利用质谱－质谱法进行稠环芳烃化合物的结构解析

应用（ＥＩ）ＭＳ／Ｍｓ法研究了吡啶并苯并蒽酮以及苯并苯并蒽酮类异构体的裂解方式及其与结构之间的相关性，探讨了不同异构体中由Ｍ￣（ｉ＋）产生的［Ｍ－Ｈ］＋、［Ｍ－ＨＣＮ］＋、［Ｍ－ＣＯＨ］＋、［Ｍ－ＣＯ］（ｉ＋）、［Ｍ－（ＣＯ＋２Ｈ）］（ｉ＋）以及［Ｍ－（ＣＯ＋ＨＣＮ）］（ｉ＋）（ｉ＝１，２）等１价及２价离子在ＭＳ／ＭＳ－ＣＩＤ谱上的强度差异和裂解方式，发现是否含有氮原子以及氮原子和苯环位置的差异，是支配这类化合物在ＣＩＤ谱中裂解行为的主要因素。研究结果表明，２价离子的ＣＩＤ谱能更有效地反映这类杂环芳烃异构体之间的结构差异和裂解特性。     

氯代甲苯异构体双电荷离子电子捕获诱导解离谱研究

研究了４种Ｃ７Ｈ７Ｃｌ异构体在７０ｅＶ电子轰击下产生的［Ｃ７Ｈ７Ｃｌ］＾２＋、［Ｃ７Ｈ６Ｃｌ］＾２＋．和［Ｃ７Ｈ５Ｃｌ］＾２＋ ３种双电荷离子的电子捕获诱导解离（ＥＣＩＤ）反应。分子离子的ＥＣＩＤ反应明显的邻位效应，表明其结构仍保持中性分子的结构特征；而由各异构体产生的［Ｃ７Ｈ６Ｃｌ］＾２＋．和［Ｃ７Ｈ５Ｃｌ］＾２＋离子异构化成同一结构。３种双电荷离子ＥＣＩＤ反应的产物与离子所带电子的奇偶性有关，     

利用质谱—质谱法进行稠环芳烃化合物的结构解析

应用（ＥＩ）ＭＳ／ＭＳ法研究了吡啶并苯并蒽酮以及苯并苯并蒽酮类异构体的裂解方式及其与结构之间的相关性，探讨了不同异构体中由Ｍ＾ｉ＋产生的［Ｍ－Ｈ］＾＋、［Ｍ－ＨＣＮ］＾＋、［Ｍ－ＣＯＨ］＾＋、［Ｍ－ＣＯ］＾ｉ＋、［Ｍ－（ＣＯ＋２Ｈ）］＾ｉ＋以及［Ｍ－（ＣＯ＋ＨＣＮ）］＾ｉ＋（ｉ＝１，２）等１价及２价离子在ＭＳ／ＭＳ－ＣＩＤ谱上的强度差异和裂解方式，发现是否含有氮原子以及氮原子和苯环位置的差异，是支     

C60的胺加成反应和电喷雾电离质谱（ESI—MS）检测

报道了Ｃ６０与１，３－丙二胺和Ｎ，Ｎ－二甲基－１，３－丙二胺的加合反应，反应产物未经预先离子化处理直接用ＥＳＩ－ＭＳ进行检测。由于反应产物从甲苯溶液中析出，避免了生成多胺基加合物，产物以单加成物为主。当加合反应在空气氛下进行时，有加合氧的产物Ｃ６０Ｏｎ（ＮＨ２－ＣＨ２ＣＨ２ＣＨ２ＮＲ２）ｍ（Ｒ＝Ｈ，ＣＨ３）存在。实验发现：Ｎ，Ｎ－二甲基－１，３－丙二胺比１，３－丙二胺更容易与Ｃ６０发生多胺基加成和     

HC60CH2C6H5的结构及光谱的理论研究

用ＩＮＤＯ系列方法研究了由Ｃ６０＾２－制备的衍生物ＨＣ６０ＣＨ２Ｃ６Ｈ５的结构和ＵＶ光谱。结果表明，六元环上的１，２－异构体具有Ｃｓ对称性，１，４－异构体具有Ｃ１对称性。以优化构型为基础，计算两种加成产物的ＵＶ光谱，表明１，２－异构体的特征吸收与实验值相符；同时，对１，４－异构体的ＵＶ光谱进行了理论预测，对电子跃迁进行了理论指认，并分析了光谱红移的原因。     

