Application of CdSe–PVK Nanocomposite as a Hole Transport Layer for OLEDs

An organic light‐emitting diode was fabricated using cadmium selenide (CdSe)/poly(N‐vinylcarbazole) nanocomposite as the hole transport layer (HTL). The CdSe nanoparticles (NPs) with a mean crystallite size of 6.2 nm were prepared by high‐energy ball milling. Based on the current–voltage curves, the threshold voltage (V _th) of the composite diode was found to be ~1.3 ± 0.1 V lower than that of the diode without CdSe, with a significant increase in the current density for the composite diode. Moreover, the electroluminescence (EL) properties (luminous flux, emittance, and intensity) of the diode were found to be enhanced by ~16% with respect to those of the diode without CdSe. The decrease of the threshold voltage and the increase of the current density and the EL were due to the CdSe NPs that operate as hole trap centers in the HTL.     

Organic electroluminescent device with an aromatic amine-containing polymer as a hole transport layer (I): Poly[N-[p-N′ -phenyl-N′-[1,1′-biphenyl-4′-[N″-phenyl-N″-(2-methylphenyl)amino]-4-amino]]phenyl methacrylamide]

Electroluminescent devices were fabricated using a holetransporting polymer, poly[N-[p-N′ -phenyl-N′-[1,1′-biphenyl-4′-[N″-phenyl-N″-(2-methylphenyl)amino]-4-amino]]phenyl methacrylamide] (PTPDMA), and tris(8-quinolinolato)aluminum(III) complex, Alq, as the hole transport layer and the emitter layer, respectively. A device structure of glass substrate/indium–tin–oxide/PTPDMA/Alq/Mg:Ag was employed. Hole injection from the electrode through the PTPDMA layer to the Alq layer and concomitant electroluminescence from the Alq layer were observed. Bright green luminescence with a luminance of 20,000 cd/m² was obtained at a drive voltage of 14 V.     

Determination of Cr(VI) Using a Pulse Amperometric Method with an Ionophore‐Immobilized Membrane Electrode

A pulse amperometric method for the determination of Cr(VI) in aqueous solution has been investigated with an ionophore‐immobilized membrane electrode. The double potential step chronoamperometry was applied to measure the current for the facilitated transfer of Cr(VI) by the membrane with N,N,N′,N′‐tetrakis(3‐aminopropyl)‐1,4‐butanediamine (DABAm4) coated on a silver electrode. The current responses were stably detected by the pulse amperometry while voltage pulses, ΔE=?240 mV, of short duration of 50 ms were employed at the interval of 5 s. In the range of 1.65–81.3 μM, Cr(VI) in water could be selectively determined in the presence of various interfering anions below 100 μM without removal of Cr(VI) from the interferences using an ion exchange column.     

Electronic Transport Through N24B24 Molecular Junction

We have investigated the electron transport properties of a N₂₄B₂₄ molecule coupled to two metallic contacts with a combination of GW approximation and the non-equilibrium Green's-function technique. The calculations indicate that the four and three resonant tunneling peaks are seen for the density of states (DOS) curves in the cases of single and multiple atomic contacts, respectively. The off state and negative di erential resistance (NDR) effect are observed in the I-V characteristics of the N₂₄B₂₄ molecule. The NDR behavior is also observed in voltages of about ∓4.5, ∓4, ∓4.6, and ∓4.3 V for one, four, six, and eight atomic contacts. Also, the I-V characteristics of N₂₄B₂₄ are in off state at low voltages that is independent of the contact types. The current curves against the gate voltage depend on contact types and indicate that N₂₄B₂₄ molecule behaves as a semiconductor.     

Synthesis and mesogenic properties of a novel family of oligothiophene derivatives

With the aim of developing new oligothiophene-based liquid crystals involving hydrogen bonding, new terthiophene derivatives containing an alkylamide group, N,N'-distearyl-2,2' : 5',2"-terthiophene-5,5"-dicarboxamide (DNC₁₈3T) and N,N'-dialkyl-5,5"-dibromo-2,2' : 5',2"-terthiophene-4,4"-dicarboxamides (DNC_nDBr3T, n = 5, 8, 16, 18), were designed and synthesized, and their thermal behaviour examined. While DNC₁₈3T did not exhibit liquid crystallinity, DNC_nDBr3T compounds with n = 8, 16, 18 were found to form smectic A phases. In addition to liquid crystal behaviour, crystal polymorphism was also observed for DNC₁₆DBr3T. It is shown that both the position of the amido group and the alkyl chain length greatly affect liquid crystal phase formation. The absence of liquid crystallinity in the corresponding ester derivatives suggests that intermolecular hydrogen bonding also plays a role in the formation of liquid crystal phases in the DNC_nDBr3T system.     

