首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
合成了以芴为取代基,P原子为核的一类新型有机膦化合物.此类化合物的HOMO值在-5.35~-5.24eV之间.在二氯甲烷中的最大紫外吸收光谱峰值在313~351nm之间,荧光光谱峰值在334~397nm之间.利用此类小分子与纯聚芴进行掺杂,制作了有机电致发光器件.低HOMO值有机膦化合物的引入有效地降低了聚芴发光器件的开启电压,提高了器件的发光效率.  相似文献   

2.
瓯柑石油醚提取物的GC-MS分析   总被引:2,自引:0,他引:2  
为了研究瓯柑的挥发性成分和脂溶性成分, 采用GC-MS分析法进行分离鉴定, 并用面积归一法确定各成分的质量分数. 从瓯柑果肉石油醚提取物中分离鉴定出11种成分, 占总提取物的97.43%, 其主要成分为(Z, Z)-9, 12-十八碳二烯酸(37.46%)、γ-谷甾醇(22.91%);从瓯柑皮石油醚提取物中分离鉴定出10种成分, 占总提取物的99.79%, 其主要成分为柠檬烯(86.39%).  相似文献   

3.
Five arsenic-resistant freshwater algae which had been isolated from an arsenic-polluted environment were studied for the biotransformation of arsenic compounds accumulated by them from the aqueous phase. The algal cells bioaccumulating arsenic were digested by 2 mol dm?3 NaOH at 95°C, the As? C bonds except for As? CH3 were cleaved by the treatment and the methylated arsenic compounds were reduced to the corresponding arsines by sodium borohydride (hydride generation). The arsines were chromatographically separated on the basis of their boiling-point difference and determined by atomic absorption spectrophotometry. Methylated arsenic compounds were found in all algal cells. The predominant arsenic species in the cells, however, were non-methylated arsenic compounds which were mainly present in the residue of a chloroform–methanol extract. The non-methylated arsenic compounds were found to be not present in the free inorganic arsenic substrate and to be bound strongly with proteins or polysaccharides in the cells. Methylated arsenic compounds were found mainly in the lipid-soluble fractions and the major form was a dimethylarsenic compound. Trimethyl- and monomethyl-arsenic compounds were detected but at very low level. The dimethylarsinic acid was not present in the free form in the lipid-soluble fraction and should be bound with a lipid molecule. It was also found that the accumulation of arsenic by Nostoc occurred only in living cells.  相似文献   

4.
苯并噻唑螺萘并噁嗪类化合物的微波合成与性质   总被引:6,自引:0,他引:6  
以苯并噻唑衍生物、1-亚硝基-2-萘酚为原料,三乙胺为催化剂,无水乙醇为溶剂,采用微波辐射法合成了苯并噻唑螺萘并噁嗪光致变色化合物.通过元素分析,IR,MS,1H NMR对结构进行了表征,并用紫外分光仪研究了溶剂效应和荧光分光光度计研究了荧光效应,结果表明该类化合物具有较好的荧光性能,其开环体的λmax与溶剂的极性常数呈较好的线形相关性.  相似文献   

5.
The synthesis, characterization, and mesomorphic properties of a new type of heteronuclear compounds derived from pyrimidine as core group are reported. These compounds were prepared by condensation reactions of appropriate acetophenones and benzonitriles in the presence of trifluoromethanesulphonic anhydride. They were characterized by 1 H and 13 C NMR spectroscopy and elemental analysis, and their phase transitions characterized and studied by thermal analysis and polarizating microscopy. These compounds exhibit hexagonal columnar (Col h ) phases, as expected for disk-like molecules; the formation of columnar phases was found to be dependent on the numbers of alkoxy side chains attached. For those compounds having the same numbers of flexible side chains attached, the one with a preferred unsymmetric structure exhibited better mesomorphic properties. The observed improved mesomorphic behaviour of these compounds over other similar all-carbon heterocyclic compounds is attributed to the greater polarization of nitrogen atoms in the core ring.  相似文献   

6.
The synthesis, characterization, and mesomorphic properties of a new type of heteronuclear compounds derived from pyrimidine as core group are reported. These compounds were prepared by condensation reactions of appropriate acetophenones and benzonitriles in the presence of trifluoromethanesulphonic anhydride. They were characterized by 1H and 13C NMR spectroscopy and elemental analysis, and their phase transitions characterized and studied by thermal analysis and polarizating microscopy. These compounds exhibit hexagonal columnar (Colh) phases, as expected for disk-like molecules; the formation of columnar phases was found to be dependent on the numbers of alkoxy side chains attached. For those compounds having the same numbers of flexible side chains attached, the one with a preferred unsymmetric structure exhibited better mesomorphic properties. The observed improved mesomorphic behaviour of these compounds over other similar all-carbon heterocyclic compounds is attributed to the greater polarization of nitrogen atoms in the core ring.  相似文献   

