- Pd(II)-catalyzed base-free oxidative homocoupling of fluorene diboronic acid ester: A new approach for the synthesis of π-conjugated polymers
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A new route, Pd(II)-catalyzed base-free oxidative homocoupling, has been successfully used for the synthesis of polyfluorene. Using only diboronic esters and a stable Pd(II) catalyst in the absence of base can greatly simplify the synthetic condition of conjugated polymers.
- Yuan, Chao,Hong, Jia,Liu, Yanmei,Lai, Hua,Fang, Qiang
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- Salen-based enantiomeric polymers for enantioselective recognition
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This paper describes how the spatial arrangement of the building blocks in a polymer chain influences the recognition properties of polymers. Here, we have designed and synthesized a series of fluorene based (A-B)n type salen polymers where the A-part is a fluorophore and the B-part is a recognition site using the condensation reaction of a fluorene based di(salicylaldehyde) compound (FSal) with diamines. Among the polymers, two are chiral (P1 and P2) which are enantiomeric (1R,2R vs. 1S,2S) to each other and three are achiral polymers (P3, P4 and P5). Circular dichroism studies of two chiral polymers reveal more or less equal and opposite CD intensities, indicating the induction of handedness in the polymer backbone. All polymers (P1-P5) contain the same recognition site but the spatial arrangements of the recognition sites are different from one another. We have studied the recognition properties of the polymers towards phenylglycinol. Only P1 and P2 exhibit good enantioselective recognition towards phenylglycinol through turn-on fluorescence enhancement because the microenvironment of the recognition sites is well organized to accommodate guest molecules. Three achiral polymers P3, P4 and P5 have no capacity to capture the guest molecules due to the lack of a suitable microenvironment at the recognition sites. This observation supports the phenomenon that the spatial arrangement of the building blocks in a main chain polymer determines its recognition properties. Moreover, P1 and P2 recognize the guest molecules through turn-on fluorescence (bright blue) in solution which gives a good platform for real application purposes.
- Bera, Manas Kumar,Chakraborty, Chanchal,Malik, Sudip
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p. 8074 - 8080
(2016/09/12)
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- Highly emissive excited-state intramolecular proton transfer (ESIPT) inspired 2-(2′-hydroxy)benzothiazole-fluorene motifs: Spectroscopic and photophysical properties investigation
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Tuning or switching of the solid state luminescence of organic materials is an attractive target for both basic research and practical applications. In the present study, solid state emissive compounds with very high quantum efficiencies (ΦF up
- Padalkar, Vikas S.,Sakamaki, Daisuke,Tohnai, Norimitsu,Akutagawa, Tomoyuki,Sakai, Ken-Ichi,Seki, Shu
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p. 80283 - 80296
(2015/10/05)
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- Fluorene-based chemodosimeter for "turn-on" sensing of cyanide by hampering ESIPT and live cell imaging
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A new salicylaldehyde appended fluorene-based chemodosimeter (FSal) has been designed by taking consideration of the special nucleophilicity of cyanide ion. FSal shows selective affinity towards CN- over other anions (namely F-, Br-, NO3-, ClO 4-, N3-, H2PO 4-, AcO-, I-, Cl-, and NO2-) through turn-on fluorescence with a minimum detection limit of 0.06 ppm. The turn-on fluorescence of the FSal-CN complex resulting from hampering ESIPT is also supported by DFT and TDDFT calculations. Biological compatibility and live cell imaging of this unique probe have also been explored.
