水相金属有机化学

本文对近年来锡、锌、铋等介入下的水相金属有机化学作了综述。特别对水相Barbier 反应作了较详细的介绍, 同时也描述了一些典型的水相金属有机反应,如Immonium 阳离子的烷基化反应, α, β 不饱和化合物的共轭加成, 醇醛缩合反应及水溶性金属有机化合物的反应等。某些反应的机理也被讨论。     

空气敏感样品的电子能谱测定方法

电子能谱用于化学分析,常遇到测定一些特殊试样。如某些金属有机化合物在进样测试过程中遇潮气、氧气等就会分解或改变中心原子的化合价;有些经特殊处理的样品(如某些催化剂),其表面不宜暴露于空气;有些化学反应中间体不能与空气接触。为了适合于这些样品的测定,设计了一套隔离空气的进样装置。本装置成功地用于镧系金属有机络合物电子能谱的研究,并证明二茂镧系金属(钆、镝、钬、铒、镱和镥等)氯化物与2,2′联吡啶之间形成配位键。还测定了茂基钕与邻-菲啰啉形成的络合物,含磷钛酸酯等,最近对有机硼化合物也有应用。能谱测试国产NP-1型X射线光电子能谱仪,用MgK_αX     

超铀金属有机化学研究进展

锕系金属有机化合物因其独特的电子结构和成键性质而备受关注.锕系元素的高毒性和放射性以及对水和氧的超敏感性造成锕系金属有机化合物的合成条件及表征手段都比较苛刻.而超铀元素的获取途径更为严苛,加之极其强的放射性,超铀金属有机化合物的研究报道甚少.近年来,随着合成技术及表征技术的快速发展,一些结构新颖的超铀金属有机化合物被合成,通过对其电子结构、成键模式及理化性质的研究进一步加深了对超铀元素的认识和理解.综述了近年来超铀金属有机化合物的合成及其成键性质的研究,以期为系统地理解超铀元素的电子结构和成键规律以及合成结构新颖的超铀金属有机化合物提供指导.     

金属苯炔的合成与化学性质

金属苯炔是一类新颖的杂环芳香化合物.它们可看成是苯炔分子中的一个碳原子被等瓣的过渡金属基团取代而衍生出来的六元杂环化合物.近年来,金属苯炔的化学引起了人们的兴趣和关注.一系列含锇和铼的金属苯炔已被成功地合成和鉴定.这些金属苯炔不仅具有有机化合物的芳香性,还具有金属有机化合物的属性.它们既可以发生芳香体系的经典反应(如亲电取代反应),也可以发生金属有机化合物的反应(如卡宾化合物的形成).     

阳离子型稀土金属有机化合物

阳离子型金属有机化合物是催化烯烃聚合反应的活性物种,其结构与性质直接影响所得聚合物的微观结构和性能,具有重要的研究价值。对四族金属有机化合物的深入研究也推动了对其他前过渡金属和稀土金属有机化合物的研究。与为数众多的中性及阴离子型稀土金属有机化合物相比,由于具有较高的反应性、合成与分离不易,阳离子型稀土金属有机化合物直到最近才逐渐得到重视。本文介绍了近年来在阳离子型稀土金属有机化合物的合成、结构和催化烯烃聚合反应领域的研究进展。     

超分子光化学的前景

近二十年来光化学研究取得了巨大进展.其基本状况可归纳为下列几个方面:一是大量的有机分子、配位化合物、金属有机化合物的光化学和光物理行为已被了解,并得到理论上的阐明,许多重要激发态在结构上、能量上以及动态学方面的研究也已相当深入和完善;另一方面,人们对自然界存在的某些重要的光生物过程也有了相当的认识,包括如光合作用,视觉过程等,但尚未完全弄清.     

中国化学会第五届金属有机化学学术讨论会征文通知

中国化学会第五届金属有机化学学术讨论会拟于1988年9月下旬在兰州召开,现开始征集论文。 (一)征文范围 1.金属有机化合物的合成、结构及反应; 2.金属有机化合物的催化反应及动力学研究; 3.金属有机化合物在有机合成中的应用; 4.金属有机化合物在农业,工业,医疗,     

Cu(Ⅰ)有机化合物在有机合成中的应用

一、前言过渡金属有机化合物在近代有机合成中,日益显示出其重要作用,为有机合成工作提供了许多崭新而独特的新方法。 Cu(Ⅰ)有机化合物近十多年来在有机合成中的应用,正可以作为这方面有力的例证。 Cu(Ⅰ)有机化合物中含有碳负离子,属于亲核进攻试剂,在某些取代反应中,Cu(Ⅰ)有机化合物比传统的格林纳试剂(RMgX)及有机锂化     

