研究固体表面上的吸附

应用JEOL FX-90Q NMR谱仪测定了吸附在NaY分子筛,氧化铝,二氧化硅上的四甲基硅烷和正己烷的核磁氢谱和碳谱.结果表明,在一些吸附体系的研究中,现有仪器适用于液体样品,以氢谱和碳谱比较发现碳谱在分辨率分方面较之氢谱有几个优点,顺磁杂质对谱线宽度有明显影响.在NaY分子筛上预先吸附氢以后再吸附乙烯,其吸附速率低于未吸附氢的样品.     

两种立体构型的1,3,5,-三-α-萘基苯的合成

通过Adole反应和Grigard反应合成了相应的两种立体异构的1,3,5-三-α-萘基苯. 报道了它们的UV, IR, FD-MS和NMR . 论了两种异构体的^1H NMR 和^1^3C NMR的区别.     

Structure elucidation and NMR spectral assignment of five new xanthones from the bark of Garcinia xanthochymus

Five new xanthones, namely Garcinexanthones A-E (1-5), were isolated from the barks of Garcinia xanthochymus. Their structures were elucidated by spectral analysis, primarily NMR, MS, and UV. The complete assignments of the (1)H NMR and (13)C NMR chemical shifts for the compounds were achieved by using 1D and 2D NMR techniques, including DEPT, HSQC, and HMBC NMR experiments.     

苯乙烯-马来酸酐共聚物的核磁共振分析

利用^1H NMR、^13C NMR及DEPT(无畸变极化转移增强)核磁共振技术研究了苯乙烯-马来酸酐共聚物(SMA)的序列结构和组成，并比较了几种核磁共振实验技术对分析SMA结果的准确性；实验表明^1H NMR是分析组成的简单、快速而有效的方法，DEPT谱进行序列结构计算准确度较高。     

1.5T核磁共振弛豫时间分析仪的研制及其潜在应用

介绍了国产1.5T核磁共振弛豫时间分析仪的基本组成、性能指标,研发过程中攻克的技术难题。该仪器主要由磁体部分、电子部分、软件部分组成,具有体积小、信噪比高、检测无损、使用和维护简便和造价低廉等优点。同时对该系统磁体频率和磁信号的稳定性进行了相关的测试,结果表明该系统稳定可靠。该仪器的磁场强度增加到1.5T,在同等外界条件和环境下,信噪比增加约为0.5T系统的10倍,检测灵敏度大幅度提高;该仪器为食品品质鉴定、食品安全检测、医学诊断、生物标志物的大规模筛选等生化分析提供一个全新的途径。     

NMR Studies of polymeric materials - an overview

NMR has been used extensively in studies of synthetic polymers. The approaches employed may require solution NMR, solid state NMR, or NMR imaging. In each case, different techniques and analytical methodologies have been devised to facilitate experimentation or to maximize information output. These techniques are not mutually exclusive and often provide complementary information. A selective review is made herewith of polymer/NMR studies, with emphasis on the contributions made at NMR symposia held in Detroit in October, 1993 as part of the 20th FACSS meeting.     

Hyphenation of capillary separations with nuclear magnetic resonance spectroscopy

The hyphenation of small-volume separations to information-rich detection offers the promise of unmatched analytical information on the components of complex mixtures. Nuclear magnetic resonance (NMR) spectroscopy provides information about molecular structure, although sensitivity remains an issue for on-line NMR detection. This is especially true when hyphenating NMR to capillary separations as the observation time and analyte mass are decreased to the point where reduced information is obtained from the eluting analytes. Because of these limitations, advances in instrumental performance have a large impact on the overall performance of a separation–NMR system. Instrumental aspects and the capabilities of cLC–NMR, CEC–NMR and CE–NMR are reviewed, and applications that have used this technology highlighted. Recent trends towards small volume capillary scale separations are emphasized, as is the recent success of capillary-isotachophoresis (cITP)–NMR.     

µ-NMR at the point of care testing

NMR shows strong analytical capability for obtaining molecular information on materials and is used in a variety of fields. Micro-NMR (µNMR) is mainly based on low-field NMR (LF-NMR), which makes NMR detection portable and inexpensive. Point-of-care testing (POCT) has gradually become an area of major concern, and scientists have made much progress in applying µNMR systems for POCT. To the best of our knowledge, this is the first review of the latest development in miniaturization of µNMR systems. Then, we discuss cutting-edge µNMR-based applications in POCT and the outlook for future developments.     

