蝎型钒氧配合物的合成、结构及量子化学研究

设计合成了两种新型的以聚类吡唑硼酸盐为配体的钒氧配合物VO(acac)[HB(pz)3](1)和VO(acac)[HB(3,5-Me2pz)3]·CH3CN(2). 运用元素分析、 红外光谱和紫外光谱对所合成的配合物进行了表征, 并用X射线衍射测定了它们的晶体结构. 同时, 采用量子化学的Hartree Fock方法和自然轨道分析方法(NBO), 使用3-21G*(6d, 7f)基组计算得到了两个分子体系的分子轨道、原子电荷以及键级, 并对其结构进行了分析.     

Direct melting polycondensation and characterization of poly(ɛ-caprolactone-co-lactic acid)

A kind of biodegradable material, poly(ɛ-caprolactone-co-lactic acid) [P(CL-co-LA)] was synthesized via the direct melting polycondensation of lactic acid (LA) and ɛ-caprolactone (CL). The influences of the polycondensation time, and the catalyst type on the intrinsic viscosity of P(CL-co-LA) were also investigated. The results indicate that P(CL-co-dl-LA), with an intrinsic viscosity of 0.4733 dL/g, can be prepared by direct melting polycondensation with the molar ratio LA/CL = 3:7 at 180°C and 70 Pa for 12 h, using 0.5% (mass fraction) of SnCl₂ as the catalyst. Compared with lactide ring-opening polycondensation (ROP), the direct melting polycondensation of LA and CL is more practicable and simple. Translated from Journal of South China University of Technology, 2006, 34(7): 7–11 (in Chinese)     

Simultaneous EQCM and diffuse reflectance UV-visible spectroelectrochemical measurements: poly(aniline-co-o-anthranilic acid) growth and property characterization

Piezoelectric diffuse reflectance spectroelectrochemistry (PDRSEC), a new technique of diffuse reflectance spectroelectrochemistry (DRSEC) in combination with electrochemical quartz crystal microbalance (EQCM), was developed to study the electrochemical copolymerization of aniline and o-anthranilic acid in 1.0 mol l(-1) HClO4 and the properties of these copolymers. The DRSEC using an integral sphere was proven to possess a higher optical sensitivity at the unpolished piezoelectric quartz crystal electrodes used than the mirror reflectance spectroelectrochemistry mode. The copolymers grown from the copolymerization bath of different molar fractions of o-anthranilic acid (F1, relative to the total amount of the two monomers) showed intermediate properties between those of the homopolymers, which varied gradually with F1. The swelling/dissolution behavior of the copolymers vs solution pH was traced via the EQCM frequency and resistance signals, and its large dependence on F1 was found and discussed. In a HAc-NaAc buffer solution at pH 5.6, the amount of adsorbed lysozyme was found to be positively correlated with F1, via an EQCM impedance investigation, demonstrating the feasibility of using poly(aniline-co-o-anthranilic acid) as a load-adjustable immobilization matrix for cationic proteins. The novel PDRSEC method proposed is highly recommended for surface electrochemistry studies at relatively rough electrodes.     

Octasilsesquioxane Chemistry II. Hydrosilylation Reaction of Octa(hydrido)silsesquioxane with Unsaturated Substrates and Product Properties

The hydrosilylation reaction of octa(hydrido)silsesquioxane with ω‐halo‐1‐alkenes and other unsaturated substrates allows attachment of 8 long‐chain functionalized alkyls on the cubic Si₈O₁₂ skeleton. Pt/C and H₂PtCl₆ have been adopted as the catalysts, the yields being 74–98% for compounds 2–9 . For terminal alkenes, the hydrosilylation follows the anti‐Markonikov's rule. The morphological state of 2–9 ranges from viscous liquid to crystalline materials. The pyrolysis results indicate that 7 , a material of hard spherical core and soft flexible shell, may likely act as nanometer‐size ball bearings up to more than 400 °C. The X‐ray structure of 9 reveals that the molecule is required to possess a center of symmetry crystallographically. The linear arms on 9 , except for two of them, are virtually all‐trans in conformation, not counting the ω‐C‐Cl bond.     

A New Asterosaponin from the Starfish Culcita novaeguineae

A new asterosaponin named novaeguinoside A, along with a known saponin, asteronyl pentaglycoside sulfate, was isolated from the starfish Culcita novaeguineae. The new compound was identitied to be sodium 6α-O-{β-D-fucopyranosyl-(1→2)-β-D-fucopyranosyl-(1→4)-[β-D-quinovopyranosyl-(1→2)]-β-D-xylopyranosyl-(1→3)-[β-D-quinovopyranosyl}-5α-pregn-9(11)-en-20-one-3β-yl-sulfate by extensive spectral analysis and chemical evidence.     

