Grozema Ferdinand C, Swart Marcel, Zijlstra Robert W J, Piet Jacob J, Siebbeles Laurens D A, van Duijnen Piet Th
DelftChemTech, Section Opto-Electronic Materials, Delft University of Technology, Mekelweg 15, 2629 JB Delft, The Netherlands.
J Am Chem Soc. 2005 Aug 10;127(31):11019-28. doi: 10.1021/ja051729g.
In this paper the role of the solvent in the formation of the charge-separated excited state of 9,9'-bianthryl (BA) is examined by means of mixed molecular mechanical/quantum mechanical (QM/MM) calculations. It is shown that in weakly polar solvents a relaxed excited state is formed with an interunit angle that is significantly smaller than 90 degrees . This relaxed excited state has a considerable dipole moment even in weakly polar solvents; for benzene and dioxane dipole moments of ca. 6 D were calculated, which is close to experimental data. These dipoles are induced by the solvent in the highly polarizable relaxed excited state of BA, and the dipole relaxation time is governed by solvent reorganizations. In polar solvent the charge separation is driven to completion by the stronger dipoles in the solvent and a fully charged separated excited state is formed with an interunit angle of 90 degrees.
在本文中，通过混合分子力学/量子力学（QM/MM）计算研究了溶剂在9,9'-联蒽（BA）电荷分离激发态形成中的作用。结果表明，在弱极性溶剂中形成了一种弛豫激发态，其单元间角度明显小于90度。即使在弱极性溶剂中，这种弛豫激发态也具有相当大的偶极矩；对于苯和二氧六环，计算出的偶极矩约为6 D，这与实验数据相近。这些偶极是由溶剂在BA的高极化弛豫激发态中诱导产生的，偶极弛豫时间由溶剂重排控制。在极性溶剂中，电荷分离由溶剂中较强的偶极驱动至完全完成，并形成单元间角度为90度的完全电荷分离激发态。
