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1.
1,3,4-噁二唑衍生物的双光子吸收和双光子泵浦荧光 总被引:1,自引:0,他引:1
依据“推电子基-共轭中心-拉电子基-共轭中心-推电子基”的模型将电荷传输型1,3,4-噁二唑环嵌入芳香共轭体中, 通过Wittig-Horner反应合成了2种对称型强双光子吸收和双光子诱导荧光分子2,5-二[4-(2-芳基乙烯基)苯基]-1,3,4-噁二唑. 它们的氯仿溶液在锁模Nd: YAG激光器800 nm激光照射下, 发射出很强的双光子上转换荧光, 其最强荧光分别在波长507和475 nm. 采用非线性透过率法测得其双光子吸收截面分别为1.07×10-46和6.6×10-47 cm4•s•photon-1. 这2个对称型D-π-A-π-D生色分子从激发端基到π共轭桥的有效能量传输, 对双光子吸收和双光子荧光发射能力贡献较大. 相似文献
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C60-吡咯烷衍生物的合成及非线性光学性质的研究 总被引:1,自引:0,他引:1
通过富勒烯C60与肌氨酸和有机醛化合物的1,3-偶极环加成反应, 获得了九种含不同有机功能基团的C60吡咯烷衍生物1~9, 用1H NMR, 13C NMR, FTIR, UV-vis和FAB-MS进行了结构表征; 利用皮秒激光光源, 采用z扫描技术测定了分子的三阶非线性超极化率γ(3), 结果显示: 化合物3 (γ(3)=4.14×10-33 esu)具有最大的三阶非线性光学系数, 说明增加噻吩共轭链的长度, 使三阶非线性活性增加; 对具有相同共轭链的C60-噻吩吡咯烷衍生物(2, 5, 1和4), 吸电子取代基减小了三阶光学非线性活性, 给电子基增大了三阶光学非线性活性; 同时发现喹啉环2-位键联(7)比4-位(8)有更好的三阶光学非线性活性. 相似文献
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拟利用枞酸分子中的非同环共轭二烯在氯化锌作用下异构化成具有同环共轭二烯的海松酸结构, 再与C60进行Diels-Alder加成反应, 预测可以得到Diels-Alder加成产物. C60、枞酸及氯化锌在邻二氯苯溶剂中, 在氮气保护下于175~180 ℃反应8 h, 将反应物洗涤后进行硅胶柱层析分离, 采用FT-IR, 13C NMR, 1H NMR和MALDI-TOF-MS等分析方法对反应主要产物进行结构测定, 却意外发现得到C60与枞酸的加成过程中发生了脱羧脱氢反应且产物含有芳环的化学结构. 相似文献
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中国南海海绵Cinachyrella australiensis中(3E)-胆甾-4-烯-3,6-二酮-3-肟的结构鉴定 总被引:4,自引:0,他引:4
从南中国海海绵Cinachyrella australiensis的乙酸乙酯萃取部分分离出一个结构特别的甾体化合物, 应用UV, IR, MS, 1H NMR, 13C NMR, DQCOSY, NOESY, TOCSY, HMQC和HMBC等光谱分析技术, 确定它为(3E)-胆甾-4-烯-3,6-二酮-3-肟(1). 化合物1为新天然甾体化合物, 通过生理活性实验表明其对乙肝病毒Hep G2细胞有较强的细胞毒活性. 本文对其波谱数据作了详细报道. 相似文献
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Mutsuo Tanaka Yoshihiro Higuchi Yasuhiko Shibutani Shinpei Kado Keiichi Kimura 《Tetrahedron》2005,61(34):8159-8166
Polybenzyl ether type dendrons bearing the crown ether moieties at the periphery, namely, crowned dendrons were synthesized, and the effect of complex formation on their flexibility with metal-ion binding properties was examined. Upon addition of Na+, 1H NMR spectra of the crowned dendrons in CD3CN were significantly broadened, reflecting the flexibility restriction of the crowned dendrons by the complex formation with Na+. Such a significant flexibility restriction was observed only with Na+, although ESI-MS studies revealed that the crowned dendrons formed 1:2 complexes (a metal ion:the crown ether moiety) regardless of the kind of metal ions. The flexibility restriction became significant with increasing dendron generation on the basis of 1H NMR spectra and spin-lattice relaxation time (T1) measurements. Binding constants of the crowned dendrons with metal ions in CD3CN decreased with the increase of the dendron generation, reflecting an influence of the charge repulsion as well as a dendrimer effect to cause the steric hindrance. The examination of UV-vis absorption spectra for complexes of the crowned dendron with metal picrates in THF displayed the formation of a loose ion-pair complex with Na+, namely, a typical sandwich type complex. However, in CH3CN, all metal picrates were solvated to be in a loose ion-pair even without complex formation. These results suggested that the control of macromolecular flexibility with metal ions is feasible by the integration of crown ether moieties with a dendritic structure. 相似文献
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Andreas M. Nystrm Istvn Fur Eva Malmstrm Anders Hult 《Journal of polymer science. Part A, Polymer chemistry》2005,43(19):4496-4504
Dendronized polymers with a methacrylate backbone bearing pendant aliphatic polyester dendrons based on 2,2‐bis(methylol)propionic acid have been investigated by rheological measurements, differential scanning calorimetry (DSC), size exclusion chromatography (SEC), and 1H NMR self‐diffusion techniques. The change in material properties due to the attachment of larger dendrons and/or different end‐groups to a backbone of the same length is investigated. Dendronized polymers of the second to fourth generation with hydroxyl, acetonide, or hexadecyl end‐group functionalities have been studied. DSC revealed that the glass transition temperature of the amorphous polymers increases with increasing size of the dendrons, and that the ability for the hexadecyl functional polymers to crystallize decreases with increasing size of dendrons. 1H NMR self‐diffusion and longitudinal relaxation data are consistent with an elongated rod‐like model of the polymers in solution. Larger dendrons lead to a larger rod diameter that approximately double when increasing the generation of dendronized polymer from two to four. Rheological measurements demonstrated that the complex viscosity at low frequency increased with dendron size. Independently of the functionality, the second and third generation samples initially showed a Newtonian plateau, followed by a shear thinning region at higher frequencies. The fourth generation samples only showed shear thinning over the whole frequency region. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4496–4504, 2005 相似文献
