Solvent effect on the excited-state proton transfer of 7-hydroxyquinoline along a hydrogen-bonded ethanol dimer
Solvent effect on the excited-state proton transfer of 7-hydroxyquinoline along a hydrogen-bonded ethanol dimer
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DOI：
10.1039/c0cp02347g
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发表时间：
2011-01-01
影响因子：
3.3
通讯作者：
Lee, Jin Yong
中科院分区：
文献类型：
--
作者：
Kang, Baotao;Ko, Kyoung Chul;Lee, Jin Yong
采用从头计算方法研究了7-羟基喹啉与乙醇二聚体相互作用的基态和激发态质子转移沿着中溶剂效应对体系结构和势能面的影响。不仅在真空中，而且在正庚烷、乙醇和二甲基亚砜溶剂中，基态质子转移都是被禁止的。在激发态，虽然质子转移在真空中是被禁止的，但由于其大大降低的势垒（类似于10 kcal mol（-1））和高度稳定的产物，在溶剂中是可能的。从计算中还发现，激发态的质子转移势垒随着溶剂的介电常数的增加而减小。我们的计算是一致的实验结果，质子转移不发生在基态和激发态质子转移率增加溶剂极性的增加。我们计算的吸收和发射性质与实验结果非常吻合。投影因子（反映从基态到激发态的几何变化）和重组能量与激发态质子转移的几个低频振动进行了讨论。
We have studied the solvent effect on structures and potential energy surfaces along proton transfer in the ground and the excited states of 7-hydroxyquinoline interacting with an ethanol dimer using ab initio calculations. The proton transfer is forbidden in the ground state not only in vacuum but also in solvents of n-heptane, ethanol, and dimethyl sulfoxide. In the excited state, although the proton transfer is forbidden in vacuum, it is possible in solvent due to its greatly reduced barrier (similar to 10 kcal mol(-1)) and highly stabilized product. It has also been found from the calculations that the proton-transfer barrier in the excited state decreases as the dielectric constant of a solvent increases. Our calculations are consistent with experimental results that the proton transfer does not take place in the ground state and that the excited-state proton-transfer rate increases as the solvent polarity increases. Our calculated absorption and emission properties are in excellent agreement with experimental results. Projection factors (reflecting geometrical change from the ground state to the excited state) and reorganization energies for several low frequency vibrations in connection with the excited-state proton transfer are discussed as well.