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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Excited-State Proton Transfer and Proton Reactions of 6-Hydroxyquinoline and 7-Hydroxyquinoline in Water and Ice
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Excited-State Proton Transfer and Proton Reactions of 6-Hydroxyquinoline and 7-Hydroxyquinoline in Water and Ice

机译：水和冰中6-羟基喹啉和7-羟基喹啉的激发态质子转移和质子反应

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摘要

Time-resolved and steady-state emission spectroscopies as well as absorption UV-vis spectroscopy were employed to study the photoprotolytic cycle and other protic processes of the bifunctional 6-hydroxy- and 7-hydroxyqunoline molecules in methanol-doped ice over a wide range of temperatures. In ice at high temperatures of T > 173 K, the excited-state proton transfer rate decreases as the temperature decreases. The emission band of the H~+NRO~-* zwitterion, where the imine nitrogen is protonated and the hydroxyl is deprotonated, is observed. At T > 173 K, the formation rate of the H~+NRO~-* emission band is approximately that of the decay rate of the neutral form, NROH*. Below 173 K, the rate of the photoprotolytic process is much slower than the radiative and the nonradiative rates, and the excited-state proton transfer could not be clearly observed. Addition of a small concentration of acetic acid increases the proton transfer rate significantly at temperatures below 235 K. The reaction rate in the presence of acetic acid is temperature-independent over a wide range of temperatures (80-235 K). We propose as an explanation for this observation that there exists a direct proton transfer from the hydroxyl group to water-acetic acid complexes at temperatures below 235 K.
机译：时间分辨和稳态发射光谱以及吸收紫外可见光谱被用于研究甲醇掺杂冰中双功能6-羟基和7-羟基喹啉分子的光蛋白水解循环和其他质子过程。温度。在T> 173 K的高温冰中，激发态质子转移速率随温度降低而降低。观察到H〜+ NRO〜-*两性离子的发射带，其中亚胺氮被质子化，羟基被去质子化。在T> 173 K时，H〜+ NRO〜-*发射带的形成速率近似于中性形式NROH *的衰减速率。低于173 K，光蛋白水解过程的速率比辐射速率和非辐射速率要慢得多，并且不能清楚地观察到激发态质子转移。在低于235 K的温度下，添加低浓度的乙酸会显着提高质子转移速率。在存在乙酸的情况下，反应速率在很宽的温度范围（80-235 K）中与温度无关。我们建议对此现象进行解释，说明在低于235 K的温度下，质子会直接从羟基转移至水-乙酸络合物。

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