含全碳和多炔阴离子配体的银簇化合物的超分子组装及其结构研究

总结了我们在新型炔银簇化合物研究方面的最新进展. 这些化合物分为以下几种类型: (a)1,3,5-己三炔基和1,3,5,7-辛四炔基; (b)1,5-己二炔基; (c)经膦酸配体组装的乙炔基和烷基乙炔基; (d)苯乙炔基、 环烷基乙炔基和含氮杂环基乙炔基结构单元的银簇化合物; (e)经不同类型的银-碳配位键连接, 并进一步通过分子内/分子间作用力稳固其配位网络的炔银化合物. 我们还进一步讨论了溶剂、 配体的位阻大小和辅助配体类型对于多维配位网络结构的影响.     

葛花中异黄酮类化学成分的RRLC-Q-TOF MS/MS研究

采用快速分离液相色谱-四极杆-飞行时间质谱联用(RRLC-Q-TOF MS/MS)技术对葛花中的异黄酮类成分进行了研究, 得到了相应化合物的保留时间、 分子量及结构信息. 研究结果表明, 葛花水提取液的主要成分为异黄酮类及其苷类化合物, 并含有皂苷类和酚类化合物. 在葛花中首次发现同属植物狐尾葛特有化合物Alopecuroides A和葛根中的化合物3'-甲氧基大豆苷元-7-O-甲醚. 讨论了异黄酮类化合物的质谱碎裂途径及规律.     

含全碳和多炔阴离子配体的银簇化合物的超分子组装及其结构研究（英文）

总结了我们在新型炔银簇化合物研究方面的最新进展.这些化合物分为以下几种类型:(a)1,3,5-己三炔基和1,3,5,7-辛四炔基;(b)1,5-己二炔基;(c)经膦酸配体组装的乙炔基和烷基乙炔基;(d)苯乙炔基、环烷基乙炔基和含氮杂环基乙炔基结构单元的银簇化合物;(e)经不同类型的银-碳配位键连接,并进一步通过分子内/分子间作用力稳固其配位网络的炔银化合物.我们还进一步讨论了溶剂、配体的位阻大小和辅助配体类型对于多维配位网络结构的影响.     

带有不同端炔保护基团的新型苯乙炔树枝状化合物的合成

以1,3,5-三溴苯为原料,通过Sonogashira反应,设计并合成了两种带有不同端炔保护基团的1,3,5-取代的苯乙炔树枝状化合物:1,3,5-三[3-(3-甲基-3-羟基-1-丁炔基)-5-(三异丙基硅乙炔基)苯基乙炔基]苯(B1)和1,3,5-三[3-(三甲基硅乙炔基)-5-(三异丙基硅乙炔基)苯基乙炔基]苯(B2),并对合成路线的选择进行了比较和讨论.用1H NMR,13C NMR,质谱,元素分析等表征手段确认了中间体及最终产物的结构.这两种苯乙炔树枝状化合物各自带有两类不同的周边端炔保护基团,可根据其脱保护条件的不同引入不同的周边功能基团.     

新型丁二炔-二酰胺大环化合物的合成及与TTF和DNP在溶液中的络合行为

由三甘醇和四甘醇出发,经炔丙基烷基化、Mitsunobu反应和Eglinton偶联反应3步合成了2个含均苯四甲酸二酰亚胺结构单元以及丁二炔结构单元的大环化合物,关环产率分别为81%和85%.大环化合物及中间体的化学结构经核磁共振氢谱、碳谱、低分辨质谱、高分辨质谱或元素分析等确认.通过氘代丙酮中1HNMR实验以及氯仿中紫外滴定实验研究了这类大环化合物与客体分子四硫富瓦烯(TTF)和1,5-二甲氧基萘(DNP)在溶液中的相互作用,结果发现,大环化合物的核磁化学位移及紫外光谱均发生变化.通过得到的主-客体间的络合常数可知,此类新型大环化合物与TTF和DNP之间有一定的络合作用.     

