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991.
通过结合杂化密度泛函和前线轨道理论与弹性散射格林函数方法研究了BE- MP(benzene-1,4-di-ethynyl-4-mercaptophenyl)和TEMP(thiophene-2,5-di-ethynyl-4- mercaptophenyl)两分子结的输运性质。基于杂化密度泛函方法计算两扩展分子电子结构的基础上,计算了两分子的输运性质.计算结果显示:电流增加来源于电极和分子轨道的共振;电导曲线呈现出平台特征.在此基础上从扩展分子A(Au-BEMP-Au)中间的苯环的旋转而引起电流减小的角度解释了负微分电阻现象. 相似文献
992.
Single crystals of NaKZnP2O7 were grown, and their crystal structure was determined by X-ray diffraction (space group P21/n, a = 12.585(5) Å, b = 7.277(5) Å, c = 7.428(5) Å, β = 90.00(5)°, Z = 4, 1916 F(hkl), R 1 = 0.0461). The structure contains a 3D tetrahedral zinc phosphate framework with a system of intersecting channels running along the b and c axes. The sodium and potassium atoms are coordinated to six and seven oxygen atoms, respectively, and reside inside these channels; the potassium cations, which are larger than the sodium cations, are located at channel intersections. 相似文献
993.
994.
Two title compounds, 4,4'-diformyl-diphenoxyethane (compound 1, C16H14O4)and 4,4',4'-triformyl-triphenoxytriethylamine (compound 2, C27H27NO6), were synthesized by condensation of 4-hydroxybenzaldehyde with 1,2-dichloroethane and tris2-chloroethylamine, respectively in dimethyl formamide in the presence of anhydrous potassium carbonate. The crystal data are: monoclinic, P21/c, a = 7.571(2), b = 12.608(3), c = 7.357(2) ', = 105.823(6)o, V = 675.7(2)'3, Mr = 270.3, Z = 2, Dc = 1.328 g/cm3, F(000) = 284, (MoK = 0.096 mm-1, R = 0.0537 and wR = 0.2189 for compound 1; and monoclinic, P21/n, a = 11.7162(6), b = 9.0042(6), c = 22.908(2) ', = 99.505(1)°, V = 2383.5(3) '3, Mr = 461.50, Z = 4, Dc = 1.286 g/cm3, F(000)= 976, (MoK = 0.091 mm-1, R = 0.0464 and wR = 0.1462 for compound 2. The molecule of compound 1 dialdehyde is located at the crystallographic inversion center nearby the midpoint of C8-C8A single bond. The three chains in the molecule of compound 2 trialdehyde are of non-crystallographic pseudo-C3 symmetry, and each of them is quite planar. 相似文献
995.
Enkhtsetseg Dashjav Guido Kreiner Walter Schnelle Frank R. Wagner Rüdiger Kniep 《无机化学与普通化学杂志》2004,630(5):689-696
Carbometalates: Complex Anions equation/tex2gif-stack-4.gif [MoC4/26—] in the Crystal Structure of Pr equation/tex2gif-stack-5.gif [MoIIC2] Criteria for the existence of carbometalates are established and discussed in a broader context. The concept is then applied to the novel compound Pr2[MoC2], which is characterized by chemical analyses, X‐ray diffraction and metallography. The crystal structure (tetragonal, P42/mnm, Z = 4, a = 581.29(8) pm, c = 1032.53(14) pm) consists of layered polyanions equation/tex2gif-stack-6.gif[MoC4/26—] of distorted vertex and edge sharing MoC4 tetrahedra. Praseodymium is also in a distorted tetrahedral coordination by carbon. The physical properties show “bad metal” behaviour and localized magnetic 4f‐moments in agreement with the existence of Pr3+‐species. A detailed bonding analysis using both the electron localization function ELF and the COHP method justifies the interpretation of the title compound as a carbomolybdate(II). 相似文献
996.
1 INTRODUCTION The pyridyl-phosphine ligands have been widely used for many years to synthesize hetero- or homo-nuclear metal complexes[1], as electronic differentiation associated with the hard (N) and soft (P) donor atoms dictates their unique reactivities and coordination modes. One of the most common pyridylphosphines studied to date is (2-C5H4N)PPh2 which displays numerous ligating modes ranging from P-coordination and P,N-chelation to the more common P,N-bridging of two metal … 相似文献
997.
A novel 1-D Cd(Ⅱ) coordination polymer, [Cd(p-BDOA)·2H2O]n(I) ( p-BDOA2-=benzene-1,4-dioxyacetate dianion) has been synthesized and characterized by elemental analysis, IR, PL, TG and X-ray single crystal diffraction. The Crystal crystallizes in monoclinic system, the space group is C2/c, with the crystal cell parameters a=1.175 1(1) nm, b=0.551 0(1) nm, c=1.827 7(2) nm, β=96.14(2)°, and V=1.176 6(3) nm3,, Mr=372.60, R=0.045 9, wR=0.127 9. The Cd(Ⅱ) ion has a trigonal prism coordination configuration that defined by four carboxyl O atoms from two different p-BDOA2- ligands and two water molecules. Adjacent Cd(Ⅱ) ions are linked by carboxylate groups with the bidentate coordination mode, giving rise to a chain structure with the adjacent Cd…Cd distance of 1.526 3(5) nm. Furthermore, such chains are linked by hydrogen bonds to form supramolecular network. The results of PL and TG show that the complex exhibits intense fluorescent emissions and its chain skeleton is thermally stable up to 419 K. CCDC: 220443. 相似文献
998.
STUDY ON 1-HEXENE POLYMERIZATION BASED ON ZIEGLER-NATTA CATALYSTS WITH DOPED SUPPORT 总被引:1,自引:0,他引:1
XueJiang Zhi-qiangFan 《高分子科学》2004,(4):305-308
A series of Ti/Mg supported catalysts are prepared by using ball-milled mixtures of MgCl2-ethanol adducts and NaCl as supports, and 1-hexene polymerizations catalyzed by the novel catalysts are studied. It is found that the molecular weight distribution of poly(1-hexene) becomes apparently narrower when catalysts with doped supports are used, indicating that changing the structure of the support is an effective way to regulate the active center distribution of heterogeneous Ziegler-Natta catalyst. 相似文献
999.
JIANG Yin-Zhi HU Wei-Xiao② 《结构化学》2004,(8)
1 INTRODUCTION The azine derivatives are useful compounds because of their special properties. On the one hand, the azines and ,-dichloro-azines are very impor- tant intermediates[1, 2] for synthesizing s-tetrazines which have some peculiar properties, s… 相似文献
1000.
An oligosaccharide homologue named SnS-2 was isolated from the root of Scrophularia ningpoensis Hemsl.SnS-2 was purified by means of gel-permeation chromatography and ion-exchange chromatography. Its physicochemical properties, including carbohydrate content and molecular weight were determined. The structure of SnS-2 was elucidated by chemical methods along with ^1H and ^13C NMR spectroscopy, including two-dimensional DQCOSY and H-detected ^1H, ^13C HMQC experiments. These results show that SnS-2 possesses a backbone consisting of terminal α-Galp-(1→, α-Galp-(1→6), α-Glcp-(1→6) and nonreducing end β-Fruf-(2→. The bioactive assay showed that it could inhibit the growth of Lewis pulmonary carcinoma implanted in mice. 相似文献