Orientations of special water dipoles that accelerate water molecules exiting from carbon nanotube

One-dimensional ordered water molecules entering and exiting from a carbon nanotube with an appropriate radius are studied with molecular dynamics simulations. It can be found that a water molecule near the nanotube end is more likely to be expelled from the nanotube if its dipole is almost perpendicular to the nanotube axis. The key to this observation is that those water molecules are closer to the wall of the nanotube away from the equilibrium position of the Lennar-Jones (LJ) potential. Thus, the interaction energy for those water molecules is relatively high. There are two particular structures of the perpendicular water molecule depending on the dipole direction of the adjacent water molecule in the nanotube. Although the probabilities of these structures are quite small, their contributions to the net flux across the nanotube end are approximately equal to the predominant structures. The present findings further show the possibility of controlling the water flow by regulating the dipole directions of the water molecules inside the nanochannels.     

Two Polymorphs of the Inclusion Compound [（n-C4H9）4N] ＋（C13H9O3）-H2O

Two polymorphs of the inclusion compound [(n-C4H9)4N]+·(C13H9O3)-·H2O havebeen prepared and characterized by X-ray crystallography. Polymorph 1: triclinic P 1 , a =13.4982(2), b = 13.5743(2), c = 17.1996(2) , α = 67.045(1), β = 77.845(1), γ = 88.762(1)°, V =2830.43(7)3, Z = 4, R = 0.0491, wR = 0.1276; Polymorph 2: tetragonal P43, a = b = 13.53690(1) , c = 30.8491(8) , V = 5653.02(16)3, Z = 8, R = 0.0448, wR = 0.0984. In these two crystalstructures, the hydrogen-bonded ribbons built of 4,4 -dihydroxybenzophenone (DHBP, C13H10O3)anions and water molecules are orderly arranged to generate two-dimensional host layers, withtetrabutylammonium cations contained between the layers to form the sandwich-like inclusioncompounds. The structures of 1 and 2, which exist as two polymorphs, both display the similarpacking pattern and hydrogen-bond linking model.     

乙醇-水分子团簇C2H5OH(H2O)n (n=1-9)稳定结构的量子化学研究

采用密度泛函理论B3LYP方法, 在B3LYP/6-311++G(2d,2p)//B3LYP/6-311++G(d,p)基组水平上对乙醇-水分子团簇(C₂H₅OH(H₂O)_n (n=1-9))的各种性质进行研究, 如: 优化的几何构型、结构参数、氢键、结合能、平均氢键强度、自然键轨道(NBO)电荷分布、团簇的生长规律等. 结果表明, 从二维(2-D)环状结构到三维(3-D)笼状结构的过渡出现在n=5的乙醇-水分子团簇中. 此外, 利用团簇结合能的二阶差分、形成能、能隙等性质, 发现在n=6时乙醇-水分子团簇的最低能量结构稳定性较好, 可能为幻数结构. 最后, 为了进一步探讨氢键本质, 将C₂H₅OH(H₂O)_n (n=2-9)最低能量结构的各种性质与纯水分子团簇(H₂O)_n (n=3-10)比较, 结果表明前者与后者中的水分子之间氢键相似.     

磁场对冷表面上结霜过程影响的实验研究

本文对磁性表面上结霜现象进行了初步的实验研究.实验观察发现,磁性表面上水滴的凝结、霜晶的形成过程和霜晶的形态与非磁性表面上的情况是完全不同的,在磁性表面上凝结形成的液滴较非磁性表面上形成的液滴粒径更小、分布更加均匀,霜层结构更松散,更容易被去除.文章最后从理论上分析了这种现象产生的原因.     

Synthesis,Structure, Electrochemistry and Fluorescence Properties of a One-dimensional Coordination Polymer {[ CdLu-（4,4＇-dps） ]2（H2O）2]＇（4＇abs ）2（H2O）2

A new cadmium（N） compound, {[ CdLu-（4,4＇-dps） ]2（H2O）2]＇（4＇abs ）2（H2O）2n 1 （4,4＇-dps = 4,4＇-dipyridylsulfide, 4-abs = deprotonated 4-amino benzenesulfonic acid）, has been synthesized and structurally characterized. It belongs to the orthorhombic system, space group Pbcn with a = 19.950（3）, b = 10.6381（13）, c = 18.055（2）A, V= 3831.8（8） A3, Z = 4, C32H36CdN6010S4, Mr = 905.31, F（000） = 1848, μ= 0.850 mm^-1, Dc = 1.569 Mg/m^3, the final R = 0.0238 and wR = 0.0589 for 3080 observed reflections with I 〉 2σ（I）. Complex I is a one-dimensional linear chain coordination polymer and the repeat unit is comprised of doubly charged cadmium complex cation, uncoordinated 4-aminobenzene sulfonate anions and water molecules. The cadmium（H） ion adopts a six-coordinate distorted octahedral geometry. Complex 1 is stabilized and linked into a three-dimensional layered structure through intermolecular O-H…O and N-H…O hydrogen bonds together with electrostatic force. The cyclic voltammograms and fluorescence spectrum of 1 were also measured. It shows one irreversible redox process and emits a very strong and sharp fluorescent band at about 341 nm.     

