- Self-assembly behaviors of the cholesteryl trimeric-phenylene vinylene derivative in the H2O/THF system
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Cholesteryl trimeric phenylene vinylene (Chol-TPV) has been synthesized and characterized. The self-assembly behaviors of Chol-TPV in THF/H2O system at different water content (water content: 40% and 80%) and different solute concentration (solute concentration: 1.0 × 10-5 mol/L and saturated concentration) were studied using UV-vis spectrophotometry, photoluminescence spectrophotometry, and circular dichroism spectroscopy. Based on an analysis of the UV-vis and photoluminescence spectra, Chol-TPV shows the typical H-type aggregation at saturated concentration in 80% aqueous THF. However, Chol-TPV shows the non-typical H-type aggregation under other conditions. The circular dichroism signal suggests that the Chol-TPV exists in the right handed helical architectures with high water content at a concentration of 1.0 × 10-5 mol/L, and a helix inversion was found at saturated concentration.
- Zhao, Yu-Zhen,Zhang, Zhen-Lin,Li, Ying,Liu, Xue-Qiang,Liu, Shi-Min,Yu, Jin-Ku,Zhang, Hai-Quan
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- New cyanopyridine based conjugative polymers as blue emitters: Synthesis, photophysical, theoretical and electroluminescence studies
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Herein, we report the design of three new blue light emitting conjugated polymers (Th-Py-1, Th-Py-2 and Th-Py-3), carrying cyanopyridine ring as a strong electron accepting unit and thiophene as well as phenylene vinylene scaffolds with different substituents, as electron donating moieties. The newly designed monomers/polymers were synthesized using well-known synthetic protocols such as cyclocondensation, O-alkylation, Suzuki cross coupling, Wittig and Knoevenagel reactions. They were well-characterized by spectral, thermal, photophysical, electrochemical and gel permeation chromatography (GPC) techniques. Further, they were subjected to theoretical studies using DFT simulations, performed at B3LYP/TZVP level using Turbomole 7.2 V software package. The new polymers were tested in PLED devices (ITO/PEDOT: PSS/Polymer/Al) as emissive materials. Optical studies revealed that, all the polymers displayed light absorption in the range of 377–397 nm and blue light emission in the order of 432–482 nm, respectively. Further, their band-gaps were calculated to be in the order of 2.55–2.64 eV using both optical and electrochemical data. Furthermore, the TGA study indicated that, they possess good thermal stability with onset decomposition temperature, greater than 300 ?C under nitrogen atmosphere. Interestingly, use of these polymers in new PLEDs as emissive layers, has shown improved performance when compared to previously reported polymers in similar type of devices. They show blue light emission with a low threshold voltage of 3.5–3.9 V, affirming an efficient electron injection in the diodes.
- Pilicode, Naveenchandra,K M, Nimith,M N, Satyanarayan,Adhikari, Airody Vasudeva
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- Electronic and structural properties of polymers based on phenylene vinylene and thiophene units. Control of the gap by gradual increases of thiophene moieties
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Several poly(thiophene) derivatives containing p-phenylenevinylene (PV) as an electron-donor were synthesized using FeCl3. PV units are regularly spaced in two, four and eight thiophenyl units across the main chain. PV units and the gradual increase in the number of thiophene units affect the properties of polymers such as poly(3-hexylthiophene), (P3HT). Polymers, labeled as poly(FV1Th), poly(FVBiTh) and poly(FVTeTh) were characterized by FT-IR and UV-Vis spectrometry, elemental analysis, thermal stability (TGA), differential scanning calorimetry (DSC) and cyclic voltammetry (CV). Conjugation increases with increasing thiophene rings in the main chain and the conjugation is higher in polymers that exhibited different optical absorption, effective conjugation, similar intrinsic viscosity, and high thermal stability with a weight loss less than 10% at decomposition temperatures higher than 300 °C (except poly(FVTeTh). DSC showed melting points over 200 °C and the formation of crystalline zones was found in all cases. An increase in the number of thiophene rings in the main chain resulted in a more ordered crystalline molecular structure. Moreover, the polymers presented redox processes at a potential lower than that of P3HT. The Highest Occupied Molecular Orbital (HOMO), Lowest Unoccupied Molecular Orbital (LUMO) and optical band gap (Eg) were measured and the values obtained were compared with those of P3HT. The effect caused by PV units and the increase of thiophenyl units in the chains on HOMO, LUMO, band gap, fusion, crystallinity and TGA is reported. The Eg of the monomers was greater than that of P3HT. The results showed that with respect to P3HT, polymers HOMO and LUMO are lower and in some cases by a slight change in Eg. The PV effect as an electron donor causes a decrease in the HOMO and LUMO, envisaging them as potential polymers to be studied in organic photocells.
