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101.
选用2-(N,N-双(二苯基膦基甲基))胺基吡啶(bdppmapy)为膦配体、二吡啶并[3,2-a∶2'',3''-c]吩嗪(dppz)为氮配体、[Cu (CH3CN)4]BF4为铜盐,在常温下进行反应,制备了3种新型Cu(Ⅰ)配合物,分别为[Cu (dppz)(bdppmapy)]2(BF4)2·H2O (CuBF4-1)、[Cu (dppz)(bdppmapy)]BF4(CuBF4-2)和[Cu (dppz)(bdppmapy)]BF4(CuBF4-3)。获得了CuBF4-1和CuBF4-3的单晶,发现了单晶到单晶转化过程的现象,并探究了溶剂分子的存在对配合物结构和光物理性能的影响。通过单晶X射线衍射确定配合物CuBF4-1和CuBF4-3的结构,使用粉末X射线衍射(PXRD)、红外光谱(IR)和核磁共振氢谱/磷谱(1H/31P NMR)对合成的3个配合物进行结构表征。对配合物进行紫外可见吸收光谱(UV-Vis)、荧光光谱、荧光寿命及量子产率等光物理性质的表征和分析,比较了配合物发光性质的差异,探讨了溶剂分子对配合物结构和光物理性质的影响规律。太赫兹时域光谱对配合物的研究提供了帮助。 相似文献
102.
A theoretical model is summarized into the shorter vector principle. It is used to predict the topological structure of wave function and the oscillation rule of energy gap in various types of finite carbon nanotubes (CNTs). The theoretical model indicates that the characteristics of the electronic states only depend on the nanotube size and its symmetry along the shorter vector direction. In this direction, the wave functions of the original 3m (or 3m/2) periodicity are also suitable for armchair, chiral and zigzag finite CNTs with the C2 (Cs), C1 and Cn point groups, respectively. Energy gaps present the oscillation with 3m (or 3m/2) or odd-even n. The first principle calculations for some prototype systems are performed. The results are consistent with the theoretical model. 相似文献
103.
《Solid State Sciences》2012,14(9):1263-1266
Four isostructural transition metal-based MIL-53 anologues, [M(ntd)(e-urea)] (M = Mn, 1; Co, 2; Zn, 3; Cd, 4; ntd = 1,4-naphthalenedicarboxylate; e-urea = ethyleneurea), are urothermally synthesized and structurally characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), elemental analysis (EA) and Infrared Spectroscopy (IR). The results of TGA and PXRD for these isostructural compounds show that they exhibit distinct thermal behaviors, where the Zn- and Cd-forms are much easier to lose the ligated e-urea molecules from the frameworks than the Mn- and Co-forms. The CO2 sorption properties and photoluminescent properties of compounds 3 and 4 were also investigated. 相似文献
104.
Metallic thin-walled round tubes are widely used as energy absorption elements. However, lateral splash of the round tubes under impact loadings reduces the energy absorption efficiency and may cause secondary damage. Therefore, it is necessary to assemble and fasten round tubes together by boundary constraints and/or fasteners between tubes, which increases the time and labor cost and affects the mechanical performance of round tubes. In an effort to break through this limitation, a novel self-locked energy-absorbing system has been proposed in this paper. The proposed system is made up of thin-walled tubes with dumbbell-shaped cross section, which are specially designed to interlock with each other and thus provide lateral constraint under impact loadings. Both finite element simulations and impact experiment demonstrated that without boundary constraints or fasteners between tubes, the proposed self-locked energy-absorbing system can still effectively attenuate impact loads while the round tube systems fail to carry load due to the lateral splashing of tubes. Furthermore, the geometric design for a single dumbbell-shaped tube and the stacking arrangement for the system are discussed, and a general guideline on the structural design of the proposed self-locked energy absorbing system is provided. 相似文献
105.
The long pulse operation of ultraviolet (UV) laser attributed to multi-reflection is presented on an acousto-optic (AO) Q-switched
ultraviolet laser system blocking green light inside a cavity. The ultraviolet laser with the highest average power of 456
mW is obtained with 20 kHz repetition-rate. The numerical simulation of UV pulse broadening was studied using Gaussian curve
approximation. The conclusion suggests that the short multi-reflected cavity and high incident pump power will be beneficial
to alleviate the width broadening effect. The results, for the first time, would provide the technology for controlling the
pulse width of an AO Q-switched DUV laser. 相似文献
106.
