219 resultados para Conjugated dienes


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合成了具有大π共轭性的对称型芴类衍生物9,9-二(2-乙基已基)-2,7-(2-(4-甲氧基)苯-2,1-乙烯基)芴(简写为MO-F1u—MO)。通过元素分析、质谱、紫外-可见光谱和红外光谱对其进行了表征。测试了该染料在乙腈、二氯甲烷、四氢呋喃和正己烷4种不同极性溶剂中的线性吸收光谱和单光子荧光谱。结果发现溶剂效应对吸收光谱和荧光光谱表现出不同程度的影响,对产生这些光谱行为的主要原因进行了讨论。

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One- and two-photon absorption properties of a series of fluorene derivatives with symmetrical charge transfer D-IT-D and A-IT-A structural motifs have been theoretically investigated with ZINDO/S method. The optimized structures and the characterization of frontier molecular orbitals were obtained by using AMI calculations. Two-photon absorption properties of molecules have been studied using three-state model. The calculation results have shown that fluorene-thiophene derivatives exhibit larger two-photon absorption cross-section as compared with other studied molecules. To illustrate the results, the crucial effects of thiophene ring on fluorenethiophene derivatives and the net charge changes on the pi-conjugated bridges are analyzed theoretically. (c) 2006 Elsevier B.V. All rights reserved.

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Up-converting phosphor technology (UPT)-based lateral-flow immunoassay has been developed for quantitative detection of Yersinia pestis rapidly and specifically. In this assay, 400 nm up-converting phosphor particles were used as the reporter. A sandwich immumoassay was employed by using a polyclonal antibody against F1 antigen of Y. pestis immobilized on the nitrocellulose membrane and the same antibody conjugated to the UPT particles. The signal detection of the strips was performed by the UPT-based biosensor that could provide a 980 nm IR laser to excite the phosphor particles, then collect the visible luminescence emitted by the UPT particles and finally convert it to the voltage as a signal. V-T and V-c stand for the multiplied voltage units for the test and the control line, respectively, and the ratio V-T/V-C is directly proportional to the number of Y pestis in a sample. We observed a good linearity between the ratio and log CFU/ml of Y pestis above the detection limit, which was approximately 10(4) CFU/mI. The precision of the intra- and inter-assay was below 15% (coefficient of variation, CV). Cross-reactivity with related Gram-negative enteric bacteria was not found. The UPT-LF immunoassay system presented here takes less than 30 min to perform from the sample treatment to the data analysis. The current paper includes only preliminary data concerning the biomedical aspects of the assay, but is more concentrated on the technical details of establishing a rapid manual assay using a state-of-the-art label chemistry. (c) 2006 Elsevier B.V. All rights reserved.

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Many fluorescent probes excited by visible light have been used to assess sperm quality by flow cytometry. Developing a viability evaluation method using UV excited stains would be useful for multiparameter analysis of sperm function. This investigation was conducted to determine the efficacy of Hoechst 33342 (H342) and propidium iodide (PI) dual staining for evaluating rhesus monkey sperm viability through use of flow cytometry and excited by a single UV laser. The results showed that the live cells stained only with H342 strongly correlated with expected sperm viability, and flow cytometric analyses were highly correlated with fluorescence microscopic observation. Using H342/PI/SYBR-14 triple staining method, it was found that the live/dead sperm distributions were completely concordant in both H342/PI and SYBR-14/PI assays. In addition, this dual staining was extended with fluorescein isothiocyanate-conjugated peanut agglutinin (FITC-PNA) to simultaneously analyze viability and acrosome integrity of sperm cryopreserved using two different extenders, TTE and TEST, and indicated that TTE offered better Preservation of plasma and acrosome integrity than TEST Therefore, the H342/PI dual staining provides an accurate technique for evaluating viability of rhesus monkey sperm and should be valuable for multiparameter flow cytometric analysis of sperm function.

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Tin mono-sulphide (SnS) nanoparticles were synthesized by a facile method. Reactions producing narrow size distribution SnS nanoparticles with the diameter of 5.0-10 nm were carried out in an ethylene glycol solution at 150 degrees C for 24 h. Bulk heterojunction solar cells with the structure of indium tin oxide (ITO)/polyethylenedioxythiophene polystyrenesulphonate (PEDOT PSS)/SnS polymer/Al were fabricated by blending the nanoparticles with a conjugated polymer to form the active layer for the first time. Current density-voltage characterization of the devices showed that due to the addition of SnS nanoparticles to the polymer film, the device performance can be dramatically improved, compared with that of the pristine polymer solar cells. (c) 2009 Published by Elsevier B.V.