- Sánchez,Sobarzo,Gatica
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p. 7979 - 7987
(2015/10/12)
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- Controlled stacking and unstacking of peripheral chlorophyll units drives the spring-like contraction and expansion of a semi-artificial helical polymer
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Developing new strategies for controlling polymer conformations through precise molecular recognition can potentially generate a machine-like motion that is dependent on molecular information - an important process for the preparation of new intelligent nanomaterials (e.g., polymer-based nanomachines) in the field bordering between polymer chemistry and conventional supramolecular sciences. Herein, we propose a strategy to endow a helical polymer chain with dynamic spring-like (contraction/expansion) motion through the one-dimensional self-assembly (aggregation/disaggregation) of peripheral amphiphilic molecules. In this developing system, we employed a semi-artificial helical polysaccharide presenting peripheral amphiphilic chlorophyll units as a power device that undergoes contractive motion in aqueous media, driven by strong π-π interactions of its chlorophyll units or by cooperative molecular recognition of bipyridyl-type ligands through pairs of chlorophyll units, thereby converting molecular information into the regulated motion of a spring. In addition, this system also undergoes expansive motion through coordination of pyridine. We anticipate that this strategy will be applicable (when combined with the established wrapping chemistry of the helical polysaccharide) to the development of, for example, drug carriers (e.g., nano-syringes), actuators (stimuli-responsive films), and directional transporters (nano-railways), thereby extending the frontiers of supramolecular science. Copyright
- Numata, Munenori,Kinoshita, Daiki,Hirose, Naoya,Kozawa, Tomohiro,Tamiaki, Hitoshi,Kikkawa, Yoshihiro,Kanesato, Masatoshi
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supporting information
p. 1592 - 1598
(2013/03/14)
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- Fluorescent sensor based on a novel conjugated polyfluorene derivative
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A novel water-soluble polyfluorene derivative, poly[(9,9-bis(3′-((N, N-dimethylamino)N-ethylammonium)propyl)-2,7-fluorene)-alt-2,7-(9, 9-p-divinylbenzene)]dibromide (P-2) was synthesized by the palladium-catalyzed Suzuki coupling reaction and it's quaternized ammonium polyelectrolyte derivatives was obtained through a postpolymerization treatment on the terminal amino groups. The electrochemical and optical properties of the copolymers was fully investigated. The results showed that the new polyfluorene derivative had high electronic conductivity and strong fluorescence, therefore it had good potential to be used in chemical and biological sensors, as shown in optical sensing of bovine albumin (BSA) in this study.
- Gao, Weiqiang,Yan, Mei,Ge, Shenguang,Liu, Xiaoxia,Yu, Jinghua
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p. 218 - 223
(2012/08/08)
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- Chain length effect of dialkoxynaphthalene end-capped divinylbenzene for OTFT
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The new organic semiconductors which are composed of divinylbenzene core unit and alkoxynaphthalene on both sides, 1,4-bis-2-(6-octyloxy)naphthalen-2- ylvinylbenzene (BONVB), 1,4-bis-2-(6-decyloxy)naphthalen- 2-ylvinylbenzene (BDNVB) and 1,4-bis-2-(6-dodecyloxy)naphthalen-2-ylvinylbenzene (BDDNVB) were synthesized by Wittig reaction. The structures of obtained BONVB, BDNVB and BDDNVB were confirmed by FT-IR and mass spectroscopy. UV-absorption of thin film showed H-aggregates and J-aggregates due to closely packed structure between adjacent molecules. The characterization of vacuum-evaporated films by Xray diffraction (XRD) and atomic force microscopy (AFM) showed that the chain length of alkoxy group affects the crystallinity and morphology. BONVB with octyloxy group showed the mobility of 0.011 cm2/V·s, on/off ratio of 1.31 × 105, and a subthreshold slope of 0.93 V.
