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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Temperature dependence of the excited-state proton-transfer reaction of quinone-cyanine-7
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Temperature dependence of the excited-state proton-transfer reaction of quinone-cyanine-7

机译：醌-花菁7的激发态质子转移反应的温度依赖性

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摘要

Steady-state and time-resolved fluorescence techniques were used to study the temperature dependence of the photoprotolytic process of quinone-cyanine-7 (QCy7), a very strong photoacid, in H_2O and D_2O ice, over a wide temperature range, 85-270 K. We found that the excited-state proton-transfer (ESPT) rate to the solvent decreases as the temperature is lowered with a very low activation energy of 10.5 ± 1 kJ/mol. The low activation energy is in accord with free-energy-correlation theories that predict correlation between ΔG of reaction and the activation energy. At very low temperatures (T < 150 K), we find that the emission band of the RO-, the deprotonated form of QCy7, is blue-shifted by ～1000 cm~(-1). We attributed this band to the RO -···H_3O~+ ion pair that was suggested to be an intermediate in the photoprotolytic process but has not yet been identified spectroscopically.
机译：稳态和时间分辨荧光技术用于研究H_2O和D_2O冰中的强酸光子醌-菁7（QCy7）的光解过程在85-270的宽温度范围内的温度依赖性K.我们发现，随着温度的降低，以10.5±1 kJ / mol的极低活化能，对溶剂的激发态质子转移（ESPT）速率降低。低活化能与预测反应的ΔG与活化能之间的相关性的自由能相关理论相符。在非常低的温度（T <150 K）下，我们发现RO-的发射带（QCy7的去质子化形式）蓝移了约1000 cm〜（-1）。我们将此谱带归因于RO-···H_3O〜+离子对，该离子对被认为是光蛋白水解过程的中间产物，但尚未通过光谱鉴定。

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