首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   12篇
  免费   1篇
  国内免费   5篇
化学   14篇
力学   1篇
物理学   3篇
  2021年   1篇
  2019年   1篇
  2017年   1篇
  2015年   2篇
  2014年   1篇
  2012年   2篇
  2011年   3篇
  2009年   2篇
  2008年   1篇
  2006年   2篇
  2003年   1篇
  1996年   1篇
排序方式: 共有18条查询结果,搜索用时 78 毫秒
1.
王家喜  杨德育 《结构化学》1996,15(6):473-477
用X-射线晶体结构衍射法测定了双[1-苄基-1-乙基丙基环戊二烯基]二氯化锆[η5-C5H4C(C2H5)2CH2C6H5]2ZrCl2(I)及(1,2-二异丁基-1,2-甲基-乙基桥联)双环戊二烯基二氯化锆[η5-C5H4C(CH3)(C4H9-i)C(CH3)(C4H9-i)C5H4-η5]ZrCl2(Ⅱ)的结构。二者皆为单斜晶系,(I)的空间群为P2/n,a=12.582(3),b=7.992(2),c=14.979(3)A,β=101.68(1)°,V=1474.9(9)A3,Mr=612.84,Z=2,Dx=1.38g/cm3,μ=5.69cm(-1),F(000)=640,R=0.033,Rω=0.036。(Ⅱ)的空间群为Cc,a=13.309(3),b=9.591(1),c=16.449(8)A。β=4.83(3)°,V=209.2(2)A3,Mr=458.63,Z=4,Dx=1.456g/cm3,μ=7.77cm(-1),F(000)=952,R=0.051,Rω=0.061。化合物(I)以重叠式存在,两个苄基处于反式。晶体(Ⅱ)以交叉式存在,甲基、异丁基以反式构象存在。  相似文献   
2.
铜-镍合金电极表面组成及状态的变化对硝基苯电还原的影响;Monel合金电极;表面状态;硝基苯;对氨基苯酚;电还原  相似文献   
3.
A series of Cu(I) complexes with a [Cu(NN)(PP)](+) moiety, [Cu(phen)(pba)](BF(4)) (1a), [Cu(2)(phen)(2)(pbaa)](BF(4))(2) (2a), [Cu(2)(phen)(2)(pnaa)](BF(4))(2) (3a), [Cu(2)(phen)(2)(pbbaa)](BF(4))(2) (4a), [Cu(dmp)(pba)](BF(4)) (1b), [Cu(2)(dmp)(2)(pbaa)](BF(4))(2) (2b), [Cu(2)(dmp)(2)(pnaa)](BF(4))(2) (3b) and [Cu(2)(dmp)(2)(pbbaa)](BF(4))(2) (4b) (phen = 1,10-phenanthroline, dmp = 2,9-dimethyl-1,10-phenanthroline, pba = N,N-bis((diphenylphosphino)methyl)benzenamine, pbaa = N,N,N',N'-tetrakis((diphenylphosphino)methyl)benzene-1,4-diamine, pnaa = N,N,N',N'-tetrakis((diphenylphosphino)methyl)naphthalene-1,5-diamine and pbbaa = N,N,N',N'-tetrakis((diphenylphosphino)methyl)biphenyl-4,4'-diamine), were rationally designed and synthesized. These complexes were characterized by (1)H and (31)P NMR, electrospray mass spectrometry, elemental analysis and X-ray crystal structure analysis. Introduction of different central arene spacers (phenyl, naphthyl, biphenyl) into ligands, resulting in the size variation of these complexes, aims to tune the photophysical properties of the complexes. Each Cu(I) ion in these complexes adopts a distorted tetrahedral geometry constructed by the chelating diimine and phosphine groups. Intermolecular C-H···π and/or π···π interactions are involved in the solid states. The dmp-containing complex exhibits better emission relative to the corresponding phen complex due to the steric encumbrance of bulky alkyl groups. Furthermore, for complexes with identical diimine but different phosphine ligands, the tendency of increased emission lifetime as well as blue-shifted emission in the solid state follows with the decrease in size of complexes. Intermolecular C-H···π interactions have an influence on the final solid state photophysical properties through vibrationally relaxed non-radiative energy transfer in the excited state. Smaller-sized complexes show better photophysical properties due to less vibrationally relaxed behavior related to flexible C-H···π bonds. Nevertheless, the tendency for increased quantum yield and emission lifetime, as well as blue-shifted emission in dilute solution goes with the increase in size of complexes. The central arene ring (phenyl, naphthyl or biphenyl) has an influence on the final photophysical properties. The larger the π-conjugated extension of central arene ring is, the better the photophysical properties of complex are. The rigid and large-sized complex 3b, with a high quantum yield and long lifetime, is the best luminophore among these complexes.  相似文献   
4.
