Photophysical Model of 10-Hydroxybenzo[h]quinoline: Internal Conversion and Excited State Intramolecular Proton Transfer
作者:Junghwa Lee、Taiha Joo
DOI:10.5012/bkcs.2014.35.3.881
日期:2014.3.20
Photophysics of 10-hydroxybenzo[h]quinoline (HBQ) has been in controversy, in particular, on the nature of the electronic states before and after the excited state intramolecular proton transfer (ESIPT), even though the dynamics and mechanism of the ESIPT have been well established. We report highly time resolved fluorescence spectra over the full emission frequency regions of the enol and keto isomers and the anisotropy in time domain to determine the accurate rates of the population decay, spectral relaxation and anisotropy decay of the keto isomer. We have shown that the ~300 fs component observed frequently in ESIPT dynamics arises from the $S_2\rightarrow}S_1$ internal conversion in the reaction product keto isomer and that the ESIPT occurs from the enol isomer in $S_1$ state to the keto isomer in $S_2$ state.
10-羟基苯并[h]喹啉(HBQ)的光物理特性一直存在争议,特别是关于分子内质子转移(ESIPT)激发态之前和之后的电子态性质,尽管ESIPT的动力学和机理已经得到充分证实。我们报告了烯醇和酮异构体全发射频率区域的高度时间分辨荧光光谱以及时域各向异性,以确定酮异构体的精确衰减率、光谱弛豫和各向异性衰减。我们已经证明,在ESIPT动力学中经常观察到的约300飞秒的成分来自反应产物酮异构体的$S_2\rightarrow}S_1$内部转换,并且ESIPT发生在烯醇异构体从$S_1$状态到酮异构体从$S_2$状态。