Electrochemical Preparation of Poly(Malachite Green) Film Modified Nafion‐Coated Glassy Carbon Electrode and Its Electrocatalytic Behavior Towards NADH,Dopamine and Ascorbic Acid

Poly(malachite green) film modified Nafion‐coated glassy carbon electrodes have been prepared by potentiodynamic cycling in malachite green solution. The pH of polymerisation solution has only minor effect on film formation. Electrochemical quartz crystal microbalance (EQCM) was used to monitor the growth of the poly(malachite green) film. Cyclic voltammogram of the poly(malachite green) film shows a redox couple with well‐defined peaks. The redox response of the modified electrode was found to be depending on the pH of the contacting solution. The peak potentials were shifted to a less positive region with increasing pH and the dependence of the peak potential was found to be 56 mV per pH unit. The electrocatalytic behavior of poly(malachite green) film modified Nafion‐coated glassy carbon electrodes was tested towards oxidation of NADH, dopamine, and ascorbic acid. The oxidation of dopamine and ascorbic acid occurred at less positive potential on poly(malachite green) film compared to bare glassy carbon electrode. In the case of NADH, the overpotential was reduced substantially on modified electrode. Finally, the feasibility of utilizing poly(malachite green) film electrode in analytical estimation of ascorbic acid was demonstrated in flow injection analysis.     

双8-羟基喹啉端开链冠醚金属络合物的光物理性质

设计合成了双8-羟基喹啉端的开链冠醚QP3Q,研究了金属离子铝或锌与其形成络合物的组成和发光性质,并测定了络合物的激发态寿命.这些络合物在溶液中有较高的荧光量子产率,所得到的络合物固体具有较强的蓝光发光性能.结果表明,有可能通过QP3Q与不同离子形成的络合物得到不同发光波长的发光材料.     

Solution chemistry of uranyl ion with iminodiacetate and oxydiacetate: A combined NMR/EXAFS and potentiometry/calorimetry study

The solution chemistry of uranyl ion with iminodiacetate (IDA) and oxydiacetate (ODA) was investigated using NMR and EXAFS spectroscopies, potentiometry, and calorimetry. From the NMR and EXAFS data and depending on stoichiometry and pH, three types of metal:ligand complex were identified in solution in the pH range 3-7: 1:1 and 1:2 monomers; a 2:2 dimer. From NMR and EXAFS data for the IDA system and previous studies, we propose the three complex types are [UO(2)(IDA)(H(2)O)(2)], [UO(2)(IDA)(2)](2)(-), and [(UO(2))(2)(IDA)(2)(mu-OH)(2)](2)(-). From EXAFS spectroscopy, similar 1:1, 2:2, and 1:2 complexes are found for the ODA system, although (13)C NMR spectroscopy was not a useful probe in this system. For the 1:1 and 1:2 complexes in solution, EXAFS spectroscopy is ambiguous because the data can be fitted with either a long U-N/O(ether) value (ca. 2.9 A) suggesting 1,7-coordination of the ligand or a U-C interaction at a similar distance, consistent with terminal bidentate coordination. However, the NMR data of the IDA system suggest that 1,7-coordination is the more likely. The stability constants of the three complexes were determined by potentiometric titrations; the log beta values are 9.90 +/-, 16.42 +/-, and 10.80 +/- for the 1:1, 1:2, and 2:2 uranyl-IDA complexes, respectively, and 5.77 +/-, 7.84 +/-, and 4.29 +/- for the 1:1, 1:2, and 2:2 uranyl-ODA complexes, respectively. The thermodynamic constants for the complexes were calculated from calorimetric titrations; the enthalpy changes (kJ mol(-)(1)) and entropy changes (J K(-)(1) mol(-)(1)) of complexation for the 1:1, 1:2, and 2:2 complexes respectively are the following. IDA: 12 +/- 2, 230 +/- 8; 8 +/- 2, 151 +/- 9; -33 +/- 3, -283 +/- 11. ODA: 26 +/- 2, 198 +/- 12; 20 +/- 2, 106 +/- 8; -24 +/- 2; -219 +/- 8.     

