一维多重接力COSY和选择性远程DEPT核磁共振技术在新分子骨架生物碱结构测定和谱峰归属研究中的应用

自防已科千金藤根中分得一个新型分子骨架的四氢异喹林类生物碱—excentricine(1)。本工作采用一维多重接力COSY和选择性远程DEPT核磁共振新技术成功地确定谱峰归属,鉴别和连结被季碳和杂原子分割开的自旋体系,测定了其结构。     

核磁共振法测定高聚物的结构—核磁共振二维谱

介绍了核磁共振(NMR)波谱,尤其是核磁共振二维谱(2D NMR)在最近几年内的进展。内容包括怎样用NMR测定高聚物的序列分布、共聚物结构、聚合物的混溶性、聚合物液晶的取向度、分子量、短链度和长链支化度、凝聚态高聚物的多相结构等。     

二维核磁共振技术在结构解析中的应用

进入21世纪以来,核磁共振技术有了飞速的发展.在硬件方面:9000 MHz核磁共振仪(900MHz,场漂移＜1.5 Hz/hr)的投入使用,标志着超导核磁共振仪向大型化又迈出了重要的一步.与此同时,H/C/N超导核磁共振仪又为生物大分子的结构剖析提供了新的手段和方法.在软件方面:新的脉冲系列不断地被开发,针对某一领域的软件系统也在不断地更新.核磁共振技术发挥着重要的作用.     

聚丁二烯的核磁共振二维谱研究

<正> 聚丁二烯分子中有三种微观结构,顺式-1,4,反式-1,4和-1,2。这三种结构单元的含量和序列长度对聚丁二烯的物性有很大影响。异构单元的含量可用IR和氢谱测定。序列分布可用氢谱和碳谱测定。已经有许多工作致力于聚丁二烯碳谱的谱图解析。因为各作者使用不同的经验式或半经验式,统计方法也不一样,结论不尽相同。最近Sato等     

二维NMR确定吡喃酮衍生物C_9H_（12）O_4的结构

利用Ｈ－ＨＣＯＳＹ和Ｃ－ＨＣＯＳＹ谱实现对~１Ｈ和~（１３）Ｃ谱的指认和归属；利用ＨＭ－ＢＣ谱确定分子的骨架；根据~１Ｈ－~１Ｈ标量偶合常数的大小推出相邻碳原子上质子的相对位置；并结合其它谱学数据，确定了从天然产物分离得到的吡喃酮衍生物Ｃ_９Ｈ_（１２）－Ｏ_４的化学结构并命名为２－（１’，２’－环氧丙烷基）－４－羟基－５－甲基－２－戊烯－５－酸内酯。     

核磁共振研究蛋白二级结构的方法

核共振共振法常规应用于解析化学物质结构和反应性能,现已发展成为生物化学和分子生物学的重要实验技术,尤其是在确定溶液中蛋白和多肽结构方面起着其它物理分析方法不可比拟的作用。文章综述了化学位移,偶合常数。核Ｏｖｅｒｈａｕｓｅｒ效应（ＮＯＥ）以及同位素交换等确定蛋白或多肽二级结构的方法。     

二维疏水铜基纳米片的合成及在硫醚类化合物催化氧化中的应用

二维纳米材料因其具有独特的物理化学性质得到了广泛的研究与关注.然而,自下而上制备稳定的二维纳米材料仍然面临巨大挑战.本工作以1,4-苯二硫醇为有机配体和Cu⁺为金属前驱体,通过配位相互作用自组装构筑了一种新型的二维金属有机配合物纳米片(Cu-BDT).Cu-BDT纳米片的形貌和结构被多种技术详细表征,包括粉末X射线衍射(P-XRD)、傅里叶变换红外光谱(FT-IR)、激光拉曼光谱(Raman)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、原子力显微镜(AFM)、X射线光电子能谱(XPS)、电感耦合等离子体发射光谱仪(ICP-OES)和接触角测试.催化实验证实,Cu-BDT纳米片表面暴露充分的活性位点和疏水特性有利于硫醚类化合物氧化反应的进行,可高效转化为亚砜类产物.     

应用二维核磁共振系列技术鉴定罕见的19-羟基多羟基甾醇的结构

本文应用COSY, TOCSY, 13C-1H COSY, ROESY, NOE差谱等NMR技术, 对新的19-羟基多羟基甾醇(Nephalstenol-A)的结构进行了鉴定, 并确定了其立体构型。     

2,2‘—二取代—1,1’—联萘化合物的NMR研究

用二维核磁共振谱进一步研究了２，２’－二羟基－１－１’－联萘（１）、２，２’－二四收据 －１－１’－联萘（２）、２．２－亚甲二氧基－１，１’－联萘（３）、２，２’－亚乙二氧基－１－１’－联萘（４）、２－羟基－２’－甲氧基１，１’     

月光花素甲(Ⅰ)、(Ⅱ)整体分子结构的测定

本文对月光花素甲(Calonyctin A)的整体分子结构分析加以完善并进行总结。前文报道月光花素甲是两个分子量相差28a.m.u的糖甙类同系物分子的混合物。这两个分子(简称M_1和M_2)分别称为月光花素甲(Ⅰ)与月光花素甲(Ⅱ)(Calonyctm A_1,CalonyctinA_2),分子量分别为938与910。它们分别含     

Structure Determination of a New Chromone Glycoside by 2D INADEQUATE NMR and Molecular Modeling

The structure of a new chromone glycoside isolated from smilax glabra, named smiglanin [3,5,7-trihydroxychromone 3-O-α-L -rhamnopyranoside] (C₁₅H₁₆O₉), was determined using NMR techniques. The carbon skeleton of the molecule was established mainly by the 2D INADEQUATE method coupled with a computerized spectral analysis. Complete ¹H and ¹³C resonance assignments were made based on the INADEQUATE and other 1D and 2D NMR techniques, including long-range HETCOR and indirect detection HMBC. The vicinal proton–proton coupling constants, together with proton–proton distance constraints derived from the NOESY experiment, were incorporated as molecular modeling parameters to give the energetically most favorable conformation.     