AgOTf催化的一锅法合成1-(1H-吡咯-3-基)-1,2-二氢异喹啉衍生物

Ag OTf催化的三组分2-炔基苯甲醛,胺和吡咯"一锅法"高效合成了一类吡咯取代的1,2-二氢异喹啉化合物,合成了13个未见文献报道的1,2-二氢异喹啉化合物,通过红外(IR)、核磁共振氢谱、碳谱以及高分辨质谱对合成的化合物进行结构表征.     

超高效液相色谱-四极杆-飞行时间质谱定性研究茶叶籽中的酚类化合物

采用超高效液相色谱(UHPLC)-四极杆-飞行时间质谱(Q-TOF/MS)技术定性分析茶叶籽中的酚类化合物。茶叶籽样品经乙醇水溶液提取后经反相色谱分离,通过Q-TOF/MS进行化合物的鉴定。基于山茶属及相关植物化学组成的文献,建立了一个含有106种酚类化合物的数据库。对UHPLC-Q-TOF/MS采集得到的一级质谱数据进行数据库检索,然后对检索到的化合物色谱峰进行二级质谱扫描,根据得到的碎片离子推断化合物的结构。初步推断出茶叶籽提取物中的24种酚类化合物,包括13种酚酸类、4种儿茶素类和7种黄酮类化合物,并通过与标准品比对,进一步确证了这些化合物。结果表明UHPLC-Q-TOF/MS技术可以用于对茶叶籽中酚类化合物进行快速、准确、可靠的定性分析,促进新化合物的发现与鉴别。     

利用三级质谱与二级质谱匹配策略鉴定丹参中酚酸类成分

多级质谱信息(MS/MS information)可提供鉴定化合物结构的关键线索,多级质谱(MS/MS)图谱到结构的转换(MS/MS spectrum to structure)是精准鉴定化合物结构的重要过程。本研究提出了化合物的三级质谱(MS³)图谱与其结构单元的二级质谱(MS²)图谱匹配策略,实现了化合物结构的精准鉴定。首先,利用三重四极杆复合线性离子阱质谱仪(Qtrap-MS)的双碰撞池,采集酯类化合物酯基质谱裂解产生的特征碎片离子(c^–和y^–)在线性离子阱(LIT)内经第二次碰撞诱导解离(Collision-induced dissociation, CID)后的MS³图谱,并同步采集其结构单元化合物([M–H]^–)在LIT中经碰撞诱导解离后的MS²图谱,结果表明,酯类化合物特征碎片离子的MS³图谱与结构单元化合物的MS²图谱匹配。最后,采用HR-MS/MS对丹参总酚酸(Total ...     

液相色谱-串联质谱法测定果蔬中4种新型卵菌纲杀菌剂残留

建立了蔬菜和水果中噻唑菌胺、苯噻菌胺、氟啶酰菌胺和双炔酰菌胺4种新型卵菌纲杀菌剂的分散固相萃取-液相色谱-串联质谱检测方法.样品经乙腈均质提取,混合使用乙二胺-N-丙基硅烷(PSA)和ODSC18-N两种基质分散净化剂净化,采用液相色谱-三重四级杆串联质谱(LC/MS/MS)检测.实验通过空白基质溶液稀释标准建立校正的...     

1,7-二芳基-1,6-庚二炔化合物的合成

1,6-庚二炔是有机合成的重要中间体,我们以Pd Cl2/Cu I为催化剂,NEt3为碱,在四氢呋喃溶剂中实现了二炔与卤代芳烃Sonogashira偶联反应,合成了10个1,7-二芳基-1,6-庚二炔化合物,该方法也适用于二卤芳烃如1,8-二碘萘与末端炔偶联合成1,8-二苯乙炔基萘.所有合成的目标化合物结构经1H NMR,13C NMR,IR和MS表征.     