聚羟基丁酯酯缓释微球的制备及性能

用溶剂蒸发法制备了以新型生物可降解材料聚羟基丁酸酯为载体、以安定为模药的缓释微球,讨论了药物与载体之比对药物含量与包封率的影响,以及制备微球条件对药物释放性能的影响;微球平均粒径为３０～４０μｍ,粒径分布在１～１．５之间,最大载药量为１９．５１％;最高包封率为６７．１１％;体外累积释放曲线呈“两相”释放特征并拌随初始的“突释效应”。扫描电镜观察微球表面呈皱缩表观形态结构,微球内部横断面具有孔道与孔     

Tetraazadibora[3, 3]paracyclophane

Starting from the para‐phenylenediamine derivative HN(SiMe₃)‐C₆H₄‐NH(SiMe₃), a lithiation and subsequent borylation give [(MeO)₂B]N(SiMe₃)‐C₆H₄‐N(SiMe₃)[B(OMe)₂] ( 1 ), the hydridation of which yields Li₂[(H₃B)N(SiMe₃)‐C₆H₄‐N(SiMe₃)(BH₃)] ( 2 ). Applying ZrCl₄ upon 2 initiates a condensation to give the title compound [‐N(SiMe₃)‐p‐C₆H₄‐N(SiMe₃)‐BH‐]₂, a hetero[3, 3]paracyclophane with two N‐B‐N chains that connect the para‐phenylene units. The product 3 crystallizes in the orthorhombic space group P2₁2₁2₁.     

On subspectral problem—benzenoid hydrocarbons with common eigenvalues ±1

Summary The method for the contraction and expansion of graphs is used to treat the subspectrality of benzenoid hydrocarbons in relation to eigenvalues ±1. Counts of benzenoid hydrocarbons together with degeneracies of eigenvalues have been carried out for all species having h 7 hexagons. In addition, twelve homologous series are evaluated, and the closed results for the distribution of eigenvalues ± 1 and degeneracies in terms of the number of repeated units are tabulated. This method is universal and applicable to cases sharing other eigenvalues and to nonbenzenoid systems.Also known as Yuan-sun Kiang     

邻近C-H键对中心金属原子的配位作用—[Fe(PH3)3(C8H13)]+的定域分子轨道研究

采用INDO方法计算了{Fe[P(OMe)_3]_3(C_8H_(13))}~+的简化离子[Fe(PH_3)_3(C_8H_(13))]~+,将正则分子轨道用Edmiston-Ruedenberg定域化方法变换为定域分子轨道,结果表明:在对应C_1-H_(1A)键的定域分子轨道中,明显包含有铁原子轨道成分(7.8％),Fe-H_(1A)和Fe—C_1键级分别为0.190和0.302。指出C_1-H_(1A)键是以一对成键σ电子配位到铁原子上的。C_8H_(13)环以包含三个碳原子的η~4—共轭体系与铁原子相互作用。铁以二价(d~6-Fe(Ⅱ)的形式存在于该离子中。C_1-H_(1A)键的配位满足了文献[15]提出的Fe(Ⅱ)的共价12价。     

掺杂ZrO＿2的Pt／Al＿2O＿3表面氧性质及一氧化碳氧化性能研究

用ＴＰＤ－ＭＳ、ＴＰＳＲ－ＭＳ及ＣＯ氧化活性测定等方法研究了Ｐｔ／Ａｌ２Ｏ３和掺杂超细ＺｒＯ２的样品的表面氧脱出－恢复性能、ＣＯ表面氧化性能及催化氧化性能．结果表明，在Ｐｔ／Ａｌ２Ｏ３中掺杂ＺｒＯ２后，样品表面上的氧物种脱出和氧化恢复性能明显提高，脱氧量也明显增大；并发现在ＣＯ－ＴＰＳＲ过程中程脱物ＣＯ２的脱附量大小及峰顶温度次序与对ＣＯ的催化氧化活性也有一致的关系     

Fourth-derivative spectrophotometric determination of neodymium in mixed rare earths with methyl thymol blue and cetylpyridinium chloride

A sensitive and selective method is described for the determination of neodymium in mixed rare earths using fourth-derivative spectrophotometry. The method is based on the absorption spectra of 4f electron transitions of the complex of neodymium with methyl thymol blue and cetylpyridinium chloride. The influence of various instrumental parameters and reaction conditions for maximum colour development are investigated. The calibration curve is linear over the range 0–3.5 g ml^–1 neodymium. The relative standard deviation for determination of 1.4 g ml^–1 neodymium (n = 7) is 1.6%. The detection limit (signal-to-noise ratio = 3) is 0.2 g ml^–1.