《Journal of Analytical and Applied Pyrolysis》2011,90(2):250-254
The thermal decomposition of lutetium(III) propionate monohydrate (Lu(C2H5CO2)3·H2O) in argon was studied by means of thermogravimetry, differential thermal analysis, IR-spectroscopy and X-ray diffraction. Dehydration takes place around 90 °C. It is followed by the decomposition of the anhydrous propionate to Lu2O2CO3 with evolution of CO2 and 3-pentanone (C2H5COC2H5) between 300 °C and 400 °C. The further decomposition of Lu2O2CO3 to Lu2O3 is characterized by an intermediate constant mass plateau corresponding to a Lu2O2.5(CO3)0.5 overall composition and extending from approximately 550 °C to 720 °C. Full conversion to Lu2O3 is achieved at about 1000 °C. Whereas the temperatures and solid reaction products of the first two decomposition steps are similar to those previously reported for the thermal decomposition of lanthanum(III) propionate monohydrate, the final decomposition of the oxycarbonate to the rare-earth oxide proceeds in a different way, which is here reminiscent of the thermal decomposition path of Lu(C3H5O2)·2CO(NH2)2·2H2O. 相似文献
107.
Tingjiang Yan 《Journal of solid state chemistry》2011,184(2):357-6257
This work explored the selective synthesis of polymorphs of CdWO4 in either tetragonal or monoclinic phase by optimizing the experimental parameters. Systematic characterization indicated that both polymorphs possessed similar spherical morphologies but different structural building blocks. Electronic structures calculations for both polymorphs demonstrated the same constructions of conduction band or valence band, while the conduction band widths of both polymorphs were quite different. Both CdWO4 polymorphs exhibited good photocatalytic activity for degradation of methyl orange under UV light irradiation. When comparing to some other well-known tungstate oxide materials, the photocatalytic activity was found to follow such a consequence, monoclinic CdWO4≈monoclinic ZnWO4>tetragonal CdWO4>tetragonal CaWO4. The specific photocatalytic activity of monoclinic CdWO4 was even higher than that of commercial TiO2 photocatalyst (Degussa P25). The increased activity from the tetragonal CdWO4 to the monoclinic was consistent with the trend of the decreased symmetry, and this could be explained in terms of the geometric structures and electronic structures for both polymorphs. 相似文献
108.
Syntheses and Characterization of Two Diiron Dithiolate Complexes Containing 4-Dimethylaminopyridine
YAN Qing-Yun HU Ming-Qiang WEN Hui-Min CHEN Hui MA Cheng-Bing CHEN Chang-Neng 《结构化学》2011,30(9):1341-1347
Two diiron dithiolate complexes, (μ-pdt)Fe2(CO)5(C7H10N2) 3 and (μ-edt)-Fe2(CO)5(C7H10N2) 4 (pdt = -S(CH2)3S-, edt = -S(CH2)2S-), have been synthesized and characterized by single-crystal X-ray diffraction. Complex 3 crystallizes in the monoclinic system, space group P21/c with a = 10.168(4), b = 11.816(4), c = 16.595(7) and β = 95.195(6)o; and complex 4 crystallizes in the orthorhombic system, space group P212121 with a = 9.317(3), b = 11.898(4), c = 34.006(10) .The distances of Fe(1)–Fe(2) are 2.5058(9) in 3 and 2.4942(10) in 4, falling in the normal range of Fe–Fe bond length (2.49~2.57 ). The cyclic voltammograms show that 3 and 4 display irreversible reduction peaks (FeIFeI/ FeIFe0) at –1.717 V and –1.673 V vs. Ag/AgCl, respectively. With different acids, complex 3 has distinguishable behavior, two protonations in addition of HBF4-Et2O and single protonation besides HOAc-CH3CN, and complex 4 has a similar action to 3 with HOAc-CH3CN for a semblable structure. 相似文献
109.
Four novel 1D lanthanide coordination polymers with formula [Ln(3,4-pybz)3(H2O)2· H2O]n (Ln = 1 Sm; 2 Eu; 3 Tb; 4 Dy, 3,4-Hpybz = 3-(pyridin-4-yl)benzoic acid) have been synthesized by hydrothermal reactions of lanthanide oxide and 3-(pyridine-4-yl) benzoic acid. Single-crystal X-ray diffraction shows that the four compounds are isostructural. They all crystallize in a monoclinic system, space group P1. They have a doubly carboxylate-bridged infinite-chain structure with alternating Ln-(carboxylate)2-Ln linkages and one chelating carboxylate group on each metal center. The Ln ion also combines to two water molecules to form an eight-coordinate square antiprismatic geometry. The pyridine nitrogen atoms of the ligand do not coordinate to the metal centers but direct the formation of a 3D network through hydrogen bonding with coordinated water molecules. The photoluminescent properties of 2 and 3 have been also studied. 相似文献
110.
采用水热反应合成了有机-无机杂化的Keggin型配合物(C12H9N2)3[PMo12O40],并通过X-射线单晶衍射对其结构进行了分析。该配合物为正交晶系P212121空间群,晶胞参数为a=1.20800(1)nm,b=2.10108(4)nm,c=2.24234(5)nm。配合物包含了孤立的Keggin型[PMo1... 相似文献