Excitation spectra of nitro-diphenylaniline: accurate time-dependent density functional theory predictions for charge-transfer dyes.
Using time-dependent density functional theory (TD-DFT) and the polarizable continuum model (PCM), we have computed the absorption spectra of nitro-diphenylamine dyes. It turns out that the 6-311+G(2d,p) and 6-311G(d,p) basis sets provide, respectively, almost perfectly converged excitation spectra and geometries. Using the PBE0 hybrid functional, we obtain a valuable correlation between PCM-TD-DFT and experimental lambdamax with mean signed/absolute deviations of -4 nm (0.03 eV)8 nm (0.06 eV) and relatively small extreme discrepancies, although the excitations responsible for the color of this class of dyes present a charge-transfer character. The changes in the electron density upon absorption are analyzed through an orbital picture. In addition, a relationship between the light fastness and a well-identified vibrational frequency is proposed.
Jacquemin
Denis
D
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
Bouhy
Michaël
M
Perpète
Eric A
EA