Anodic behaviour of mono- and bisdithiafulvenyl-9,9′-spirobifluorene: insertion of vinylogous TTF into the spirobifluorenyle framework

New three-dimensional copolymers containing 9,9′-spirobifluorenyl-ethylene units were prepared by anodic oxidation of 9,9′-spirobifluorenes 2-mono- or 2,7′-disubstituted by a dithiafulvenyl unit. The synthesis, physicochemical properties and electrochemistry of both monomers and derived oligomers and polymers are reported.     

Adsorptive Voltammetry of Polyelectrolyte Complex Between 11‐Ferrocenyltrimethylundecylammonium and Polyanions at Carbon Paste Electrode

For polyelectrolyte complex between cationic surfactant and polyanion, the adsorptive voltammetry at carbon paste electrode using an electroactive cationic surfactant was examined. The adsorption state of the cationic surfactant in the complexes at CPE was estimated from the half‐height width of the oxidation waves. The half‐height width for poly(styrene sulfonate) was independent of the molecular weight, and was same as that for poly(vinyl sulfate). The half‐height width for heparin was broad and different from that of the vinyl polyanions. According to the analysis by Frumkin isotherm, the interaction between cationic surfactants was attractive in heparin complex at CPE, however, in the vinyl polyanion complexes at CPE the interaction was non‐cooperative as that predicted with the Langmuir isotherm. In spite of the same adsorption state, the concentration dependency of the peak current for poly(styrene sulfonate) was quite different from that for poly(vinyl sulfate). The concentration dependence indicated the reactive property of each polyanion on the association with the cationic surfactant in aqueous solution.     

REDOX ACTIVE,MULTI-CHROMOPHORE RU(II) POLYPYRIDYL-CARBAZOLE COPOLYMERS: SYNTHESIS AND CHARACTERIZATION

A novel diimine ligand, 2-(2-pyridyl) 4-carboxyquinoline (pcq) and its corresponding polypyridyl Ru(II) complex were synthesized, characterized, and covalently attached to a carbazole based copolymer via post polymer modification. The resulting modified electroactive and multi-chromophoric polymer was readily characterized by UV-visible, FT-IR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and elemental and electrochemical analysis. Results from cyclic voltammetry and FT-IR analysis both confirmed the covalent attachment of redox active Ru(II) center into the polymer. The emission spectrum of the copolymer, in comparison to that of Ru(II) complex, demonstrated that the excited-state properties of the metal complex is maintained, in contrast to the electronic absorption spectrum, which is sensitive to the hydrophobic polymeric chain surrounding the redox sites. The thermal analysis suggested that this metallopolymer also possesses high thermal stability. The ruthenium content was also found to be 7%, which corresponds to 80% of the maximum loading, by elemental analysis.     

Polypyrrole Hollow Nanotubes Loaded with Au and Fe3O4 Nanoparticles for Simultaneous Determination of Ascorbic Acid,Dopamine, and Uric Acid

An ultrasensitive electrochemical biosensor was fabricated for electroanalytical determination of ascorbic acid(AA), dopamine(DA) and uric acid(UA) individually and simultaneously based on polypyrrole hollow nanotubes loaded with Au and Fe₃O₄ nanoparticles(NPs) uniformly(PPy@Au-Fe₃O₄). The PPy@Au-Fe₃O₄ nanotubes were synthesized in one-pot using MoO₃ nanorods as templates and the polymerization of Py, the formation of Au and Fe₃O₄ NPs and the removel of MoO₃ templates took place stimultaneously. Electrochemical studies reveal that PPy@Au-Fe₃O₄modified glassy carbon electrode(GCE) possesses excellent electro-catalytic activities toward the oxidation of AA, DA and UA. Their oxidation peak currents increase linearly in the concentration ranges of 1-2000 μmol/L for AA, 0.01-25 and 25-300 μmol/L for DA and 0.1-300 μmol/L for UA. Their detection limit values(S/N=3) were calculated as 0.45, 0.0049, and 0.051 μmol/L for AA, DA and UA in the individual detection. By changing the concentrations simultaneously, the calibration curves showed linearity to 1000, 200, and 200 μmol/L with detection limit of 0.39, 0.0060, and 0.060 μmol/L for AA, DA, and UA, respectively. Finally, the obtained biosensor was successfully applied to the detection of AA, DA, and UA with satisfactory results on actual samples.     

Electroactive conducting polymers for corrosion control

There is an intensive effort underway to develop new corrosion control coatings for structural metals. In part, this effort has been motivated by the desire to replace chromium(VI)-containing coatings currently used for corrosion control of iron and aluminum alloys. Cr(VI) has been shown to be hazardous to the environmental and to human health, and its use in many countries will be sharply curtailed in the coming years. Electroactive conducting polymers (ECPs) represent a class of interesting materials currently being explored for use in corrosion control coating systems, possibly as a replacement for Cr(VI)-based coatings. The electroactivity and the electronic conductivity (or semiconductivity) of ECPs set them apart from traditional organic coatings. As with chromate, interesting and potentially beneficial interactions of ECPs with active metal alloys such as steel and aluminum are anticipated, with concomitant alteration of their corrosion behavior. A review of this active research area will be presented in two parts. Here in Part 1, a general introduction to the topic of corrosion control by ECPs will be presented, including an overview of corrosion and its control by traditional methods, an introduction to ECPs and their properties, and a discussion of the processing issues surrounding the use of ECPs as coatings. Part 1 also includes a review of the literature on the use of ECPs as coatings (or components of coatings) on non-ferrous active metals, principally aluminum and aluminum alloys, although some work on zinc, copper, silver, titanium and silicon will also be described. In Part 2 of this review (to be published in the next issue of this journal), the rather extensive literature on the use of ECPs for the corrosion control of ferrous alloys (steels) will be reviewed. Electronic Publication     

