Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India.
Department of Chemistry, Acharya Institute of Technology, Soldevanahalli, Bangalore 560107, India.
Anal Chem. 2020 Mar 17;92(6):4541-4547. doi: 10.1021/acs.analchem.9b05753. Epub 2020 Feb 27.
We report the independent role of isomerism of secondary sphere substituents over their nature, a factor often overlooked in molecular electrocatalysis pertaining to electrochemical sensing, by establishing that isomerism redefines the electronic structure at the catalytic reaction center via geometrical factors. UV-vis spectroscopy and X-ray photoelectron spectroscopy suggest that a substituent's isomerism in molecular catalysts conjoins molecular planarity and catalytic activation through competing field effects and resonance effects. As a classical example, we demonstrate the influence of isomerism of the -NO substituents for the electrocatalytic multi electron oxidation of As(III), a potentially important electrochemical pathway for water remediation and arsenic detection. The isomerism dependent oxidative activation of catalytic center leads to a nonprecious molecular catalyst capable for direct As(III) oxidation with an experimental detection limit close to WHO guidelines. This work opens up an unusual approach in analytical chemistry for developing various sensing platforms for challenging chemical and electrochemical reactions.
我们报告了二级球取代基的立体异构性相对于其性质的独立作用，这是分子电催化中电化学传感中经常被忽视的一个因素，通过确立立体异构性通过几何因素重新定义催化反应中心的电子结构。紫外可见光谱和 X 射线光电子能谱表明，分子催化剂中取代基的异构性通过竞争场效应和共振效应将分子平面性和催化活性结合在一起。作为一个经典的例子，我们展示了 -NO 取代基的异构性对 As(III)的电催化多电子氧化的影响，这是水修复和砷检测的一种潜在重要电化学途径。催化中心的异构依赖性氧化活化导致非贵金属分子催化剂能够直接氧化 As(III)，实验检测限接近世界卫生组织的指导方针。这项工作为开发用于挑战性化学和电化学反应的各种传感平台开辟了分析化学中的一种不寻常方法。
