Theoretical investigation on the excited state intramolecular proton transfer in Me2N substituted flavonoid by the time-dependent density functional theory method
Theoretical investigation on the excited state intramolecular proton transfer in Me2N substituted flavonoid by the time-dependent density functional theory method
复制标题
时变密度泛函理论研究Me2N取代黄酮类化合物激发态分子内质子转移
DOI：
10.1088/1674-1056/27/5/058201
复制
发表时间：
2018
影响因子：
1.7
通讯作者：
Shi Ying
中科院分区：
文献类型：
--
作者：
Yin Hang;Shi Ying
采用含时密度泛函理论（TDDFT）方法研究了Me 2N取代类黄酮（MNF）化合物激发态分子内质子转移（ESIPT）过程的细节以及温度对Enol*/Keto* 发射比的影响机制. S 0和S1态的几何结构表示为Enol、Enol* 和Keto*。此外，还计算了吸收峰和荧光峰。计算得到的大斯托克斯位移与实验结果符合得很好。此外，我们的研究结果证实，ESIPT过程发生在光激发，这是明显的监测的红外（IR）光谱的特征峰的形成和消失参与质子转移和势能曲线。最高占据分子轨道（HOMO）和最低未占分子轨道（LUMO）的计算结果表明，质子受体的电负性变化是由于S1态分子内电荷重新分布引起的.此外，对MNF的热力学计算表明，随着温度的升高，Enol*/Keto* 发射比下降，这是由于ESIPT的势垒降低。
Time-dependent density functional theory (TDDFT) method is used to investigate the details of the excited state intramolecular proton transfer (ESIPT) process and the mechanism for temperature effect on the Enol*/Keto* emission ratio for the Me2N-substited flavonoid (MNF) compound. The geometric structures of the S0 and S1 states are denoted as the Enol, Enol*, and Keto*. In addition, the absorption and fluorescence peaks are also calculated. It is noted that the calculated large Stokes shift is in good agreement with the experimental result. Furthermore, our results confirm that the ESIPT process happens upon photoexcitation, which is distinctly monitored by the formation and disappearance of the characteristic peaks of infrared (IR) spectra involved in the proton transfer and in the potential energy curves. Besides, the calculations of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) reveal that the electronegativity change of proton acceptor due to the intramolecular charge redistribution in the S1 state induces the ESIPT. Moreover, the thermodynamic calculation for the MNF shows that the Enol*/Keto* emission ratio decreasing with temperature increasing arises from the barrier lowering of ESIPT.