Electroactive shape memory cyanate/polybutadiene epoxy composites filled with carbon black

Electroactive shape memory composites were synthesized using polybutadiene epoxy(PBEP) and bisphenol A type cyanate ester(BACE) filled with different contents of carbon black(CB). Dynamic mechanical analysis(DMA), scanning electron microscopy(SEM), electrical performance and electroactive shape memory behavior were systematically investigated. It is found that the volume resistivity decreased due to excellent electrical conductivity of CB, in turn resulting in good electroactive shape memory properties. The content of CB and applied voltage had significant influence on electroactive shape memory effect of developed BACE/PBEP/CB composites. Shape recovery can be observed within a few seconds with the CB content of 5 wt% and voltage of 60 V. Shape recovery time decreased with increasing content of CB and voltage. The infrared thermometer revealed that the temperature rises above the glass transition temperature faster with the increase of voltage and the decrease of resistance.     

meso-Dithiole and tetrathiafulvalene dipyrromethanes a route to metal dithiole-dipyrrin complexes and to fluorescent tetrathiafulvalene-BODIPY

A series of meso-dithiole and tetrathiafulvalene (TTF) dipyrromethanes have been prepared via the reaction of the appropriate aldehyde with either pyrrole or 3-ethyl-2,4-dimethyl-pyrrole under acid catalysis. Oxidation to the corresponding meso-dithiole dipyrrins is reported together with the formation of the metal chelate complexes (M=Zn, Cu, Ni) as well as the meso-dithiole boron-dipyrromethene (BODIPY). The molecular structures of these metal (Cu, Ni) and boron complexes are presented and discussed. According to a similar strategy the meso-TTF BODIPY is prepared and its photophysical properties are presented and compared with those of the meso-dithiole BODIPY.     

Sensitive voltammetric detection of DNA damage at carbon electrodes using DNA repair enzymes and an electroactive osmium marker

This paper presents a new approach to electrochemical sensing of DNA damage, using osmium DNA markers and voltammetric detection at the pyrolytic graphite electrode. The technique is based on enzymatic digestion of DNA with a DNA repair enzyme exonuclease III (exoIII), followed by single-strand (ss) selective DNA modification by a complex of osmium tetroxide with 2,2'-bipyridine. In double-stranded DNA possessing free 3'-ends, the exoIII creates ss regions that can accommodate the electroactive osmium marker. Intensity of the marker signal measured at the pyrolytic graphite electrode responded well to the extent of DNA damage. The technique was successfully applied for the detection of (1) single-strand breaks (ssb) introduced in plasmid DNA by deoxyribonuclease I, and (2) apurinic sites generated in chromosomal calf thymus DNA upon treatment with the alkylating agent dimethyl sulfate. The apurinic sites were converted into the ssb by DNA repair endonuclease activity of the exoIII enzyme. We show that the presented technique is capable of detection of one lesion per approximately 10(5) nucleotides in supercoiled plasmid DNA.     

Transition metal binding properties of the redox-active 1,4,7,10,13,16-hexa(ferrocenylmethyl)-1,4,7,10,13,16-hexaazacyclooctadecane and its electrochemical behaviour in a non-aqueous solvent

Solution studies to elucidate the coordination behaviour and the electrochemical response of the ferrocene-functionalized polyazamacrocycle 1,4,7,10,13,16-hexa(ferrocenylmethyl)-1,4,7,10,13,16-hexaazacyclooctadecane (L¹) by potentiometric methods and electrochemical techniques have been carried out. Potentiometric methods in the presence of Cd²⁺, Hg²⁺, Pb²⁺ and Zn²⁺ were carried out in 1,4-dioxane/water (70:30 v/v, 25°C, 0.1 mol dm⁻³ KNO₃). Electrochemical studies were carried out in acetonitrile/dichloromethane (50:50 v/v, 25°C, 0.1 mol dm⁻³ TBAClO₄) in the presence of transition metal ions and anions.     

主链含偶氮电活性聚酰胺材料的合成与性质

社会的发展和科技的进步不断对材料提出新的要求,功能材料已经成为新的研究热点,因此设计和研究高分子材料的多功能一体化具有重要的科学和现实意义。作为功能高分子材料的一种,聚苯胺因具有原料廉价、制备简便、环境稳定性好等一系列优点,以及特殊的光学、电学、磁学性质等而成为最具应用潜力的导电高分子材料[1-4]。然而聚苯胺结构上的缺陷和不溶不熔的现象,阻碍了人们对聚苯胺的微观研究和加工应用[5,6]。苯胺齐聚物具有明确的分子结构和良好的溶解性,同时光学和电学性质与聚苯胺十分相似[7,8],基本具备了成为聚苯胺替代者的条件,仅由于缺乏良好的机械性能和环境稳定性而发展受到限制。因此我们从分子设计入手,采用氧化偶联聚合方法,将苯胺齐聚物链段和具有光致异构特性的偶氮苯基团同时引入到具有良好综合性能的聚酰胺主链中,制备出一种兼具光活性和电活性的多功能聚合物材料。