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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Studies on photoinduced H-atom and electron transfer reactions of o-naphthoquinones by laser flash photolysis
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Studies on photoinduced H-atom and electron transfer reactions of o-naphthoquinones by laser flash photolysis

机译：激光闪光光解法研究邻萘醌的光诱导H原子和电子转移反应

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摘要

The quenching of the triplets of 1,2-naphthoquinone (NQ) and 1,2-naphthoquinone-4-sulfonic acid sodium salt (NQS) by various electron and H-atom donors was investigated by laser flash photolysis measurement in acetonitrile and benzene. The results showed that the reactivities and configurations of (3)NQ*((3)NQS*) are governed by solvent polarity. All the quenching rate constants (k(q)) measured in benzene are larger than those in acetonitrile. The SO3Na substituent at the C-4 position of NQS makes 3NQS* more reactive than 3NQ* in electron/H-atom transfer reactions. Large differences of kq values were discovered in H-atom transfer reactions for alcohols and phenols, which can be explained by different H-abstraction mechanisms. Detection of radical cations of amines/anilines in time-resolved transient absorption spectra confirms an electron transfer mechanism. Triplets are identified as precursors of formed radical anions of NQ and NQS in photoinduced reactions. The dependence of electron transfer rate constants on the free energy changes (Delta G) was treated by using the Rehm-Weller equation. For the four anilines with different substituents on the para or meta position of amidocyanogen, good correlation between log k(q) values with Hammett sigma constants testifies the correctness of empirical Hammett equation. Charge density distributions, adiabatic ionization/affinity potentials and redox potentials of NQ ( NQS) and some quenchers were studied by quantum chemistry calculation.
机译：通过在乙腈和苯中的激光快速光解测量，研究了各种电子和氢原子给体对1,2-萘醌（NQ）和1,2-萘醌-4-磺酸钠（NQS）的三重态的猝灭。结果表明，（3）NQ *（（3）NQS *）的反应性和构型受溶剂极性控制。在苯中测得的所有猝灭速率常数（k（q））都大于在乙腈中的猝灭速率常数。在电子/氢原子转移反应中，NQS的C-4位的SO3Na取代基使3NQS *的反应性高于3NQ *。在醇和酚的H原子转移反应中发现kq值存在较大差异，这可以通过不同的H吸收机理来解释。在时间分辨的瞬态吸收光谱中检测胺/苯胺的自由基阳离子证实了电子转移机理。三重态被确定为在光诱导反应中形成的NQ和NQS自由基阴离子的前体。通过使用Rehm-Weller方程来处理电子传输速率常数对自由能变化（Delta G）的依赖性。对于酰胺基氰的对位或间位上具有不同取代基的四个苯胺，log k（q）值与Hammett sigma常数之间的良好相关性证明了经验Hammett方程的正确性。通过量子化学计算研究了NQ（NQS）和一些猝灭剂的电荷密度分布，绝热电离/亲和势和氧化还原势。

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