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Compared to conjugated polymer poly[2-methoxy-5- (3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) solar cells, bulk heterojunction solar cells composed of zinc oxide (ZnO) nanocrystals and MDMO-PPV have a better energy conversion efficiency, However, ultraviolet (UV) light deteriorates the performance of solar cells composed of ZnO and MDMO-PPV. We propose a model to explain the effect of UV illumination on these ZnO:MDMO-PPV solar cells. According to this model, the degradation from UV illumination is due to a decrease of exciton dissociation efficiency, Our model is based on the experimental results such as the measurements of current density versus voltage, photoluminescence, and photocurrent.

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Monomers of methacrylate with various pi -conjugated pendants were designed and prepared in our laboratory, The monomer with suitable end-group was successfully assembled with nano-scale inorganic particles to form an orderly-aligned structure that showed special optical properties, both absorption and emission band were much red-shifted compared with the monomer, A new type of organic/inorganic hybrid materials was obtained by in situ polymerization of the assembly, The hybrid materials could also show special optical properties as the assembly, This might open a new route to tune the emission color.

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In order to understand the relationship between phospholipid molecular structures and their olfactory responses to odorants, we designed and synthesized four phosphatidylcholine analogues with different long hydrocarbon (CH) chains and selected three natural phospholipids with different head-groups. By using interdigital electrodes (IEs) as olfactory sensors (OSs), we measured the responses of the Ifs coated with these seven different lipid membranes to four alcohol vapors in a gas flow system. The Ifs voltage changes were recorded and the voltage-relative saturate vapor pressure (V-P/P degrees) curves were also plotted. It was found that with a methyl (-CH3) placed at the C-8 position in the 18-carbon chain, the olfactory responses could be improved about ten times and with conjugated double bonds (C=C) in the long chains, the sensitivity could be increased by 3 similar to 4 orders of magnitude. As to head-groups, choline is preferred over ethanolamine and serine in phospholipid structures in terms of high olfactory sensitivity: These results are expected to be useful in further designing and manufacturing lipid-mimicking OSs. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.

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Poly(3,4-ethylenedioxythiopliene):poly(styrene sulfonate) (PEDOT:PSS) films have been electrochemically polymerized in situ on ITO glass substrate in boron trifluoride diethyl etherate electrolyte (BFEE). Cyclic voltammograms show good redox activity and stability of the PEDOT films. These films had been directly used to fabricate organic-inorganic hybrid solar cells with the structure of ITO/PEDOT/ZnO:MDMC-PPV/Al. The solar cells made of electrochemically polymerized films exhibit higher energy conversion efficiencies compared with that prepared by the spin-coating method, and the highest value is 0.33%. This in-situ electropolymerized method effectively simplifies fabricating procedures and may blaze a facile and economical route for producing high-efficiency solar cells.

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Recording with both parallel and orthogonal linearly polarized lights, polarization holographic storage in genetic mutant BR-D96N film is reported with both transmission type geometry and reflection type geometry. Polarization properties of diffraction light and scattering light are discussed for two different cases, parallel polarization recording and orthogonal polarization recording. It shows that, compared with recording with parallel polarization lights, orthogonal polarization holography can separate the diffraction light from the scattering noise, therefore improving the signal-to-noise ratio. It also shows that, compared with reconstruction with reference light, reconstruction with phase conjugated wave of the reference light can improve the signal-to-noise ratio of the reconstructed diffraction image, and also the wave-front aberration of the object light introduced by irregular phase object in the optical pass-way can also be corrected effectively, which ensures that the reconstructed diffraction image has a better fidelity. The preliminary angle-multiplexed volume holographic storage multiplexed by transmission type geometry and reflection type geometry is demonstrated in the BR-D96N film. Experiment shows that there is no cross-talk between the two pages of images except for some scattering noises.