- Bera, Manas Kumar,Chakraborty, Chanchal,Singh, Pradeep Kumar,Sahu, Chandan,Sen, Kaushik,Maji, Samir,Das, Abhijit Kumar,Malik, Sudip
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p. 4733 - 4739
(2014/07/21)
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- Synthesis, structure, and optoelectronic properties of phosphafluorene copolymers
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(Chemical Equation Presented) Copolymers of phosphafluorenes are obtained through Suzuki copolymerization. The phosphorus-containing copolymers show unique optical, electrochemical, and optoelectronic properties. Blue and white electroluminescence can be
- Chen, Run-Feng,Zhu, Rui,Fan, Qu-Li,Huang, Wei
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supporting information; scheme or table
p. 2913 - 2916
(2009/05/27)
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- π-conjugated chelating polymers with charged iridium complexes in the backbones: Synthesis, characterization, energy transfer, and electrochemical properties
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A series of π-conjugated chelating polymers with charged iridium (Ir) complexes in the backbones were synthesized by a Suzuki polycondensation reaction, leading to homogeneous polymeric materials that phosphoresce red light. The fluorene and bipyridine (bpy) segments were used as polymer backbones. 5.5′-Dibromobipyridine served as a ligand to form a charged iridium complex monomer with 1-(9′9-dioctylfluorene-2-yl)isoquinoline (Fiq) as the cyclometalated ligand. Chemical and photophysical characterization confirmed that Ir complexes were incorporated into the backbones as one of the repeat units by means of the 5.5′-dibromobipyridine ligand. Chelating polymers showed almost complete energy transfer from the host fluorene segments to the guest Ir complexes in the solid state when the feed ratio was 2 mol%. In the films of the corresponding blend system, however, energy transfer was not complete even when the content of Ir complexes was as high as 16 mol%. Both intra- and in termolecular energy-transfer processes existed in this host-guest system, and the intramolecular energy transfer was a more efficient process. All chelating polymers displayed good thermal stability, redox reversibility, and film formation. These chelating polymers also showed more efficient energy transfer than the corresponding blended system and the mechanism of incorporation of the charged Ir complexes into the π-conjugated polymer backbones efficiently avoided the intrinsic problems associated with the blend system, thus offering promise in optoelectronic applications.
- Liu, Shu-Juan,Zhao, Qiang,Chen, Run-Feng,Deng, Yun,Fan, Qu-Li,Li, Fu-You,Wang, Lian-Hui,Huang, Chun-Hui,Huang, Wei
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p. 4351 - 4361
(2008/02/06)
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- Hyperbranched oxadiazole-containing polyfluorenes: Toward stable blue light PLEDs
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The synthesis of hyperbranched oxadiazole-containg polyfluores using 'A2 + A2′ + B3' approach based on Suzuki polycondensation was investigated. The molecular structures of the sample polymer were characterized with high-resolution NMR spectroscopy and elemental analysis. The solubility was found to be poor in organic solvents for hyperbranched polymers with higher contents of 2-(4-bromophenyl)-5-(3,5-dibromophenyl)-1,3,4-oxadiazole monomer. The sample polyfluores showed stable blue light emission even after being annealed in the elevated temperatures in the N2 and air.
- Xin, Yu,Wen, Gui-An,Zeng, Wen-Jing,Zhao, Lei,Zhu, Xing-Rong,Fan, Qu-Li,Feng, Jia-Chun,Wang, Lian-Hui,Wei, Wei,Peng, Bo,Cao, Yong,Huang, Wei
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p. 6755 - 6758
(2007/10/03)
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- High-efficiency red-light emission from polyfluorenes grafted with cyclometalated iridium complexes and charge transport moiety
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We report a new route for the design of electroluminescent polymers by grafting high-efficiency phosphorescent organometallic complexes as dopants and charge transport moieties onto alky side chains of fully conjugated polymers for polymer light-emitting diodes (PLED) with single layer/single polymers. The polymer system studied involves polyfluorene (PF) as the base conjugated polymer, carbazole (Cz) as the charge transport moiety and a source for green emission by forming an electroplex with the PF main chain, and cyclometalated iridium (Ir) complexes as the phosphorescent dopant. Energy transfer from the green Ir complex or an electroplex formed between the fluorene main chain and side-chain carbazole moieties, in addition to that from the PF main chain, to the red Ir complex can significantly enhance the device performance, and a red light-emitting device with the high efficiency 2.8 cd/A at 7 V and 65 cd/m2, comparable to that of the same Ir complex-based OLED, and a broad-band light-emitting device containing blue, green, and red peaks (2.16 cd/A at 9 V) are obtained. Copyright
- Chen, Xiwen,Liao, Jin-Long,Liang, Yongmin,Ahmed,Tseng, Hao-En,Chen, Show-An
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p. 636 - 637
(2007/10/03)
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