High-efficiency, environment-friendly electroluminescent polymers with stable high work function metal as a cathode: green- and yellow-emitting conjugated polyfluorene polyelectrolytes and their neutral precursors

A series of aminoalkyl-substituted polyfluorene copolymers with benzothiadiazole (BTDZ) of different content were synthesized by Suzuki coupling reaction, and their quaternized ammonium polyelectrolyte derivatives were obtained through a postpolymerization treatment on the terminal amino groups. Copolymers are soluble in environmentally friendlier solvents, such as alcohols. It was found that the efficient energy transfer occurs by exciton trapping on the narrow band gap BTDZ site under UV illumination. Only 1% of BTDZ content is needed to completely quench a fluorene emission for both the neutral and the quaternized copolymers in the neat film. Absolute PL efficiencies of copolymer films were greatly enhanced as a result of the suppression of excimer formation. Light-emitting devices fabricated from these copolymers show high external quantum efficiencies over 3% and 1% for the neutral precursor and the quaternized copolymers, respectively, with high work function metals such as Al as a cathode. To the best of our knowledge, this is the first report on an electroluminescent polymer which bears the high EL efficiency, the electron-injection ability from high work function metals, and the solubility in environment-friendly solvents at the same time. These features make them a promising candidate for the next generation of light-emitting copolymers in PLED flat panel display application.     

Synthesis of Imidazo[2,1‐a]isoquinolines from α‐Tosyloxyketones and 1‐Aminoisoquinoline in Ionic Liquid Solvent

The room temperature ionic liquid n‐butylpyridinium tetrafluoroborate (BPyBF₄) is used as a ‘green’ recyclable alternative to classical molecular solvents for the cyclocondensation of α‐tosyloxyketones with 1‐aminoisoquinoline to prepare imidazo[2,1‐a]isoquinolines in good yields.     

Accuracy, precision and sensitivity in cyclic INAA with short-lived radionuclides

Repeated irradiation enhances the precision and sensitivity of INAA based on short-live radionuclides, but entail systematic losses due to dead time. The relative standard deviation in the net peak area decreases with the square root of the number of cycles while the systematic bias increases with it. The limits of decision, detection and determination decrease in a somewhat more complicated way with the number of cycles. The derived formulation is applied to the determination of selenium in hair by the 161.9 keV photopeak of^77mSe,T _1/2=17.8 s.     

Novel Z-selective head-to-head dimerization of terminal alkynes catalyzed by lanthanide half-metallocene complexes

Various terminal alkynes have been cleanly dimerized into the corresponding head-to-head (Z)-enynes by use of the half-metallocene lutetium alkyl complexes Me2Si(C5Me4)(NAr)Lu(CH2SiMe3)(THF) (Ar = Ph, C6H3Me2-2,6, C6H2Me3-2,4,6) as catalysts. Aromatic C-Cl, C-Br, and C-I bonds, which are known to be extremely susceptible to reductive cleavage by transition metals, survived in the present reactions. The corresponding dimeric alkynide species [Me2Si(C5Me4)(NAr)Lu(mu-CCR)]2 are thought to be the true catalysts, some of which have been isolated and structurally characterized. These alkynide species were thermally stable and soluble at the reaction temperatures (80-110 degrees C), but they precipitated upon cooling to room temperature after completion of the reaction. Therefore, this catalyst system works homogeneously but can be separated and reused, thus constituting the first example of a recyclable catalyst system for the dimerization of terminal alkynes and also the first example of (Z)-selective head-to-head dimerization of aromatic terminal alkynes.     

AQC柱前衍生反相高效液相色谱法测定土壤中氨基酸

以2-氨基丁酸为内标物,6-氨基喹啉基-N-羟基琥珀酰亚氨基甲酸酯(AQC)为柱前衍生试剂,用XTerraC18柱,1.8mmol/L甲酸铵溶液(pH=3.0)和乙腈为流动相,采用梯度洗脱,光电二极管(PDA)检测器在248nm波长处检测,建立了一种利用反相高效液相色谱同时测定土壤中17种氨基酸的分析方法。方法重现性好,精密度高,氨基酸浓度在25~600μmol/L范围内,线性相关系数均大于0.99;各氨基酸检出限≤0.5pmol。并且在该色谱条件下,获得了灵敏度较高,彼此分离良好的17种AQC衍生氨基酸的LC-MS质谱总离子流图,为今后土壤氨基酸的深入研究提供了更加有利的手段。     