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Dr. Chang‐Qi Ma Dr. Elena Mena‐Osteritz Dr. Markus Wunderlin Dr. Gisela Schulz Prof. Dr. Peter Bäuerle 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(40):12880-12901
The synthesis of generational dendritic oligothiophenes (DOTs) has been successfully achieved by a divergent/convergent approach that involves halogenation, boronation, and palladium‐catalyzed Suzuki coupling reactions. The key point in the presented synthetic approach is the use of trimethylsilyl (TMS) protecting groups, which allow for the core‐lithiation and subsequent boronation of the dendrons and for the peripheral ipso‐substitution with iodine monochloride or N‐bromosuccimide. In addition, the TMS protecting groups can be completely removed by using tetrabutylammonium fluoride, thus yielding only‐thiophene‐based dendrons and dendrimers. Due to their highly branched structure, all these synthesized DOTs are soluble in organic solvents. Chemical structures were confirmed by NMR spectroscopic, mass spectrometric, and elemental analysis. Concentration‐dependent 1H NMR spectroscopic investigations revealed that the higher generation compounds tend to aggregate in solution. Such an aggregation behavior was further confirmed by measuring with MALDI‐TOF MS. Both MALDI‐TOF MS and gel‐permeation chromatography (GPC) analyses confirmed the monodispersity of the DOTs. Furthermore, GPC results revealed that these DOT molecules adopt a condensed globular molecular shape. Their optical and electronic properties were also investigated. The results indicated that these DOTs comprise various conjugated α‐oligothiophenes with different chain lengths, which results in the higher generation compounds showing broad and featureless UV/Vis absorption spectra and ill‐defined redox waves. 相似文献
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Hailong Chen Dr. Yang Yang Yizhan Wang Prof. Lixin Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(33):11051-11061
A series of cationic dendrons bearing triethylene glycol monomethyl ether terminal groups of different generations have been synthesized and used to encapsulate an inorganic polyanionic cluster [K12.5Na1.5(NaP5W30O110)] through electrostatic interactions. The resulting dendritic cation–encapsulated polyoxometalate (POM) complexes, cluster–dendrimers, are soluble in water and exhibit lower critical solution temperatures (LCST). The thermoresponsivities of these complexes in aqueous solutions were studied by turbidimetry and variable‐temperature 1H NMR spectroscopy. The observed cloud points show a remarkable dependence on the generation of the dendrons. Complexes composed of first‐generation dendrons exhibit no obvious thermoresponsive properties, but for complexes bearing second‐generation dendrons, the LCST decreases as the number of dendritic cations around the POM cluster increases. Complexes composed of third‐generation cations underwent reversible aggregation and disaggregation upon heating and cooling, respectively. This thermally induced self‐aggregation was characterized by DLS and TEM. In addition, the effects of salt and solvent on the LCST were investigated. This research demonstrates a new type of thermoresponsive dendritic organic–inorganic hybrid complex and provides a general route to the endowment of POMs with temperature‐sensitive properties through electrostatic interactions. 相似文献
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Murat Tonga Gulen Yesilbag Tonga Gonca Seber Ozgul Gok Amitav Sanyal 《Journal of polymer science. Part A, Polymer chemistry》2013,51(23):5029-5037
Dendronized copolymers bearing two different dendrons as side chains have been synthesized using a modular orthogonal “double‐click” reaction based strategy. The orthogonality of the Huisgen‐type azide‐alkyne cycloaddition and the Diels–Alder reaction was utilized to attach different dendrons to the polymer backbone via the “graft‐to” strategy. First through third generations of polyaryl ether dendrons appended with an alkyne group and polyester dendrons possessing a furan‐protected maleimide group at their focal point were reacted with a styrene based copolymer containing azide and anthracene moieties as side chains. The efficiency and selectivity of the orthogonal dendronization of the copolymers were examined via various analytical methods such as 1H NMR spectroscopy, FTIR and gel permeation chromatography. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5029–5037 相似文献