A quantum mechanical test of diophantine methods

A blend of Haselgrove's method and the biased selection method for evaluating multidimensional integrals was tested. The results were mixed. The error estimate varied from being proportional to 1/N when N was less than ca. 60,000 to being proportional to 1/√N when N was greater than 60,000. Also, for N greater than 60,000, the error estimate was one-half the error estimate given by biased selection alone. These numbers should be compared with the 10,000 points used to find an optimum set of Haselgrove's parameters. It is reasonable to expect that if 100,000 points were used in the optimization of Haselgrove's parameters that the above results would be found with 60,000 replaced by 600,000.     

Voltammetry Under Microfluidic Control,a Flow Cell Aproach

A generic approach to the design, construction and experimental characterization of novel microelectrochemical reactors (MECR) is presented. Structurally well‐defined rectangular microchannels incorporating electrochemical sensors were fabricated using a propriety photosensitive glass and photolithographic techniques. Microelectrode sensors were produced via evaporation to yield, gold, silver or platinum bands of approximate lengths 10–50 μm. The approach outlined permits cells of dimensions in the range: height 50–100 μm, width 100–500 μm and length 1–3 cm to be accurately constructed, in single or array configurations and were characterized via a voltammetric study utilizing electrolyte solutions containing N,N,N′N′‐Tetramethyl‐1,4‐phenylenediamine. In all cases, the test cells were constructed so that the three dimensional hydrodynamic boundary layer within the cells would significantly influence the reagent transport and therefore the observed current density at the microelectrodes. The current/flow rate relationship observed was analogous to the response of the observed within the macroscopic channel flow cells, where typically the cell design is restricted to configurations where a two dimensional transport analysis can be performed.     

Capillary electrophoresis-atmospheric pressure chemical ionization-mass spectrometry using an orthogonal interface: Set-up and system parameters

The feasibility of atmospheric pressure chemical ionization (APCI) as an alternative ionization technique for capillary electrophoresis-mass spectrometry (CE-MS) was investigated using a grounded sheath-flow CE-MS sprayer and an orthogonal APCI source. Infusion experiments indicated that highest analyte signals were achieved when the sprayer tip was in close vicinity of the vaporizer entrance. The APCI-MS set-up enabled detection of basic, neutral, and acidic compounds, whereas apolar and ionic compounds could not be detected. In the positive ion mode, analytes could be detected in the entire transfer voltage range (0–5 kV), whereas highest signal intensities were observed when the corona discharge current was between 1000 and 2000 nA. In the negative ion mode, the transfer voltage typically was 500 V and the optimum corona discharge current was 6000 nA. Analyte signals were raised with increasing nebulizing gas pressure, but the pressure was limited to 25 psi to avoid siphoning and current drops. Signal intensities appeared to be optimal and constant over a wide range of sheath liquid flow rate (5–25 μL/min) and vaporizer temperature (200–350 °C). APCI-MS signals were unaffected by the composition of the background electrolyte (BGE), even when it contained sodium phosphate and sodium dodecyl sulfate (SDS). Consequently, BGE composition, sheath-liquid flow rate, and vaporizer temperature can be optimized with respect to the CE separation without affecting the APCI-MS response. The analysis of a mixture of basic compounds and a steroid using volatile and nonvolatile BGEs further demonstrates the feasibility of CE-APCI-MS. Detection limits (S/N = 3) were 1. 6–10 μM injected concentrations.     

Electronic Structure and Electrooptical Properties of Radicals Formed upon Reduction of <Emphasis Type="Italic">N</Emphasis>-Alkyl 4,4′-Bipyridylium Salts

N-Alkyl 4,4'-bipyridylium salts were synthesized and characterized. Cyclic voltammetry investigation showed that monosubstited 4,4'-bipyridylium salts are prone to reversible single-electron reduction. The formal redox potentials vs. a saturated silver chloride electrode were determined for different potential sweep rates. High-resolution ESR spectra of the radical cations formed upon the reduction of N-substituted 4,4'- bipyridylium salts in acid media were measured and interpreted. The substituent structure and the type of anion in the molecule have a considerable effect on the spin density distribution, current–voltage characteristics, and elctrooptical properties. The applicability of monosubstituted 4,4'-bipyridylium salts as photoelectrochromic compounds was studied.     

