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991.
Two Coordination Polymers based on 2‐Ethyl‐1H‐imidazole‐4,5‐dicarboxylic Acid and 1,3‐Bis(4‐pyridyl)propane: Synthesis,Crystal Structures,and Photoluminescent Properties 下载免费PDF全文
Haibing Wang Ping Tang Guowang Xu Yenan Wang Fuchao Hu Dongsheng Li 《无机化学与普通化学杂志》2015,641(5):848-852
Two coordination polymers, [Cd(Heidc)(bpp)]n ( 1 ) and [Zn3 (eidc)2(bpp)(H2O)2] · 2H2O}n ( 2 ) (H3eidc = 2‐ethyl‐4,5‐imidazole dicarboxylic acid, bpp = 1,3‐bis(4‐pyridyl)propane) were hydrothermally synthesized and characterized by elemental analysis, IR, spectroscopy single‐crystal X‐ray diffraction, and thermogravimetric analyses. Compound 1 features a 2D layer formed by C–H ··· π stacking interactions between adjacent chains, whereas compound 2 shows a 3D (83)2(85.10)‐tfc framework constructed of the 2D (6,3) layer. The result demonstrates that the central metal atoms play a key role in governing the coordination motifs. Moreover, solid‐state properties such as thermal stabilities and photoluminescence of 1 and 2 were also investigated. 相似文献
992.
The reaction of PbO with cyanuric acid was reported to give lead cyanurate, described in the literature as Pb3(O3C3N3)2 · 2H2O. Crystalline powders were prepared and investigated by X‐ray powder diffraction, yielding a monoclinic crystal structure (space group Cc, a = 16.6217(1) Å, b = 6.7161(1) Å, c = 12.4308(1) Å, β = 117.567(1)°). The structure solution and refinement yielded lead oxide isocyanurate corresponding to the formula Pb3O2(O3C3N3H2)2, with a layered arrangement of [Pb3O2]2+ ions and monovalent isocyanurate anions in an alternating fashion. 相似文献
993.
Reactions of Polyarsenides with Acetylene: Synthesis and Characterization of [Cs([18]crown‐6)]2As7C14H11·6NH3 and As2C6H6
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The reaction of Cs3As7 with diphenylacetylene in the presence of 18 crown‐6 in liquid ammonia results in the formation of the new compound [Cs( 18 crown‐6)]2As7C14H11 · 6NH3, which crystallizes in black monoclinic crystals. It contains the first monosubstituated heptaarsenide anion with a hydrocarbon‐only substituent and theoretical calculations show a significant influence of the organic substituent on the electronic structure within the cage. The (Z)‐1, 2‐diphenylethenyl‐heptaarsenide di‐anion can be seen as the first step towards the formation of 1, 2,3‐triarsolides. Further experiments regarding the reaction of Rb3As11 and Cs3As11 with acetylene gas in liquid ammonia reveal the formation of the diarsabarrelene As2C6H6, which crystallizes as colorless orthorhombic crystals. Calculations based on the structural data obtained by X‐ray crystallography show the electronically inert character of the arsenic lone pair. 相似文献
994.
The gallides SrRh2Ga2, SrIr2Ga2, and Sr3Rh4Ga4 were obtained from the elements by induction melting and subsequent annealing. They were investigated by powder and single‐crystal X‐ray diffraction: CaRh2B2 type, Fddd, a = 573.2(1), b = 1051.3(1), c = 1343.7(2) pm, wR2 = 0.0218, 398 F2 values, 15 variables for SrRh2Ga2; a = 576.0(1), b = 1045.5(1), c = 1350.6(3) pm for SrIr2Ga2, and Na3Pt4Ge4 type, I$\bar{4}$ 3m, a = 777.4(2) pm, wR2 = 0.0234, 190 F2 values, 11 variables for Sr3Ir4Ga4. The gallides SrRh2Ga2 and Sr3Ir4Ga4 exhibit complex, covalently bonded three‐dimensional [Rh2Ga2] and [Ir4Ga4] networks with short Rh–Ga (241–246 pm) and Ir–Ga (243–259 pm) distances. The strontium atoms fill large cages within these networks. They are coordinated by 8 Rh + 10 Ga in SrRh2Ga2 and by 4 Ir + 8 Ga in Sr3Ir4Ga4. The structure of SrRh2Ga2 is discussed along with the monoclinic distortion variants HoNi2B2 and BaPt2Ga2 on the basis of a group‐subgroup scheme. 相似文献
995.
采用水热法合成了一个钨-钒簇聚物[Cu(en)2]2[WⅥ4.5WV2 VVVⅣ9.5O44{Cu(en)2(H2O)}2]·3H2O(1, en=乙二胺),并通过X射线单晶衍射、元素分析、傅里叶变换红外光谱、X射线粉末衍射、热重分析、价键计算、X射线光电子能谱、电子顺磁共振和磁性分析对其结构和性能进行了表征.结果表明,化合物1是以双支撑的四帽Keggin结构[WⅥ4.5WV2 VⅣ9.5O40(VVO4){Cu(en)2(H2O)}2]4-钨-钒簇合物阴离子为基本结构单元,与4个[ Cu( en)2]2+配合物阳离子以共价键和弱键相连接形成二维层状结构,相邻层又通过氢键连接成三维超分子网络.研究了化合物1的磁性及光催化降解罗丹明B的活性. 相似文献
996.
