Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education, Department of Chemistry, Beijing Normal University, Xin-wai-da-jie No. 19, Beijing, 100875, China.
Phys Chem Chem Phys. 2014 Mar 7;16(9):4242-50. doi: 10.1039/c3cp54462a.
A combined approach of the multiconfigurational perturbation theory with the Rice-Ramsperger-Kassel-Marcus methodology has been employed to calculate the minimum potential energy profiles and the rates of excited state intra-molecular proton transfer (ESIPT) for the WOLED material molecule of HBFO and its four meta- or para-substituted compounds in gas phase, acetonitrile and cyclohexane solvents. The kinetic control for these reactions is quantitatively determined and extensively studied on the basis of the accurate potential energy surfaces when the thermodynamic factor associated with the free energy change becomes negligible in the case of the existence of a significant barrier in the ESIPT process. These computational efforts contribute to a deep understanding of the ESIPT mechanism, dual emission characteristics, kinetic controlling factor, substituent and solvent effects for these material molecules. The white light emission is generated by the establishment of dynamic equilibrium between enol and keto forms in the charge transfer excited SCT((1)ππ*) state. The performance of white light emission is quantitatively demonstrated to be mainly sensitive to the molecular tailoring approach of the electronic properties of meta- or para- substituents by the modulation of the forward/backward ESIPT rate ratio. The quality of white light emission is slightly tunable through its surrounding solvent environment. These computational results will provide a useful strategy for the molecular design of OLED and WOLED materials.
采用多组态微扰理论与 Rice-Ramsperger-Kassel-Marcus 方法相结合，对气相、乙腈和环己烷溶剂中 HBFO 及其四个间位或对位取代化合物的 WOLED 材料分子的最低势能曲线和激发态分子内质子转移（ESIPT）速率进行了计算。在 ESIPT 过程中存在显著势垒的情况下，当与自由能变化相关的热力学因子变得可以忽略不计时，基于准确的势能面，对这些反应的动力学控制进行了定量确定和广泛研究。这些计算工作有助于深入了解 ESIPT 机制、双发射特性、动力学控制因素、取代基和溶剂对这些材料分子的影响。白光发射是通过在电荷转移激发 SCT((1)ππ*)态中烯醇和酮式之间的动态平衡来建立的。通过调节正向/反向 ESIPT 速率比来调制间位或对位取代基的电子性质的分子修饰方法，定量证明了白光发射的性能主要对其敏感。通过其周围溶剂环境，可略微调整白光发射的质量。这些计算结果将为 OLED 和 WOLED 材料的分子设计提供有用的策略。