中药白头翁化学成份的核磁共振研究

中药白头翁为莨科白头翁属植物,临床用于治疗阿耙和细菌性痢疾。 其化学成份主要为三萜苷,苷元为羟基白桦酸。从该植物根茎中分得一新的皂苷,本文采用最近提出的二维解力HOHAHA,一维多重接力COSY和选择性远程~13CDEPT 等新技术进行了研究,其结构确定为23-羟基白桦酸-28--O-β-D-吡喃葡萄糖-C-67-β-D-吡喃葡萄糖。     

碳碳相关谱测定泽泻萜醇F的结构

从泽泻中分离出新化合物泽泻萜醇F，采用二维核磁共振碳相关技术研究了该化合物的骨架结构。结合碳碳相关谱及远程碳氢相关谱等其它二维核磁共振技术，分析了该化合物的常规氢谱和碳谱，并准确归属了质子和碳核的化学位移。     

A metabonomics investigation of multiple sclerosis by nuclear magnetic resonance

Multiple sclerosis (MS) is a nervous system disease that affects the fatty myelin sheaths around the axons of the brain and spinal cord, leading to demyelination and a broad range of signs and symptoms. MS can be difficult to diagnose because its signs and symptoms may be similar to other medical problems. To find out which metabolites in serum are effective for the diagnosis of MS, we utilized metabolic profiling using proton nuclear magnetic resonance spectroscopy (¹H‐NMR). Random forest (RF) was used to classify the MS patients and healthy subjects. Atomic absorption spectroscopy was used to measure the serum levels of selenium. The results showed that the levels of selenium were lower in the MS group, when compared with the control group. RF was used to identify the metabolites that caused selenium changes in people with MS by building a correlation model between these metabolites and serum levels of selenium. For the external test set, the obtained classification model showed a 93% correct classification of MS and healthy subjects. The regression model of levels of selenium and metabolites showed the correlation (R²) value of 0.88 for the external test set. The results indicate the suitability of NMR as a screen for identifying MS patients and healthy subjects. A novel model with good prediction outcomes was constructed between serum levels of selenium and NMR data. Copyright © 2012 John Wiley & Sons, Ltd.     

月光花素甲的糖组份的结构测定

厦门大学植物激素研究组从月光花(Calonyction aculeatum L. House)叶中提取出一种活性物质,称为月光花素甲。它对植物具有明显的生理活性,并能促进作物生长,达到增产的效果。方一苇等通过质子核磁共振和电子轰击质谱分析,初步确定月光花素甲是11-羟基一十六烷酸乙酯和6-去氧己醛糖组成的糖甙类物质。     

核磁共振氢谱法测定甘露聚糖肽中多糖的含量

以甘露聚糖肽为研究对象,首次采用1H-NMR法测定多糖产品中的多糖含量。以基准试剂邻苯二甲酸氢钾为内标,考察了弛豫延迟时间和采样次数对测定结果的影响。选定核磁共振参数弛豫延迟时间1 s,采样次数16次。考察结果表明,该方法具有很好的重复性和精密度。在对甘露聚糖肽定性鉴定的基础上,采用绝对定量方式测定了甘露聚糖肽实际样品的多糖含量,结果与苯酚-硫酸法一致。该方法专属性高,操作方便,结果准确,不仅可用于甘露聚糖肽中多糖含量的测定,还可用于其它结构明确的多糖含量测定。     

Conformational studies of novel estrogen receptor ligands by 1D and 2D NMR spectroscopy and computational methods

The solution conformations of the novel estrogen receptor ligands (17α,20E)‐(p‐trifluoromethylphenyl)vinylestradiol ( 1 ) and (17α,20E)‐(o‐trifluoromethylphenyl)vinylestradiol ( 2 ) were investigated in 2D and 1D NOESY studies and by comparison of ¹³C NMR chemical shifts with theoretical shieldings. The ¹H and ¹³C assignments of 1 and 2 were determined by DEPT, COSY and HMQC experiments. The conformations of the 17α‐phenylvinyl substituents of 1 and 2 are of interest because of their differing receptor binding affinities and effects in in vivo uterotrophic growth assays. A statistical method of evaluating contributing conformers of 1 and 2 from predicted ¹³C shifts of possible structures correlated fairly well with conformational conclusions derived from the NOE data. The 17α substituents of 1 and 2 apparently exist in similar conformational equilibria, suggesting that while 1 and 2 would occupy a similar receptor volume, interactions with the protein may shift the equilibrium and thereby influence the expression of the ligand. Copyright © 2003 John Wiley & Sons, Ltd.     

精氨酸甘草次酸的制备及核磁共振谱分析

以18β-甘草次酸为原料,合成了一种新的甘草次酸盐类衍生物——精氨酸甘草次酸,利用1HNMR、13CNMR、DEPT、1H-1HCOSY、HMQC、HMBC等1D和2DNMR技术对其碳和氢质子信号进行了全归属,并通过与两种原料化合物核磁共振谱数据的对比,揭示了该成盐反应的作用机制和产物的结构类型。