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141.
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143.
A novel blue-emitting phosphor, LiSrPO4:Eu2+, was prepared by the solid-state reaction and X-ray powder diffraction (XRD) analysis confirmed the formation of LiSrPO4:Eu2+. Photoluminescence (PL) results showed that the phosphor can be efficiently excited by UV-visible light from 250 to 440 nm, and exhibited bright blue emission. The effects of the doped-Eu2+ concentration in LiSrPO4:Eu2+ on the PL were investigated in detail. The results showed that the relative PL intensity increases with Eu2+-concentration increasing until a maximum intensity is reached, and then it decreases due to concentration quenching and a red-shift appears, which are explained satisfactorily with the luminescent theory. Upon excited with 396 nm light, the present synthesized phosphor has higher emission intensity than that from the commercial blue phosphor, BaMgAl10O17:Eu2+. Bright blue light-emitting diodes were fabricated by the combination of the synthesized LiSrPO4:Eu2+ with ∼397 nm emitting InGaN-based chips. 相似文献
144.
New “Magic Blue” reagent, namely, the blue solution in F113 (CClF2CCl2F) containing H-abstracting agent bis[ω-fluorosulfonylperfluoroalkyl] nitroxide RFN(O)RF2 and ω-fluorosulfonylperfluoronitrosoalkane spin trap RFNO 3 both generated in the reaction of ω-fluorosulfonylperfluorodiacyl peroxide [FO2SCF2CF2OCF(CF3)CF2OCF(CF3)COO]21 with sodium nitrite in F113 (CClF2CCl2F) at room temperature, reacted with a series of p-substituted benzaldehydes 4 via regio-selective abstraction of the formyl hydrogen followed by spin trapping of the acyl radical intermediate 5, thus led to the formation of stable spin adducts ω-fluorosulfonylperfluoroalkyl p-substituted benzoyl nitroxides 6. The correlation analyses of aN values of nitroxides 6 with various substituent constants disclose that the polar effects are the major factors varying the spin density on the nitroxyl-nitrogen while the effect through spin-delocalization is felt slightly. 相似文献
145.
A new homogeneous fluoroimmunoassay method based on the use of dynamic long-wavelength fluorescence polarization is presented here for the first time. This methodology, which is applied to the determination of linear alkylbenzenesulfonates (LASs) in water samples, involves the use of a new long-wavelength tracer synthesized from the oxazine dye Nile Blue (NB) via a carbodiimide method. This tracer exhibits fluorescent properties at λex 626 and λem 674 nm. The variation of fluorescence polarization with time is followed using the T-format configuration of the spectrofluorimeter and the analytical parameter used is the initial rate, which is measured in only 0.7 s. The dynamic range of the calibration graph is 0.05-4.7 mg/L, with a detection limit of 0.03 mg/L. The precision, expressed as relative standard deviation was assayed at 0.05 and 1 mg/L, giving values in the range 7.6-9.1%. Other anionic, cationic and non-ionic surfactants were tolerated at much higher concentration levels than that of the analyte. The method has proven its practical usefulness for the analysis of water samples, in which only a solid phase extraction step is necessary. Recoveries ranged from 80.8 to 119.8%, with a mean value of 100.8%. 相似文献
146.
SYNTHESIS AND PHOTOLUMINESCENCE OF AN ANTHRACENE-CONTAINING HYPERBRANCHED POLY(ARYLENEETHYNYLENE) 总被引:1,自引:0,他引:1
Yong-qiang Dong Zhen Li Jacky W. Y. Lam Yu-ping Dong Xin-de Feng Ben-zhong Tang 《高分子科学》2005,(6):665-669
A hyperbranched poly(aryleneethynylene) containing anthracene chromophore was synthesized by palladiumcatalyzed cross-coupling reaction of 2,4,6-triiodophenyl 9-anthracenylcarboxylate with 9,9-bis[4-(2-propynyloxy)phenyl]- 9H-fluorene. The structure and properties of the polymer are characterized and evaluated by NMR, IR, UV, PL and TGA analyses. The polymer is soluble in common organic solvents, possesses high thermal stability (Td 〉 330℃), and emits a strong blue light of 465 nm in both solution and solid states. 相似文献
147.
