Coupled electron-proton transfer in interactions of triplet C60 with hydrogen-bonded phenols:: Effects of solvation, deuteration, and redox potentials
Coupled electron-proton transfer in interactions of triplet C60 with hydrogen-bonded phenols:: Effects of solvation, deuteration, and redox potentials
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DOI：
10.1021/ja9727528
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发表时间：
1997-12-24
影响因子：
15
通讯作者：
Linschitz, H
中科院分区：
文献类型：
--
作者：
Biczók, L;Gupta, N;Linschitz, H
吡啶的加入大大增强了苯酚对三价化合物C-60的猝灭作用，并降低了苯酚的伏安氧化电位。闪蒸光解反应表明，该猝灭反应的产物为C-60。-)阴离子自由基，中性苯氧基（或萘氧基）自由基和质子化吡啶。通过二级动力学分析，得到了氢键苯酚-吡啶对的猝灭速率常数和生成常数。后者与从广泛的酚类、吡啶类和溶剂的吸收光谱中得到的结果一致。观察到明显的氘同位素动力学效应，表明质子转移和氢键对提高反应速率都很重要。猝灭速率和自由基产率随溶剂极性的增加而增加。这一猝灭过程涉及到C-3（60）与苯酚-吡啶配合物的相互作用，其中苯酚向C-3（60）的电子转移与苯酚向氢键吡啶的质子转移是一致的。
The quenching of tripler C-60 by phenols is greatly enhanced by addition of pyridines, which also lower the phenol voltammetric oxidation potentials. Flash photolysis shows that the products of this quenching reaction are the C-60(.-) anion radical, neutral phenoxy (or naphthoxy) radicals, and protonated pyridines. Analysis of the second-order kinetics gives quenching rate constants and values of formation constants of hydrogen-bonded phenol-pyridine pairs. The latter agree with those derived from absorption spectra over a wide range of phenols, pyridines, and solvents. Significant deuterium kinetic isotope effects are observed, indicating the importance of both proton transfer and hydrogen bonding in enhancing the rate. Quenching rates and radical yields both increase with solvent polarity. It is concluded that this quenching process involves interaction between C-3(60) and a hydrogen-bonded phenol-pyridine complex, in which electron transfer from the phenol to C-3(60) is concerted with proton transfer from phenol to hydrogen-bonded pyridine.