四卤合金属酸十八铵的X射线光电子能谱和质谱研究

利用Ｘ射线光电子能谱（ＸＰＳ）、质谱（ＭＳ）方法分别研究了１５种四卤合金属酸十八铵化合物。通过ＸＰＳ讨论了这些化合物的金属、卤素、氮原子的核心结合能的化学位移。根据Ｐａｕｌｉｎｇ电负性讨论了这些数据和计算电荷的关系。讨论了配位体Ｘ（Ｃｌ、Ｂｒ、Ｉ）、中心离子Ｍ（Ｚｎ、Ｃｏ、Ｃｕ、Ｍｎ、Ｃｄ）和质子化十八胺Ｃ１８Ｈ３７ＮＨ＋３的关系。通过ＭＳ讨论了在电子轰击、化学电离条件下，四碘合钴酸十八铵、四氯合钴酸十八铵加热分解产生的Ｃ１８Ｈ３７ＮＨ＋３（ｍ／ｚ２７０）离子碰撞诱导解离谱（ＣＩＤＭＳ）。通过低碰撞能量范围（０～１０ｅＶ），多次碰撞条件下观察到的远电荷碎裂反应，得出该离子比直接由正十八胺质子化得到的离子具有较高的内能     

两种氨基酸中[MH-CO2H2]+的特征质谱碎裂

运用低能碰撞诱导解离（ＣＩＤ）研究了电子轰击（ＥＩ）、快原子轰击（ＦＡＢ）电离条件下质子化亮氨酸与异亮氨酸解离产生亚稳离子「ＭＨ－ＣＯ２Ｈ２」的单分子质谱破裂，二种异构体呈现出了各自不同的解离特征，根据ＣＩＤ的特征碎片离子和氘代同位素标记实验，提出了其破裂过程的存在离子／中性（碎片）复合物中间体机理，并对有关的特征离子的形成进行了讨论。     

1,2-双(四甲基环戊二烯基)四甲基二硅烷与六羰基钼的反应

１,２－双（四甲基环戊二在）四甲基二硅烷与正丁基锂作用生成（四甲基二硅撑）双（四甲基环戊二烯基负离子盐）,后者随即与六羰基钼反应形成１,１＇－（四甲基二硅撑）双（四甲基环戊二烯基钼负离子盐）－－（Ｍｅ２ＳｉＳｉＭｅ２）〖Ｍｅ４ＣｐＭｏ（ＣＯ）３－Ｌｉ＾＋〗２（１）,１与冰醋酸作用,随即分别与ＣＣＩ４,ＮＢＳ及Ｉ２反应,生成相应的钼卤化合物（Ｍｅ２ＳＩＳｉＭｅ２）〖Ｍｅ４ＣｐＭｏ（ＣＯ）３Ｘ〗２〖Ｘ     

参考答案

参考答案单元练习一参考答案及提示一、二、三、选择题四、２８．Ｏ２＋２ＫＩ＋Ｈ２Ｏ→２ＫＯＨ＋Ｉ２＋Ｏ２;Ｉ２,ＫＯＨ２９．１０００ｍ／１６ａ;１４．Ｚａ／ｂ;３０．ＣＨ４;Ｈ２;１：２;因为Ｃ：Ｈ＝３／１２：１＝１：４,ＣＨ４分子里Ｃ与Ｈ的质量比为３...     

[Fe（CN）6]^4—还原trans—[Co（en）2（ImH02]^3＋的电子转移反应 …

在不同的温度下，考察了六氰合铁配阴离子「Ｆｅ（ＣＮ）５」＾４－还原ｔｒａｎｓ－「Ｃｏ（ｅｎ）２（ＩｍＨ０２」＾３＋的反应动力学。结果表明，反应遵循Ｈ．Ｔａｕｂｅ所提出的外配位界电子传递机理。在２５℃，Ｉ＝０．５ｍｏｌ．Ｌ＾－１，ｔｒａｎｓ－「Ｃｏ（ｅｎ）２（ＩｍＨ）２」＾３＋／「Ｆｅ（ＣＮ）６」＾４－反应体系的前驱配合物离子对形成常数为Ｑ１ｐ＝９８．９ｍｏｌ＾－１．Ｌ，电子转移速率常数为Ｋｍ＝１．     