- Kim, Ran,Yun, Hui-Jun,Yi, Mi Hye,Shin, Sung Chul,Kwon, Soon-Ki,Kim, Yun-Hi
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supporting information; experimental part
p. 420 - 425
(2012/05/05)
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- Derivatives of 1,4-bis(3-hydroxycarbonyl-4-hydroxyl)styrylbenzene as PTP1B inhibitors with hypoglycemic activity
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Disalicylic acid derivatives with stilbene and bis-styrylbenzene skeleton were synthesized as PTP1B inhibitors. The most potent in this series exhibited a submicromolar IC50 value. One of the compounds 7b was tested in an animal model for its efficacy as an anti-diabetic or an anti-obesity agent. In feeding compound 7b to diet-induced obese mice, no significant differences in weight gain and food consumption were observed between the drug-treated and the obese control mice. However, 7b significantly lowered the fasting glucose level and improved the glucose tolerance in the obesity-induced diabetic mice.
- Shrestha, Suja,Bhattarai, Bharat Raj,Kafle, Bhooshan,Lee, Keun-Hyeung,Cho, Hyeongjin
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p. 8643 - 8652
(2008/12/23)
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- Synthesis, complexation, and photoisomerization studies on some chiral monocyclic stilbenophanes and bis-cyclophanes
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Various chiral stilbenophanes with small and large rigid cavities have been synthesized. Bis-cyclophanes with a stilbene-bridging unit have also been synthesized. Some of the stilbenophanes form charge transfer complexes with either TCNQ or TCNE. Photoisomerization of the bis-cyclophanes has also been studied.
- Rajakumar, Perumal,Selvam, Subramaniyan
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p. 8891 - 8901
(2008/02/11)
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- Triaryl boron-based A-π-A vs triaryl nitrogen-based D-π-D quadrupolar compounds for single- and two-photon excited fluorescence
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(Equation Presented) Three new A-π-A-type compounds with trivalent boron, protected by two mesityl groups, as electron acceptor have been synthesized and investigated together with their two diphenylamino-ended D-π-D analogues. These boranes exhibit large two-photon absorption cross sections and high fluorescence quantum yields.
- Liu, Zhi-Qiang,Fang, Qi,Cao, Du-Xia,Wang, Dong,Xu, Gui-Bao
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p. 2933 - 2936
(2007/10/03)
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- [5]Helicenes by tandem radical cyclisation
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A new and rapid approach to [5]helicenes is described. A central feature is the use of a sequential, non-reducing radical cyclisation reaction of (Z,Z)-1,4-bis(2-iodostyryl)benzene derivatives, viz. 3→1, mediated by tributyltin hydride.
- Harrowven, David C.,Nunn, Michael I.T.,Fenwick, David R.
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p. 7345 - 7347
(2007/10/03)
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- Synthesis and x-ray analysis of new [5]helicenes - HMO calculations on the photocyclization of the stilbene precursors
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The syntheses of the new pentahelicenes 5, 11, 17, 21, and 28 with various substituents are described. In the case of 2,13-dicyano-[5]helicene (11) optical resolution was achieved by HPLC using a column packed with γ- cyclodextrin. However, the enantiomers racemized within a few hours. On the other hand, the enantiomers of 28 turned out to be stable after separation on triacetylcellulose using MPLC. The crystal structures of 11, 17, and 21 were solved and indicated the typical distortions which are expected for helicenes. The model of the sum of free valence numbers was applied in order to rationalize the reactivity pattern of the photochemical phenanthrene cyclization.
- Stammel, Christian,Froehlich, Roland,Wolff, Christian,Wenck, Hans,De Meijere, Armin,Mattay, Jochen
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p. 1709 - 1718
(2007/10/03)
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