Carbon-13 NMR spectra of all-trans-N-retinylidene-n-butylamine as an analogue of the Schiff's base linkage-compound in visual pigment

Carbon-13 NMR spectra have been obtained for all-trans-N-retinylidene-n-butylamine as an analogue of the Schiff's base linkage compound in visual pigment. The chemical shift changes on going from all-trans-retinal₁ to all-trans-N-retinylidene-n-butylamine are observed. These changes indicate the collapse of the bond alternation in conjugated polyene carbons, whereas N-protonation in all-trans-N-retinylidene-n-butylamine does not affect the bond alternation.     

Electrical properties of polypyrrole/p‐InP structure

The polypyrrole/p‐InP structure has been fabricated by the electrochemical polymerization of the organic polypyrrole onto the p‐InP substrate. The current–voltage (I–V), capacitance–voltage (C–V), and capacitance–frequency (C–f) characteristics of the PPy/p‐InP structure have been determined at room temperature. The structure showed nonideal I–V behavior with the ideality factor and the barrier height 1.48 and 0.69 eV respectively. C–f measurements of the structure have been carried out using the Schottky capacitance spectroscopy technique and it has been seen that there is a good agreement between the experimental and theoretical values. Also, it has been seen that capacitance almost show a plateau up to a certain value of frequency, after which, the capacitance decreases. The higher values of capacitance at low frequencies were attributed to the excess capacitance resulting from the interface states in equilibrium with the p‐InP that can follow the a.c. signal. The interface state density N_ss and relaxation time τ of the structure were determined from C–f characteristics. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1572–1579, 2006     

Acylaminoacetyl derivatives of active methylene compounds. 4

Meldrum's acid has been found to be effectively acylated using the imidazolides of N-protected glycines, X-NHCH₂COOH (X = -COPh, -COMe, -Z, -Boc, -COOMe and -COOEt). The corresponding C-acylation compounds were isolated in high yields and were readily converted to the N-protected tetramic acids. It was shown by pmr spectroscopy that these acids exist as the enol tautomers in DMSO-d₆ solution, whereas in deuteriochloroform solution both the enol and keto tautomers can be observed.     

Chemical constitution and activity of bipyridylium herbicides. Part IX. N-alkoxy quaternary salts of 4,4′bipyridyl

4,4′-Bipyridyl N-oxide and 4,4′-bipyridyl N,N'-dioxide react with alkating agents to afford N-alkoxy N'-alkyl and N,N'-dialkoxy diquaternary salts of 4,4′-bipyridyl respectively. The diquaternary salts were very much less active as herbicides than paraquat. Unlike paraquat they cannot be regarded as reversible one electron transfer systems.     

Far infrared-assisted extraction followed by MEKC for the simultaneous determination of flavones and phenolic acids in the leaves of Rhododendron mucronulatum Turcz

A method based on micellar electrokinetic chromatography with amperometric detection and far infrared‐assisted extraction has been developed for the simultaneous determination of two flavones (rutin and farrerol) and three phenolic acids (syringic acid, vanillic acid, and 4‐hydroxybenzoic acid) in the dried leaves of Rhododendron mucronulatum Turcz., a commonly used traditional Chinese medicine. The effects of some important factors such as the voltage applied on the infrared generator, irradiation time, the concentration of borate and sodium dodecylsulfate (SDS), separation voltage, and detection potential were investigated to acquire the optimum conditions. The detection electrode was a 300‐μm diameter carbon disc electrode. The five analytes could be well separated within 8 min in a 40 cm‐long capillary at a separation voltage of 12 kV in a 50 mM borate buffer (pH 9.2) containing 50 mM SDS. The relationship between peak current and analyte concentration was linear over about three orders of magnitude with the detection limits (S/N=3) ranging from 0.20 to 0.46 μM. The results indicated that far infrared irradiations significantly enhanced the extraction efficiency. The extraction time was substantially reduced to 6 min compared with 3 h for conventional hot solvent extraction.     

n-型有机半导体插入层提高p-型并五苯薄膜晶体管性能(英文)

在金电极和p-型并五苯有源层之间插入n-型有机半导体层显著提高了并五苯薄膜场效应晶体管的性能。在插入2nm厚的N,N-bis(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl)-1,4,5,8-naphthalenetetracarboxylicdiimide(NTCDI-C8F)和N,N′-dioctyl-3,4,9,10-perylenedicarboximide(PTCDI-C8)层后,器件的阈值电压由-19.4V显著降低到-1.8和-8.7V、迁移率提高了约2倍、电流开关比保持在105~106。这为通过简单地在电极和有机半导体有源层之间引入其他有机半导体薄层的方法来构建具有低阈值电压和高迁移率特征的有机薄膜场效应晶体管器件提供思路。     

