Synthesis of the first rare earth metal bis(alkyl)s bearing an indenyl functionalized N-heterocyclic carbene

Treatment of indenyl-modified imidazolium bromide [C9H7CH2CH2(NCHCHN(C6H2Me3-2,4,6)CH)Br] ((IndH-NHC-H)Br) with rare earth metal tetra(alkyl) lithium (Ln(CH2SiMe3)(4)Li(THF)(4)) or with (trimethylsilylmethyl)lithium (LiCH2SiMe3) and rare earth metal tris(alkyl)s (Ln(CH2SiMe3)(3)(THF)(2)) sequentially afforded the first NHC-stabilized monomeric rare earth metal bis(alkyl) complexes (Ind-NHC)Ln(CH2SiMe3)(2) (1, Ln = Y; 2, Ln = Lu; 3, Ln = Sc) via double-deprotonation reactions. Complexes 1-3 are THF-free isostructural monomers. The monoanionic Ind-NHC species bond to the central metal ion in a eta(5):kappa(1) constrained geometry configuration (CGC) mode, which combine with the two cis-located alkyl moieties to form a tetrahedron ligand core, leading to the chirality of the complexes. Under the presence of activators AlEt3 and [Ph3C][B(C6F5)(4)], complex 2 showed catalytic activity toward the polymerization of isoprene to afford 3,4-regulated polyisoprene (91%).

Molecular design on highly efficient white electroluminescence from a single-polymer system with simultaneous blue, green, and red emission

A highly efficient white electroluminescent polymer with simultaneous blue, green, and red emission is reported, developed using a dopant/host strategy by covalently attaching both a green- and a red-light-emitting dopant to the side chain of a blue-light-emitting polymer host (see figure). In a single-layer device a maximum luminance efficiency of 7.3 cd A(-1) with CIE coordinates of (0.31,0.32) is achieved.

White electroluminescence from a single polymer system: Improved performance by means of enhanced efficiency and red-shifted luminescence of the blue-light-emitting species

High-efficiency white electrolurninescence from a single polymer is achieved by enhancing the electroluminescence efficiency and effecting a red-shift in the emission spectrum of the blue emissive species. A single-layer device of the resultant polymer exhibits a higher luminous efficiency than the nonmodified species (12.8 cd A(-1), see figure) and an external quantum efficiency of 5.4 % with CIE coordinates of (0.31,0.36), exemplifying the success of the reported methodology.

Three-color white electroluminescence from a single polymer system with blue, green and red dopant units as individual emissive species and polyfluorene as individual polymer host

A white electroluminescent single polymer system with both high electroluminescence efficiency and excellent color rendering index (CRI) value is developed by covalently attaching blue, green, and red dopant units as individual light-emitting species to the side chain of polyfluorene as individual polymer host. A luminous efficiency of 8.6 cd A(-1), CIE coordinates of (0.33, 0.36) and CRI value of 88 was demonstrated with their single-layer devices.

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).

两种黄酮醇苷同分异构体的电喷雾质谱区分

Two flavonol glycoside isomers of Icariside Ⅰ and Caohuoside C were differentiated by electrospray ionization tandem mass spectrometry (ESI-MSn) method.In the negative ion mode,the two compounds with different glycosyl moieties showed the same ESI-MS spectrum,but obvious different MS2 spectra and thus they can be distinguished rapidly,accurately and easily by ESI-MS.

Liquid crystal properties of a mesogenic polyacetylene, poly(11-[(4 '-heptoxy-4-biphenylyl)carbonyloxy]-1-undecyne)

The liquid crystalline properties of a mesogenic poly(1-alkyne) and the corresponding monomer were studied using transmission electron microscopy, X-ray diffraction, polarizing optical microscopy and differential scanning calorimetry. The monomer exhibits a monotropic smectic A phase and a metastable crystalline phase. The rigid polymer backbones do not prevent the mesogenic moieties from packing into smectic A and B phases in the temperature ranges 127.6 - 74.1degreesC and 74.1degreesC - room temperature, respectively, on cooling from the isotropic melt.

Electric-field-induced molecular alignment of side-chain liquid-crystalline polyacetylenes containing biphenyl mesogens

Electric-field-induced molecular alignments of side-chain liquid-crystalline polyacetylenes [-{HC=C[(CH2)(m)OCO-biph-OC7H15]}-, where biph is 4,4'-biphenylyl and m is 3 (PA3EO7) or 9 (PA9EO7)] were studied with X-ray diffraction and polarized optical microscopy. An orientation as high as 0.84 was obtained for PA9EO7. Furthermore, the molecular orientation of]PA9EO7 was achieved within a temperature range between the isotropic-to-smectic A transition temperature and 115 degreesC, and this suggested that the orientational packing was affected by the thermal fluctuation of the isotropic liquid and the mobility of the mesogenic moieties. The maximum achievable orientation for PA9EO7 was much greater than that for PA3EO7. This was the first time that the electric-field-induced molecular orientation of a side-chain liquid-crystalline polymer with a stiff backbone was studied.