13C and 15N NMR studies of iron-bound cyanides of heme proteins and related model complexes: sensitive probe for detecting hydrogen-bonding interactions at the proximal and distal sides

Studies of the 13C and 15N NMR paramagnetic shifts of the iron-bound cyanides in the ferric cyanide forms of various heme proteins containing the proximal histidine and related model complexes are reported. The paramagnetic shifts of the 13C and 15N NMR signals of the iron-bound cyanide are not significantly affected by the substitution of the porphyrin side chains. On the other hand, the paramagnetic shifts of both the 13C and 15N NMR signals decrease with an increase in the donor effect of the proximal ligand, and the 13C NMR signal is more sensitive to a modification of the donor effect of the proximal ligand than the 15N NMR signal. With the tilt of the iron-imidazole bond, the paramagnetic shift of the 13C NMR signal increases, whereas that of the 15N NMR signal decreases. The hydrogen-bonding interaction of the iron-bound cyanide with a solvent decreases the paramagnetic shift of both 13C and 15N NMR signals, and the effect is more pronounced for the 15N NMR signal. Data on the 13C and 15N NMR signals of iron-bound cyanide for various heme proteins are also reported and analyzed in detail. Substantial differences in the 13C and 15N NMR shifts for the heme proteins can be explained on the basis of the results for the model complexes and structures around the heme in the heme proteins. The findings herein show that the paramagnetic shift of the 13C NMR signal of the iron-bound cyanide is a good probe to estimate the donor effect of the proximal imidazole and that the ratio of 15N/13C NMR shifts allows the hydrogen-bonding interaction on the distal side to be estimated.     

NMR位移试剂Eu(fod)~4^-对锍盐^1H和^1^3C NMR的影响

合成了八种新的四氟硼酸二甲基苯基锍，用元素分析和核磁共振对其结构进行了表征。研究了以CDCl~3为溶剂，NMR位移试剂Eu(fod)~4^-对所合成锍盐的^1H和^1^3C NMR的影响。结果表明，Eu(fod)~4^-是一个对锍盐非常有效的位移试剂，且Eu(fod)~4^-对二甲基苯基锍盐之甲基的^1H和^1^3C NMR的位移呈线性关系。     

NMR波谱技术在两亲分子聚集体研究中的应用

NMR technologies such as relaxation, self-diffusion coefficient and other NMR methods were reviewed. The results of NMR measurements, especially, on 1H, 13C, 19F-NMR spectra and quadrupolar echo of 2H-NMR spectra on self-assembled properties and structures have been obtained. The investigations on the self-assembly of amphiphiles and the transition of self assembled structures were introduced and the determination of NMR measurements on micelles, vesicles and microemulsions was summed.     

二醋酸纤维素 -聚乙二醇接枝共聚物的核磁共振表征

用^1H NMR和^13C NMR核磁共振技术研究了二醋酸纤维素和聚乙二醇的接枝反应,并确定了^1H NMR和^13C NMR谱中各谱峰的归属,为证明二醋酸纤维素和聚乙二醇的接枝反应提供了依据。     

Investigation of structure, vibrational and NMR spectra of oxycodone and naltrexone: a combined experimental and theoretical study

In this work, two important opioid antagonists, naltrexone and oxycodone, were prepared from thebaine and were characterized by IR, (1)H NMR and (13)C NMR spectroscopy. Moreover, computational NMR and IR parameters were obtained using density functional theory (DFT) at B3LYP/6-311++G** level of theory. Complete NMR and vibrational assignment were carried out using the observed and calculated spectra. The IR frequencies and NMR chemical shifts, determined experimentally, were compared with those obtained theoretically from DFT calculations, showed good agreements. The RMS errors observed between experimental and calculated data for the IR absorptions are 85 and 105 cm(-1), for the (1)H NMR peaks are 0.87 and 0.17 ppm and for those of (13)C NMR are 5.6 and 5.3 ppm, respectively for naltrexone and oxycodone.     