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和共轭聚合物相比,单分散共轭齐聚物具有结构确定、易提纯等优点,不仅是建立共轭体系结构与性能关系的最佳模型,而且是一类高纯度光电子材料,还是构造具有规整结构嵌段共聚物和超分子体系的理想构造单元。鉴于基于芴单元的共轭齐聚物与聚合物具有优异的光电性能,引入不同端基能够有效调节共轭齐聚物的性能,本论文以端基官能化齐聚芴为研究对象,设计与合成了具有不同端基结构的系列单分散齐聚芴,研究了它们基本的物理化学性质,主要成果与创新点如下: 1、利用Horner-Wadsworth-Emmons反应、Wittig反应和Heck偶联反应,交替引入极性、非极性反应端基,成功解决了发散法合成较长单分散共轭齐聚物过程中产物难以提纯的技术问题,合成了系列芴撑乙烯撑共轭齐聚物。其中,最长的齐聚物含11个芴单元,光谱外推得到的有效共轭长度可达19个重复单元。DSC和偏光显微镜研究表明,芴单元数大于5的齐聚物可形成向列型液晶相。含7个芴单元以上的齐聚物可用于制备有机发光二极管,含11个芴单元的齐聚物电致发光效率是相应聚合物的5倍。 2、通过Hagigara-Sonogashira偶联、Diels-Alder环加成等反应合成了一系列端基为刚性的苯乙炔基和五苯基苯的单分散齐聚芴。但典型Scholl反应条件不能实现完全氧化脱氢,获得六苯并晕苯封端的齐聚芴。光谱研究表明苯乙炔基的引入导致吸收光谱和荧光光谱有1-2 nm的红移。五苯基苯结构的引入能显著提高齐聚芴的Tg,从而提高齐聚物的形态稳定性。 3、利用Yamamoto反应,采用端基溴代的齐聚芴大分子单体聚合结合制备色谱分离,成功地制备了分子量超过20000 Da的单分散共轭聚合物,说明大分子单体聚合结合制备色谱分离制备单分散共轭聚合物是可行的。 4、通过Horner-Wadsworth-Emmons反应合成一系列端基为三苯胺乙烯撑的单分散齐聚芴,其中,最长的齐聚物含9个芴单元。光谱研究表明,随芴单元数的增加,两个三苯胺乙烯撑端基间共轭作用显著减弱,最大吸收波长蓝移;当芴的单元数≥3时,最大发射波长均位于450 nm,和聚芴和齐聚芴相比,这类共轭齐聚物的蓝光发光峰位更佳。电化学研究表明三苯胺乙烯撑单元的氧化还原过程不受齐聚芴单元长度的影响,该封端齐聚芴的HOMO能级主要是由三苯胺乙烯撑单元决定。 关键词:端基官能化,齐聚芴,单分散共轭聚合物