Electron and chemical ionization mass spectrometry in stereochemical differentiation of some 1,3-amino alcohols

Mass spectral fragmentations of two cyclopentane, eight cyclohexane and four norbornane/one 1,3-amino alcohols were studied under electron ionization (EI) by low-resolution, high-resolution, metastable ion analysis and collision-induced dissociation (CID) techniques. All stereoisomeric compounds gave rise to identical 70 eV EI mass spectra. However, the spectra of positional isomers clearly differed. The main fragmentation pathway for the saturated compounds began as an α-cleavage reaction with respect to the nitrogen atom. For the norbornene compounds a retro-Diels—Alder reaction was favoured. Relative to the aminomethyl-substituted compounds the fragmentation patterns for the compounds having the amino group connected directly to the ring were more complicated. The chemical ionization (CI) mass spectra were recorded using ammonia, isobutane, methane, dichloromethane and acetone as reagent gas. From the norbornane/One compounds the di-exo isomers decomposed more easily than the di-endo isomers with most of the reagent gases used. Differences between stereoisomers were observed directly only under methane CI. The decomposition products of the [M + H]⁺ ions generated under ammonia and isobutane CI were studies by recording their CID mass spectra. These spectra allowed the differentiation of the stereoisomers, at least to some extent.     

Electrospray Ionization Mass Spectra of Amino Acid Methyl Ester 5′-Phosphoramidates of 2′,3′-Isopropylideneuridine

IntroductionIn recent years, nucleosides and their analogshave been extensively studied as potential anticancerand antiviral agents[1—3]. For example, several purineand pyridine bases and nucleoside analogs are used aschemotherapeutic arsenal. For their biological activity,these analogs should be intracellularly metabolized to5′-mononucleotides by kinase-mediated phosphoryla-tion[4]. To overcome the problemof drug resistance andto improve the membrane penetration, a series of aminoacid phosp…     

Electrospray Ionization Mass Spectra of Amino Acid Methyl Ester 5 ＇-Phosphoramidates of 2＇, 3＇-Isopropylideneuridine

Amino acid methyl ester phosphates were synthesized and determined by using positive-ion mode dectrospmy ionization mass spectrometry（ESIMS） in combination with multistage tandem mass spectrometry. The fragmentation pathways were investigated, and it was observed that most fragment ions contained the phosphoryl group. It was interesting to observe that the fragmentation pathways of the protonated molecule show some differences when compared with those of the sodium ion adduct. The methoxy group of amino acid methyl ester can migrate from the carbonyl group to the phosphoryl group in the sodium ion adduct.     

Electrospray Ionization Mass Spectra of Amino Acid Methyl Ester 5′-Phosphoramidates of 2′,3′-Isopropylideneuridine

Amino acid methyl ester phosphates were synthesized and determined by using positive-ion mode electrospray ionization mass spectrometry(ESIMS) in combination with multistage tandem mass spectrometry. The fragmentation pathways were investigated, and it was observed that most fragment ions contained the phosphoryl group. It was interesting to observe that the fragmentation pathways of the protonated molecule show some differences when compared with those of the sodium ion adduct. The methoxy group of amino acid methyl ester can migrate from the carbonyl group to the phosphoryl group in the sodium ion adduct.     

Derivatization of protonated peptides via gas phase ion—molecule reactions with acetone

The protonated [M + H]+ ions of glycine, simple glycine containing peptides, and other simple di- and tripeptides react with acetone in the gas phase to yield [M + H + (CH3)2CO]+ adduct ion, some of which fragment via water loss to give [M + H + (CH3)2CO - H2O]+ Schiff's base adducts. Formation of the [M + H + (CH3)2CO]+ adduct ions is dependent on the difference in proton affinities between the peptide M and acetone, while formation of the [M + H + (CH3)2CO - H2O]+ Schiff's base adducts is dependent on the ability of the peptide to act as an intramolecular proton "shuttle." The structure and mechanisms for the formation of these Schiff's base adducts have been examined via the use of collision-induced dissociation tandem mass spectrometry (CID MS/MS), isotopic labeling [using (CD3)2CO] and by comparison with the reactions of Schiff's base adducts formed in solution. CID MS/MS of these adducts yield primarily N-terminally directed a- and b-type "sequence" ions. Potential structures of the b1 ion, not usually observed in the product ion spectra of protonated peptide ions, were examined using ab initio calculations. A cyclic 5 membered pyrrolinone, formed by a neighboring group participation reaction from an enamine precursor, was predicted to be the primary product.     

