Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
27152 | Journal of Photochemistry and Photobiology A: Chemistry | 2010 | 12 Pages |
The electronic structure of the lowest excited singlet states and molecular geometries of a series of dialkylaminopyridines (DAAPs) representing electron donor–acceptor systems were studied by photostationary and time-resolved UV–vis spectroscopic methods and quantum chemical calculations. The comparative studies allow us to rationalize dual luminescence of 4-DAAPs in terms of the TICT state model—the analysis of the electronic transition dipole moments indicates a nearly orthogonal conformation of the fluorescent ICT states. Introduction of the amino group at meta position as in 3-diisopropylaminopyridine completely changes photophysics of these pyridine derivatives: (i) the Franck-Condon excited state initially reached upon excitation and the solvent equilibrated fluorescent state are most probably of the same nature (both excited states do not correspond to a full separation of charges) and (ii) the electronic structure and geometry of the fluorescent CT states of m-DIAP are solvent dependent.