Oligo(ethylene glycol)-Spacered Siloxane Redox Polymers: Highly Diffusive Media for Electrochemical Redox Catalysis
Oligo(ethylene glycol)-Spacered Siloxane Redox Polymers: Highly Diffusive Media for Electrochemical Redox Catalysis
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低聚（乙二醇）间隔硅氧烷氧化还原聚合物：用于电化学氧化还原催化的高扩散介质
DOI：
10.1021/ja00108a006
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发表时间：
1995
影响因子：
15
通讯作者：
H. Bachmann
中科院分区：
文献类型：
--
作者：
A. Merz;H. Bachmann
氧化还原改性的低聚硅氧烷由Si 60低聚（氢硅氧烷）和3-羧基-2，2，5，5-四甲基-Δ 3-吡咯啉-1-氧基（PROXYL-COOH）的烯丙基封端的低聚（乙二醇）（OEG）酯制备。用旋涂法制备了膜厚为10 nm ~ 15 μ m的改性硅氧烷膜修饰玻碳圆盘电极，并在乙腈和水中用循环伏安法、计时电流法和旋转圆盘伏安法进行了分析。由于OEG含量，硅氧烷基质提供了相对于氧化还原中心和溶质物质的迁移率的高扩散率。在旋涂玻碳圆盘电极上，以二甲基吡啶为碱，乙腈为溶剂，在pH= 7的缓冲水溶液中，用循环伏安法研究了PROXYL介导的对甲氧基苯甲醇（PMBOH）氧化为茴香醛的催化反应.在后一种介质中，催化效率高10倍。在控制电位微电解中，电流密度高达15 mA/cm* 12，催化剂周转率高达30 000次。0.1 mmol/cm 2底物转化率。膜性能的关键因素是厚度和均匀性，这仍然是很难控制在较大面积的碳毡电极。氧化还原修饰电极的设计和应用1已经迅速发展以来的第一次报告的分子共价键合到电极表面2和聚合物修饰电极。3单层电极涂层可通过表面衍生化2或最近通过直接吸附自组装获得。含有氧化还原中心的聚合物膜可以通过从预先形成的聚合物溶液到电极表面的膜浇铸，或者通过从单体直接电化学引发的聚合而附着到表面。11
Redox-modified oligosiloxanes were prepared from an Si6o oligo (hydrogen siloxane) and allyl-terminated oligo (ethyleneglycol)(OEG) esters of 3-carboxy-2, 2, 5, 5-tetramethyl-A3-pyrroline-l-oxyl (PROXYL-COOH). Glassy carbon disk electrodes coated with the modified siloxane films were obtained by spin coating with film thicknesses between 10 nm and 15 fim and analyzedby cyclic voltammetry, chronoamperometry, and rotating disk voltammetry in acetonitrile and water. Due to the OEG content, the siloxane matrix offers a high diffusivity with respect to the mobility of redox centers and solute species. The PROXYL-mediated catalysis of the oxidation of 4-methoxybenzyl alcohol (PMBOH) to anisaldehyde was studied at spin-coated glassy carbon disk electrodes by cyclic voltammetry in acetonitrile with lutidine as a base and in buffered aqueous solution at pH= 7. The catalytic efficiency is 10-fold higher in the latter medium. In controlled potential microelectrolyses, current densities up to 15 mA/cm* 12 and catalyst turnovers up to 30 000 were determined at ca. 0.1 mmol/cm2 substrate conversion. Crucial factors of film performance are thickness and homogeneity, which are still difficult to control at larger area carbon felt electrodes.The design and application of redox-modified electrodes1 have been rapidly developingsince the first reports of molecules covalently bound to electrode surfaces2 and of polymer-modified electrodes. 3 Monolayered electrode coatings are available by surface derivatization2 or, more recently, by direct adsorptive self-assembly. lc Polymers films containing redox centers can be attached to surfacesby film casting from solutions of preformed polymers to the electrode surface or, alternatively, by direct electrochemically initiated polymerization from the monomers. 11