Mechanistic Insight into the Reactivities of Aqueous-Phase Singlet Oxygen with Organic Compounds
Mechanistic Insight into the Reactivities of Aqueous-Phase Singlet Oxygen with Organic Compounds
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DOI：
10.1021/acs.est.1c01712
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发表时间：
2021-06-07
影响因子：
11.4
通讯作者：
Minakata, Daisuke
中科院分区：
文献类型：
--
作者：
Barrios, Benjamin;Mohrhardt, Benjamin;Minakata, Daisuke
单线态氧（O-1（2））是一种选择性活性氧，在阳光照射下的水环境、工程水氧化系统、大气水滴和生物医学系统中对各种有机化合物的命运起着关键作用。虽然O-1（2）的初始速率决定电荷转移反应机理和动力学已被广泛研究，但尚未进行全面的研究来阐明具有各种官能团的有机化合物的反应机理。在这项研究中，我们使用密度泛函理论计算来确定各种有机化合物的基元反应机制。将理论计算的单电子转移和O-1（2）加成反应的水相活化自由能与文献中实验测定的速率常数进行比较，以确定线性自由能关系。理论计算的自由能的活化酚盐和苯酚的基团表现出良好的相关性与哈米特常数，通过共振接受电子密度。对各组化合物的主要基元反应机理进行了讨论。作为一个实际的含义，我们证明了在不同的pH值下光化学产生的中间物种诱导的环境相关的有机化合物的命运和评估的影响，预测速率常数的半衰期。
Singlet oxygen (O-1(2)) is a selective reactive oxygen species that plays a key role for the fate of various organic compounds in the aquatic environment under sunlight irradiation, engineered water oxidation systems, atmospheric water droplets, and biomedical systems. While the initial rate-determining charge-transfer reaction mechanisms and kinetics of O-1(2) have been studied extensively, no comprehensive studies have been performed to elucidate the reaction mechanisms with organic compounds that have various functional groups. In this study, we use density functional theory calculations to determine elementary reaction mechanisms with a wide variety of organic compounds. The theoretically calculated aqueous-phase free energies of activation of single electron transfer and O-1(2) addition reactions are compared to the experimentally determined rate constants in the literature to determine linear free-energy relationships. The theoretically calculated free energies of activation for the groups of phenolates and phenols show excellent correlations with the Hammett constants that accept electron densities by through-resonance. The dominant elementary reaction mechanism is discussed for each group of compounds. As a practical implication, we demonstrate the fate of environmentally relevant organic compounds induced by photochemically produced intermediate species at different pH and evaluate the impact of predicting rate constants to the half-life.