Ce3(PO4)4在酸性溶液加热条件下化学形态转化及机理研究

磷酸高铈(Ce3(PO4)4)是一种难溶于水的化合物,本文测定磷酸高铈在常温pH=0.4的Ksp值为1~8×10-34,但在测定过程中发现Ce3(PO4)4的溶解度受温度变化的影响较大,尤其在50℃以上时,Ce3(PO4)4饱和溶液体系中的Ce4 、PO43-和pH值均变化异常。根据测得的Ce4 、PO43-浓度以及pH值,推断出50℃以上时Ce3(PO4)4转化为Ce(HPO4)2,并建立了相应的转化机理,测定出Ce(HPO4)2的Ksp为3~7×10-13。     

极低放射性废物填埋场土壤理化指标的测定

如何安全、经济、妥善地处理和处置核废物,成为核工业可持续发展所面临的重要问题之一[1~4]。目前,退役过程中产生的极低放废物的常用处置方法是就近选址进行填埋处置。那么填埋场场址地段的地球化学特征直接决定填埋场的安全性、可靠性[5]。以铀为例,在酸性条件下以UO22 形式存在,而pH值大于7时,会形成U2O52 ,UO2(OH)2,UO2(OH) 等水解聚合产物,使得铀既有吸附和交换作用,又有沉淀作用,会加速U的吸附[6,7]。同样,核素的化学形态同样也会受到氧化还原反应的影响。因此,查明极低放废物填埋场场址地段土壤理化性质,可为了解核素在土壤介…     

Preparation and Crystal Structure Determination of the New Intermetallic Compound RbGa3

The compound has tetragonal symmetry, space group I4 m2 with: a=b=6.315(2) and c = 15.000(2) Å and contains 6 formula units. Diffraction data with 0 < 2θ < 50° (MoKα radiation) were collected on a Nonius CAD-4 automatic diffractometer within the octant hkl. The structure was solved by Patterson synthesis and refined by full-matrix least squares to a final R(F) of 4.9% for 159 independent reflections with I > 3σ(I). The structure consists of a stacking of gallium triangular-faced dodecahedra linked to each others through direct and bifurcated Ga? Ga bonds in a non-compact netting leaving room for a sublattice of rubidium atoms with shortened Rb? Rb distances.     

Single crystal tin nano-rod arrays electrodeposited by a soft template

Single crystal tin nano-rod arrays were fabricated by the electrodeposition method when amphiphilic triblock copolymer P123 was used as a soft template at a concentration much lower than that for forming a liquid crystalline phase.     

Preparation and electrochemistry of azobenzene self-assembled monolayers on gold--long range tunneling and end-group hydrogen bonding effect

A series of thiol-functionalied azobenzene derivatives (RAzoCnSH: R=H for n=3-6, abbreviated as AzoCnSH; R=CH(3)CONH for n=4, abbreviated as aaAzoC4SH) on gold electrodes were prepared and their self-assembly and electrochemical properties were studied by cyclic voltammetry. They all formed uniform and reproducible self-assembled monolayers (SAMs) on gold and showed well-behaved voltammetric responses in aqueous solution. Both the length of the alkyl chain spacer and the H-bonding of the end acetamino group had effects on the stability and the electrochemical kinetics of the SAMs, and the effect of the H-bonding was dominant. The surface coverage of the SAMs (AzoCnSH) is gradually increased with an increase of the alkyl chain spacer length, whereas the presence of the terminal acetamino group leads to a greater increase of the surface coverage. At a low scan rate, voltammetric responses corresponding to an irreversible two-electron, two-proton reduction/oxidation of the trans-azobenzene redox center were obtained in the range of +300 mV and -800 mV, which exhibited very large peak-to-peak splitting. At a high scan rate of 500 mV/s, two steps of reversible one-electron, one-proton reduction/oxidation corresponding to the cis-isomer in azobenzene-thiol SAMs (n is odd) was clearly observed between +300 and -200 mV. The apparent electron-transfer rate is decreased with increasing distance between the azobenzene redox center and the gold electrode. The existence of the end acetamino group which restricted the conformational change during the redox process also led to a decrease of the standard rate constant, and this restriction effect is more predominant than the distance effect.