共查询到20条相似文献,搜索用时 31 毫秒
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Nikolay A. Pushkarevsky Anton V. Lonchakov Nikolay A. Semenov Enno Lork Lev I. Buravov Lidia S. Konstantinova Georg T. Silber Neil Robertson Nina P. Gritsan Oleg A. Rakitin J. Derek Woollins Eduard B. Yagubskii Jens Beckmann Andrey V. Zibarev 《Synthetic Metals》2012
The first charge-transfer complexes of tetrathiafulvalene (1) with 1,2,5-chalcogenadiazole derivatives, i.e. with [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole (2) and 3,4-dicyano-1,2,5-telluradiazole (3), were designed, prepared in the form of air and thermally stable single crystals and structurally defined by X-ray diffraction as 1·2 and 1·32, respectively. Starting compound 2 (effective electron acceptor with potentially broad application in the field) was synthesized by a new efficient one-pot method from 3,4-diamino-1,2,5-oxadiazole and disulfur dichloride. The electronic structure of complexes 1·2 and 1·32 and thermodynamics of their formation were studied by means of DFT and QTAIM calculations and UV–Vis spectroscopy. The electrical properties of single crystals of the complexes were investigated revealing semiconductor properties with an activation energy of 0.34 eV for 1·2 and 0.40 eV for 1·32. Polycrystalline films of the complexes displayed photoconductive effects with increased conductivity under white-light illumination. 相似文献
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Neutron diffraction and magnetization measurements have been performed on the Tb5Si3 compound (hexagonal Mn5Si3-type, hP16, P63/mcm) to understand its magnetic structure and magnetic properties. The temperature-dependent neutron diffraction results prove that this intermetallic phase shows a complex flat spiral magnetic ordering, presenting three subsequent changes in magnetization at on cooling. However, the magnetization data depict two transitions at 72 K (TN1) and 55 K (TN2). The extended temperature range between and over which the neutron diffraction patterns slowly evolve might correspond to the high-temperature antiferromagnetic transition at TN1 and low-temperature antiferromagnetic transition at TN2 of the magnetic data. Between Tb5Si3 shows a flat spiral antiferromagnetic ordering with a propagation vector K1 = [0,0, ±1/4]; then, between the flat spiral type ordering is conserved, but by two coexisting propagation vectors K1 = [0,0, ±1/4] and K2 = [0,0, ±0.4644(3)]. The terbium magnetic moments arrange in the XY(ab) plane of the unit cell. Below the magnetic component with K1 = [0,0, ±1/4] vanishes and magnetic structure of Tb5Si3 is a flat spiral with K2 = [0,0, ±0.4644(3)], only. Low field magnetization measurements confirm the occurrence of complex, multiple magnetic transitions. The field dependence of the magnetization indicates a metamagnetic transition at a critical field of 3 T. 相似文献
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A series of the statistical copolymers of tetradecyloxy-3,5-bis-{2-(4-bromo-phenyl)-[1,3,4]oxadiazole}-benzene (4), 1,4-didecyloxy-2,5-diiodobenzene (5) and 1,4-dodecyloxy-2,5-divinylbenzene (6), for efficient light emitting diode were synthesized. As the feed ratio of compound 4 decreased, the absorption band at 320–360 nm decreased in the UV–vis spectra. In addition, as the composition of compound 4 decreased, the absorption intensity ratio at 1541 cm−1 decreased in the FT-IR spectra. The photoluminescence and electroluminescence emission color of P showed green-yellow color (λmax = 552 nm). However, the maximum wavelength of photoluminescence and electroluminescence of P1 and P2 were 581 and 583 nm, respectively, which were dramatically red-shifted than that of P. Moreover, these values were almost the same as the values of P3 (580 nm). It is concluded that the energy transfer from high energy oxadiazole segments to low energy alkoxy-PPV segments occurred completely. The efficiency of ITO/P2/Al was 0.0181%, which is the best efficiency among the device based on the copolymers. This is presumably due to that P2 has the best balanced hole- and electron-injection/transporting properties among the copolymers. 相似文献
