Highly efficient red electroluminescent polymers with dopant/host system and molecular dispersion feature: polyfluorene as the host and 2,1,3-benzothiadiazole derivatives as the red dopant

By selecting polyfluorene as the polymer host, choosing 2,1,3-benzothiadiazole derivative moieties as the red dopant units and covalently attaching 0.3 mol% of the dopant units to the side chain of the polymer host, we developed a novel series of red electroluminescent polymers of dopant/host system with molecular dispersion feature. Their EL spectra exhibited predominant red emission from the dopant units because of the energy transfer and charge trapping from the polymer backbone to the dopant units. The emission wavelength of the polymers could be tuned by modifying the chemical structures of the dopant units.

Synthesis of Liquid Polybutadiene Having Desired 1,2-Vinyl Content with Co(naph)(2)-Al-2(C2H5)(3)Cl-3-P(OPh)(3) Catalyst System

Liquid polybutadiene with desirable 1,2-units content was synthesized by Co(naph)(2)-Al-2(C2H5)(3)Cl-3-P(OPh)(3) catalyst system. It was shown that liquid polybutadiene having adequate 1,2-unit content (vinvl =35%-40%) molecular weight(M-n = 700-3500), and acceptabele conversion(>= 55%) can synthesized after optimizing polymerization conditions.

N-Acetyl-N-{2-[(Z)-2-chloro-3,3,3-trifluoroprop-1-enyl]phenyl}acetamide

The title compound, C13H11ClF3NO2, adopts a Z conformation. Halogen center dot center dot center dot oxygen interactions [Cl center dot center dot center dot O = 2.967 (3) angstrom] in the crystal packing lead to the formation of a dimer joined by two Cl center dot center dot center dot O bonds.

Uniform Ln(OH)(3) and Ln(2)O(3) (Ln = Eu, Sm) Submicrospindles: Facile Synthesis and Characterization

Monodisperse hexagonal Ln(OH)(3) (Ln = Eu, Sm) submicrospindles with uniform morphology and size have been Successfully synthesized in a large scale via a Facile aqueous solution route from the mixture of aqueous solutions or LnCl(3) and NaOH at 5 degrees C without using any surfactant or template. The as-synthesized products are characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), energy-dispersive X-ray (EDX) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). The SEM and TEM images show that the as-formed Ln(OH)(3) samples have a spindlelike shape with an equatorial diameter of 80-200 nm and a length of 500-900 nm, which are aggregates of even smaller nanoparticles.

Blue amplified spontaneous emission from 2, 1, 3-benzothiadiazole attached polyfluorene semiconductor polymer with high photoluminescence efficiency

The amplified spontaneous emission properties of a 2, 1, 3-benzothiadiazole attached polyfluorene semiconductor polymer were studied. The conjugated polymer shows a high photoluminescence quantum efficiency of 67% and emits a narrowed blue emissive spectrum with a full width at half-maximum of 3.6 nm when optically pumped, indicating better lasing action. A threshold energy as low as 0.22 mJ pulse(-1) cm(-2), a net gain of 40.54 cm(-1) and a loss of 7.8 cm(-1) were obtained, demonstrating that this conjugated polymer could be a promising candidate as the gain medium for the fabrication of blue polymer lasers.

Why [6,6]- and 1,2-Benzal-3-N-4-O-Cyclic Phenylimidate C-60 Undergo Electrochemically Induced Retro-Addition Reactions while 1,4-Dibenzyl-2,3-Cyclic Phenylimidate C-60 Does Not? C-H center dot center dot center dot X (X = N, O) Intramolecular Interactions in Organofullerenes

The electrochemical properties of a series of structurally related fullerooxazoles, [6,6] cyclic phenylimidate C-60 (1), 1,2-benzal-3-N-4-O-cyclic phenylimidate C-60 (2), and 1,4-dibenzyl-2,3-cyclic phenylimidate C-60 (3), are described, and the spectroscopic characterizations of their anionic species are reported. The results show that compounds I and 2 undergo retro-cycloaddition reactions that lead to the formation of C-60 and C61HPh, respectively, upon two-electron-transfer reduction. However, compound 3 demonstrates much more electrochemical stability as no retro-cycloaddition reaction occurs under similar conditions. Natural bond orbital (NBO) calculations on charge distribution show there is no significant difference among the dianions of 1, 2, and 3, indicating that the electrochemical stability of 3 is unlikely to be caused by the charge distribution difference of the dianions of three compounds. Examination on the crystal structure of compound 3 reveals close contacts of the C-H group with the heteroatoms (N and O) of cyclic phenylimidate, suggesting the existence of C-H center dot center dot center dot X (X = N, O) intramolecular hydrogen bonding among the addends, which is further confirmed by NBO analysis.

