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61.
Andrew C. Benniston Anthony Harriman Peiyi Li James P. Rostron 《Tetrahedron letters》2005,46(43):7291-7293
The synthesis is described of two N,N′-dimethyl-4,4′-bipyridinium salts for which the two pyridinium rings are connected via varying length alkoxy chains attached at the 3,3′-locations. 相似文献
62.
Direct electrochemical and electrocatalytic behavior of hemoglobin (Hb) immobilized on glass carbon electrode (GCE) containing gelatine (Gel) films was investigated. The characteristics of Hb/Gel film modified GC electrode were performed by using SEM microscopy, UV-vis spectroscopy and electrochemical methods. The immobilized Hb showed a couple of quasi-reversible redox peak with a formal potential of −0.38 V (versus SCE) in 0.1 M pH 7.0 PBS. The formal potential changed linearly from pH 4.03 to 8.41 with a slope value of −52.0 mV pH−1, which suggested that a proton transfer was accompanied with each electron transfer (ET) in the electrochemical reaction. The Hb/gelatine/GCE displayed a rapid amperometric response to the reduction of H2O2 and nitrite. 相似文献
63.
A new series of group 6 carbonyl complexes of N-[(2-pyridyl)methyliden]-α (or β)-aminonaphthalene (α/β-NaiPy) are described in this work. The complexes are formulated as cis-[M(CO)4(α/β-NaiPy)] by elemental, mass and other spectroscopic data. The complexes show emission spectra at room temperature and their quantum yield lies between 0.4 and 0.5. All the complexes exhibit negative solvatochromism. Cyclic voltammetry shows metal centred oxidation and ligand reductions. 相似文献
64.
Jan S. Jaworski 《Monatshefte für Chemie / Chemical Monthly》1984,115(4):415-418
A two parameter approach to solvent variations in the electroreduction rate constants of cobalt complexes and europium cations is presented and discussed in terms of solvent—solute and solvent—solvent interactions.
Ein Zwei-Parameter Donor-Acceptor-Ansatz für Lösungsmitteleffekte bei der Elektrodenkinetik von Kationen (Kurze Mitteilung)
Zusammenfassung Es wird eine Zwei-Parameter-Annäherung der Lösungsmitteleinflüsse auf die Geschwindigkeitskonstanten der Elektroreduktion von Kobalt-Komplexen und Europium-Kationen präsentiert und auf der Basis von Lösungsmittel—gelöster Stoff- und Lösungsmittel—Lösungsmittel-Wechselwirkung diskutiert.相似文献
65.
Detection of single molecules, particles, and rapid redox events is a challenge of electrochemical investigations and requires either an amplification strategy or significant averaging for the electrochemical current to exceed the noise level. We consider the minimum number of electrons required to reach the limit of quantification in these electrochemical measurements. A survey of the literature indicates that the state-of-the-art limit in current detection for different types of measurements (e.g. voltammetry, single-molecule redox cycling, ion channel recordings of single molecules, metal nanoparticle collision, and phase nucleation) is independent of the nature of the measurement and increases linearly with reciprocal response time, Δt?1, over ~5 orders of magnitude (from ~10 to ~106 s?1). We demonstrate that the practical limit of quantification requires cumulative measurement of ~2100 electrons during Δt and is determined by statistics of counting electrons, that is, the shot noise in the current. 相似文献
66.
67.
A thiophene-functionalised macrocyclic ligand trans-6,13-dimethyl-6-((thiophen-3-ylmethyl)amino)-1,4,8,11-tetraazacyclotetradecane-13-amine (L1) has been prepared and complexed with CoIII. The ligand L1 binds as a pentadentate in the crystallographically characterised complexes [CoL1(OAc)](ClO4)2 and [CoL1Cl]Cl2. Electro-copolymerisation of [CoL1Cl]Cl2 with 3,4-ethylenedioxythiophene (EDOT) in a 1:2 ratio on a preformed poly-3,4-ethylenedioxythiophene (PEDOT) film resulted in metal–polymer hybrid films of high quality, consistency and uniformity in appearance. The copolymerised films were characterised by XPS indicating a 1:11 ratio of incorporation of complex to EDOT. Electrochemistry of the Co-PEDOT film (cast on an indium-doped tin oxide working electrode) in water revealed a CoIII/II redox couple at a potential ca. −600 mV (vs Ag/AgCl) which is similar to that seen in solution for the monomeric aqua complex [CoL1(OH2)]3+. 相似文献
68.
The electrochemistry of 1,1′-bis(diphenylphosphino)ferrocene (dppf) derivatives of Ru3(CO)12 was investigated. Two known compounds [Ru3(CO)8(μ-dppf)2 (1) and Ru3(CO)10dppf (2)] and a new compound [Ru3(CO)11(μ-dppf)Ru3(CO)11 (3)] were prepared. Compound 3 was characterized spectroscopically and an X-ray crystal structure was obtained. The reductive electrochemistry of 1 and 2 showed an irreversible reduction and a follow-up oxidation, similar to Ru3(CO)12. The electrochemistry of compound 3 showed two irreversible waves and a follow-up oxidation. A trend in the reduction potential vs. the number of coordinated phosphorus atoms was noted. The oxidative electrochemistry of 1-3 showed a dppf-based chemically reversible wave, and an irreversible wave similar to that of Ru3(CO)12. Trends were also noted between the oxidation potential and the number of coordinated phosphorus atoms. 相似文献
69.
Electrochemical Oxidation of Quercetin 总被引:1,自引:0,他引:1
《Electroanalysis》2003,15(22):1745-1750
The mechanism of electrochemical oxidation of quercetin on a glassy carbon electrode has been studied using cyclic, differential pulse and square‐wave voltammetry at different pH. It proceeds in a cascade mechanism, related with the two catechol hydroxyl groups and the other three hydroxyl groups which all present electroactivity, and the oxidation is pH dependent. Quercetin also adsorbs strongly on the electrode surface; and the final oxidation product is not electroactive and blocks the electrode surface. The oxidation of the catechol 3′,4′‐dihydroxyl electron‐donating groups, occurs first, at very low positive potentials, and is a two electron two proton reversible reaction. The hydroxyl group oxidized next was shown to undergo an irreversible oxidation reaction, and this hydroxyl group can form a intermolecular hydrogen bond with the neighboring oxygen. The other two hydroxyl groups also have an electron donating effect and their oxidation is reversible. 相似文献
70.
以常见的阴、阳离子的检验为例,研究了如何实施基于标准的教学。校本教材的开发为标准、教材、教学、评价的一致性提供保障;以学生应知的和能做的驱动课堂活动;根据达成标准应有怎样的质量表现,试卷编制先于教学设计。课堂上,“教”“学”双方都明确学习目标,教师提供多种策略来满足学生多样的学习需要,如提供工具,搭建脚手架,并以“微”研究性学习的方式展开教学,给学生提供了充分的进步空间。 相似文献