同时测定食用植物油中抗氧剂叔丁基对羟基茴香醚和2，6－二叔丁基对甲酚的方法

报道了用高效液用色谱法同时测定食用植物油中的抗氧剂叔丁基对羟基茴香醚（ＢＨＡ）和２，６－二叔丁基对甲酚（ＢＨＴ）的实验方法。采用ＺｏｒｂａｘＯＤＳＣ_（１８）色谱住，甲醇：水（９０：１０，Ｖ／Ｖ）作流动相，检测波长为２４５ｎｍ，流速为１ｍＬ／ｍｉｎ。检测下限分别为１５ｎｇ（ＢＨＡ），９０ｎｇ（ＢＨＴ），回收率分别是９６．８％±９．８％（ＢＨＡ），９９．０％±３．２％（ＢＨＴ）。方法快速、准确，灵敏度高。     

The global topological meaning of cocycles in a Gauge group

This Letter shows explicitly that the descent sequence of cocycles in a gauge group realizes the ech-de Rham double complex. Meanwhile the ech complex corresponds to finite gauge transformations. This Letter also shows how the indices of each order of cocycles characterizes the obstructions on overlapping spheres in different dimensions and how these indices are equal to a common one.     

New features in the catalytic cycle of cytochrome P450 during the formation of compound I from compound 0

Density functional theory (DFT) is applied to the dark section of the catalytic cycle of the enzyme cytochrome P450, namely, the formation of the active species, Compound I (Cpd I), from the ferric-hydroperoxide species (Cpd 0) by a protonation-assisted mechanism. The chosen 96-atom model includes the key functionalities deduced from experiment: Asp(251), Thr(252), Glu(366), and the water channels that relay the protons. The DFT model calculations show that (a) Cpd I is not formed spontaneously from Cpd 0 by direct protonation, nor is the process very exothermic. The process is virtually thermoneutral and involves a significant barrier such that formation of Cpd I is not facile on this route. (b) Along the protonation pathway, there exists an intermediate, a protonated Cpd 0, which is a potent oxidant since it is a ferric complex of water oxide. Preliminary quantum mechanical/molecular mechanical calculations confirm that Cpd 0 and Cpd I are of similar energy for the chosen model and that protonated Cpd 0 may exist as an unstable intermediate. The paper also addresses the essential role of Thr(252) as a hydrogen-bond acceptor (in accord with mutation studies of the OH group to OMe).     

Self-assembly of a series of novel metal-organic compounds containing ferrocenecarboxylate components

Using FcCOONa (Fc = (eta(5)-C(5)H(5))Fe(eta(5)-C(5)H(4))) as starting material, we obtained an unprecedented metal-organic coordination polymer containing ferrocenecarboxylate components [[Pb(2)(FcCOO)(eta(2)-FcCOO)(mu(2)-eta(2)-FcCOO)(mu(3)-eta(2)-FcCOO)(CH(3)OH)].1.5CH(3)OH.H(2)O](n) (1), tetramer [Zn(4)(mu(2)-FcCOO)(6)(mu(4)-O)] (2), and coordination polymers [Pb(FcCOO)(mu(2)-FcCOO)(bpe)](n) (3) (bpe = 1,2-bis(4-pyridyl)ethene), [[Zn(FcCOO)(2)(bpt)].2.5H(2)O](n) (4) (bpt = N,N'-bis(3-pyridylmethyl)thiourea), and [Zn(FcCOO)(eta(2)-FcCOO)(bbp)](n) (5) (bbp = 4,4'-trimethylene-dipyridine). Compounds 1 and 2 are formed by ferrocenecarboxylate units coordinating with Pb(II) or Zn(II). In polymer 1, ferrocenecarboxylate units have four kinds of coordinate modes; just these novel coordinate modes lead to the unprecedented one-dimensional polymer where two kinds of rhomboids are arranged alternatively along the chain. Compound 2 is a tetramer, in which a distinct connectivity of the six ferrocene units is established through the four Zn atoms. Compounds 3-5 are obtained by organic ligands bridging Pb(II) or Zn(II), leading to a new type of metal-organic coordination polymer.