二氧化铅修饰玻碳电极的镀膜/循环伏安法制备及电催化性能

采用镀膜/循环伏安法制备了PbO2修饰玻碳电极.在Pb(NO3)2溶液中,在-0.7 V 将Pb膜沉积在玻碳电极表面,然后在5 mol/L NaOH溶液中以100 mV/s速度在-1.0～1.0 V循环伏安扫描20次,PbO2膜均匀沉积在玻碳电极表面.采用交流阻抗法监控电极修饰每一过程,环境扫描电镜表征电极表面形貌.探讨了PbO2膜的沉积机理及其电化学行为,表面活性位点覆盖量为7.5×10-10 mol/cm2.PbO2修饰电极对H2O2电氧化表现出较高催化活性,起始氧化电位低至0.1 V,考察了影响催化活性的因素.计时电流法测定H2O2 (工作电位0.40 V),响应时间小于2 s; 线性范围为5.0 ×10-6 ～ 5.5×10-4 mol/L;检出限1.1×10-6 mol/L (信噪比为3).在实际水样中H2O2测定结果满意.电极在室温环境下储存30 d,其催化活性基本不变.该修饰电极制备工艺简单、重现性良好、稳定性高.     

Intramolecular stacking interaction in mixed-ligand complexes containing ATP4- and aromatic N-heterocyclic ligands

The stability constants of the binary ML2+ and ternary M(ATP)L2- complexes,where L=Iq (isoquinoline) or BIm (benzimidazole) and M=Zn2+ or Cd2+,have been determined by poten-tiometric pH titration in aqueous solution at I=0.1 mol/L (NaClO4),T=25℃.The stability of the ternary complexes characterized by corresponding to the equilibrium M(ATP)2-+ML2+=M(ATP)L2-+M2+ is higher than what would be expected on statistical grounds.The increase may be related to the stacking interaction between the aromatic ring of the ligands L and the purine moiety of ATP4- 1H NMR studies of Zn2+/ATP4-/L confirm the presence of stacking in the ternary complexes.It is concluded that the strength of the intramolecular stacking interaction is dependent on the structure of the aromatic ring of the ligand L and the formation of a metal ion bridge.Possible implications are discussed briefly.     

新癌药物的电化学研究1: 一种Fe(III) Schiff碱配合物的基本电化学性质及其与DNA的相互作用

研究了一种自合成的Schiff碱配合物的电化学行为及其与氧和DNA的相互作用。发现此种Schiff碱配合物能与氧发生相互作用而具有吸氧功能, 并对氧的电还原有催化作用, 同时还发现dsDNA能与此种Schiff碱配合物发生较强的相互作用, 特别是Fe(II)Schiff碱配合物更易与dsDNA结合。     

Fabrication of TiO2 Grating with Composites of Azobenzene Polymer and TiO2 Nanoparticles

We have used the formation of surface relief gratings (SRG) on azobenzene polymers to manipulate TiO₂ nanoparticles and to fabricate TiO₂ nanoparticle gratings. Suspensions of an azobenzene polymer (PDO3) and TiO₂ were used to spin coat thin films on glass slide substrates. By interfering coherent light from an Argon laser on the surface of the PDO3‐TiO₂ composite films, SRGs were fabricated. Atomic force microscopic images of the SRGs show TiO₂ nanoparticles dispersed throughout the sample, and in particular, at the peaks of the SRG after oxygen plasma treatment. The lateral forces acting on the azobenzene polymer during the SRG fabrication drag the TiO₂ nanoparticles. These results indicated that it is feasible to create TiO₂ nanoparticle gratings with the composites.     