One-step synthesis of Ru(2,2 '-bipyridine)(3)Cl-2-immobilized silica nanoparticles for use in electrogenerated chemiluminescence detection

One-step synthesis of Ru (bpy)(3) Cl-2-immobilized (bpy = 2,2'-bipyridine) silica nanoparticles (Ru-silica nanoparticles) for use in electrogenerated-chemiluminescence (ECL) detection is reported. Ru-silica nanoparticles are prepared by using the Stober method. Compared with free Ru(bpy)(3)Cl-2, Ru-silica nanoparticles are seen to exhibit a red-shift of the UV-vis absorbance peak and a longer fluorescence lifetime, which are attributed to the electrostatic interaction of Ru(bpy)(3)(2+) and silica. Because silica nanoparticles are used as immobilization matrices, the surfaces of Ru-silica nanoparticles are easily modified or functionalized via the assembly of other nanoparticles, such as Au. For ECL detection, Au-colloid-modified Ru-silica nanoparticles are immobilized on a 3-mercaptopropyl-trimethoxysilane-modified indium tin oxide electrode surface by Au-S interaction; the surface concentration of electroactive Ru(bpy)(3)Cl-2 is obviously higher than that in silica films.

Microstructures and mechanical properties of Mg-8Gd-0.6Zr-xNd (x=0, 1, 2 and 3 mass%) alloys

Mg-8Gd-0.6Zr-xNd (x = 0, 1, 2 and 3 mass%) alloys were prepared by metal mould casting method, and the microstructures, age hardening responses and mechanical properties have been investigated. The microhardness of the as-cast alloys is increased with increasing Nd content. The age hardening behavior and mechanical properties are enhanced significantly by adding Nd element. The peak ageing hardness of the Mg-8Gd-0.6Zr-3Nd alloy is 103, it is about 1.3 times more than that of the Mg-8Gd-0.6Zr alloy. The aged Mg-8Gd-0.6Zr-3Nd alloy exhibits maximum ultimate tensile strength and yield strength, and the values are 271 and 205 MPa at room temperature, 205 MPa and 150 MPa at 250 degrees C, respectively. Which are about 2 times higher than those of Mg-8Gd-0.6Zr alloy. The improved hardness and strength are mainly attributed to the fine dispersiveness Of Mg5RE and Mg12RE precipitates in the alloy.

Vilsmeier-Haack reactions of 2-arylamino-3-acetyl-5,6-dihydro-4H-pyrans toward the synthesis of highly substituted pyridin-2(1H)-ones

A facile and efficient one-pot synthesis of highly substituted pyridin-2(IH)-ones was developed via Vilsmeier-Haack reactions of readily available enaminones, 2-arylamino-3-acetyl-5,6-dihydro-4H-pyrans, and a mechanism involving sequential ring-opening, haloformylation, and intramolecular nucleophilic cyclization reactions is proposed.

White electroluminescence from a single-polymer system with simultaneous two-color emission: Polyfluorene as blue host and 2,1,3-benzothiadiazole derivatives as orange dopants on the side chain

Four single polymers with two kinds of attachment of orange chromophore to blue polymer host for white electroluminescence (EL) were designed. The effect of the side-chain attachment and main-chain attachment on the EL efficiencies of the resulting polymers was compared. The side-chain-type single polymers are found to exhibit more efficient white EL than that of the main-chain-type single polymers. Based on the side-chain-type white single polymer with 4-(4-alkyloxy-phenyl)-7-(4-diphenylamino-phenyl)-2,1,3-benzothiadiazoles as the orange-dopant unit and polyfluorene as the blue polymer host, white EL with simultaneous orange (lambda(max) = 545 nm) and blue emission (lambda(max) = 432 nm/460 nm) is realised. A single-layer device (indium tin oxide/poly(3,4-ethylenedioxythiophene)/polymer/Ca/Al) made of these polymers emits white light with the Commission Internationale de l'Eclairage coordinates of (0.30,0.40), possesses a turn-on voltage of 3.5 V, luminous efficiency of 10.66 cd A(-1), power efficiency of 6.68 lm W-1, and a maximum brightness of 21240 cd m(-2).

Green light-emitting polyfluorenes with improved color purity incorporated with 4,7-diphenyl-2,1,3-benzothiadiazole moieties

By incorporating 4,7-diphenyl- 2,1,3 benzothiadiazole instead of 2,1,3-benzothiadiazole into the backbone of polyfluorene, we developed a novel series of green light- emitting polymers with much improved color purity. Compared with the state-of-the-art green light-emitting polymer, poly(fluorene-co-benzothiadiazole) (lambda max = 537 nm), the resulting polymers (lambda(max) = 521 nm) showed 10-20 nm blueshifted electroluminescence (EL) spectra and greatly improved color purity because the insertion of two phenylene units between the 2,1,3-benzothiadiazole unit and the fluorene unit reduced the effective conjugation length in the vicinity of the 2,1,3-benzothiadiazole unit. As a result, the resulting polymers emitted pure green light with CIE coordinates of (0.29, 0.63), which are very close to (0.26, 0.65) of standard green emission demanded by the National Television System Committee (NTSC). Moreover, the insertion of the phenylene unit did not affect the photoluminescence (PL) and EL efficiencies of the resulting polymers. PL quantum efficiency in solid films up to 0.82 was demonstrated. Single-layer devices (ITO/PEDOT/ polymer/Ca/Al) of these polymers exhibited a turn-on voltage of 4.2 V, luminous efficiency of 5.96 cd A(-1) and power efficiency of 2.21 lm W-1. High EL efficiencies and good color purities made these polymers very promising for display applications.