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Two novel complexes [Cd(phen)(NO3)(NO2)(H2O)]n (1) and Cd(phen)2(NO3)(NO2) (2) (phen = 1,10-phenanthroline) have been synthesized by the reductive reaction of metal source Cd(NO3)2·4H2O with phen and benzidine in the mixed solution of DMF, ethanol and water. Crystal structures of complexes 1 and 2 were determined by single-crystal X-ray diffraction. Complex 1 is a one-dimensional (1D) zig-zag infinite chain in which (phen)Cd(II) units were bridged by two O atoms of NO2−. The three-dimensional (3D) supramolecular structure of 1 is constructed through hydrogen-bond and aromatic π–π stacking interactions between adjacent metal–organic polymeric coordination chains. Complex 2 is a mononuclear structure, and self-assembled through π–π stacking interactions to form a three-dimensional (3D) supramolecular structure. The complex 1 exhibits luminescent property in the near-UV at room temperature in solutions of DMSO and DMF with the emission energy following the order DMF < DMSO, which might be ascribed to the presence of a highly polarized ground state. Complexes 1 and 2 have blue-purple luminescence at room temperature in the solid state. The blue-purple luminescence of the complexes is due to π* → π transition of phen. 相似文献
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S. Levcenco D. Dumcenco Y.S. Huang E. ArushanovV. Tezlevan K.K. TiongC.H. Du 《Journal of Alloys and Compounds》2011,509(25):7105-7108
Polarization-dependent electrolyte electroreflectance (EER) measurements were carried out on the oriented Cu2ZnSiS4 and Cu2ZnSiSe4 single crystals at room temperature. Thin blade single crystals of Cu2ZnSiS4 and Cu2ZnSiSe4 were grown by chemical vapor transport technique using iodine as a transport agent. Laue pattern normal to the basal plane of the as-grown crystal revealed the formation of orthorhombic structure with the normal along [2 1 0] and the c axis parallel to the long edge of the crystal platelet. The polarized EER spectra in the vicinity of the direct band edge of Cu2ZnSiS4 displayed distinct structures associated with transitions from two upper-most valence bands to the conduction band minimum at Γ point. In the E⊥c configuration, the feature designated as EA ∼ 3.345 eV was detected and for Е‖c, only EB ∼ 3.432 eV appeared. For Cu2ZnSiSe4, three features denoted as EA, EB, and EC at around 2.348, 2.406 and 2.605 eV, respectively, were recorded for E⊥c polarization, whereas in the Е‖c, only EB and EC were the allowed transitions. Based on the experimental observations and a recent band-structure calculation by Chen et al. [Phys. Rev. B 82 (2010) 195203], plausible band structures near the direct band edge of Cu2ZnSiS4 and Cu2ZnSiSe4 have been proposed. 相似文献
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Hard slip mechanisms in B2 CoTi 总被引:1,自引:0,他引:1
R.P. MulayS.R. Agnew 《Acta Materialia》2012,60(4):1784-1794
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Guodong Tang Yuan Cao Jinfang Zhang Yu Zhang Yinglin Song Fengli Bei Lude Lu Chi Zhang 《Synthetic Metals》2008
A series of new candidates as nonlinear optical materials, tetra-nuclear heterobimetallic clusters [MOS3M3′Y(PPh3)3] (M = Mo, M′ = Ag, Y = Br 1; M = W, M′ = Ag, Y = I 2; M = Mo, M′ = Cu, Y = I 3; M = W, M′ = Cu, Y = I 4), have been synthesized by newly developed ligand-redistribution reaction for third-order nonlinear optical (NLO) studies. Single-crystal X-ray diffraction shows that clusters [MoX(μ3-S)3(μ3-Br)(AgPPh3)3] 1 and [WX(μ3-S)3(μ3-I)(CuPPh3)3] 4 (X = O0.5S0.51, O 4) adopt an isomorphous neutral cubane-like skeleton. Their optical nonlinearities were measured by Z-scan technique with an 8 ns pulsed laser at 532 nm. These clusters were found to exhibit effective nonlinear absorption, self-focusing effects and large optical limiting capabilities. The effective NLO susceptibilities χ(3) and the corresponding second-order hyperpolarizabilities γ of these clusters are also reported. The influence of cluster composition on NLO properties has been discussed accordingly. 相似文献
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Xiao-Lian Hu Li-Jian Zuo Ya-Xiong Nan Martin Helgesen Ole Hagemann Eva Bundgaard Min-Min Shi Frederik C. Krebs Hong-Zheng Chen 《Synthetic Metals》2012
