钴镍取代杂多酸盐甘氨酸超分子化合物的合成及性质

Supermolecular compounds of glycine monosubstituted heteropolytungstates isomer with Keggin structure β_i-K_6-n(HGly)_n[SiW₁₁M(H₂O)O₃₉]·xH₂O (M=Co²⁺, Ni²⁺； β_i=β₂, β₃) were synthesized and characterized by means of elementary analysis, IR, UV, TG-DTA, X-ray diffraction, polarography and CV. The results indicate that glycin combines the electrostatic effect with heteropolytungstates isomer. The heteropoly anion still remains its Keggin structure in supermolecular compounds. The electrochemical behavior of the compound in 1 mol·L^-1 HAc-NaAc shows that two redox waves correspond to two two-electron processes attributing to the reduction of [SiW₁₁Co(H₂O)O₃₉]^6-. Steady-state fluorescence spectrum shows two intenser fluorescence emission peaks in 447 nm and 486 nm appeared after the supermolecular compound being excited by the excitation wavelength in 274 nm.     

Water polarizability in condensed phase: ab initio evaluation by cluster approach

The polarizability of a water molecule in liquid is evaluated via ab initio and density functional calculations for water clusters. This work has considerably improved our previous effort [J Chem Phys 1999, 110, 11987] to attain quantitative accuracy for polarizability. The calculations revealed that the water polarizability in the liquid is reduced from that in the gaseous phase by 7-9%. These results suggest significant implications for polarizable water models.     

Hydration scheme of uracil and cytosine

The comparison of a pure electrostatic approximation and complete supermolecule SCF ab initio computations on the hydration scheme of uracil and cytosine shows that the electrostatic procedure is capable to reproduce the general aspects of the results of the supermolecule treatment provided that different distances of shortest approach be adopted for the distances between the oxygen of water and the nitrogen of NH₂ or NH groups or the oxygen of C-O groups on the one hand and the oxygen of water and pyridine-type nitrogens on the other hand.     

邻-甲氧基苯酚和α-,β-环糊精包合现象的理论与实验研究

通过紫外可见光谱法考察了水溶液中邻-甲氧基苯酚(o-Mop)和α-与β-环糊精(CD)的分子间相互作用, 利用Hildebrand-Benesi方程给出了两个包合物的稳定常数(K_s). 采用半经验PM3方法研究了α-,β-CD和o-Mop及其类似物苯酚(Phe)、丁香酚(Eug)之间的包络作用, 阐述了这些主客体包合作用过程中体系能量随主客体相对位置改变而变化的细节, 据此推断出主-客体包合物可能的分子结构, 计算了包合物的稳定化能(ΔE_s). 研究结果表明, 本文所选主客体体系而言, 当客体和同一种主体分子作用时, 超分子包合物的ΔE_s随着客体分子苯环上取代基团数目的增多而增加. 基于PM3方法优化得到的主-客体包合物在真空中的分子结构和通过实验方法在水溶液中测定的结构一致.     

Supramolecular Metal Complex with Ferrocene-conjugated Macrocyclic Triaza Crown Ether as Ligand and Its Electrochemical Property

LigandscontainingelectrochemicallyresponsivecentrearegoodsubjectsforthestUdyofintfamolecularandhost-guestillteraction.Forthisreason,tYemendousamoulltsofsuchligandsandtheircomplexeshavebeensynthesized.'-'AnobservationfromthestudiesofthesecomPlexesisthattheguestionhasapermrbationonthehostcelltre.2'7-9Forexample,itwasdocumelltedthatintroductionofCo(II)ionontoN-ferrocenylmethyl-l,4,7-triazacyclononane(fcmtacn)causesapositiveshiftintheredoxpotentialofferrocenylgroupfromthatofferrocenegroupinfree…     

