Theoretical studies toward understanding the excited state dynamics of a bichromophoric molecule

摘要

By means of the time-dependent density functional theory, the authors study the torsional dynamics of the lowest singlet electronic excited state (S-1) of a bichromophoric molecule, 2-(9-anthryl)-1H-imidazo [4,5-f]-phenanthroline (AIP). The intramolecular dynamical relaxation process, the S-1 potential energy surface, and the vibrationally resolved electronic absorption and fluorescence spectra are estimated. The results reveal that the strong electron-nuclear coupling leads to a dynamic structural distortion in S-1 state so that the mirror-image symmetry of absorption and fluorescence spectra of AIP breaks down. The torsional motion between the donor and acceptor moieties in AIP favors the intramolecular electronic energy transfer process. The transfer rate is dominated by the relaxation time along S-1 low-frequency torsional motion. (c) 2007 American Institute of Physics.