Chiral 1,4-benzodiazepines. IX. Attempts at a preparation of 7-chloro-5-phenyl-3(S)methyl-1,4-benzodiazepin-2-one through C(5)?C(5a) bond formation

During attempts at preparation of 7-chloro-5-phenyl-3(S)methyl-1,4-benzodiazepin-2-one ( 9 ) by cyclisation of N'-α-chlorobenzylidene-(S)alanyl-p-chloroaniline ( 7 ) and the related o,p-dichloroaniline derivative ( 8 ), it was observed that the intermediate products, both N'-benzylidene-(S)alanyl-p-chloroaniline ( 5 ), as well as the related o,p-dichloroaniline derivative ( 6 ), undergo cyclisation to N-(p-chlorophenyl)-2-phenyl-4(S)methylimidazolidin-5-one ( 17 ), and N-(o,p-dichlorophenyl)imidazolidin-5-one ( 18 ), respectively. Isolation and properties of the side products, N'-benzylated-(S)alanyl-p-chloro-, and o,p-dichloroanilines ( 15 and 16 ), as well as of N'-benzoylated-(S)alanyl-p-chloroanilines ( 19 and 20 ) are described.     

Characteristics of Atmospheric Pressure Air Glow Discharge with Aqueous Electrolyte Cathode

We investigated the characteristics of atmospheric pressure (AP) air glow discharge with aqueous electrolyte cathode. Distilled water or aqueous solutions of HNO₃, KCl, KBr and KI were utilized as a cathode. The cathode voltage drop, electric field strength, gas temperature as well as emission intensity of some lines of OI, H, K, Na and bands of N₂, OH, NO were measured at discharge current from 10 to 50 mA. The procedure of gas temperature measurement on the base of non-resolved structure of N₂(C³Π_u → B³Π_g) bands was described. The reduced electric field strength (E/N) was obtained, which showed that the discharge existed in the normal mode. On the base of these data, the regularities of optical emission were discussed.     

Thermal behaviour and electro-optical properties of a series of liquid crystals based on palladium complexes with mixed ligands

A series of ortho-metallated palladium(II) complexes with two dimeric liquid crystals Schiff base (methoxy and decyloxy as terminal groups) as cyclometallated ligands and N-aryl-N′-benzoyl thiourea derivatives as co-ligands were prepared and investigated for their liquid crystalline properties. Their structures were assigned based on elemental analysis, FT-IR and ¹H NMR spectroscopy while the thermal behaviour was investigated by differential scanning calorimetry and polarising optical microscopy. The complexes with Schiff base ligand bearing methoxy group as terminal group show extensive decomposition during melting while the complexes with Schiff base having decyloxy group as terminal group show monotropic nematic phases, with the mesophase stability strongly related to the type of N-aryl-N′-benzoyl thiourea derivative used. Their liquid crystalline properties are compared with their analogues having N,N-dialkyl-N′-benzoyl thiourea as co-ligands which were reported previously. One of the latter complexes was also investigated by thermally stimulated depolarisation currents method while the optical transmission was recorded simultaneously. The thermally stimulated depolarisation currents and optical transmission spectra confirmed the previous observation regarding the phase transition temperatures. The current intensity–applied voltage dependencies of this complex were investigated by specific electrical measurements.     

Determination of Four Phenolic Compounds in Scirpus yagara Ohwi by CE with Amperometric Detection

A method based on capillary electrophoresis with amperometric detection has been developed for the determination of trans-resveratrol, scirpusin A, scirpusin B, and p-hydroxycinnamic acid in the rhizomes of Scirpus yagara Ohwi. The effects of the acidity and the concentration of the running buffer, separation voltage, injection time, and detection potential were investigated to acquire the optimum conditions. The detection electrode was a 300 μm diameter carbon disc electrode at a detection potential of +0.90 V. The four analytes could be well separated within 12 min in a 40 cm length fused silica capillary at a separation voltage of 12 kV in a 50 mM borate buffer (pH 9.2). The relation between peak current and analyte concentration was linear over about three orders of magnitude with detection limits (S/N = 3) ranging from 32.2 to 63.4 μg L⁻¹ for the four analytes.