Mg和Ca-PDTA金属络合物分子内过程的DNMR谱

~1H NMR不但可以研究有机化学、金属有机化合物的立体结构,而且在某些适当的金属络合物体系中,还可以研究金属离子和配体间的迁移性及分子内过程的动力学。对于EDTA类金属络合物的DNMR研究表明分子内过程包括三种形式,即Δ≒Λ构型转化,N原子反转以及所谓的B≒R转化。本文作者为进一步探讨分子内过程,选PDTA为配体进行了DNMR研究,取得一些有意义的新结果。实验部分     

有机金属化合物分析研究(Ⅱ)离子选择性电极法测硫

有机化合物中硫的测定,通常用Shoniger氧瓶燃烧法,生成的硫酸根用钡盐来滴定,但是用这个方法分析有机金属化合物样品,常遇到这样一些困难:燃烧后用钡盐溶液滴定时,某些金属离子干扰络合指示剂指示终点;一些碱土金属或重金属生成难溶性硫酸盐(如Ca、Sr、Ba、Mg、Pb等),致使结果偏低。在前人工作基础上,对分析方法作了改进,采用金     

Comparison of different search engines using validated MS/MS test datasets

Massive amounts of tandem mass spectra are produced in high-throughput proteomics studies. The manual interpretation of these spectra is not feasible. Instead, search engines are used to match the tandem mass spectra with sequence information contained in proteomics and genomics databases. Typically, these search engines provide a list of the best matching peptide sequences for an individual tandem mass spectrum. As well, they provide scores that are somewhat related to the confidence level in the match. Many peptide tandem mass spectra search engines have been reported. These search engines provide very different results depending on the type of mass spectrometers used and their input parameters. Here we describe a comparative analysis of different search engines using validated test sets of tandem mass spectra. We have defined test sets of MS/MS spectra derived from high throughput proteomics experiments performed by HPLC-ESI-MS/MS on ion trap (LCQ) and tandem quadrupole time-of-flight instruments with a pulsar functionality (Qstar Pulsar) mass spectrometers. We analyzed the ability of the different search engines to identify the correct peptides, and the cross-validations of the different search engines.     

Improved ion optics for introduction of ions into a 9.4‐T Fourier transform ion cyclotron resonance mass spectrometer

Enhancements to the ion source and transfer optics of our 9.4 T Fourier transform ion cyclotron resonance (ICR) mass spectrometer have resulted in improved ion transmission efficiency for more sensitive mass measurement of complex mixtures at the MS and MS/MS levels. The tube lens/skimmer has been replaced by a dual ion funnel and the following octopole by a quadrupole for reduced ion cloud radial expansion before transmission into a mass‐selective quadrupole. The number of ions that reach the ICR cell is increased by an order of magnitude for the funnel/quadrupole relative to the tube lens/skimmer/octopole. Copyright © 2015 John Wiley & Sons, Ltd.     

Clarification of a peak at m/z 1634 from tryptically digested cytochrome c

A peptide peak at m/z 1634 in the mass spectrum of tryptically digested cytochrome c has been ambiguously assigned to either a peptide IFVQKCAQCHTVEK or a peptide CAQCHTVEK combined with a heme group (CAQCHTVEK + heme (Fe(III))). A comprehensive investigation was performed to clearly identify the origin of the peak. Tryptic digests of cytochrome c were analyzed by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS), liquid chromatography‐tandem MS (LC‐MS/MS), LC‐ultraviolet (LC‐UV), and MALDI Fourier transform‐ion cyclotron resonance (FT‐ICR) MS. The use of instruments with extremely high mass accuracy revealed the mass difference between the IFVQKCAQCHTVEK and the (CAQCHTVEK + heme (Fe(III))) ions. Fragmentation of the peptide associated with the unknown peak yielded a heme ion and other fragment ions originating from a (CAQCHTVEK + heme (Fe(III))) ion. Furthermore, an absorption peak at 395 nm confirmed the presence of a heme group in the unknown peptide. High mass accuracy analyses of MS and MS/MS spectra, in addition to three‐dimensional UV contour mapping, showed that the peak at m/z 1634 is due to a (CAQCHTVEK + heme (Fe(III))) ion and not from protonated IFVQKCAQCHTVEK. Copyright © 2012 John Wiley & Sons, Ltd.     