7.
A method was developed for the multiple determination of semivolatile organic compounds found in groundwater, river water, seawater, sediment, and soil. Forty standard compounds were determined: n-alkenes, cycloalkanes, aromatic hydrocarbons, and polycyclic aromatic hydrocarbons. The compounds were isolated from water and soil samples by using an essential oil distillator (cyclic steam distillator) with hexane as a solvent. The extract was cleaned by using a silica gel cartridge with an acetone-hexane solution. The compounds were determined by using a gas chromatograph/mass spectrometer with 12 stable isotope-labeled compounds (surrogate compounds). The efficiencies of recoveries from water samples were 80.0-106% for groundwater, 80.1-106% for river water, and 81.2-103% for seawater. The relative standard deviation (RSD) values were 2.05-16.0% for groundwater, 3.22-16.6% for river water, and 4.45-16.0% for seawater. The efficiencies of recoveries from sediment and soil were 71.5-96.4% and 70.1-99.8%, respectively. RSD values ranged from 2.27 to 16.0% for sediment and from 2.12 to 15.1% for soil. Adjustment of recovery efficiencies of standard compounds by using surrogate compounds gave more accurate values. The present study proved that an essential oil distillator provides satisfactory results for multiple determinations of the semivolatile compounds in environmental waters, sediment, and soil.  相似文献   

8.
The collison-induced dissociation of a range of organotin compounds has been examined by tandem (MS–MS) mass spectrometry in order to investigate the potential of the technique for speciation without prior chromatographic separation. Tables of parent–daughte ion relationships are prepared for a group of six closely related compounds. The results obtained are sufficiently characteristic to distinguish between the isolated compounds and to identify the individual components of a simple mixture. This procedure has potential applications for less volatile compounds and for quantitative analysis.  相似文献   

9.
Cultures of the fungus Scopulariopsis brevicaulis were grown in antimony-rich media. Although volatile compounds of other elements were readily detected in the culture headspace, volatile antimony compounds were formed irreproducibly and at only ultratrace levels. In order to monitor the media for nonvolatile methylantimony compounds, a method of sample preparation was developed, based on solid-phase extraction. This enabled the separation of large quantities of soluble inorganic antimony species from trace amounts of organoantimony compounds before speciation by HG–GC–AAS. By this methodology methylated antimony compounds were detected at concentrations of 0.8– 7.1 µg Sbl−1 in all media in which S. brevicaulis was grown in the presence of antimony(III) compounds. These methylantimony species were not detected in any of the nonliving or medium-only controls. Methylated compounds were not detected where S. brevicaulis was grown in the presence of antimony(V) compounds. This is the first study to show that antimony(III) compounds are biomethylated by S. brevicaulis under aerobic-only growth conditions. Copyright © 1998 John Wiley & Sons, Ltd.  相似文献   

10.
The class of antimetabolite chemotherapeutical agents has been used to treat cancers in humans for almost 50 years and gives significant results by binding dihydrofolate reductase (DHFR), a key enzyme in DNA synthesis. Therefore, finding new active compounds inhibiting DNA synthesis through their binding to DHFR is of prime interest. The aim of this work is to describe a protocol designed to study the binding of compounds to DHFR. This screening protocol involves matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) detection of target-bound compounds. Firstly, a screening protocol is developed and proves to be a simple, fast, and specific method to characterize the binding capability of a compound. Secondly, the possibility of determining the relative affinities of DHFR-binding compounds by comparing MALDI-TOFMS data is discussed. A ratio is calculated for a compound X such as R(X) = A.I.(denaturation)(X)/A.I.(direct)(X) (where AI(direct) and AI(denaturation) are the average absolute intensities of a binding compound X before and after denaturation of DHFR). It is shown that by using this protocol, one can characterize the strength of the binding of different compounds. These two strategies are then applied to screen green tea (Camellia sinensis) extracts for DHFR-binding compounds, and epigallocatechin gallate is shown to be an active compound with a relative affinity between those of pyrimethamine and methotrexate.  相似文献   

11.
收集了常见的31种含磷无机化合物和84种含磷有机化合物,首次建立了含磷化合物的核磁共振谱图库,并以此为依据建立了31P NMR技术快速检测洗涤剂中含磷化合物的方法.对洗衣粉、金属清洗剂和除油剂样品进行31P NMR分析,经与31P谱图库比对,可快速确定含磷化合物的结构.结果表明,10种洗衣粉中仅有1种检出含磷化合物,其...  相似文献   

12.
王少芬  魏建谟 《分析化学》2001,29(6):725-730
超临界流体色谱(SFC)在色谱分离过程中能在较低的温度下分析对热不稳定性的化合物,包括金属络合物和金属有机化合物。本文总结了近来文献报道的各种过渡金属、重金属、镧系和锕系以及铅、汞和锡的金属有机化合物的SFC分离,还讨论了SFC检测系统和金属有机化合物的溶解度的测定。  相似文献   