The synthesis and catalytic activity of poly(bis(imino)pyridyl) iron(II) metallodendrimer

The first and second generation carbosilane dendrimers with silicon hydride terminated were synthesized, and then reacted with bis(imino)pyridyl containing allyl [4-CH2==CHCH2-2,6-(Pr2C6H3N)-Pr-i==CMe(C5H3N)MeC==N(2,6-'Pr2C6H3)], in the presence of H2PtCl6 as a hydrosilylation catalyst, to afford the first and second generation carbosilane supported ligands. Complexation reactions with FeCl(2)(.)4H(2)O give rise to iron-containing carbosilane dendrimers with FeCl2 moieties bound on the periphery. The metallodendrimers were used as catalyst precursors, activated with modified methylaluminoxane, for the polymerization of ethylene. In the case of low Al/Fe molar ratio, the metallodendrimers display much higher catalytic activity towards ethylene polymerization and produce much higher molecule weight polyethylenes than the corresponding single-nuclear complex under the same conditions.

Multiple-stage tandem mass spectrometry for differentiation of isomeric saponins

Four isomers of steroidal saponins were differentiated using multiple-stage tandem mass spectrometry combined with electrospray ionization (ESI-MSn). With the addition of lithium salt, the [M+Li](+) ions of saponins were observed in the ESI spectra. MSn spectra of these [M+Li](+) ions provided detailed structural information and allowed differentiation of the four isomeric saponins. The cross-ring cleavage ions from the saccharide chains of the saponins could be used as diagnostic ions for information concerning the linkage of the sugar moieties of the saponins. The masses of the X, A, Y and C type fragment ions formed from [M+Li](+) ions of the isomeric saponins provided information defining the methyl group locations.

Novel hole-transporting materials based on 1,4-bis(carbazolyl)benzene for organic light-emitting devices

Novel hole-transporting molecules containing 1,4-bis(carbazolyl)benzene as a central unit and different numbers of diphenylamine moieties as the peripheral groups have been synthesized and characterized. These compounds are thermally stable with high glass transition temperatures of 141-157 degreesC and exhibit chemically reversible redox processes. Their amorphous state stability and hole transport properties can be significantly improved by increasing the number of diphenylamine moieties in the outer part and by controlling the symmetry of the carbazole-based molecules. These compounds can be used as good hole-tran sporting materials for organic electroluminescent (EL) devices. The device performance based on tri- and tetra-substituted carbazole derivatives is comparable to that of a typical 4,4'-bis[N-(1-naphthyl)-N-phenylamino] biphenyl (NPB)-based device.

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.

White polymeric light-emitting diodes with high color rendering index

The efficient white polymeric light-emitting diodes based on a white emissive polymer doped with a red phosphorescent dopant were fabricated by spin-coating method. The emission spectrum of the device is broadened to cover the full visible region by doping the red phosphorescent dye and thereby realizes white emission with high color-rendering index (CRI). By controlling the contents of the doped electron-transporting 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole and the red phosphorescent dopant, a luminous efficiency as high as 5.3 cd/A and a power efficiency of 3 lm/W were obtained with a CRI of 92.

Phenylene vinylene-based electroluminescent polymers with electron transport block in the main chain

We report a new route for the design of soluble phenylene vinylene (PV) based electroluminescent polymers bearing electron-deficient oxadizole (OXD) and triazole (TZ) moieties in the main chains with the aryloxy linkage. Both series of the PV-based polymers were prepared by Wittig reaction. By properly adjusting the OXD and/or TZ content through copolymerization, we can achieve an enhanced balance of hole- and electron injections, such that the device efficiency is significantly improved. Light-emitting diodes fabricated from P1, P2, P3, P4, P5, P6, and P7 with the configuration of Indium-Tin Oxide (ITO)/Poly (styrene sulfonic acid) doped poly (ethylenedioxythiophene) (PEDOT)/polymer/Ca/Al, emit bright green light with the maximum peak around 500 nm. For the device using the optimal polymer (P4) as emitting layer, a maximum brightness of 1300 cd/m(2) at 20 V and a maximum luminance efficiency of 0.325 cd/A can be obtained.

Synthesis, characterization and fabrication on a glassy carbon electrode of a tetra-iron substituted sandwich-type pentadecatungstodiarsenate heteropolyanion

A novel sandwich-type compound, Na-12[Fe-4(H2O)(2)(As2W15O56)2].41H(2)O, has been synthesized. The compound was well-characterized by means of IR, UV-vis, W-183 NMR and elemental analyses. The compound crystallizes in the triclinic, P (1) over bar symmetry group. The structure of the compound is similar to that of Na-16[M-4(H2O)(2)(As2W15O56)(2)].nH(2)O (M = Cu, Zn, Co, Ni, Mn, Cd), and consists of an oxo-aqua tetranuclear iron core, [(Fe4O14)-O-III(H2O)(2)], sandwiched by two trivacant alpha-Wells-Dawson structural moieties, alpha-[As2W15O56]. Redoxelectrochemistry of the compound has been studied in buffer solutions at pH = 4.7 using polarography and cyclic voltammetry ( CV). The compound exhibited four one-electron couples associated with the Fe(III) center followed by three four-electron redox processes attributed to the tungsten-oxo framework. The compound-containing monolayer and multilayer films have been fabricated on a 4-aminobenzoic acid modified glassy carbon electrode surface by alternating deposition with a quaternized poly(4-vinylpyridine) partially complexed with [Os(bpy)(2)Cl](2+/-). CV, X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy and atomic force microscopy (AFM) have been used to characterize the multilayer films.