The Role of Electron-Donor Substituents in the Family of OPBAN-Cu Water Oxidation Catalysts: Effect on the Degradation Pathways and Efficiency
The Role of Electron-Donor Substituents in the Family of OPBAN-Cu Water Oxidation Catalysts: Effect on the Degradation Pathways and Efficiency
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DOI：
10.1002/ejic.201801534
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发表时间：
2019-04-24
影响因子：
2.3
通讯作者：
Maseras, Feliu
中科院分区：
文献类型：
--
作者：
de Aguirre, Adiran;Garrido-Barros, Pablo;Maseras, Feliu
用密度泛函理论（DFT）研究了OPBAN-Cu（OPBAN = 1，2-亚苯基双（草酰胺酸）的四阴离子衍生物）水氧化催化剂族的效率。我们研究了四种不同的四酰胺铜配合物[（L1 - 4）Cu]（2-）（其中L1是N1、N1 ′-（1，2-亚苯基）双（N2-甲基草酰胺）和L2 - 4是在环骨架中具有供电子基团的相同配体的变体），确定了配体在活化过程中的氧化还原活性特征和单电子转移-水亲核攻击（SET-WNA）O-O键形成步骤的机制。有趣的是，在四个反应中常见的两中心三电子（2c3e（-））中间体的稳定性与实验效率相关。此外，我们还探索了两种催化剂降解途径：羟基阴离子对配体的苯基阳离子自由基的攻击和pH降低时酰胺基的质子化降解。这最后一步得到了循环伏安法pH依赖性实验的支持。
The efficiency of the OPBAN-Cu (OPBAN= tetraanionic derivative of 1,2-phenylene bis(oxamic acid)) water oxidation catalyst family has been studied by DFT calculations. We have explored four different tetraamidate copper complexes [(L1-4)Cu](2-) (where L1 is N1,N1 '-(1,2-phenylene)bis(N2-methyloxalamidate) and L2-4 are variations of the same ligand with electron donating groups in the ring backbone), determining the redox active character of the ligand in the activation process and the Single Electron Transfer-Water Nucleophilic Attack (SET-WNA) mechanism for the O-O bond formation step. Interestingly, the stability of the two-center three-electron (2c3e(-)) intermediate, common in the four reactions, correlates with the experimental efficiency. Additionally, we explored two pathways of catalyst degradation: the attack of a hydroxyl anion to the phenyl cation radical of the ligand and the degradation by protonation of the amidate groups when pH decreases. This last step is supported by cyclic voltammetry pH-dependent experiments.