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5-氟尿嘧啶(5-Fluorouracil, 5-FU)是一种抗代谢药物,广泛用于临床治疗结直肠癌、胃癌、乳腺癌等多种癌症,但其首过代谢显著、亲脂性较低,选择性差、毒副作用大。为克服这些缺点人们对5-FU进行了大量的修饰工作,包括小分子修饰以及与各种载体形成微球、微囊、纳米粒、共价前药等。 环糊精(Cyclodextrin,简称CD),可被结肠中的糖苷酶特异性地降解成小分子糖,而胃和小肠中由于缺乏相应的酶而使环糊精不被降解,这一特性在结肠药物的靶向输送及释放中有重要应用价值。环糊精中含有丰富的羟基,易进行化学修饰,将药物与环糊精通过共价键结合制成前药,使其在胃和小肠中不降解,而在盲结肠中被特异性的酶降解释出药物,达到结肠靶向释药的目的。研究表明,环糊精作为一种前药载体为结肠靶向释药和缓释、控释系统提供了一种有效的手段。 本工作选择5-氟尿嘧啶为模型药物、β-环糊精作为载体,通过中间体5-FU羧酸衍生物的制备及其与β-环糊精的偶联,合成了系列5-FU-β-CD前体药物,并利用紫外、红外、质谱、核磁、元素分析、热分析等手段对其进行结构表征。同时,还研究了前体药物的体外释药性质。具体内容包括: 1. 含有羧基的5-FU衍生物中间体的合成:(5-氟尿嘧啶-1-基)-乙酸(FUAC)、3-(5-氟尿嘧啶-1-基)-丙酸(FUPC)、5-(5-氟尿嘧啶-1-基)-戊酸(FUVC)的合成。 2. 中间体5-FU的羧酸衍生物与β-CD的偶联:分别通过以6-OTs-β-CD为中间体的取代法和活化酯法,合成了第一面取代和第二面取代的5-FU-β-CD大分子前体药物。在二面取代的前体药物制备中,通过改变原料的比例,合成了系列不同取代度(DS)的2-[(5-氟尿嘧啶-1-基)-乙酰基] -β-环糊精结合物。 3. 对上述前体药物进行体外释放研究:分别考察了前体药物在不同pH缓冲溶液中的水解行为及其在小鼠胃肠道人工体液中的酶解行为,并通过UV-Vis及HPLC对前体药物释放情况进行检测分析。 5-Fluorouracil(5-Fu), commonly known as a broad-spectrum antineoplastic drug, has been widely used in the treatment of various kinds of cancer including colon cancer for 40 years. However, this antitumor agent exhibits serious adverse effects, such as their marrow toxicity, gastrointestinal reaction and low selectivity in their clinical use. In order to improve its antitumor activity and reduce its toxicity, the compound was modified in various ways, including the formation of conjugated prodrugs with kinds of carrier, microsphere and nanoparticles etc. Cyclodextrins(CDs) are known to be barely capable of being hydrolyzed and only slightly absorbed in passing through the stomach and small intestine; however they are fermented into small saccharides by colonic microflora and thus absorbed as small saccharides in the large intestine. This biodegradation property of CDs may be useful as a colon-targeting carrier, and thus CD prodrugs may serve as a source of site-specific delivery of drugs to colon. It was demonstrated that prodrugs of CDs can provide a versatile means for construction of not only colon targeted delivery systems, but also delayed release systems. 5-Fluorouracil was taken as a model drug and β-CD as the carrier in this study. Series prodrugs of 5-FU was prepared through the preparation of reactive 5-FU derivatives containing carboxyl group and coupling to hydroxyl groups of CD. The structures of the conjugates were charactered by using IR, UV–vis, ESI-MS, 1H, 13C-NMR spectra, elemental analyses, and thermal analysis. In vitro hydrolysis behavior in aqueous solution and in rat gastrointestinal tract contents of the conjugates were also investigated. The main content of this dissertation includes following aspects: 1. The preparation of 5-FU derivatives containing carboxyl group: 5-Fluorouracil- acetic acid(FUAC)、3-(5-FU-1)-propionic acid (FUPC)、and 5-(5-FU-1)-valeric acid(FUVC). 2. The coupling of 5-FU derivatives to β-CD: 5-FU was selectively conjugated onto the primary or secondary hydroxyl groups of β-CD through an ester linkage, by the substitution of 6-OTs-β-CD and the activated ester method respectively. For the secondary face conjugation, the degree of substitution(DS) can be controlled by changing the mole ratio of the starting materials(FUAC and β-CD). 3. In vitro release behavior of the conjugates in aqueous solution and in rat gastro- intestinal tract contents of the conjugates were investigated, and the reaction was monitored and analyzed by using UV-Vis and HPLC methods.

