有序自组装聚合物纳米结构

采用水辅助方法(water-assisted fabrication method),分别以4-十二烷基苯磺酸掺杂的聚苯胺(PANI-DBSA)和聚2-甲氧基-5-(2′-乙烯基-己氧基)苯乙炔(MEH-PPV)两种功能高聚物为成膜材料,冷凝水滴为模板,利用水滴在聚合物溶液表面的自组装,制备出了两种纳米层次以上的蜂窝状有序多孔聚合物薄膜.通过原子力显微镜和共聚焦荧光显微镜对其形貌、电学性质和荧光图像进行了表征.     

Synthesis of new trans double-bond sphingolipid analogues: Delta(4,6) and Delta(6) ceramides

Unsaturation was introduced at Delta(4,6) and Delta(6) of the sphingoid chain of naturally occurring ceramide 1 via a beta-keto sulfoxide (12) and sulfone (18) derived from N-Boc-L-serine methyl ester acetonide (9), affording two novel ceramide analogues, (2S,3R)-2-octanoylamidooctadeca-(4E,6E)-diene-1,3-diol (2) and (2S,3R)-2-octanoylamidooctadec-(6E)-ene-1,3-diol (3). After C-alkylation of 12 with (E)-1-bromo-2-tetradecene (8), a trans double bond was installed by elimination of PhS(O)H, providing conjugated dienone oxazolidine 13. Reaction of 18 with 8, followed by desulfonation (Al(Hg)), afforded keto-oxazolidine 20, which bears a (E)-Delta(6) double bond. The syntheses of analogues 2 and 3 from ketones 13 and 20, respectively, were completed by the following sequence of reactions: diastereoselective reduction (NaBH(4)/CeCl(3) or DIBAL-H), hydrolysis of the oxazolidine ring, liberation of the amino group, and installation of the N-amide group.     

Composite Electrode SnO2／TiO2 for Dye-Sensitized Solar Cells

Composite nanoporous electrode SnO2/TiO2 was fabricated for the dye sensitized solar cell (DSSC) with N3 (Cis-Ru). After introducing of TiO2, the open-circuit photovoltage (Voc) was higher than that of the pure SnO2 electrode, while short-circuit photocurrent (Isc) was varied with the ratio of the TiO2. Appropriate content of the TiO2 can be beneficial to the efficiency of the solar cell, and it gives negative impact on the composite electrode when the content of TiO2 is higher.     

密胺-脲甲醛树脂合成工艺放大研究

以密胺－脲甲醛树脂合成的小试工艺条件为依据，完成了放大试验过程的工艺研究。研究结果与小试研究的工艺条件相吻合。     

窄分布聚丙烯酸-g-聚甲基丙烯酸酯接枝共聚物的合成

利用合成的一种新型原子转移自由基聚合大分子引发剂和从主干接枝的方法制备了窄分布的两亲性接枝共聚物聚丙烯酸-g-聚甲基丙烯酸酯, 并对其结构进行表征. 产物主链和侧链的分子量可分别通过调整单体与引发剂的投料比和反应时间进行控制, 结构规整, 侧链单体适用范围广. 该合成方法不仅推动了接枝共聚物合成研究的进展, 其产物更为两亲性接枝共聚物自组装行为的研究提供了很好的研究对象.     

Synthesis and Mesogenic Properties of Liquid Crystals Containing Terminal Cyclohexylmethanol,Cyclopentylmethanol, Cyclobutylmethanol and Cyclopropylmethanol Moiety

Four series of compounds 11?50 containing terminal alicyclic rings such as cyclohexylmethyl, cyclopentylmethyl, cyclobutylmethyl, and cyclopropylmethyl rings were synthesized and their liquid crystal behavior studied. The ring size and the length of flexible alkoxy chain influence the phase formation in different ways. While the smaller ring and the shorter alkoxy chain tend to favor the formation of the N phase, the larger ring and the longer alkoxy chain tend to favor the formation of the SmC phase. All the compounds except 11 and 21 exhibit SmA phases. The widest temperature range of the N, SmA, and SmC phases are found in the compounds 41 , 46 , and 20 , respectively, which are 75 °C for 41 , 115 °C for 46 , and 100 °C for 20 .     

