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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Ultrafast Excited-State Deprotonation and Electron Transfer in Hydroxyquinoline Derivatives
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Ultrafast Excited-State Deprotonation and Electron Transfer in Hydroxyquinoline Derivatives

机译：羟基喹啉衍生物的超快激发态去质子和电子转移

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摘要

Excited-state proton transfer,electron transfer,and solvent relaxation processes in N-methyl-6-hydroxyquino-linium(NM6HQ~+)and N-methyl-7-hydroxyquinolinium(NM7HQ~+)iodides have been investigated in both acidic and basic solutions.The hydroxyl group behaves like a superacid in the excited state,exhibiting deprotonation times in acidic aqueous solution for NM6HQ~+and NM7HQ~+of 2.0 and 4.5 ps,respectively.These rates for intermolecular proton transfer to water molecules are among the fastest reported to date.This high photoacidity correlates with ultrafast intramolecular electron transfer from the hydroxylate(-O~-)group to the positively charged pyridinium ring,which can be observed in separate measurements in basic solution,where the ground states exist as the deprotonated neutral forms Af-methyl-6-oxyquinolinium(NM6OQ)and N-methyl-7-oxyquinolinium(NM7OQ).The most obvious effect in basic solution is a Stokes shift resulting from solvent relaxation(1.0 ps),driven by the dipole moment change resulting from ultrafast excited-state electron transfer,apparently on the time scale <450 fs.Studies of such coupling between proton transfer and electron transfer offer to provide new insights into the interpretation of other phototautomerization processes.
机译：在酸性和碱性条件下，研究了N-甲基-6-羟基喹啉（NM6HQ〜+）和N-甲基-7-羟基喹啉（NM7HQ〜+）碘化物中的激发态质子转移，电子转移和溶剂弛豫过程。羟基在激发态下表现得像超酸，在NM6HQ〜+和NM7HQ〜+的酸性水溶液中的质子化时间分别为2.0和4.5 ps。这些分子间质子转移到水分子的速率是最快的这种高的光酸度与分子内电子从羟基（-O〜-）基团向带正电的吡啶鎓环的超快转移有关，这可以在碱性溶液中的单独测量中观察到，其中基态以去质子化的中性存在形成Af-methyl-6-oxyquinolinium（NM6OQ）和N-methyl-7-oxyquinolinium（NM7OQ）。在碱性溶液中最明显的作用是由偶极矩cha驱动的溶剂弛豫（1.0 ps）引起的斯托克斯位移超快激发态电子转移产生的nge，显然是在<450 fs的时间尺度上进行的。质子转移与电子转移之间这种耦合的研究为理解其他光互变异构过程提供了新的见识。

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