光激发四苯基卟啉钴氧化还原反应机理研究

金属卟啉在光激发条件下会呈现出重要催化特性和光学性质。四苯基卟啉亚钴(Co~Ⅱ TPP)性质稳定,难以通过强氧化剂氧化至四苯基卟啉钴(Co~ⅢTPP)。本文分别利用全波长氙灯与355nm激光脉冲诱导Co~Ⅱ TPP,探究其分子内的氧化还原过程。研究发现,Co~Ⅱ TPP的Soret带最大吸收峰随光照时长的递增出现红移,且吸收强度呈现先下降后上升的趋势,最大吸收峰位置由415nm逐渐红移至433nm,其Q带最大吸收峰位置由532nm逐渐红移至545nm。两种光源诱导Co~Ⅱ TPP均出现稳态吸光度的降低,分子内的活性中心钴离子由Co~(2+)氧化到Co~(3+)。咪唑使得Co~Ⅱ TPP受光诱导后更易出现稳态吸收峰红移。Co~Ⅱ TPP的瞬态吸收光谱有3个瞬态吸收峰,激光激发含咪唑的Co~Ⅱ TPP溶液仅在396nm出现单个瞬态吸收峰。数据表明光激发时,电子从卟啉的π成键分子轨道向具有配体特征的π~*反键分子轨道迁移,发生金属对配体的电荷迁移,生成稳定的高价态Co~Ⅲ。     

Stereospecific Redox Reaction Directed by a Sulfinyl Group

Stereochemistry of reductions of a pyridinium and quinoliniums with an asymmetric sulfinyl group has been studied. Dithionite and borohydride prefer the face characterized by a lone pair on sulfur atom. Dihydropyridine prefers the face characterized by a S-O bond.     

Redox Tuning of a Direct Asymmetric Aldol Reaction

Presented herein is a redox tuning strategy for asymmetric aminocatalysis with a designed chiral ferrocenophane. Under redox control, the ferrocenophane catalyst efficiently catalyzes the asymmetric aldol reaction at room temperature with excellent yield and good stereoselectivity. Moreover, the redox‐active ferrocene moiety also served as phase‐tag to facilitate catalyst recovery and reuse. The catalyst can be reused for five cycles without much loss of activity. Ferrocenium of the oxidized ferrocenophane was proposed to serve as Lewis acidic site, thus accounting for the stereo control.     

室温氧化还原反应制备AgCuSe三元纳米棒

AgCuSe nanorods were prepared at room temperature by a redox reaction. The as-prepared product was characterized by X-ray powder diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy.X-ray powder diffraction shows that the as-prepared product is the tetragonal phase of AgCuSe. Transmission electron microscopy shows that the sample consists of nanorods with a diameter varying from 5 nm to 20 nm and a length varying from 200 nm to 600 nm. X-ray photoelectron spectroscopy shows that the purity of the sample is high. The formation mechanism of AgCuSe and the growth mechanism of AgCuSe nanorods were discussed.Thermodynamic calulations show that the final product in the synthetic system is pure AgCuSe. The solvent ethylenediamine did not only acts a didentate ligand to form relatively state Ag + and Cu + complexes, but also dissolved Se and enhanced the reactivity of Se. It played an important role in controlling the nucleation and growth of AgCuSe nanorods.     

Redox Reaction of Disulfide/Polyaniline in Aqueous Solution

Introductionlthasbeensh0wnthat0rganodisulfidesIikeDMcTc0uldbep0lymerizedanddepolymerizedreversibly,correspondingtotheirchemical0reIectr0chemicaloxidati0nandreductionreactions.Thisisduetothereversibletbrmationandscissi0nofthedisulfidebond,atw0-electr0ntransferpr0cess(Schemel).LithiumsecondarybatterieswithatheoreticalenergydensityoflO7OWhjkgwereset-upusingtheabovedisulfidecompoundasthean0dicmaterial.H0wever,theredoxreacti0n0fdisulfidewasveryslowatr0omtemperature,thus,thechargeanddischargepro…     

An Unexpected Redox Reaction between Tris(Z-phenylethenyl)phosphine and 4-Hydroxy-4-methyl-2-pentynonitrile

Russian Journal of General Chemistry -     

Disulfide Bond Cleavage: A Redox Reaction Without Electron Transfer

By using Car–Parrinello molecular dynamics (CPMD) simulations we have simulated a mechanically induced redox reaction. Previous single‐molecule atomic force microscopy (AFM) experiments demonstrated that the reduction of disulfide bonds in proteins with the weak reducing agent dithiothreitol depends on a mechanical destabilization of the breaking bond. With reactive molecular dynamics simulations the single steps of the reaction mechanism can be elucidated and the motion of the electrons can be monitored. The simulations show that the redox reaction consists of the heterolytic cleavage of the S? S bond followed by a sequence of proton transfers.     

A New Redox Reaction of Ascorbic Acid at Platinum Electrodes

A pair of new redox peaks of ascorbic acid at a platinum electrode was found and studied in detailed by spectroelectrochemistry and electrochemistry technologies. This is a quasi‐reversible redox reaction with a one‐electron transfer process. The intermediate of tertiary carbon free radical exists in this process. The appearance reaction rate constant and the diffusion coefficient were investigated. A possible reaction mechanism has been proposed.     

Catalytic Electrophilic Alkylation of p-Quinones through a Redox Chain Reaction

Allylation and benzylation of p-quinones was achieved through an unusual redox chain reaction. Mechanistic studies suggest that the existence of trace hydroquinone initiates a redox chain reaction that consists of a Lewis acid catalyzed Friedel–Crafts alkylation and a subsequent redox equilibrium that regenerates hydroquinone. The electrophiles could be various allylic and benzylic esters. The addition of Hantzsch ester as an initiator improves the efficiency of the reaction.     