Investigation of liquid chromatography–mass spectrometry analysis of a peptide aldehyde SJA6017 with identifying its hemiacetal,gem-diol,and enol ether

The quantitative analysis of SJA6017, a peptide aldehyde inhibitor of calpain (Calpain Inhibitor VI), has encountered challenges in preclinical drug studies. The complex reverse-phase HPLC chromatographic behavior exhibits two peaks, each containing multiple species. An liquid chromatography–mass spectrometry (LC–MS/MS) study proposed an explanation for this phenomenon, caused by the amide aldehyde structure of SJA6017. Four chemical species corresponding to the two HPLC peaks have been identified as SJA6017 and its methyl hemiacetal, methyl enol ether, and gem-diol. In many instances of preclinical studies, methanol is favored as a substitute for DMSO. The hemiacetal is formed when the amide-activated peptide aldehyde reacts with methanol, which can then be further dehydrated in the mass spectrometer ion source under high temperature to form the methyl enol ether. The hemiacetal and gem-diol can also be decomposed to SJA6017 in the ion source. Additionally, the amide-activated peptide aldehyde can easily hydrate to the gem-diol of SJA6017 during sample incubation or sample preparation. The hemiacetal and gem-diol of SJA6017 are stable enough to have different retention times in the liquid chromatography, which explains why SJA6017 appears as two peaks, each containing multiple species. An LC–MS/MS tandem quadrupole mass spectrometer quantitative analysis method is proposed, enabling the analysis of these types of samples. This work serves as both an illustrative example and a cautionary note for mass analysis, sample incubations, and sample preparations involving compounds of peptide aldehyde, including similar aldehyde-containing metabolites, especially when methanol is present. This study provides the information needed to understand peptide aldehyde behavior at various steps of preclinical in vitro studies in the presence of methanol. It has assisted in the development of the SJA6017 bioanalysis method and will also aid in the development of bioanalysis methods for similar peptide aldehydes.     

Identification and structural characterization of in vivo metabolites of ketorolac using liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS)

In vivo metabolites of ketorolac (KTC) have been identified and characterized by using liquid chromatography positive ion electrospray ionization high resolution tandem mass spectrometry (LC/ESI‐HR‐MS/MS) in combination with online hydrogen/deuterium exchange (HDX) experiments. To identify in vivo metabolites, blood urine and feces samples were collected after oral administration of KTC to Sprague–Dawley rats. The samples were prepared using an optimized sample preparation approach involving protein precipitation and freeze liquid separation followed by solid‐phase extraction and then subjected to LC/HR‐MS/MS analysis. A total of 12 metabolites have been identified in urine samples including hydroxy and glucuronide metabolites, which are also observed in plasma samples. In feces, only O‐sulfate metabolite and unchanged KTC are observed. The structures of metabolites were elucidated using LC‐MS/MS and MSⁿ experiments combined with accurate mass measurements. Online HDX experiments have been used to support the structural characterization of drug metabolites. The main phase I metabolites of KTC are hydroxylated and decarbonylated metabolites, which undergo subsequent phase II glucuronidation pathways. Copyright © 2012 John Wiley & Sons, Ltd.     

Development of tandem mass spectrometry: one perspective

The historical roots of tandem mass spectrometry or MS/MS (an invaluable tool for determining molecular structure and mixture analysis) are reviewed from the perspective of an active participant. The driving force for creating the first (and only) five-sector tandem mass spectrometer in the period 1962–1965 was to establish mechanisms of low energy ion–molecule reactions unequivocally and to evaluate the dependence of these reactions on ion kinetic energy. The invention and deployment of several other specialized instruments in the 1970s (drift cell and tandem ion cyclotron resonance spectrometers, hybrid tandems, and triple quadrupole instruments) also had fundamental studies of ion reactions as the research objective. The focus on low energy ion chemistry has evolved into collisional activation, the basis of analytical applications of MS/MS, as a natural evolution of scientific interest. The first such studies utilizing a crossed-beam hybrid MS/MS addressed single collision gas phase activation and has recently been extended to surface collision activation. The important parallel development of these methods and the metamorphosis of MS/MS from a suite of research tools into analytical practice using commercial instrumentation are discussed briefly.     

