title: An ab initio study of the absorption spectra of indirubin, isoindigo, and related derivatives.
abstract: The UV/visible spectra of a series of indirubin, isoindigo, and other indigo/thioindigo related dyes have been evaluated in various solvent environments by using the time-dependent density functional theory in conjunction with the polarizable continuum model. Even for molecules of the same family, significant differences in the excitation processes have been noted. Two hybrid functionals have been selected: B3LYP and PBE0. For a set of the 50 selected molecular cases, both functionals provide accurate lambda(max), with mean absolute deviations limited to 0.1 eV. Actually, isoindigo is the main challenging series, with systematically underestimated excitation energies, due to the different nature of the excitation process. In most cases, we found that PBE0 is more efficient in reproducing the experimental values than B3LYP for sulfur-containing dyes not featuring internal hydrogen bonds, the reverse assertion being also true. In addition, the spectra of a series of unknown dyes have been predicted.
authors.affiliation: Laboratoire de Chimie Théorique Appliquée, Facultés Universitaires Notre-Dame de la Paix, Namur, Belgium.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Perpète
authors.forename: Julien
authors.initials: J
authors.lastname: Preat
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: André
authors.forename: Denis
authors.initials: D
authors.lastname: Jacquemin
mesh_terms: D003198:Computer Simulation; D007211:Indoles / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D011789:Quantum Theory; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
chemical_list: D007211:Indoles; C049010:isoindigotin; C027185:indirubin