五水合3,5-二羧基吡啶钴(Ⅱ)配合物的制备及其晶体结构   总被引:11,自引:0,他引:11  
最近 ,具有开放框架结构或微多孔结构的金属有机化合物由于在分子识别、分离、催化等方面的潜在应用而受到关注 .用刚性多官能团配体如均苯三甲酸、对苯二甲酸和联吡啶类配体桥连金属离子成为二维或三维结构的研究已有报道 [1~ 5] .用相同的多官能团配体 ,在不同的反应条件下 (溶剂、酸碱度、反应温度等 )可以形成不同结构的化合物 . 1 973年 ,Fusao等 [6]已经测定了 3 ,5 -二羧基吡啶 (3 ,5 -Pydc)的晶体结构 . 1 991年 ,Felice等 [7] 用 3 ,5 - Pydc与 Ti和 Zr反应合成了一系列金属有机配位化合物 ,这些配合物通过 3 ,5 - Pydc羧基上…  相似文献   
5.
A new coordination polymer associated with zinc ion,[Zn(Tda)(bpp)] n (1,H 2 tda=thiophene-2,5-dicarboxylic acid,bpp=1,3-bis(4-pyridyl)propane),was prepared under solvothermal conditions,and characterized by single-crystal X-ray diffraction,elemental analysis and IR spectra.The complex belongs to monoclinic,space group P2 1 /c with a=9.8799(4),b=12.0430(6),c=15.4269(9),β=95.424(5) o,V=1827.33(16) 3,Z=4,D c=1.577 g/cm 3,S=1.074,μ=1.486 mm-1,F(000)=888,M r=433.80,R=0.0359 and wR=0.0968 for 2685 observed reflections (I > 2σ(Ⅰ)).Complex 1 displays an interesting 2D lattice structure.In 1,four coordinated zinc ions were bridged by Tda and bpp ligands to generate a (4,4) two-dimensional layer.The thermogravimetric analysis,powder X-ray diffraction (XRD) and luminescent properties for 1 also have been explored.  相似文献   
6.
A new Nd(Ⅲ) coordination polymer [Nd(pidc)(H2O)4]·pidc-·7H2O(1,pidc2-= 2-py-ridyl-4,5-imidazoledicarboxylate) has been synthesized by solvothermal reaction at 120 ℃ and structurally characterized.The complex belongs to triclinic,space group P with a = 9.022(2),b = 13.731(3),c = 13.782(3) ,α = 70.87(3),β = 71.71(3),γ = 71.71(3),V = 1488.6(7) 3,Z = 2,Dc = 1.798 g/cm3,S = 1.04,μ = 1.839 mm-1,F(000) = 814,Mr = 805.76,Rint = 0.081 and wR = 0.1644 for 5242 observed reflections(I > 2(I)).Each Nd3+ ion is nine-coordinated by five O atoms from three pidc ligands,and four O atoms from lattice water molecules.Each pidc is coordinated to three Nd3+ ions with a μ3-κO:κO':κO",κO'"-μ2 coordination mode into 1D chains,which can be further built into a 3D framework through intermolecular N-H···O and O-H···O hydrogen bonds.Photolu-minescent studies have shown that 1 exhibits emission at 439 nm(λex = 395 nm).  相似文献   
7.