Phosphodiester Cleavage Promoted by an Asymmetric Dinuclear Zinc Complex: Synthesis,Structure, and Catalytic Activity 下载免费PDF全文
The dinuclear ZnII complex [Zn2L(DNBA)2]BPh4 · EtOH ( 1 ) (DNBA = 3,5‐dinitrobenzonic acid) with an asymmetric dinuclear ligand, N‐4‐methyl‐homopiperazine‐N′‐[N‐(2‐pyridylmethyl)‐N‐2‐(2‐pyridylethyl)amine]‐1,3‐diamino‐propan‐2‐ol (HL), was synthesized and characterized. Single crystal X‐ray crystallographic analysis shows that the coordination around the two ZnII ions in 1 is significantly asymmetric, and the distance between both atoms is 3.426 Å, which is close to the Zn···Zn distance in related natural dinuclear metalloenzymes. Phosphodiesterase activity of Zn2L in situ formed from a 2:1 mixture of Zn2+ ion and HL was investigated using bis(4‐nitrophenyl) phosphate (BNPP) as substrate. The pH dependence of the BNPP cleavage in aqueous buffer media reveals a bell‐shaped pH‐kobs profile with an optimum at about pH 7.9, which is parallel to the formation of the dinuclear species Zn2L‐OH obtained from the potentiometric titration. The catalytic rate constant (kcat) is 6.30 × 10–4 s–1 at pH 7.9 and 25 °C, which is approx. 108‐fold higher than that of the uncatalyzed reaction. The homopiperazine bound deprotonated Zn‐OH group is responsible for the hydrolysis reaction. The possible mechanism for the BNPP cleavage promoted by Zn2L is proposed on the basis of kinetic and spectral analysis. 相似文献
997.
The first montmorillonite‐supported surface single‐structure titanium complex: synthesis,characterization and catalytic activity in alkene epoxidation 下载免费PDF全文
Wei Xu Bo Yu Huaming Sun Jindou Yang Ying Zhang Zhenhua Wang Xi Chen Guofang Zhang Ziwei Gao 《Surface and interface analysis : SIA》2015,47(3):308-314
A well‐defined single‐site titanium‐modified montmorillonite (MMT) with only one geometric construction ((?SiO)3–Ti–NMe2) was obtained in moderate conditions. Reaction of tetrakis(dimethylamido)titanium with hydroxylated MMT was conducted by surface organometallic chemistry technique, and the surface structure was characterized by in situ Fourier transform infrared spectroscopy, 13C cross polarization magic angle spinning nuclear magnetic resonance, X‐ray photoelectron spectroscopy, extended X‐ray absorption fine structure, and elemental analysis. The catalytic activity in alkene epoxidation was evaluated, and the results revealed that the steric hindrance of the substances is responsible for the catalytic activity of the MMT‐supported titanium complex but to the characteristic restricted layer‐like structure of the MMT. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
998.
Lukáš Grajciar 《Journal of computational chemistry》2015,36(20):1521-1535
A new low‐memory modification of the density fitting approximation based on a combination of a continuous fast multipole method (CFMM) and a preconditioned conjugate gradient solver is presented. Iterative conjugate gradient solver uses preconditioners formed from blocks of the Coulomb metric matrix that decrease the number of iterations needed for convergence by up to one order of magnitude. The matrix‐vector products needed within the iterative algorithm are calculated using CFMM, which evaluates them with the linear scaling memory requirements only. Compared with the standard density fitting implementation, up to 15‐fold reduction of the memory requirements is achieved for the most efficient preconditioner at a cost of only 25% increase in computational time. The potential of the method is demonstrated by performing density functional theory calculations for zeolite fragment with 2592 atoms and 121,248 auxiliary basis functions on a single 12‐core CPU workstation. © 2015 Wiley Periodicals, Inc. 相似文献
999.
Yury D. Fomin Elena N. Tsiok Valentin N. Ryzhov 《Journal of computational chemistry》2015,36(12):901-906
We present the molecular dynamics study of benzene molecules confined into the single wall carbon nanotube. The local structure and orientational ordering of benzene molecules are investigated. It is found that the molecules mostly group in the middle distance from the axis of the tube to the wall. The molecules located in the vicinity of the wall demonstrate some deviation from planar shape. There is a tilted orientational ordering of the molecules which depends on the location of the molecule. It is shown that the diffusion coefficient of the benzene molecules is very small at the conditions we report here. © 2015 Wiley Periodicals, Inc. 相似文献
1000.
An in-line colorimeter that is able to quantify color changes in real time during extrusion was developed and validated. It is composed of LEDs emitting at three different wavelengths and a photocell that measures the intensity of the light transmitted through the polymer melt flow. The colorimeter was validated at the bench by employing colored aqueous solutions and in-line during the extrusion of a colored polypropylene. Furthermore, it was used to in-line quantify the color changes in a polypropylene as generated over multiple extrusions due to thermo-mechanical degradation. The technique was proved to be fast and suitable to measure color changes in real time during extrusion. 相似文献