三羰基铬苯乙烯甲酰衍生物的质谱研究

含有α、β不饱和酮和酰胺的三羰基铬芳基配合物的质谱未见有详细报道,本文报道标题化合物电子轰击(EI)质谱,并利用高分辨质谱数据和MS/MS联用技术探讨其裂解机理,观察到R基团的重排反应和在不同汽化温度下发生的双分子裂解反应和氢化反应等。     

An isomer-specific high-energy collision-induced dissociation MS/MS database for forensic applications: a proof-of-concept on chemical warfare agent markers

Spectra database search has become the most popular technique for the identification of unknown chemicals, minimizing the need for authentic reference chemicals. In the present study, an isomer‐specific high‐energy collision‐induced dissociation (CID) MS/MS spectra database of 12 isomeric O‐hexyl methylphosphonic acids (degradation markers of nerve agents) was created. Phosphonate anions were produced by the electrospray ionization of phosphonic acids or negative‐ion chemical ionization of their fluorinated derivatives and were analysed in a hybrid magnetic‐sector–time‐of‐flight tandem mass spectrometer. A centre‐of‐mass energy (E_com) of 65 eV led to an optimal sequential carbon–carbon bond breakage, which was interpreted in terms of charge remote fragmentation. The proposed mechanism is discussed in comparison with the routinely used low‐energy CID MS/MS. Even‐mass (odd‐electron) charge remote fragmentation ion series were diagnostic of the O‐alkyl chain structure and can be used to interpret unknown spectra. Together with the odd‐mass ion series, they formed highly reproducible, isomer‐specific spectra that gave significantly higher database matches and probability factors (by 1.5 times) than did the EI MS spectra of the trimethylsilyl derivatives of the same isomers. In addition, ionization by negative‐ion chemical ionization and electrospray ionization resulted in similar spectra, which further highlights the general potential of the high‐energy CID MS/MS technique. Copyright © 2011 John Wiley & Sons, Ltd.     

Identification and determination of the major constituents in Kai‐Xin‐San by UPLC‐Q/TOF MS and UFLC‐MS/MS method

In order to have overall chemical material information of Kai‐Xin‐San (KXS), the reliable ultra‐high‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometer (UHPLC–Q‐TOF‐MS) and ultra‐fast liquid chromatography mass spectrometer (UFLC‐MS/MS) methods were developed for the identification and determination of the major constituents in KXS. Moreover, the UHPLC–Q‐TOF‐MS method was also applied to screen for multiple absorbed components in rat plasma after oral administration of KXS. The UHPLC–Q‐TOF‐MS method was achieved on Agilent 6520 Q‐TOF mass and operated in the negative ion mode. Good separation was performed on a ZORBAX Eclipse Plus C18 column with a gradient elution at a flow rate of 0.2 ml/min. A total of 92 compounds in KXS were identified or tentatively characterized based on their exact molecular weights, fragmentation patterns, and literature data. A total of 26 compounds including 23 prototype components and three metabolites were identified in rat plasma after oral administration of KXS. Then, 16 major bioactive constituents were chosen as the benchmark substances to evaluate the quality of KXS. Their quantitative analyses were performed by a triple quadrupole tandem mass spectrometer (MS/MS) operating in multiple‐reaction monitoring mode(MRM). The analysis was completed with a gradient elution at a flow rate of 0.4 ml/min within 35 min. The simple and fast method was validated and showed good linearity, precision, and recovery. Furthermore, the method was successful applied for the determination of 16 compounds in KXS. All results would provide essential data for identification and quality control of active chemical constituents in KXS. Copyright © 2016 John Wiley & Sons, Ltd.     

气相色谱-单光子电离飞行时间质谱的联用及在柴油组分表征中的应用

建立了一种气相色谱(GC)与单光子电离-飞行时间质谱(SPI-TOF MS)联用(GC/SPI-TOF MS)的分析方法。首先,设计了一种双层套管的传输管用于连接GC与SPI-TOF MS,实现了GC与单光子电离离子源的无缝连接。在此基础上,以n-十五烷标准品和苯/甲苯/二甲苯的标准气为对象,对电离源的重要电压参数进行了优化,得到了纯净的分子离子峰,实现了对各类有机物的快速和准确定性。最后,将该方法用于分析柴油中的挥发性与半挥发性有机物,获得了柴油组分的二维GC×SPI-TOF MS谱图。不需要复杂的谱图解析和数据处理,根据谱图中离子的质荷比(m/z)归纳了柴油的主要成分,包括脂肪烃、芳香烃和含量很低的苯并吡咯等含氮化合物;根据色谱的保留时间将柴油中的同分异构体区分开来。结果表明GC/SPI-TOF MS法是一种简单、有效的分析方法,非常适于柴油及复杂环境样品等的分析表征。