To lower the HOMO (highest occupied molecular orbital) energy level of polythieno[3,4-b]thiophene (∼−4.5 eV), a series of ester-functionalized polythieno[3,4-b]thiophene derivatives (P1–P3) were designed and synthesized by Stille cross coupling reaction. The resulting copolymers exhibited broad and strong absorption bands from visible to near infrared region with low optical band gaps of 1.23–1.42 eV. Through cyclic voltammetry measurements, it was found that the HOMO energy levels of the copolymers gradually decreased with increasing the content of the thiophene-3,4-dicarboxylate moiety, i.e. −4.91 eV for P1, −5.00 eV for P2, and −5.11 eV for P3. Preliminary photovoltaic properties of the copolymers blended with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as electron acceptor were investigated. Among the three copolymers, P1 exhibited the best photovoltaic performance with an open circuit voltage (Voc) of 0.54 V, a short circuit current density (Isc) of 3.3 mA/cm2, a fill factor (FF) of 0.57, and a power conversion efficiency (PCE) of 1.02%. A high Voc up to 0.71 V was achieved in the solar cell based on a P3:PCBM blend. 相似文献
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Three new divinylene compounds F, C and P which contained fluorene, carbazole and phenylene as central unit, respectively, and terminal phthalimide groups were synthesized by Heck coupling. The alkyl or alkoxy chains attached to the central unit as well as the cyclohexyl ring attached to the terminal phthalimides render the samples very soluble in common organic solvents. They had relatively low glass transition temperatures (Tg's), being in the range of 54–81 °C. P was stable up to about 200 °C while F and C were stable up to 300 °C. The absorption maximum was located at 387–440 nm with optical band gap of 2.48–2.56 eV. They emitted blue-green light with emission maximum at 484–562 nm. P showed the most red-shifted absorption and emission maximum. The HOMO and LUMO levels of the compounds, estimated from their cyclic voltammograms, were −6.42 to −5.58 eV and −3.06 to −2.99 eV, respectively, from which their band gaps were estimated to be 3.36 eV, 2.68 eV, and 2.52 eV. The emission spectra and performance of the EL devices, using blends of the compounds and PVK as emitting layer, also depended strongly on the compounds. The P device emitted green light (530 nm) with maximal luminance and current efficiency being at 1358 cd/m2 and 0.57 cd/A, while those of the F device were green-blue (490 nm), 593 cd/m2 and 0.22 cd/A. 相似文献
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Some S-containing compounds newly synthesised have been tested as inhibitors for the corrosion of steel in 1 M HCl solution. Weight loss measurements, potentiodynamic polarisation and impedance spectroscopy (EIS) methods are used. The inhibiting action increases with the concentration of the compounds tested. The highest efficiency 95% is obtained at 10−4 M of [(11-hydroxyundecyl)thio]acetic acid (3 and 4). We note good agreement between gravimetric and electrochemical methods (potentiodynamic polarisation and EIS). Polarisation measurements show also that 3 and 4 act as mixed inhibitors. The cathodic curves indicate that the reduction of proton at the steel surface happens with an activating mechanism. 3 adsorbs on the steel surface according to Langmuir adsorption model. Effect of temperature is also studied between 308 K and 353 K. 相似文献
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Vinich Promarak Musubu Ichikawa Taweesak Sudyoadsuk Sayant Saengsuwan Siriporn Jungsuttiwong Tinnagon Keawin 《Synthetic Metals》2007
A novel amorphous hole-transporting carbazole dendrimer, 2,7-bis[3,6-di(carbazol-9-yl)carbazol-9-yl]-9,9-bis-n-hexylfluorene (G2CF), was synthesized by a divergent approach involving bromination and Ullmann coupling reactions. G2CF showed UV–vis absorption bands at 304 and 332 nm in chloroform solution and the photoluminescence spectra showed a maximum peak at 373 nm in a bluish-purple region. Differential scanning calorimetry (DSC) and cyclic voltammetry (CV) analysis revealed G2CF was an electrochemically and thermally stable amorphous material with a high glass transition temperature (Tg) of 237 °C. The organic light-emitting device having the structure of ITO/G2CF/Alq3/LiF:Al exhibited a bright green emission with a maximum luminescence of 11,000 cd/m2 at 16 V and a turn-on voltage of 5.4 V. 相似文献
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