The Study on the Noncovalent Complexes of Silver Ion with Xanthone Diglycosides by Electrospray Ionization with Tandem Mass Spectrometry

Xanthones are one species of C6-C1-C6 structure flavonoids, showing the various pharmacological activities, such as hepatocytes1 and antioxidative2 etc.. As one of the softest ionization technique, atmospheric pressure ionization mass spectrometry (API-MS…     

De novo analysis of electron impact mass spectra using fragmentation trees

The automated fragmentation analysis of high resolution EI mass spectra based on a fragmentation tree algorithm is introduced. Fragmentation trees are constructed from EI spectra by automated signal extraction and evaluation. These trees explain relevant fragmentation reactions and assign molecular formulas to fragments. The method enables the identification of the molecular ion and the molecular formula of a metabolite if the molecular ion is present in the spectrum. These identifications are independent of existing library knowledge and, thus, support assignment and structural elucidation of unknown compounds. The method works even if the molecular ion is of very low abundance or hidden under contaminants with higher masses. We apply the algorithm to a selection of 50 derivatized and underivatized metabolites and demonstrate that in 78% of cases the molecular ion can be correctly assigned. The automatically constructed fragmentation trees correspond very well to published mechanisms and allow the assignment of specific relevant fragments and fragmentation pathways even in the most complex EI-spectra in our dataset. This method will be very helpful in the automated analysis of metabolites that are not included in common libraries and it thus has the potential to support the explorative character of metabolomics studies.     

Negative electrospray ionization mass spectrometry: a method for sequencing and determining linkage position in oligosaccharides from branched hemicelluloses

Xyloglucans of apple, tomato, bilberry and tamarind were hydrolyzed by commercial endo β‐1‐4‐D‐endoglucanase. The xylo‐gluco‐oligosaccharides (XylGos) released were separated on CarboPac PA 200 column in less than 15 min, and, after purification, they were structurally characterized by negative electrospray ionization mass spectrometry using a quadrupole time‐of‐flight (ESI‐Q‐TOF), a hybrid linear ion trap (LTQ)/Orbitrap and a hybrid quadrupole Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometers. In order to corroborate the fragmentation routes observed on XylGos, some commercial galacto‐manno‐oligosaccharides (GalMOs) and glucurono‐xylo‐oligosaccharides were also studied. The fragmentation pathways of the ionized GalMos were similar to those of XylGos ones. The product ion spectra were mainly characterized by prominent double cleavage (D) ions corresponding to the entire inner side chains. The directed fragmentation from the reducing end to the other end was observed for the main glycosylated backbone but also for the side‐chains, allowing their complete sequencing. Relevant cross‐ring cleavage ions from ^0,2X_j ‐type revealed to be diagnostic of the 1‐2‐linked‐ glycosyl units from XylGos together with the 1‐2‐linked glucuronic acid unit from glucuronoxylans. Resonant activation in the LTQ Orbitrap allowed not only determining the type of all linkages but also the O‐acetyl group location on fucosylated side‐chains. Moreover, the fragmentation of the different side chains using the MSⁿ capabilities of the LTQ/Orbitrap analyzer also allowed differentiating terminal arabinosyl and xylosyl substituents inside S and U side‐chains of XylGos, respectively. The CID spectra obtained were very informative for distinction of isomeric structures differing only in their substitution pattern. These features together makes the fragmentation in negative ionization mode a relevant and powerful technique useful to highlight the subtle structural changes generally observed during the development of plant organs such as during fruit ripening and for the screening of cell wall mutants with altered hemicellulose structure. Copyright © 2015 John Wiley & Sons, Ltd.     

Sequential Analysis of α-Glucooligosaccharides with α-(1→4) and α-(1→6) Linkages by Negative Ion Q-TOF MS/MS Spectrometry

Negative ion Q-TOF MS/MS spectra are shown to be very useful for sequential analysis of the glycosidic linkage in the α-gluco-oligosaccharides (DP 3-6) derived from an amylopectin molecule. The composition of the fragmentation ions generated from these compounds enabled us to distinguish two kinds of glycosidic linkage, α-(1→4) and α-(1→6), at same time to determine the glucose sequence from the reducing end of the oligosaccharide.     

MS／MS Study of Deoxydinucleotides Bound with Alkali—metal Ions Using ESI—MS

Positive ion ESI-MS has been used to examine the fragmentation pathways of the complex ions of deoxydinucleotides with H^ ,Na^ ,K^ by LCQ instrument.It had been found that the dissociation Varied markedly due to the differences of the base sequence.The alkali-metal ion binding site and the charcaterization of dissociation were directed by the size of metal ion,the sequesce of base and the steric hindrance.     