Photosensitized Solid-state Polymerization of Diacetylenes in Nanoporous TiO2 Structures

In situ topochemical polymerization of two diacetylene monomers within nanoporous TiO₂ thin films was carried out under visible light irradiation. One of the monomers used contains a carboxylic acid group, which could help to link the monomer onto the TiO₂ surface covalently. UV-Vis absorption and Raman studies showed that both monomers were successfully photopolymerized. These results suggest that the covalent linkage of the diacetylene to the nanoparticle through the carboxylic acid group is not needed. Since photopolymerization of diacetylene is typically induced by excitation of the monomer at λ< 300 nm, the observed red shift of the photopolymerization wavelength is attributed to the photosensitization effect of TiO₂. The morphological study of the polydiacetylene/TiO₂ nanocomposite revealed that the diacetylene monomers were polymerized in the vicinity of the TiO₂ nanoparticles. This is attributed to the fact that the electron-transfer process occurs at the interface of nanocrystalline TiO₂ (nc-TiO₂) and the diacetylene monomer and the polymerization is expected to be initiated near the nc-TiO₂ surface. Photopolymerization of the carboxylated diacetylene monomer with other oxides nanoparticles, such as ZnO and SiO₂ was also investigated.     

聚乙烯燃烧和阻燃的热分析研究

<正> 聚乙烯是一种极易燃烧的高分子材料,氧指数仅17.6,随着其应用面的拓宽和现代社会对防火要求的提高,聚乙烯的阻燃成了越来越重要的课题。目前,聚乙烯及其共混物的阻燃配方已不计其数,理论探讨也有一些报道,但由于对阻燃效果与阻燃剂的性质之间的内在联系尚缺乏足够的认识,所以阻燃剂的选择仍主要依赖于经验及大量的配方试验,缺少系统有效地选择阻燃剂的方法。     

多吡啶-铜(Ⅱ)-L-α-氨基酸配合物与DNA的作用

应用电子吸收光谱、荧光光谱、粘度测定及琼脂糖凝胶电泳法研究了多吡啶-铜(Ⅱ)-L-α-氨基酸型配合物:[Cu(TATP)(L-Val) (H2O)]ClO4·0.5H2O (1)、[Cu(IP)(L-Val)(H2O)]ClO4·1.5H2O (2) 、[Cu(TATP)(L-Tyr)(H2O)]ClO4·H2O(3)...     

金属氧化物修饰电极的制备及最新应用

论述了金属氧化物修饰电极的制备方法,对近几年其在环境污染物处理、电分析化学、电合成及与其它方法联用等方面的应用进行了综述。指出了金属氧化物修饰电极研究中存在的问题,并展望了其发展方向与应用前景。     

Quadratic nonlinearity of one- and two-electron oxidized metalloporphyrins and their switching in solution

We report the quadratic nonlinearity of one- and two-electron oxidation products of the first series of transition metal complexes of meso-tetraphenylporphyrin (TPP). Among many MTPP complexes, only CuTPP and ZnTPP show reversible oxidation/reduction cycles as seen from cyclic voltammetry experiments. While centrosymmetric neutral metalloporphyrins have zero first hyperpolarizability, beta, as expected, the cation radicals and dications of CuTPP and ZnTPP have very high beta values. The one- and two-electron oxidation of the MTPPs leads to symmetry-breaking of the metal-porphyrin core, resulting in a large beta value that is perhaps aided in part by contributions from the two-photon resonance enhancement. The calculated static first hyperpolarizabilities, beta0, which are evaluated in the framework of density functional theory by a coupled perturbed Hartree-Fock method, support the experimental trend. The switching of optical nonlinearity has been achieved between the neutral and the one-electron oxidation products but not between the one- and the two-electron oxidation products since dications that are electrochemically reversible are unstable due to the formation of stable isoporphyrins in the presence of nucleophiles such as halides.     

色谱研究的最新进展

作为本期《色谱》的聚焦专栏评述,笔者主要介绍国内外学者在2010年3月和4月间发表的一些研究工作［1-9］,内容集中在色谱研究和应用的两个方面:新型色谱材料和方法技术的开发［1－5］;色谱在蛋白质组学分析中的新应用［6,7］。另外,近期也有不少关于微流控分析应用的具有特色的工作［8］,由于篇幅限制就不在这里详细介绍。