QM/MM Study of the Role of the Solvent in the Formation of the Charge Separated Excited State in 9,9'-Bianthryl
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- 作者：Ferdinand C. Grozema ; Marcel Swart ; Robert W. J. Zijlstra ; Jacob J. Piet ; Laurens D. A. Siebbeles ; and Piet Th. van Duijnen
- 刊名：Journal of the American Chemical Society
- 出版年：2005
- 出版时间：August 10, 2005
- 年：2005
- 卷：127
- 期：31
- 页码：11019 - 11028
- 全文大小：166K
- 年卷期：v.127,no.31(August 10, 2005)
- ISSN：1520-5126
文摘
In this paper the role of the solvent in the formation of the charge-separated excited state of9,9'-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 interunitangle that is significantly smaller than 90
. This relaxed excited state has a considerable dipole momenteven in weakly polar solvents; for benzene and dioxane dipole moments of ca. 6 D were calculated, whichis close to experimental data. These dipoles are induced by the solvent in the highly polarizable relaxedexcited state of BA, and the dipole relaxation time is governed by solvent reorganizations. In polar solventthe charge separation is driven to completion by the stronger dipoles in the solvent and a fully chargedseparated excited state is formed with an interunit angle of 90.
. This relaxed excited state has a considerable dipole momenteven in weakly polar solvents; for benzene and dioxane dipole moments of ca. 6 D were calculated, whichis close to experimental data. These dipoles are induced by the solvent in the highly polarizable relaxedexcited state of BA, and the dipole relaxation time is governed by solvent reorganizations. In polar solventthe charge separation is driven to completion by the stronger dipoles in the solvent and a fully chargedseparated excited state is formed with an interunit angle of 90.