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多羟基哌啶类化合物通常称为氮杂糖,由于与糖结构的相似性,亚胺基环醇表现出强的糖苷酶和糖基转移酶抑制活性,可调控在生物识别及酶结构控制中起到重要作用的糖蛋白的生物合成与水解。因此这类抑制剂有望成为与糖代谢紊乱有关的疾病的治疗药物,如:抗糖尿病、抗肿瘤、抗溶酶体贮积症及抗病毒感染(包括艾滋病)等药物。正是由于氮杂糖的重要生物活性及诱人的药用开发前景,近年来,有关氮杂糖及其衍生物的合成、生物活性及应用研究备受关注。 本论文探索了一系列的作为潜在的迈克加成中间体1-C-乙酰甲基/甲氧羰基甲基-5-N-取代呋喃核糖碳苷衍生物在碱的作用下先发生β-消除反应,接着发生分子内的迈克加成反应生成1-C-乙酰甲基-N-取代氮杂吡喃糖碳苷衍生物及1-C-甲氧羰基甲基-N-取代氮杂吡喃糖碳苷衍生物的方法,该转变过程为先通过β-消除得到非环状的α/β不饱和共轭酮或酯的中间体,接着5-N-取代氨基与分子内的α/β不饱和共轭酮或酯发生分子内的1,4-亲核加成,其中,2'-酯的环加成立体选择性的得到β型1-C-乙酰甲基-N-取代氮杂吡喃糖碳苷衍生物,而2'-酮的环加成得到立体异构体1-C-乙酰甲基-N-取代氮杂吡喃糖碳苷衍生物。此外,该类N-取代氮杂吡喃糖碳苷衍生物进一步脱除保护基,得到了一系列新的N-取代氮杂吡喃糖衍生物,拓展了氮杂吡喃糖碳苷分子库。 中间体1-C-(2'-oxoalkyl)-5-N-alkylated glycoribofuranoside的合成是由核糖为原料,通过对其结构修饰,在C-5氮原子上先引入不同的取代基,在C-1上引入乙酰甲基或甲氧羰基甲基。C-5取代氨基的引入通过两种方法:(a) 5-取代链状脂肪氨基可由链状的伯胺直接与5-甲磺酰基发生SN2亲核取代得到;(b) 5-取代芳香氨基可通过芳香醛与C-5氨基缩合再由硼氢化钠还原得到。2'-酰基的引入通过烯丙基氧化得到:2'-酮羰基由醋酸汞和琼斯试剂氧化得到;2'-酯基由高锰酸钾氧化再碘甲烷的作用下得到。 The polyhydroxylated piperidines, commonly be called azasugars. Iminocyclitols and their derivatives have exhibited remarkable biological activity to inhibit glycosidase-processing enzymes, with resulting potential chemotherapeutic applications against diabetes, cancer, lysosomal storage disorders and viral infections including AIDS. Recently, because of the important biological activity and excellent foreground on pharmaceutical application, great attention has been attracted to the synthesis of the new derivatives and analogues. In this dissertation, 1-C-(2'-oxoalkyl)-5-N-substituted-glycoribofuranosides, which used as latent substrates for intramolecular hetero-Michael addition, were converted to 2-ester and 2-ketone aza-C-glycopyranosides by base treatment. The transformation was achieved through β-elimination to an acyclic α/β-conjugated ketone or ester, followed by an intramolecular hetero-Michael addition by the 5-N-alkylated amino group. The 2-ester cycloaddition was highly stereoselective in favor of an equatorial 1-C-substitution while the 2-ketone cycloaddition was produced a pair of stereoisomers of 2′-ketonyl aza-C-glycoside. Additionally, the resultant different N-alkylated aza-C-glycopyranosides could be further prepared for various azasugar library constructions by removal of protecting groups. Synthesis of the key intermediate 1-C-(2'-oxoalkyl)-5-N-alkylated glycoribo- furanoside involved the introduction of 5-substituted amino and 1-C-2′-oxoalkyl groups from D-ribose. The 5-alkylated amino was introduced through two methods: (a) the 5-aliphatic series amino synthesized by the nucleophilic substitution of 5-mesylate using neat ethylamine, propylamine, butylamine, and hexylamine, (b) the 5-aromatic series amino synthesized by various aromatic aldehydes with C-5 amino under NaBH4 reduction. The 1-C-2′-oxoalkyl groups were introduced through oxidation of the ally group: the 1-C-allyl group was oxidized with Hg(OAc)2 and Jones reagent to the 2-ketonyl C-glycoside; the 1-C-allyl group was oxidized with KMnO4 and CH3I/NaHCO3 to 1-C-methyl acetate glycoside.

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In this paper, we report for the first time on the synthesis of ZnO nanocrystallites in conjugated polymer (PPV) nanofibers by the coupling of the in situ/blend methods and electrospinning. These composite nanofibers were characterized by fluorescence microscopy, atomic force microscope (AFM), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra, Fourier transform infrared (FT-IR) spectroscopy, and X-ray powder diffraction (XRD).

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Three new carbazole copolymers, poly(9-(2,5-diarene-[1,3,4]oxadiazole)-carbazole-alt-9-(2-ethylhexyl)-carbazole-3,6-diyl)s (P1), poly(9-(2,5-diarene-[1,3,4]oxadiazole)-2, 7-carbazole-alt-9-(2-ethylhexyl)-3, 6-carbazole-diyl)s (P2), and poly(9-(2,5-diarene-[1,3,4]oxadiazole)-carbazole-alt-9-(2-ethylhexyl)-carbazole-2,7-diyl)s (P3), were synthesized by the Suzuki coupling reaction