A non-covalent dimer formed in electrospray ionisation mass spectrometry behaving as a precursor for fragmentations

A non-covalent-bonded dimer was detected in the positive ion electrospray ionisation (ESI) mass spectra of a synthetic impurity. In tandem mass spectrometry (MS/MS) experiments using collision-induced dissociation (CID), the ion was found to behave as a [M+H]+-type precursor ion for fragmentation until MS5. The dimer was probably formed through multi-hydrogen bonds over a proton bridge. When the fragmentation occurred at the center of the bridge, the dimer was broken apart to give monomer fragments at MS6. However, no corresponding deprotonated dimer [2M-H]- was found in the negative ion ESI spectra. The dimer was extremely stable, and it could still be observed when a fragmentation voltage of up to 50 V was applied in the ionisation source. The formation of the non-covalent dimer was also found to be instrument-dependent, but independent of sample concentration. Accurate mass measurements of the [2M+H]+ and [M+H]+ ions, and their MSn product ions, provided the basis for assessing the fragmentation mechanism proposed for [2M+H]+. The fragmentation pathway was also illustrated for the deprotonated molecule [M-H]-.     

Peculiarities of the mass-spectrometric fragmentation of (3-quinuclidinyl)diaryl(heteryl)carbinols

The principal pathways of the fragmentation of (3-quinuclidinyl)diaryl(heteryl)carbinols that involve cleavage of the quinudidine-carbinol C-C bond and the bridge bond in the quinuclidine ring containing the substituent were studied. In addition to the indicated fragmentation pathways, fragmentation proceeding with opening of the bridge bond of quinuclidine that does not contain a substituent is observed. The rearrangement of the molecular ion that precedes fragmentation via the indicated pathway is examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1078–1082, August, 1990.The authors thank V. G. Zhil'nikov (A. N. Severtsov Institute of the Evolutionary Morphology and Ecology of Animals) for recording the high-resolution mass spectra.     

Analysis of strychnos alkaloids using electrospray ionization Fourier transform ion cyclotron resonance multi-stage tandem mass spectrometry

The fragmentations of four strychnos alkaloids have been investigated by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) in the positive ion mode. Experiments using multi-stage tandem mass spectrometry (ESI-FT-ICR-MSn) allowed us to obtain precise elemental compositions of product ions at high mass resolution. The experimental data demonstrated that the nitrogen bridge and the coordinated oxygen atom on the nitrogen bridge in the alkaloid compounds were the active sites in the MS2 fragmentations. The loss of CH3 or the OCH3 group in those alkaloids, which have an OCH3 substituent, was the dominant fragmentation mode in the MS3 fragmentations. Logical fragmentation schemes for strychnos alkaloids have been proposed and these should be useful for the identification of these compounds.     

一些双电荷离子的气相碎裂反应

借助质量分析离子动能谱和串联质谱研究了由电子轰击产生的双电荷离子的单分子亚稳碎裂及碰撞诱导分解过程,讨论了两种实验方法导致的差别因素.此外,根据质量分析离子动能谱提供的双电荷离子电荷分离反应的动能释放值计算了两电荷中心间距的最小值,以判别按不同电荷分离方式碎裂的双电荷离子的过渡态结构.     

Identification of lignans by liquid chromatography-electrospray ionization ion-trap mass spectrometry

The fragmentation pattern of 30 compounds belonging to different classes of the lignan family was studied by liquid chromatography-electrospray ionization ion-trap mass spectrometry. On the basis of the observed fragmentation patterns, identification of different types of lignans was achieved. For example, dibenzylbutyrolactone lignans showed a characteristic fragmentation pathway by the loss of 44 Da (CO(2)) from the lactone moiety, whereas dibenzylbutanediols showed a loss of 48 Da by a combined loss of formaldehyde and water from the 1,4-butanediol moiety. Lignan glycosides readily lost the sugar residue to give the parent lignan as their primary product ion. In addition, several compound-specific fragmentations were observed and used for identification of individual compounds.A versatile method for analyses of lignans was developed using LC separation on a C8 column followed by fragmentation and detection of ions produced in the ion trap.