光誘導陰離子遷移機制的深入研究

Abstract

我們對一系列磷酸鹽（化合物1[OTF]-7[OTF]）在甲苯中的光誘導陰離子遷移進行了全面的動力學研究。我們的目的是探討陰離子遷移是否存在障礙，即是否是擴散控制的過程。在1-7發生激發態分子內電荷轉移後，陽離子的電荷重新分佈觸發了陰離子的遷移，從而在實驗上觀察到發射光的時間演變。因此，我們通過引入光譜響應函數來描述光誘導陰離子的遷移。結果表明，陰離子遷移不存在障礙，遵循Stokes-Einstein關係，其動力學可以用有方向性的布朗運動來描述。最後不同鹽類間遷移速度的差異得到了限制靜電勢（RESP）計算結果的支持，指出離子遷移的過程與陽離子骨架的電荷分布息息相關。

We perform comprehensive dynamics study on the photoinduced anion migration of a series of phosphonium salts (compounds 1-7) in toluene. Our aim is to probe if the anion migration is associated with a barrier or barrier free, i.e. a diffusion-controlled process. After the occurrence of excited-state intramolecular charge transfer (ESICT) in 1-7, the charge redistribution of the cation triggers the translocation of the counter anion, resulting in emission temporal evolution experimentally. The results are supportive by computational calculations using restrained electrostatic potential (RESP) analyses. As a result, we describe the photoinduced anion migration by introducing spectral response function , a concept adopted form the solvent diffusional relaxation. The results indicate that the anion migration lacks barrier, which follows a Stokes-Einstein relationship where the dynamics can be described by a biased Brownian motion, allowing us to quantify of the anion translocation rate.