SYNTHESES AND SPECTROSCOPIC PROPERTIES OF LANTHANIDE COMPLEXES, Ln(acac)_3(Ph_3PO)_3

A series of new complexes of formula Ln(acac)_s(Ph_3PO)_3 (where Ln~(3+)=Nd~(3+), Sm~(3+), Eu~(3+), Tb~(3+), Ho~(3+)) have been prepared and characterized. The coordination of two ligands with lanthanide ions are studied by IR spectra, ~1H, ~(13)C, ~(31)P-NMR and metal-ligand charge tranafer tranaition is also discussed via electronic adaorption and luminescence spectroscopy.     

Thermodynamic molecular switch in sequence‐specific hydrophobic interactions

This communication will demonstrate the existence of a thermodynamic molecular switch in the pairwise, sequence‐specific hydrophobic interaction of Ile–Ile, Leu–Ile, Val–Leu, or Ala–Leu over the temperature range of 273–333 K reported by Nemethy and Scheraga in 1962. Based on Chun's development of the Planck–Benzinger methodology, the change in inherent chemical bond energy at 0 K, ΔH°(T₀), is 3.0 kcal mol^?1 for Ile–Ile, 2.4 for Leu–Ile, 1.8 for Val–Leu, and 1.2 kcal mol^?1 for Ala–Leu. The value of ΔH°(T₀) decreases as the length of the hydrophobic side chain decreases. It is clear that the strength and stability of the hydrophobic interaction is determined by the packing density of the side chains, with Ala–Leu being the most stable. At 〈T_m〉, the thermal agitation energy, $\int^{T}_{0}\Delta Cp^{\circ}(T)\,dT$, is about five times greater than ΔH°(T₀) in each case. Additionally, the thermal agitation energy for the same series, evaluated at 〈T_m〉, decreases in the same order, that is, as the length of the side chain decreases. This pairwise, sequence‐specific hydrophobic interaction is highly similar in its thermodynamic behavior to that of other biological systems, except that the negative Gibbs free energy change minimum at 〈T_s〉 occurs at a considerably higher temperature, 355 K compared to about 300 K. The melting temperature, 〈T_m〉, is also high, 470 K compared to 343 K in a biological system. The implication is that the negative Gibbs free energy minimum at a well‐defined 〈T_s〉 has it origin in the hydrophobic interactions, which are highly dependent on details of molecular structure. In addition to the four specific dipeptide interactions described, we have shown in our unpublished work the existence of a thermodynamic molecular switch in the interactions of 32 dipeptides wherein a change of sign in ΔCp°(T)_reaction leads to a true negative minimum in the Gibbs free energy of reaction, and hence, a maximum in the related K_eq. Indeed, all interacting biological systems that we have thus far examined using the Planck–Benzinger approach point to the universality of thermodynamic molecular switches. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001     

Kinetic investigation of the textile bleaching process

Volumetric H₂-uptake measurements on an Mo₂N (79 m²g^–1) sample reduced at 673 K have been carried out and the uptake isotherms in the temperature range of 308–623 K have been determined. Both the total and reversible hydrogen uptake increased with the uptake temperature. The irreversible hydrogen uptake increased abruptly when the uptake temperature was raised up to 423 K. The maximum of irreversible hydrogen uptake was measured at 473 K. The H_IR/Mo ratio calculated from the uptakes obtained in the temperature range of 308–623 K varies in the range of 0.0010–0.0202. One possible mechanism for hydrogen adsorption is proposed to be heterolytic dissociation on Mo-N paris, in which the molybdenum atoms are in unsaturated coordination.     

硝酸活化高灵敏度离子选择性电极法测定氟

先在0．5 mol·L-1硝酸介质中活化氟离子选择性电极,再在含硝酸的总离子强度调节混合液(TISAM)中测定氟,线性范围为1×10-7～1×10-2mol·L-1,检出限为1．9μg·L-1。该方法应用于绿茶饮料、水、牛奶中痕量氟的测定,结果的RSD小于4．8％,回收率在96．1％至100．2％之间,对氟离子选择性电极在硝酸介质中的活化机理作了阐述。