title: Time-dependent density functional theory investigation of the absorption, fluorescence, and phosphorescence spectra of solvated coumarins.
abstract: Using time-dependent density functional theory (TD-DFT) and the polarizable continuum model, we have computed the electronic transitions of a large panel of coumarin dyes in their enol, keto, cationic, and anionic forms. Several processes have been studied: absorption, fluorescence, 0-0 phosphorescence, and triplet-triplet excitations. For each process, detailed comparison with experimental data has been carried out. Using the PBE06-31+G(d) scheme, it turns out that for a given electronic transition the experimental shifts resulting from the substitution of the coumarin core are nicely reproduced. Indeed, once a simple statistical correction is applied, the mean absolute errors on the absorption and fluorescence wavelengths are limited to 8 nm (0.09 eV) and 9 nm (0.07 eV), respectively. A valuable correlation between the experimental and theoretical phosphorescence auxochromic displacements has also been unravelled. The differences between the wavelengths of the various electronic processes of a given dye tend to be fairly predicted, especially for the fluorescence-phosphoresence shifts that are strongly overestimated by TD-DFT.
authors.affiliation: Laboratoire de Chimie Théorique Appliquée, Facultés Universitaires Notre-Dame de la Paix, rue de Bruxelles, 61, B-5000 Namur, Belgium. denis.jacquemin@fundp.ac.be
authors.forename: Denis
authors.initials: D
authors.lastname: Jacquemin
authors.forename: Eric A
authors.initials: EA
authors.lastname: Perpète
authors.forename: Giovanni
authors.initials: G
authors.lastname: Scalmani
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Frisch
authors.forename: Xavier
authors.initials: X
authors.lastname: Assfeld
authors.forename: Ilaria
authors.initials: I
authors.lastname: Ciofini
authors.forename: Carlo
authors.initials: C
authors.lastname: Adamo