A New Flavonol Oligosaccharide from the Seeds of Aesculus chinensis

Aesculus chinensis is a traditional chinese medicinal plant widely distributed in China, which has been used to treat stomach disease. From recent research its seeds contain many flavonoids and proanthocyanidin A2, which have potential venotonic and vasoprotective action and powerful antioxidant activity. In this paper, we report the isolation and the structure elucidation of a new flavonol oligosacchride. Bioassay results showed that the compound exhibited an antivirus activity. …     

High‐field 95Mo and 183W static and MAS NMR study of polyoxometalates

The potential of high‐field NMR to measure solid‐state ⁹⁵Mo and ¹⁸³W NMR in polyoxometalates (POMs) is explored using some archetypical structures like Lindqvist, Keggin and Dawson as model compounds that are well characterized in solution. NMR spectra in static and under magic angle spinning (MAS) were obtained, and their analysis allowed extraction of the NMR parameters, including chemical shift anisotropy and quadrupolar coupling parameters. Despite the inherent difficulties of measurement in solid state of these low‐gamma NMR nuclei, due mainly to the low spectral resolution and poor signal‐to‐noise ratio, the observed global trends compare well with the solution‐state NMR data. This would open an avenue for application of solid‐state NMR to POMs, especially when liquid‐state NMR is not possible, e.g., for poorly soluble or unstable compounds in solution, and for giant molecules with slow tumbling motion. This is the case of Keplerate where we provide here the first NMR characterization of this class of POMs in the solid state. Copyright © 2017 John Wiley & Sons, Ltd.     

羟基聚合铝溶液的27Al 核磁(NMR)研究进展

结合国内外各课题组研究,从27Al NMR实验参数和铝形态研究两方面综合评述了液体27Al NMR的发展研究现况。首次明确提出27Al NMR测定中设置合适的预采集延迟时间的作用。将为进一步开展的27Al NMR测定研究提供有价值的参考。     

核磁共振法鉴定表面活性剂

对7种常见的表面活性剂及其二元复配体系进行了核磁共振(NMR)分析,探索了多组分表面活性剂复配物的5种分离方法,比较了这5种分离方法对二元组分表面活性剂复配物的分离效果,并初步建立了核磁共振法分析多元表面活性剂复配产品的方法.采用该方法对3种企业样品中的表面活性剂进行了NMR测试,确认了各表面活性剂1H NMR的谱峰归...     

Application of HPLC‐NMR for the Rapid Chemical Profiling of a Southern Australian Sponge,Dactylospongia sp.

Rapid chemical profiling of the antitumour active crude dichloromethane extract of the marine sponge, Dactylospongia sp. was undertaken. A combination of both offline (HPLC followed by NMR and MS) and on‐line (on‐flow and stop‐flow HPLC‐NMR) chemical profiling approaches was adopted to establish the exact nature of the major constituents present in the dichloromethane extract of this sponge. On‐flow HPLC‐NMR analysis was employed to initially identify components present in the dichloromethane extract, while stop‐flow HPLC‐NMR experiments were then conducted on the major component present, resulting in the partial identification of pentaprenylated p‐quinol ( 5 ). Subsequent off‐line RP semi‐preparative HPLC isolation of 5 followed by detailed spectroscopic analysis using NMR and MS permitted the complete structure to be established. This included the first complete carbon NMR chemical shift assignment of 5 based on the heteronuclear 2‐D NMR experiments, together with the first report of its antitumour activity. This study represents one of the few reports describing the application of HPLC‐NMR to chemically profile secondary metabolites from a marine organism.     

The Potentials of Pulsed Field Gradient NMR for Investigation of Porous Media

PFG NMR self-diffusion studies provide information on the translational mobility of fluid molecules. Since in porous media the diffusion path of fluid molecules in the pore space is affected by interaction with the pore wall, PFG NMR measurements are sensitive to structural peculiarities of the confining porous medium. The pore space properties which can be investigated depend on length scales set by the PFG NMR experiment in respect to the typical size of the structural feature studied. Based upon these length scales, an interpretation pattern for PFG NMR self-diffusion studies in porous media is given. PFG NMR self-diffusion studies in macro- and microporous systems such as sedimentary rocks and zeolite crystallites, respectively, are reviewed.