Differentiation of a pair of diastereomeric tertiarybutoxycarbonylprolylproline ethyl esters by collision-induced dissociation of sodium adduct ions in electrospray ionization mass spectrometry and evidence for chiral recognition by ab initio molecular orbital calculations

The fragmentation of the sodium adduct ions for tert-butoxycarbonyl-L-prolyl-L-proline ethyl ester (Boc-L-Pro-L-Pro-OEt) was compared with that for Boc-D-Pro-L-Pro-OEt in positive-ion electrospray ionization (ESI) mass spectrometry. In the collision-induced dissociation (CID) mass spectra of the [M + Na](+) ions, the abundance of the [M + Na - C(CH(3))(3) + H](+) ion, which is due to the loss of a tert-butyl group from the [M + Na](+) ion for Boc-D-Pro-L-Pro-OEt, was about eight times higher than that for Boc-L-Pro-L-Pro-OEt. In addition, in the CID spectra of the sodium adduct fragment ion ([M + Na - Boc + H](+)), the abundance of the [M + Na - Boc - prolylresidue + H](+) ion, which is due to the loss of prolyl residue from the [M + Na - Boc + H](+) ion for Boc-L-Pro-L-Pro-OEt, was about five times higher than that for Boc-D-Pro-L-Pro-OEt. These results indicate that Boc-L-Pro-L-Pro-OEt was distinguished from Boc-D-Pro-L-Pro-OEt by the CID mass spectra of the sodium adduct ions in ESI mass spectrometry. The optimized geometries of the [M + Na](+) and the [M + Na - Boc + H](+) ions calculated by ab initio molecular orbital calculations suggest that the chiral recognition of these diastereomers was due to the difference of the orientation of a sodium ion to the oxygen and nitrogen atoms in dipeptide derivatives, and to the difference of the total energies between them.     

Complementary structural information of positive- and negative-ion MSn spectra of glycopeptides with neutral and sialylated N-glycans

Positive- and negative-ion MSn spectra of chicken egg yolk glycopeptides binding a neutral and a sialylated N-glycan were acquired by using electrospray ionization linear ion trap time-of-flight mass spectrometry (ESI-LIT-TOFMS) and collision-induced dissociation (CID) with helium as collision gas. Several characteristic differences were observed between the positive- and negative-ion CID MSn (n = 2, 3) spectra. In the positive-ion MS2 spectra, the peptide moiety was presumably stable, but the neutral N-glycan moiety caused several B-type fragmentations and the sialylated N-glycan almost lost sialic acid(s). In contrast, in the negative-ion MS2 spectra, the peptide moiety caused several side-chain and N-glycan residue (e.g., N-acetylglucosamine (GlcNAc) residue) fragmentations in addition to backbone cleavages, but the N-glycan moieties were relatively stable. The positive-ion MS3 spectra derived from the protonated peptide ion containing a GlcNAc residue (203.1 Da) provided enough information to determine the peptide amino-acid sequence including the glycosylation site, while the negative-ion MS3 spectra derived from the deprotonated peptide containing a 0,2X1-type cross-ring cleavage (83.1 Da) complicated the peptide sequence analysis due to side-chain and 0,2X1 residue related fragmentations. However, for the structural information of the N-glycan moiety of the glycopeptides, the negative-ion CID MS3 spectra derived from the deprotonated 2,4A6-type cross-ring cleavage ion (neutral N-glycan) or the doubly deprotonated B6-type fragment ion (sialylated N-glycan) are more informative than are those of the corresponding positive-ion CID MS3 spectra. Thus, the positive-ion mode of CID is useful for the analyses of peptide amino-acid sequences including the glycosylation site. The negative-ion mode of CID is especially useful for sialylated N-glycan structural analysis. Therefore, in the structural analysis of N-glycopeptides, their roles are complementary.     