《结构化学》简介

《结构化学》是由中国科学院主管,中国化学会、中国科学院福建物质结构研究所主办的学术性期刊。1982年由我国著名化学家卢嘉锡院士创办并担任主编,现任主编是著名化学家吴新涛院士。     

Synthesis and Crystal Structure of a New Complex （H3IDC）（Prz）0.5（H2O）

The compound （H3IDC）（Prz）0.5（H2O） （H3IDC = imidazole-4,5-dicarboxylate, Prz = piperazine） has been prepared from a hydrothermal approach and was characterized by IR analysis and X-ray diffraction. Its crystal structure consists of discrete 4,5-imidazole-dicarboxylate, H2O and piperazine molecules. The whole structural motif was assembled by three different non-covalent interactions of O-H…O, N-H…O and π-π stacking, which play an important role in packing the molecules. Interestingly, the connections between imidazole-4,5-dicarboxylate molecule and water molecule result in a helical polymeric chain. Crystal data for compound 1： monoclinic system, space group P21/c, a = 6.4600（13）, b = 19.910（4）, c = 6.9123（14） A^°, β = 94.26（3）°, V= 886.6（3） A^°^3, Z= 4, C7H10O5N3, Mr = 216.18.     

Crystal Structure,Thermal Behavior and Luminescence of a One-dimensional Coordination Polymer [Zn（4-CPOA）（Phen）（H2O）]n

A novel coordination polymer of [Zn（4-CPOA）（Phen）（H2O）]n （C21H16N2O6Zn,1,4-CPOA = 4-carboxylato-phenoxyacetate dianion and Phen = 1,10-phenanthroline） has been synthesized and characterized by elemental analysis,IR,TG,PL and single-crystal X-ray diffraction. The crystal crystallizes in the triclinic system,space group of P1 with a = 9.622（3）,b = 9.631（3）,c = 11.526（4）A,α = 67.719（5）,β = 71.203（5）,γ = 83.552（6）o,V = 935.5（5） A^3,Z = 2,Dc = 1.625 g/cm^3,μ = 1.357 mm^-1 and F（000） = 468. The Zn（II） ion is surrounded by three carboxylate O atoms from two different 4-CPOA groups,two N atoms from the Phen ligand and one water molecule,forming a distorted octahedral coordination configuration. The Zn（II） ions were alternately interlinked by carboxylate groups of 4-CPOA with chelating bisbidentate and monodentate modes into a one-dimensional zigzag chain having an intrachain distance of ca. 9.631（1） . Under the direction of supramolecular recognition and attraction,the adjacent chains yield a double-stranded chain through π-π stacking between the phen ligands,which was further expanded into a 2-D framework via strong C–H–π interaction （ca. 2.95（1） ） between the 4-CPOA ligands and into a 3-D supramolecular network by strong hydrogen bond between terminal water molecule and carboxyl group. TG/DTG shows that its chain skeleton is thermally stable up to 419 oC and the blue fluorescent emission of the complex was determined at 471 nm in a solid state with its long decay lifetime of 1.83 ns.     

分子动力学模拟方法研究结构水在糖原合成酶激酶-3β中的作用

用分子动力学模拟的方法揭示了结构水分子在糖原合成酶激酶-3β(GSK-3β)中的作用. 如果没有结构水, ATP嘌呤环的结合位置将发生偏移以填补结构水留下的空间; ATP结合口袋中的氢键网络将被破坏, 保守残基Lys85与ATP的磷酸根侧链只能形成一个保守氢键, 无法维持磷酸根转移所需的线性关系; 由于失去了氢键网络的稳定作用, Glu97和Lys85会向远离ATP的方向移动, 并导致Arg96的侧链发生偏转, 使Arg96无法保持与Arg180和Lys205之间正常的相对位置, 最终影响GSK-3β与底物的结合.     

氢键对氧化石墨烯复合结构层间剪切行为影响研究

针对氧化石墨烯层状复合结构性能优化设计要求及其对环境湿度的高敏感性,开展了氧化石墨烯在湿润环境下的层间剪切行为研究.首先,采用连续力学理论,获取不同氧化浓度时氧化石墨烯层状结构层间粘结能、层间氢键相互作用能及剪切应力表达式;所获得的层间能量理论值与分子动力学模拟结果基本一致.其次,通过在氧化石墨烯层间加入不同含量水分子...