Toward quantitative prediction of molecular fluorescence quantum efficiency: Role of Duschinsky rotation
Toward quantitative prediction of molecular fluorescence quantum efficiency: Role of Duschinsky rotation
复制标题
分子荧光量子效率的定量预测：杜钦斯基旋转的作用
DOI：
10.1021/ja067946e
复制
发表时间：
2007-08-01
影响因子：
15
通讯作者：
Shao, Jiushu
中科院分区：
文献类型：
--
作者：
Peng, Qian;Yi, Yuanping;Shao, Jiushu
从第一性原理出发预测分子的荧光量子效率是一个非常迫切而又困难的任务。处于激发态的分子可以经历自发辐射、电子能量到核运动的转换或化学反应。对于相对较大的分子，不可能获得基态和激发态的全部势能面来研究激发态动力学。我们表明，在谐波近似下，通过考虑Duschinsky旋转效应，分子的荧光性质可以定量计算从第一原理加上我们的相关函数形式主义的内部转换。特别地，我们解释了顺，顺-1，2，3，4-四苯基-1，3-丁二烯和1，1，4，4-四苯基-丁二烯这两种同分异构体的特殊荧光行为，前者在溶液中不发光，而在聚集态或低温下强发光，后者在溶液中强发光。研究发现，低频苯基环扭曲运动及其杜辛斯基模式混合的作用至关重要，特别是在揭示温度依赖性方面。作为一个独立的检查，我们来看看1，4-二苯基丁二烯的三种不同构象的成熟的电子物理学。计算的辐射和非辐射率与现有的实验测量结果非常吻合。
It is a highly desirable but difficult task to predict the molecular fluorescence quantum efficiency from first principles. The molecule in the excited state can undergo spontaneous radiation, conversion of electronic energy to nuclear motion, or chemical reaction. For relatively large molecules, it is impossible to obtain the full potential energy surfaces for the ground state and the excited states to study the excited-state dynamics. We show that, under harmonic approximation by considering the Duschinsky rotation effect, the molecular fluorescence properties can be quantitatively calculated from first principles coupled with our correlation function formalism for the internal conversion. In particular, we have explained the peculiar fluorescence behaviors of two isomeric compounds, cis,cis-1,2,3,4-tetraphenyl-1,3-butadiene and 1,1,4,4-tetraphenyl-butadiene, the former being nonemissive in solution and strongly emissive in aggregation or at low temperature, and the latter being strongly emissive in solution. The roles of low-frequency phenyl ring twist motions and their Duschinsky mode mixings are found to be crucial, especially to reveal the temperature dependence. As an independent check, we take a look at the well-established photophysics of 1,4-diphenylbutadiene for its three different conformers. Both the calculated radiative and nonradiative rates are in excellent agreement with the available experimental measurements.