Fabrication and luminescent properties of rare earths-doped Gd-2(WO4)(3) thin film phosphors by Pechini sol-gel process

Rare earth ions (Eu3+ and Dy3+)-doped Gd-2(WO4)(3) phosphor films were prepared by a Pechini sol-gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM) and photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting powders and films. The results of XRD indicate that the films begin to crystallize at 600degreesC and the crystallinity increases with the elevation of annealing temperatures. The film is uniform and crack-free, WO(4)(2-)mainly consists of closely packed fine particles with an average grain size of 80 nm. Owing to an energy transfer from 4 groups, the rare earth ions show their characteristic emissions in crystalline Gd-2(WO4)(3) phosphor films, i.e., D-5(J) -F-7(J), (J = 0, 1, 2, 3; J' = 0 1, 2, 3, 4, not in all cases) transitions for Eu3+ and F-4(9/2)-H-6(J) (J = 13/2, 15/2) transitions for D Y3+, with the hypersensitive transitions D-5(0)-F-7(2) (Eu3+) and F-4(9/2) - H-6(13/2) (Dy3+) being the most prominent groups, respectively.

White electrolumineseence from a single-polymer system with simultaneous two-color emission: Polyfluorene as the blue host and a 2,1,3-benzothiadiazole derivative as the orange dopant on the main chain

New single-polymer electroluminescent systems containing two individual emission species - polyfluorenes as a blue host and 2,1,3-benzothiadiazole derivative units as an orange dopant on the main chain - have been designed and synthesized. The resulting single polymers are found to have highly efficient white electroluminescence with simultaneous blue(lambda(max) = 421 nm/445 nm) and orange emission (lambda(max) = 564 nm)from the corresponding emitting species. The influence of the photoluminescence (PL) efficiencies of both the blue and orange species on the electroluminescence (EL) efficiencies of white polymer light-emitting diodes (PLEDs) based on the single-polymer systems has been investigated. The introduction of the highly efficient 4,7-bis(4-(N-phenyl-N-(4-methylphenyl)amino)phenyl)-2,1,3-benzothiadiazole unit to the main chain of polyfluorene provides significant improvement in EL efficiency. For a single-layer device fabricated in air (indium tin oxide/poly(3,4-ethylenedioxythiophene): poly(styrene sulfonic acid/polymer/Ca/Al), pure-white electroluminescence with Commission Internationale de l'Eclairage (CIE) coordinates of (0.35,0.32), maximum brightness of 12 300 cd m(-2), luminance efficiency of 7.30 cd A(-1), and power efficiency of 3.34 lm W-1 can be obtained.

Luminescence properties of sol-gel derived spherical SiO2@Gd-2(WO4)(3): Eu3+ particles with core-shell structure

Monodisperse, core-shell structured SiO2@Gd-2(WO4)(3):Eu3+ particles were prepared by the sol-gel method. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy, transmission electron microscopy, photoluminescence (PL) and low-voltage cathodoluntinescence (CL). PL and CL study revealed that the core-shell structured SiO2@Gd-2(WO4)(3):Eu3+ particles show strong red emission dominated by the D-5(0)-F-7(2) transition of Eu3+ at 615 nm with a lifetime of 0.89 ins. The PL and CL emission intensity can be tuned by the coating number of Gd-2(WO4)(3):Eu3+ phosphor layers on SiO2 particles, the size of the SiO2 core particles, and by accelerating voltage and the filament current, respectively.

Fe(2-EHA)(3)/Al(i-Bu)(3)/hydrogen phosphite catalyst for preparing syndiotactic 1,2-polybutadiene

Polymerizing 1,3-butadiene into syndiotactic 1,2-polybutadiene with art iron(III) catalyst system has been investigated. Activity of the catalyst was affected by the type of cocatalyst alkylaluminum and the phosphorus compound as an electron donor, molar ratio of catalyst components, and their aging sequence and aging time of the catalyst. The microstructure and configuration of the polymer was decided by the catalyst components, the higher [Al]/[Fe] molar ratio tending to yield syndiotactic 1,2-polybutadiene, while the higher [P]/[Fe] molar ratio favors the formation of amorphous 1,2-polybutadiene.