Analytical and Mechanistic Studies in Electrochemistry

电化学分析和机理研究

• 批准号: 0948606
• 负责人: Dennis Evans
• 金额: $ 32.13万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0948606&HistoricalAwards=false
• 关键词: Analytical; Mechanistic; Studies; Electrochemistry

In this research supported by the Analytical and Surface Chemistry Program, Professor Dennis Evans and his group will examine intermolecular interactions and intra-molecular structural reorganization of molecules as they undergo oxidation and reduction. Weak product association effects on voltammetric signals will be examined in benzidine and biphenylene based systems using digital simulation methods and product dimerization constants obtained from independent spectroscopic experiments. This work may lead to unprecedented fast electrochemical detection of weak product associations in chemical species that are not amenable to spectroscopic analysis because of their unstable nature. Exploration will continue on potential inversion, the phenomenon where the insertion or removal of the second electron in a two electron process occurs more easily than does removal of the first electron. This work will focus on a series of dianisidine and bi-aryl compounds which undergo varying degrees of internal structural reorganization upon the first electron transfer event. This study should reveal the extent of structural change that is necessary for potential inversion. Electrochemical results will be compared with homogenous disproportionation equilibrium constants obtained via electron paramagnetic resonance (EPR). Independent determination of the inner (internal) reorganization energies of electroactive molecules will be done using photoelectron spectroscopy (PES). This study will include some species which exhibit potential inversion. The Evans group will collaborate with Professor Lai-Sheng Wang of Washington State University and the Pacific Northwest National Laboratory to determine inner reorganization energies of anion species using PES and electrospray ionization. Reactions that involve concerted electron and proton transfer (CEPT) will be of special interest. Requirements for the CEPT mechanism including kinetic barriers and the acid-base properties of reactants and products will be investigated. Experimental studies will be complimented with density functional theory calculations (DFT/COSMO) of pKa-values, which take into account solvent dielectric screening effects. This research will develop fundamental understanding of multi-electron-transfer reactions. Modern electrochemical methodology will be employed. Outcomes will be highly relevant to a wide range of areas. Processes that affect biological systems, energy production, and synthesis of high value chemicals are a few examples.

在这项由分析和表面化学计划支持的研究中，丹尼斯·埃文斯教授和他的团队将研究分子间的相互作用和分子内的结构重组，因为它们经历氧化和还原。弱产品协会伏安信号的影响将研究联苯胺和联苯系统使用数字模拟方法和产品二聚常数从独立的光谱实验。这项工作可能会导致前所未有的快速电化学检测弱产品协会的化学物种，不服从光谱分析，因为他们的不稳定性。探索将继续对潜在的反转，在两个电子的过程中，插入或删除的第二个电子的现象发生更容易比删除的第一electron. This工作将集中在一系列的联茴香胺和联芳基化合物进行不同程度的内部结构重组后的第一个电子转移事件。 这项研究应该揭示潜在反转所必需的结构变化的程度。将电化学结果与通过电子顺磁共振（EPR）获得的均相反硝化平衡常数进行比较。将使用光电子能谱（PES）独立测定电活性分子的内（内部）重组能。这项研究将包括一些物种，表现出潜在的反转。埃文斯小组将与华盛顿州立大学和太平洋西北国家实验室的王来胜教授合作，利用PES和电喷雾电离确定阴离子物种的内部重组能。 涉及协同电子和质子转移（CEPT）的反应将特别感兴趣。将研究CEPT机理的要求，包括动力学障碍和反应物和产物的酸碱性质。实验研究将补充密度泛函理论计算（DFT/COSMO）的pKa值，其中考虑到溶剂介电屏蔽效应。这项研究将发展多电子转移反应的基本理解。将采用现代电化学方法。成果将与广泛的领域高度相关。影响生物系统、能源生产和高价值化学品合成的过程就是几个例子。