C3N6H6(H3BO3)2的合成及晶体结构

以三聚氰胺和硼酸为原料在水溶液中反应合成出了一种新的BCN化合物先驱体C3N6H6(H3BO3)2。XRD表征结果表明三聚氰胺和硼酸的最佳配比为1∶3(物质的量比)。用单晶X-射线衍射分析法测定了该化合物的晶体结构。该化合物属单斜晶系,空间群为P21/C,晶胞参数为a=0.3597(7)nm,b=2.0105(4)nm,c=1.4112(3)nm,α=90,°β=92.07(3),°γ=90,°V=1.0199(3)nm3,Z=4,D c=1.627g.cm-3,μ(MoKα)=0.144mm-1,F(000)=520。晶体结构经全矩阵最小二乘法修正,最终可靠因子R1=0.0519,wR2=0.1361。该化合物是由C3N6H6分子和H3BO3分子通过氢键加合组装形成的三维超分子结构化合物。     

Ab initio calculation of the Young's modulus of α‐polyamides

In earlier works the supermolecule model has been applied to the calculation of the Young's modulus of crystalline polyethylene and polyamide‐6. In the supermolecule model a crystalline polymer is represented as a single finite chain divided into a head, body, and tail part. The body contains a number of monomer units and is representative for a polymer chain. In this article, this model has been used to study the geometric properties and the elastic moduli of the α form of other polyamides: polyamide‐2 (or polyglycine), polyamide‐3, polyamide‐4, polyamide‐11, and polyamide‐6,6. All calculations have been performed with a linearly constrained body. The results have been compared to other theoretical and experimental results if available. © 2002 Wiley Periodicals, Inc.; DOI 10.1002/qua.2002;10121     

中空纤维协同液相微萃取在4种莨菪碱分析中的应用

利用协同液相微萃取方法初步探讨氢溴酸山莨菪碱、硫酸阿托品、氢溴酸东莨菪碱和丁溴酸东莨菪碱的优势构象;阐明有机溶剂对4种莨菪碱的萃取选择性和协同萃取作用机理;探讨中空纤维与莨菪碱形成电荷转移超分子对萃取效果的影响以及4种莨菪碱结构中N原子的亲电能力;结合高效液相色谱技术测定药物制剂中4种莨菪碱的含量。4种莨菪碱的线性范围均为0.05～5mg/L(r0.99),方法RSD小于7%,消旋山莨菪碱片和颠茄片中平均回收率分别为95.0%～119.0%和93.0%～95.0%,氢溴酸山莨菪碱和丁溴酸东莨菪碱检出限为0.03mg/L,硫酸阿托品和氢溴酸东莨菪碱检测出限为0.01mg/L。     

Spectroscopic and quantum chemical study on electronic and geometric properties of free and embedded dithizone molecules

The molecular and electronic structure of the three tautomeric forms of dithizone has been calculated by using semiempirical, density functional theory (DFT), and ab initio methods. Comparison of ground‐state energies shows the symmetric form most stabilized, but there is only a small barrier (<3 kcal/mol) for the hydrogen transfer from N? H toward H? S (enol form). For understanding the origin of the optical transitions intermolecular interactions have to be taken into account. By using the supermolecule method, the absorption band pattern can be rationalized already on the level of the PM3 model. The nuclear magnetic resonance (NMR) solution spectrum is interpreted in terms of an equilibrium between the symmetric and the enol forms of dithizone. The appearance of strong EPR signals only for the solid state reflects a considerable lowering of the triplet state (symmetric form). Experimental features are discussed in view of calculated energies (stabilization), chemical shifts (NMR), and SOMO orbitals (EPR). © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001     

芳环超分子体系中的π-π作用

π-π作用是芳环超分子体系中广泛存在的一种重要的弱相互作用. 本文对π-π作用的特征、形式、有效参数和表征方法等作了比较全面的综述, 同时小结了影响π-π作用的一些重要因素, 最后还概述了近年来π-π作用在超分子组装、不对称催化、有机半导体材料等领域的研究进展.