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A new type of chiral depsipeptide dendrons based on tartaric acid as branching juncture and ω-aminocapronic acid as spacer has been prepared. Natural and unnatural tartaric acid building blocks have been incorporated, providing access to combinatorial libraries. All compounds have been completely characterized by FAB-MS, EA analysis, 1H/13C NMR- and UV/Vis-spectroscopy. 1H NMR relaxation measurements have been used to examine the conformational flexibility of these dendrons in CH3CN and CH3OH and indicate a less flexible structure in CH3CN. Pulse gradient spin echo (PGSE) NMR measurements correlate these findings to molecular dimensions. A reduced size for the dendrons in CH3CN compared to CH3OH leads to the assumption of a more compact structure in this solvent. Additional polarimetric data reveal, that observed changes in optical activity with increasing generation can in CH3OH be explained by constitutional effects of the dendron structure but not in CH3CN. CD measurements are in agreement with these findings and show a linear increase of the Cotton effects with increasing generation for CH3OH but not for CH3CN. It can be concluded that the conformation within the dendrons is very sensitive to environmental conditions and that a chiral secondary structure might be stabilized in CH3CN. Initial studies revealed that chirality transfer to the focal functionality occurs. 相似文献
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Murat Tonga Nergiz Cengiz Meliha Merve Kose Tuna Dede Amitav Sanyal 《Journal of polymer science. Part A, Polymer chemistry》2010,48(2):410-416
A modular approach toward the synthesis of polymers containing dendron groups as side chains is developed using the Diels–Alder “click” reaction. For this purpose, a styrene‐based polymer appended with anthracene groups as reactive side chains was synthesized. First through third‐generation polyester dendrons containing furan‐protected maleimide groups at their focal point were synthesized. Facile, reagent‐free, thermal Diels–Alder cycloaddition between the anthracene‐containing polymer and latent‐reactive dendrons leads to quantitative functionalization of the polymer chains to afford dendronized polymers. The efficiency of this functionalization step was monitored using 1H and 13C NMR spectroscopy and FTIR and UV–vis spectrometry. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 410–416, 2010 相似文献
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Andreas Nystrm Anders Hult 《Journal of polymer science. Part A, Polymer chemistry》2005,43(17):3852-3867
A series of polymers tethered with bis‐MPA dendrons was synthesized by a combination of divergent growth and atom transfer radical polymerization (ATRP). Macromonomers of first and second generation were synthesized utilizing the acetonide protected anhydride of bis‐MPA as the generic esterfication agent. The macromonomers were polymerized in a controlled fashion by ATRP utilizing Cu(I)/Cu(II) and N‐propyl‐2‐pyridylmethanamine as the halogen/ligand system. The end‐groups of these polymers were further tailored to achieve hydroxyl, acetate, and aliphatic hexadecyl functionality. With this approach all polymers will emanate from the same backbone, enabling for an evaluation of both the generation and end‐group dependent properties. Furthermore, a dendronized tri‐block copolymer was synthesized. All materials were analyzed by 1H and 13C NMR, as well as size‐exclusion chromatography (SEC). The SEC analysis revealed that the molecular weights of the divergently grown dendronized polymers increased with increasing generation while the polydispersity (PDI) was kept low. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3852–3867, 2005 相似文献
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Dendrimers were synthesized with phenyl and ferrocenyl-ended groups joined by vinyl moieties. All the dendrons used for dendrimers synthesis had showed trans configuration. This configuration as well as the ‘cone’ conformation of the resorcinarenes was preserved in the dendrimers, as it was shown by 1H NMR spectroscopy. The chemical structure and purity of the synthesized dendrimers were confirmed by 1H and 13C NMR, FAB+, MALDI-TOF, electrospray mass spectra, and elemental analysis. Cubic nonlinear optical behavior of this first generation of resorcinarene dendrimers was studied. The χ(3) values estimated from the THG Maker-fringe technique for the phenyl and ferrocenyl-ended resorcinarene dendrimers dispersed in thin solid films are of the order of 10−13 and 10−12 esu, respectively. 相似文献
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Dimitrios Alivertis 《Tetrahedron letters》2009,50(44):6019-4476
The ability of a series of crown ether-functionalized dendrimers to function as alkali metal picrate extraction agents is assessed by liquid-liquid extraction and 1H NMR titration experiments. Crown ether-functionalized dendrimers that contain Fréchet-type poly(benzyl ether) dendrons of different generation as building blocks display different extraction characteristics toward alkali metal cations. Positive and negative dendritic effects depending on the generation of the dendrimer are assigned in the complexation behaviour of the dendritic host compounds. 相似文献