A semi conducting polymer-modified glassy carbon electrode was fabricated by cyclically sweeping in the potential range of −0.4–1.2 V(vs. SCE) or by electrolyzation at constant potential of 1.4 V in 0.5 M sulfuric acid solution containing 1.0 mM Nile Blue. This redox active polymer could successfully be used for the amperometric determination of hemoglobin. The effect of pH was studied for the polymerization of Nile Blue. It was found that the polymerization did not occur in neutral or basic solutions. The formal potential of this film is −410 mV (pH 7.0) which is more negative than that obtained at the bare electrode in the Nile Blue bulk solution. The electrochemical characteristics of this polymer are discussed. The modified electrode could electrocatalyze the reduction of hemoglobin, and a good linear amperometric response could be obtained over the range of 0.05–7.0 mg/mL (correlation coefficient: 0.985). This modified electrode exhibited good stability and reproducibility for long-term use. 相似文献
148.
Jun-Lin Yuan Xiao-Yan Zeng Jing-Tai Zhao Zhi-Jun Zhang Hao-Hong Chen 《Journal of solid state chemistry》2007,180(11):3310-3316
A new efficient blue phosphor, Eu2+ activated SrZnP2O7, has been synthesized at 1000 °C under reduced atmosphere and the crystal structure and photoluminescence properties have been investigated. The crystal structure of SrZnP2O7 was obtained via Rietveld refinement of powder X-ray diffraction (XRD) pattern. It was found that SrZnP2O7 crystallizes in space group of P21/n (no. 14), Z=4, and the unit cell dimensions are: a=5.30906(2) Å, b=8.21392(3) Å, c=12.73595(5) Å, β=90.1573(3)°, and V=555.390(3) Å3. Under ultraviolet excitation (200-400 nm), efficient Eu2+ emission peaked at 420 nm was observed, of which the luminescent efficiency at the optimal concentration of Eu2+ (4 mol%) was estimated to be 96% as that of BaMgAl10O17:Eu2+. Hence, the SrZnP2O7:Eu2+ exhibit great potential as a phosphor in different applications, such as ultraviolet light emitting diode and photo-therapy lamps. 相似文献
149.
Two linear, stereoregular, and structurally defined PPV derivatives (PPVs), poly[distyrylbenzene-b-(ethylene oxide)]s, with respective 12 and 16 of ethylene oxide repeat units in the backbone, abbreviated as DE-1 and DE-2 thereinafter, have been prepared via a modified synthetic profile. Both DE-1 and -2 were soluble in organic solvents and able to form robust and transparent film upon spin casting. Instrument characterization, such as FTIR, 1H and 13C NMR, UV-vis and fluorescence spectroscopy, revealed the final structures as designed and novel photophysical properties in solution. Apparent spectral evidences strongly suggested the all trans conjugated DE-1 and -2 and the successful isomeirization process adopted. It was found that the aggregates were formed for both DE-1 and -2 at approximately 60% of methanol in methanol/dichloromethane (MeOH/DCM). Both DE-1 and -2 exhibited solution tailorable absorption and emission properties. Before aggregating point, the absorption profile experienced a blue shift with the increase of MeOH and a slight increase in quantum yields (QYs). At aggregating point, however, an apparent blue shift in emission profile was observed along with a remarkable decrease of QY due to aggregate quenching. 相似文献
150.
Yuzhen Zhao Xun Qiao Kexuan Li Siyi Ding Shaopeng Tian Huaping Ren 《Molecular Crystals and Liquid Crystals》2018,664(1):1-8
In the present work, the graphene oxide/blue phase liquid crystal composites and long aminoalkyl chains functionalized graphene/blue phase liquid crystal composites were prepared by doping the additives into a blue phase exhibiting liquid crystal host. It is found that the blue phase temperature range could be widened by dispersing a small amount of functionalized graphene. It suggests that anisotropic two-dimensional flake nanoparticles may be of great usefulness for stabilizing blue phases. 相似文献