Beyond Exciton Theory: A Time-Dependent DFT and Franck-Condon Study of Perylene Diimide and Its Chromophoric Dimer
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- 作者：Aurora E. Clark ; Changyong Qin ; Alexander D. Q. Li
- 刊名：Journal of the American Chemical Society
- 出版年：2007
- 出版时间：June 20, 2007
- 年：2007
- 卷：129
- 期：24
- 页码：7586 - 7595
- 全文大小：355K
- 年卷期：v.129,no.24(June 20, 2007)
- ISSN：1520-5126
文摘
The diimide perylene motif exhibits a dramatic intensity reversal between the 0 
0 and 0 1vibronic bands upon 
- stacking; this distinct spectral property has previously been used to measurefolding dynamics in covalently bound oligomers and synthetic biological hybrid foldamers. It is also usedas a tool to assess organization of the -stacking, indicating the presence of H- or J-aggregation. Thezeroth-order exciton model, often used to describe the optical properties of chromophoric aggregates, issolely a transition dipole coupling scheme, which ignores the explicit electronic structure of the system aswell as vibrational coupling to the electronic transition. We have therefore examined the optical propertiesof gas-phase perylene tetracarboxylic diimide (PTCDI) and its chromophoric dimer as a function ofconformation to relate the excited-state distributions predicted by exciton theory with that of time-dependentdensity functional theory (TDDFT). Using ground- and excited-state geometries, the Franck-Condon (FC)factors for the lowest energy molecular nature electronic transition have been calculated and the origin ofthe intensity reversal of 0 0 and 0 1 vibronic bands has been proposed.
0 and 0 1vibronic bands upon - stacking; this distinct spectral property has previously been used to measurefolding dynamics in covalently bound oligomers and synthetic biological hybrid foldamers. It is also usedas a tool to assess organization of the -stacking, indicating the presence of H- or J-aggregation. Thezeroth-order exciton model, often used to describe the optical properties of chromophoric aggregates, issolely a transition dipole coupling scheme, which ignores the explicit electronic structure of the system aswell as vibrational coupling to the electronic transition. We have therefore examined the optical propertiesof gas-phase perylene tetracarboxylic diimide (PTCDI) and its chromophoric dimer as a function ofconformation to relate the excited-state distributions predicted by exciton theory with that of time-dependentdensity functional theory (TDDFT). Using ground- and excited-state geometries, the Franck-Condon (FC)factors for the lowest energy molecular nature electronic transition have been calculated and the origin ofthe intensity reversal of 0 0 and 0 1 vibronic bands has been proposed.