One-dimensional Supramolecular Chain Based on a Dinuclear Terbium（Ⅲ） 4-Cyanobenzoate Complex

A new dinuclear Tb（Ⅲ） 4-cyanobenzoate complex [Tb2（4-cba）6（phen）2] （4-Hcba = 4-cyanobenzoic acid and phen = 1,10-phenanthroline） 1 has been synthesized by solvothermal reaction in an ethanol/water mixed solution at 100℃ and structurally characterized by single-crystal X-ray diffraction. Crystallographic data： C72H40N10O12Tb2, Mr=1554.98, triclinic Pi, a = 9.903（3）, b = 11.769（8）, c = 15.078（8）A, a = 111.42（12）, It = 96.37（19）, γ = 101-24（14）°, V= 1572（1）A3, Z= 1, Dc = 1.642 g/cm^3, F（000） = 768 μ = 2.305 mm^-1, the final R = 0.0205 and wR = 0.0543 for 5479 reflections with I 〉 2σ（I）. Structural analysis shows that 1 displays an isolated dinuclear structure. Two eight-coordinated Tb（Ⅲ） ions are bridged by four 4-cba ligands in the syn-syn bidentate coordination mode, and two other 4-cba ligands chelate these two Tb（Ⅲ） ions. The title complex molecules are connected through π-π stacking interactions to generate a one-dimensional supramolecular chain, The characteristic infrared spectra, luminescent properties and thermogravimetric analyses have also been discussed.     

Remarkably enhanced capacitance of ordered polyaniline nanowires tailored by stepwise electrochemical deposition

A stepwise deposition method was employed to create ordered polyaniline (PANI) nanowires with remarkably enhanced capacitance. Cyclic voltammetry, AC impedance, and galvanostatic charge/discharge cycling were employed to investigate the electrochemical performance of the PANI electrodes. The PANI-deposited electrode exhibits much higher capacitance than those prepared by one-step deposition method, which were mainly contributed from the unique nano structure of PANI and the increased biological, economical, and technical surface areas. The superior capacitive behaviors of the nano PANI electrodes show great potential in preparation of high efficient electrochemical capacitors or rechargeable batteries.     

Simultaneous Determination of Four Flavonoids in Pigeonpea [Cajanus cajan (L.) Millsp.] Leaves Using RP-LC-DAD

A simple and accurate RP-HPLC method using photodiode array detection (PAD) was developed for the simultaneous determination of four flavonoids, namely quercetin (QU),luteolin(LU),apigenin(AP) and isorhamnetin (IS) in pigeonpea leaves.Extract samples were separated on HIQ SIL C₁₈V column using methanol-acetonitrile-water(31:10:59, v/v/v) as mobile phase.The flavonoids were detected at 254.5 nm for QU and IS, and at 345 nm for LU and AP.Contents were determined with satisfactory repeatability (R. S. D. < 2.2%) and recovery (97.27 – 99.98%). The developed method was found to be simple and efficient.     

天然和人工培植红景天挥发油的对比研究

应用ＧＣ－ＭＳ和ＧＣ－ＩＲ两种联机法对比研究了天然和人工培植红景天挥发油、分别鉴定出２７个和２４个化合物。ＭＳ给出结构信息和ＩＲ给出官能团信息相结合，提高了分析测试复杂样品的可靠性。     

Formation and Crystal Structure of Stable Five‐coordinate Diorgano Cobalt(III) Complexes

The mer‐octahedral complexes(2‐carbonyl)(4‐Me)(6‐tBu)phenolato[C,O]hydridotris(trimethylphosphine)cobalt(III) ( 1 ) or ‐(1‐carbonyl)(2‐oxo)(1,2‐diphenylethene)[C,O]hydridotris(trimethylphosphine)cobalt(III) ( 2 ) via formal insertion of propynoic acid ethyl ester into Co‐H functions afford pentacoordinate vinylcobalt(III) 3 and 4 , respectively, that are diamagnetic and attain a square pyramidal structure as exemplified by an X‐ray diffraction analysis of 3 .     

Synthesis and Second‐Order Nonlinearities of Chiral Prolinol‐Substituted Chromophores

A new series of thiophene‐ and furan‐containing chromophores with a chiral prolinol donor and a sulfone acceptor has been synthesized. The UV‐vis absorptions, second‐order nonlinear optical properties, and X‐ray crystal structures are described.     

两个具有PTP1B抑制活性的4-羟基丁内酯化合物的全合成研究

Two new naturally 4-hydroxylated butenolides were concisely synthesized in excellent enantiomeric purities. An aldol condensation and a Suzuki reaction served successfully as the key steps in the synthesis.     

含氯聚合物和乙烯-醋酸乙烯酯共聚物共混体系的红外光谱研究

关于氯化聚乙烯(CPE)或聚氯乙烯(PVC)与乙烯—醋酸乙烯酯共聚物(EVA)共混体系相容性的研究,已有不少报道,其中Coleman等人运用FTIR方法研究了含VA45％的EVA与CPE、PVC的共混体系,测定了该体系的低临界共溶温度(LCST)。一般认为,如果VA含量更低,由于EVA本身的结晶,共混体系将变得难以     

Design,Synthesis, and Characterization of Photolabeling Probes for the Study of the Mechanisms of the Antiviral Effects of Ribavirin

Ribavirin, the only small molecule available so far for treating hepatitis‐C‐virus infection, was recently used in an emergency context to treat patients with severe acute respiratory syndrome (SARS) in the early stages of the disease. To study the mechanisms responsible for the antiviral effects of ribavirin by using a photolabeling approach, we designed, synthesized, and characterized the azidotriazole nucleosides 1 and 2 as photolabeling probes of ribavirin. These probes were synthesized either by performing nucleophilic substitution of the corresponding bromotriazole nucleoside with NaN₃ (Scheme 2) or by directly coupling the azidotriazole with the protected ribose sugar (Scheme 4). The azidotriazole nucleosides 1 and 2 showed a fast, clear‐cut photochemical reaction, which suggests that they are promising candidates for use in photolabeling studies.     

Rheological properties of multisticker associative polyelectrolytes in semidilute aqueous solutions

Multisticker associative polyelectrolytes of acrylamide (≈86 mol %) and sodium 2‐acrylamido‐2‐methylpropanesulfonate (≈12 mol %), hydrophobically modified with N,N‐dihexylacrylamide groups (≈2 mol %), were prepared with a micellar radical polymerization technique. This process led to multiblock polymers in which the length of the hydrophobic blocks could be controlled through variations in the surfactant‐to‐hydrophobe molar ratio, that is, the number of hydrophobes per micelle (N_H). The rheological behavior of aqueous solutions of polymers with the same molecular weight and the same composition but with two different hydrophobic block lengths (N_H = 7 or 3 monomer units per block) was investigated as a function of the polymer concentration with steady‐flow, creep, and oscillatory experiments. The critical concentration at the onset of the viscosity enhancement decreased as the length of the hydrophobic segments in the polymers increased. Also, an increase in the N_H value significantly enhanced the thickening ability of the polymers and affected the structure of the transient network. In the semidilute unentangled regime, the behavior of the polymer with long hydrophobic segments (N_H = 7) was studied in detail. The results were well explained by the sticky Rouse theory of associative polymer dynamics. Finally, the viscosity decreased with an increase in the temperature, mainly because of a lowering of the sample relaxation time. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1640–1655, 2004