Collisionally-induced dissociation of substituted pyrimidine antiviral agents: Mechanisms of ion formation using gas phase hydrogen/deuterium exchange and electrospray ionization tandem mass spectrometry

ESI and CID mass spectra were obtained for four pyrimidine nucleoside antiviral agents and the corresponding compounds in which the labile hydrogens were replaced by deuterium using gas-phase exchange. The number of labile hydrogens, x, was determined from a comparison of ESI spectra obtained with N(2) and with ND(3) as the nebulizer gas. CID mass spectra were obtained for [M + H](+) and [M - H](-) ions and the exchanged analogs, [M(D(x)) + D](+) and [M(D(x)) - D](-), produced by ESI using a SCIEX API-III(plus) mass spectrometer. Protonated pyrimidine antiviral agents dissociate through rearrangement decompositions of base-protonated [M + H](+) ions by cleavage of the glycosidic bonds to give the protonated bases with a sugar moiety as the neutral fragment. Cleavage of the glycosidic bonds with charge retention on the sugar moiety eliminates the base moiety as a neutral molecule and produces characteristic sugar ions. CID of protonated pyrimidine bases, [B + H](+), occurs through three major pathways: (1) elimination of NH(3) (ND(3)), (2) loss of H(2)O (D(2)O), and (3) elimination of HNCO (DNCO). Protonated trifluoromethyl uracil, however, dissociates primarily through elimination of HF followed by the loss of HNCO. CID mass spectra of [M - H](-) ions of all four antiviral agents show NCO(-) as the principal decomposition product. A small amount of deprotonated base is also observed, but no sugar ions. Elimination of HNCO, HN(3), HF, CO, and formation of iodide ion are minor dissociation pathways from [M - H](-) ions.     

Dissociation of deprotonated microcystin variants by collision-induced dissociation following electrospray ionization

Microcystins (MC) are a family of hepatotoxic cyclic heptapeptides produced by a number of different cyanobacterial species. Considering the recent advances in the characterization of deprotonated peptides by mass spectrometry, the fragmentation behavior of four structurally related microcystin compounds was investigated using collision-induced dissociation (CID) experiments on an orbitrap mass spectrometer. It is demonstrated in this study that significant structural information can be obtained from the CID spectra of deprotonated microcystins. A predominant ring-opening reaction at the isoMeAsp residue, as well as two major complementary fragmentation pathways, was observed, reducing the complexity of the product ion spectra in comparison with spectra observed from protonated species. This proposed fragmentation behavior was applied to characterize [Leu(1)]MC-LR from a cyanobacterial cell extract. In conclusion, CID spectra of microcystins in the negative ion mode provide rich structurally informative mass spectra which greatly enhance confidence in structural assignments, in particular when combined with complementary positive ion CID spectra.     

Effect of metal cationization on the low-energy collision-induced dissociation of loganin, epi-loganin and ketologanin studied by electrospray ionization tandem mass spectrometry

The effect of alkali metal and silver cationization on the collision-induced dissociation (CID) of loganin (1), epi-loganin (2) and ketologanin (3) is discussed. Their protonated molecular ions fragment mainly by glycosidic cleavages. The epimeric pairs (1 and 2) show differences in the abundances of the resulting fragment ions. Lithium cationization induces new dissociation pathways such as the retro-Diels-Alder (RDA) fragmentation followed by rearrangement. Unlike the dissociation of protonated molecular ions, the dissociation of lithiated molecules also provides lithiated sugar fragments. The CID of dilithiated molecules is substantially different from that of the monolithiated precursors. RDA reaction appears to be favoured by the presence of the additional lithium atom in the molecule. In addition, other ring cleavages are also induced. The abundances of the various fragment ions are different in the CID spectra of the epimeric pairs. Extensive D labelling and (6)Li labelling experiments confirmed many of the ion structures proposed. The CID spectra of the sodiated ions are generally weaker, although similar to those of the corresponding lithiated species. Higher alkali metal ion (K(+), Rb(+) and Cs(+)) adducts generated only the corresponding metal ions as products of CID. Similar fragmentations were also observed in the CID of the [M + Ag](+) ions of these compounds, the epimeric pairs showing characteristic differences in their CID behaviour. Copyright 2000 John Wiley & Sons, Ltd.