基于氧化还原反应的配位平衡移动总反应平衡常数的推导

配位平衡的移动,可以遵从相同的“推导总反应的平衡常数”模式来做定性和定量的探讨。但在“氧化还原反应对配位平衡的影响”中,只是对化学反应做定性描述,总反应的平衡常数并没有推导,缺乏定量的探讨。原因在于氧化还原平衡常数与其他3大平衡常数不同,无法直接查得,需借助公式算出,具有隐蔽性,给总反应的推导造成了障碍。本文通过总反应平衡常数的推导解决了这个问题。     

光电子调控的聚苯胺氧化还原反应用于铜离子可视化检测

构建了由中间价态聚苯胺(ES-PANI)和二氧化钛(TiO2)纳米粒子组成的光致变色检测平台,用于痕量铜可视化检测.在紫外光激发下,ES-PANI(墨绿色)会被TiO2产生光生空穴氧化为完全氧化态聚苯胺(深蓝色);随着Cu2+的加入,ES-PANI生成还原态聚苯胺(浅黄色),导致一系列可由肉眼观测到的颜色变化.光致变色过程中的颜色转变取决于Cu2+调控的不同价态聚苯胺.本方法结合了光电化学和可视化检测的优点,在Cu2+的检测中表现出了高选择性和灵敏度,检出限为0.4μmol/L.采用Photoshop软件读取绿通道平均强度值和用酶标仪记录紫外吸收值,发展了另外两种定量检测方法.此外,将本方法用于人类头发实际样品中Cu2+的定量检测,回收率令人满意.所建立的检测平台简单、成本低廉,无需复杂的仪器即可在几分钟内同时检测多种样品.这种光电子调控的比色策略为设计新型比色检测平台提供了新思路,并且可望应用于临床快速诊断便携试剂盒的开发.     

美国高中化学教科书中氧化还原反应图片设计分析

统计了美国高中化学教科书《化学：概念与应用》中氧化还原反应的知识内容所包含的图片类型，分析研究其作用，同时针对我国化学教科书图片设计提出了建议。     

Redox Polymerization of Acrylonitrile: Kinetics of the Reaction Initiated by the Redox System 1-Propanol—Chromic Acid

The kinetics of the aqueous polymerization of acrylonitrile initiated by the chromic acid-1-propanol redox system was investigated under a nitrogen atmosphere. The rates of polymerization and the disappearance of Cr(VI) were measured. Chromic acid alone did not initiate the polymerization under deaerated and undeaerated conditions. Water-miscible organic solvents and neutral salts depress both the rate and the conversion. On the basis of the experimental observations of the dependence of the rate of polymerization R_p and the rate of disappearance of Cr(VI)-R_m on various variables, a suitable kinetic scheme was proposed and various rate and energy parameters evaluated.     

Reaction of Hydroxyurea with Iron(III): Products and the Stoichiometry of the Redox Reaction

Products and reaction stoichiometry of the interaction between iron(III) and hydroxyurea (HU) in aqueous solutions were studied. Under condition of an excess of iron(III) over hydroxyurea, initially formed mono(hydroxyureato)iron(III) complex decomposed through redox processes, forming two moles of Fe^II, one mole of NH₄⁺, one mole of CO₂, and 0.5 mole of N₂O per 1 mole of initially present HU. Hydroxyurea radical, H₂N‐CO‐NHO^?, was detected in the course of the reaction. The possible mechanism of the formation of the products is discussed and compared with that obtained for horseradish peroxidase mediated oxidation of hydroxyurea with hydrogen peroxide. The possibility of direct reaction of hydroxyurea with the iron center of protein R2 of the ribonucleotide reductase is proposed. The reaction examined may serve as a simple model for testing the suggested hydroxyurea like activity for chemical substances.     

Catalytic Electrophilic Alkylation of p‐Quinones through a Redox Chain Reaction

Allylation and benzylation of p ‐quinones was achieved through an unusual redox chain reaction. Mechanistic studies suggest that the existence of trace hydroquinone initiates a redox chain reaction that consists of a Lewis acid catalyzed Friedel–Crafts alkylation and a subsequent redox equilibrium that regenerates hydroquinone. The electrophiles could be various allylic and benzylic esters. The addition of Hantzsch ester as an initiator improves the efficiency of the reaction.     

氧化还原反应的知识发展、教材编排与学生学习的融合

论述了氧化还原反应的知识发展顺序、教材编排顺序、学生学习顺序，并据此结合知识类型与认识兴趣理论，就教学中如何将“三序”融合安排提出建议。     

氧化还原反应相关概念学习困难诊断与教学建议

采用测验、访谈等实证研究方法,对高一新生学习氧化还原反应的困难进行诊断分析,发现学生对化合价认识不足,缺少从微观层面来理解氧化还原反应相关概念。在学习困难分析的基础上设计教学,进行课堂实践研究。     

The First Heterotriquinone and Dicyanoheterotriquinone Methide That Undergo a Five-Stage Amphoteric Redox Reaction

The dicyanomethylene group and not the quinone oxygen atoms is the site of the first one-electron reduction for the dicyanohetereotriquinone methide 1 , although the dicyanomethylene group is substituted at a cyclopentadienyl-like five-membered ring! Compound 1 is amphoteric and undergoes a five-stage sequence of one-electron redox reactions.