为认识孔隙度增加对甲醇电氧化的影响, 将熔盐法制备的La2O3颗粒与Pt/CNTs(碳纳米管)预混合然后用HClO4溶掉La2O3颗粒, 从而增加了Pt/CNTs催化层的孔隙度. 扫描电子显微镜(SEM)观察表明, 该处理可以形成孔结构. 用循环伏安和计时电流实验考察了孔隙度增加对甲醇电氧化的影响, 结果表明甲醇电氧化电流可增加57%. 分析认为, 电流增加的原因是由于多孔催化层中甲醇更易于到达Pt催化剂表面进行电氧化. 该研究表明, 通过在催化层中预混-溶解La2O3来增加孔隙是一种改善催化层性能的有效方法.  相似文献   
8.
A versatile neutral metalloligand [Cu(PySal)2] (1) (PySal = 3-pyridylmethylsalicylidene-imino) was exploited as a building unit to construct five complexes {Cu[Cu(PySal)2]2}(ClO4)2 (2), {Cd[Cu(PySal)2]2(H2O)2]} (NO3)2 · 2H2O · 4CH3OH (3), {Zn[μ2-Cu(PySal)2]Cl2}n · nCH3OH (4), {Hg[μ2-Cu(PySal)2]I2}n (5) and {Cd[μ2-Cu(PySal)2]Cl2}n · nCH2Cl2 (6). [Cu(PySal)2] acts as a chelating ligand in discrete complexes 2 and 3 with unbound anions, but as a bis-monodentate bridging ligand in polymers 4, 5 and 6 when halogen anions coordinated cooperatively to metal cations. The coordination geometry of Cu2+ is well-defined square planar in bridging [Cu(PySal)2], analogous to that in free metalloligand (1), but it is distorted square planar in chelating [Cu(PySal)2].  相似文献   
9.
Nanospheric hydroxo-bridged clusters of [M(20)(OH)(12)(maleate)(12)(Me(2)NH)(12)](BF(4))(3)(OH)·nH(2)O (M = Co (1), Ni (2)) with O(h) symmetry were afforded under hydrothermal condition with Co(BF(4))(2)·6H(2)O/Ni(BF(4))(2)·6H(2)O and fumaric acid in a DMF/EtOH mixed solvent. They are characterized by elemental analysis, IR, and X-ray diffraction. X-ray single crystal diffraction analyses show that these two complexes are isostructural containing an ideally cubic M(8) core in that each two M atoms are doubly bridged at the edges by one OH(-) and one maleate, while these OH(-) and maleate groups are coordinated further by exterior identical 12 M atoms which construct a perfect M(12) icosahedron to encapsulate the cubic core. To our knowledge, such large clusters with O(h) symmetry are seldom. The variable-temperature magnetic susceptibility studies reveal that these two isostructures exhibit antiferromagnetic interactions.  相似文献   
10.
为认识孔隙度增加对甲醇电氧化的影响,将熔盐法制备的La2O3颗粒与Pt/CNTs(碳纳米管)预混合然后用HClO4溶掉La2O3颗粒,从而增加了Pt/CNTs催化层的孔隙度.扫描电子显微镜(SEM)观察表明,该处理可以形成孔结构.用循环伏安和计时电流实验考察了孔隙度增加对甲醇电氧化的影响,结果表明甲醇电氧化电流可增加57%.分析认为,电流增加的原因是由于多孔催化层中甲醇更易于到达Pt催化剂表面进行电氧化.该研究表明,通过在催化层中预混-溶解La2O3来增加孔隙是一种改善催化层性能的有效方法.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号