13.
描述了巢湖水中半挥发性有机化合物的提取、测定过程和初步结果。湖水中半挥发性有机化合物的提取采用XAD-2和XAD-4混合树脂富集,用气相色谱-高分辨质谱法测定了所萃取的有机化合物,并给出相应的分子式和结构式。春季湖水中检测到14种有机化合物。  相似文献   

14.
New thermally stable intercalation compounds of graphite were obtained by the further intercalation of a series of organic compounds into graphite nitrate. The stabilization is explained by the formation of hydrogen bonds between the protonated form of the modifying substance and neutral surrounding molecules.  相似文献   

15.
Beckmann rearrangement of the geometrical isomer of 5α-androstanolone oximes gives the 3-aza-17β-hydroxy-A-homo-5α-androstan-4-one and the 4-aza-17β-hydroxy-A-homo-5α-androstan-3-one. These lactams were converted to the corresponding ketones by Jones reagent oxidation. Treatment with hydroxylamine produced the corresponding ketoximes. Beckmann rearrangement of the ketoximes generated the diaza compounds and the corresponding “second order” Beckmann cleavage ω-cyanoolefin. The mixture of the compounds produced, was separated by column chromatography. The structure of the compounds was apparent from spectral data.  相似文献   

16.
Conclusions In combination with HCl or H2O, EtAlCl2 is an active catalyst for alkylation of aromatic compounds by alkenylchlorosilanes, and compounds of boron, titanium, and tin are inactive in this reaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1639–1641, July, 1985.  相似文献   

17.
程春生  李志念  苏金燕  李涛  张宝砚 《有机化学》2005,25(11):1392-1397
N-甲羟胺硫酸盐和芳香族羰基化合物为主要原料合成了一系列不同的1,3-偶极化合物, 并合成了四种不同的单取代苯乙烯. 以该系列1,3-偶极化合物和单取代苯乙烯为主要中间体, 采用1,3-偶极环加成反应合成了一系列异噁唑啉类新化合物. 同时研究了1,3-偶极化合物与单取代烯发生的1,3-偶极环加成反应, 该合成过程为理想的绿色反应, 合成产物是5位取代异噁唑啉. 通过质谱和核磁共振等表征了化合物的化学结构. 同时对系列异噁唑啉类新化合物进行了实验室内植物生物活性的测试, 发现了对植物灰霉病有效的新化合物.  相似文献   

18.
An alternative technique for the isolation and concentration of odorous compounds found in potable water is described. The method currently employed by water authorities is closed-loop stripping with the collection of these substances on a small activated carbon filter. The compounds of interest are then extracted from the carbon using a suitable solvent. The authors offer a multichannel silicone rubber trap as an alternative to the carbon filter. The absorbed compounds are thermally desorbed from the trap, directly on to the gas chromatographic column for analysis by GC-MS, thereby eliminating the solvent extraction step required by the carbon filter. The multichannel silicone rubber trap, producing equivalent results, offers a number of advantages over the carbon filter.  相似文献   

19.
The objective of this work was to develop a procedure for concentrating water-soluble compounds for analysis by gas chromatography using direct aqueous injection. The procedure developed involves concentrating the compound by distillation using an efficient condenser. Recoveries were measured for a variety of compounds. Recoveries of about 90% were obtained for most compounds after a 10- to 20-fold concentration. We conclude that most water-soluble compounds boiling at 100 °C or less can be concentrated 10- to 20-fold using this technique. This concentration will enable these compounds to be determined in aqueous samples at the 10- to 100-ppb level by gas chromatography with direct aqueous injection of the concentrate, and even lower levels using mass spectrometry.  相似文献   

20.
In this paper, the volatile compounds of Schisandra chinensis obtained by different extraction techniques including supercritical fluid extraction (SFE), steam distillation (SD), Soxhlet extraction (SE) and ultrasound-assisted extraction (UAE) were investigated for the first time. The sample preparation procedure for GC-MS analysis of the volatile compounds was optimized and then 37, 45, 27 and 37 compounds were identified in the samples obtained by SFE, SD, SE and UAE methods, respectively. As the therapeutic effect of the traditional Chinese medicine is usually based on multifarious essential components or the combination of them instead of only one component, the volatile compounds were compared in groups with the extracts by SE, SD and UAE. This would be more reasonable to evaluate the effects of an alternative technique to extracting multifarious essential components. Among the identified components in the SFE extract, 32 compounds were the same as that by three conventional methods, accounting for 90.5% of the volatile compounds identified. However, as the volatile compounds were classed into groups, it was easy to see that the Schisandra chinensis oil extracted by SFE was made up largely of aromatics and sesquiterpenoids (52.1 and 27.6%, respectively), with less amounts of monoterpenoids and other compounds, distinguishing SFE from the conventional extractions.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号