Electrochemical quartz crystal microbalance study of covalent tethering of carboxylated thiol to polyaniline for electrocatalyzed oxidation of ascorbic acid in neutral aqueous solution
Electrochemical quartz crystal microbalance study of covalent tethering of carboxylated thiol to polyaniline for electrocatalyzed oxidation of ascorbic acid in neutral aqueous solution
复制标题
电化学石英晶体微天平研究羧化硫醇与聚苯胺的共价束缚用于中性水溶液中抗坏血酸的电催化氧化
DOI：
10.1039/b906079k
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发表时间：
2009-01-01
影响因子：
3.3
通讯作者：
Yao, Shouzhuo
中科院分区：
文献类型：
--
作者：
Su, Zhaohong;Huang, Jinhua;Yao, Shouzhuo
利用电化学石英晶体微天平（EQCM）研究了两种聚苯胺（PANI）-硫醇复合膜在水溶液中的电合成和电化学性能，这两种复合膜分别是通过硫醇与PANI氧化形式的共价结合（PANI（后）-硫醇，方案A）和苯胺在硫醇存在下的电聚合（PANI（聚）-硫醇，方案B）制备的。涉及的硫醇是巯基琥珀酸（MSA）、巯基乙酸（TGA）和β-巯基乙醇（ME）。使用 EQCM 原位监测 PANI(后)-硫醇结合过程，得到约 1 的摩尔结合比（r，硫醇与聚合物的苯胺单元）。这些硫醇饱和时为 0.50。由羧化硫醇制成的聚苯胺（后）-硫醇和聚苯胺（聚）-硫醇复合膜在中性甚至弱碱性磷酸盐缓冲溶液（PBS）中均表现出可控的聚苯胺部分电活性，其中聚苯胺（后）-MSA 的最大电活性约为 r = 0.11，聚苯胺（后）-TGA 的最大电活性约为 r = 0.21。 PANI-硫醇相互作用也得到了扫描电子显微镜、电化学表面等离子体共振、傅里叶变换红外光谱和紫外-可见光谱实验的支持，并简要讨论了相互作用机制。由羧化硫醇制成的聚苯胺(后)-硫醇和聚苯胺(聚)-硫醇复合膜在pH=7.3的PBS中有效地电催化抗坏血酸的氧化，并且在我们的实验条件下，聚苯胺(后)-硫醇表现出比相关聚苯胺(聚)-硫醇更高的电催化活性。将阴离子硫醇基团共价锚定在聚苯胺主链上以在中性溶液中制备电活性聚苯胺在概念上是新的，并且可以扩展到从许多其他导电聚合物和硫醇开发新的功能材料，广泛应用于催化、生物传感、分子电子学等领域。
The electrochemical quartz crystal microbalance (EQCM) was used to study the electrosyntheses and electrochemical properties of two kinds of polyaniline (PANI)-thiol composite films in aqueous solutions, which were prepared by covalent binding of a thiol to the oxidized forms of PANI (PANI(post)-thiol, protocol A), and electropolymerization of aniline in the presence of a thiol (PANI(poly)-thiol, protocol B), respectively. The thiols involved were mercaptosuccinic acid (MSA), thioglycolic acid (TGA) and beta-mercaptoethanol (ME). The PANI(post)-thiol binding processes were monitored in situ with the EQCM, giving molar binding ratios (r, thiol vs. aniline unit of the polymer) of ca. 0.50 at saturation for these thiols. Both PANI(post)-thiol and PANI(poly)-thiol composite films from the carboxylated thiols showed a controllable electroactivity of the PANI moiety in neutral even weakly alkaline phosphate buffer solutions (PBS), with maximum electroactivity roughly at r = 0.11 for PANI(post)-MSA or at r = 0.21 for PANI(post)-TGA. The PANI-thiol interaction was also supported by experiments of scanning electron microscopy, electrochemical surface plasmon resonance, Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy, and the interaction mechanism is briefly discussed. The PANI(post)-thiol and PANI(poly)-thiol composite films from the carboxylated thiols effectively electrocatalyzed the oxidation of ascorbic acid in pH = 7.3 PBS, and the PANI(post)-thiol exhibited electrocatalytic activity higher than the relevant PANI(p oly)-thiol under our experimental conditions. The covalent anchoring of anionic thiol groups on the PANI backbone to prepare electroactive PANI in neutral solutions is conceptually new and may be extended to the development of new functional materials from many other conducting polymers and thiols for wide applications in catalysis, biosensing, molecular electronics, and so on.